Butrus Khuri-Yakub

All Publications

• Acoustic radiation force for analyzing the mechanical stress in ultrasound neuromodulation. Physics in medicine and biology Kim, Y. H., Lee, C. H., Firouzi, K., Park, B. H., Pyun, J. Y., Kim, J. N., Park, K. K., Khuri-Yakub, B. T. 2023; 68 (13)

  Abstract

  Objective. Although recent studies have shown that mechanical stress plays an important role in ultrasound neuromodulation, the magnitude and distribution of the mechanical stress generated in tissues by focused ultrasound transducers have not been adequately examined. Various acoustic radiation force (ARF) equations used in previous studies have been evaluated based on the tissue displacement results and are suitable for estimating the displacement. However, it is unclear whether mechanical stress can be accurately determined. This study evaluates the mechanical stress predicted by various AFR equations and suggests the optimal equation for estimating the mechanical stress in the brain tissue.Approach. In this paper, brain tissue responses are compared through numerical finite element simulations by applying the three most used ARF equations-Reynolds stress force ((RSF)), momentum flux density tensor force, and attenuation force. Three ARF fields obtained from the same pressure field were applied to the linear elastic model to calculate the displacement, mechanical stress, and mean pressure generated inside the tissue. Both the simple pressure field using a single transducer and the complex standing wave pressure field using two transducers were simulated.Main results. For the case using a single transducer, all three ARFs showed similar displacement. However, when comparing the mechanical stress results, only the results using the RSF showed a strong stress tensor at the focal point. For the case of using two transducers, the displacement and stress tensor field of the pattern related to the standing wave were calculated only from the results using the RSF.Significance. The model using RSF equation allows accurate analysis on stress tensor inside the tissue for ultrasound neuromodulation.

  View details for DOI 10.1088/1361-6560/acdbb5

  View details for PubMedID 37366067

• Combining Acoustic Bioprinting with AI-Assisted Raman Spectroscopy for High-Throughput Identification of Bacteria in Blood. Nano letters Safir, F., Vu, N., Tadesse, L. F., Firouzi, K., Banaei, N., Jeffrey, S. S., Saleh, A. A., Khuri-Yakub, B. P., Dionne, J. A. 2023

  Abstract

  Identifying pathogens in complex samples such as blood, urine, and wastewater is critical to detect infection and inform optimal treatment. Surface-enhanced Raman spectroscopy (SERS) and machine learning (ML) can distinguish among multiple pathogen species, but processing complex fluid samples to sensitively and specifically detect pathogens remains an outstanding challenge. Here, we develop an acoustic bioprinter to digitize samples into millions of droplets, each containing just a few cells, which are identified with SERS and ML. We demonstrate rapid printing of 2 pL droplets from solutions containing S. epidermidis, E. coli, and blood; when they are mixed with gold nanorods (GNRs), SERS enhancements of up to 1500× are achieved.We then train a ML model and achieve ≥99% classification accuracy from cellularly pure samples and ≥87% accuracy from cellularly mixed samples. We also obtain ≥90% accuracy from droplets with pathogen:blood cell ratios <1. Our combined bioprinting and SERS platform could accelerate rapid, sensitive pathogen detection in clinical, environmental, and industrial settings.

  View details for DOI 10.1021/acs.nanolett.2c03015

  View details for PubMedID 36856600

• A tool for monitoring cell type-specific focused ultrasound neuromodulation and control of chronic epilepsy. Proceedings of the National Academy of Sciences of the United States of America Murphy, K. R., Farrell, J. S., Gomez, J. L., Stedman, Q. G., Li, N., Leung, S. A., Good, C. H., Qiu, Z., Firouzi, K., Butts Pauly, K., Khuri-Yakub, B. P., Michaelides, M., Soltesz, I., de Lecea, L. 2022; 119 (46): e2206828119

  Abstract

  Focused ultrasound (FUS) is a powerful tool for noninvasive modulation of deep brain activity with promising therapeutic potential for refractory epilepsy; however, tools for examining FUS effects on specific cell types within the deep brain do not yet exist. Consequently, how cell types within heterogeneous networks can be modulated and whether parameters can be identified to bias these networks in the context of complex behaviors remains unknown. To address this, we developed a fiber Photometry Coupled focused Ultrasound System (PhoCUS) for simultaneously monitoring FUS effects on neural activity of subcortical genetically targeted cell types in freely behaving animals. We identified a parameter set that selectively increases activity of parvalbumin interneurons while suppressing excitatory neurons in the hippocampus. A net inhibitory effect localized to the hippocampus was further confirmed through whole brain metabolic imaging. Finally, these inhibitory selective parameters achieved significant spike suppression in the kainate model of chronic temporal lobe epilepsy, opening the door for future noninvasive therapies.

  View details for DOI 10.1073/pnas.2206828119

  View details for PubMedID 36343238

• Multilayer Masking Technology for Fabricating Airborne CMUTs With Multi-Depth Fluidic Trenches JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Ma, B., Firouzi, K., Khuri-Yakub, B. T. 2022

  View details for DOI 10.1109/JMEMS.2022.3152943

  View details for Web of Science ID 000767802200001

• Applications of Capacitive Micromachined Ultrasonic Transducers: A Comprehensive Review IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Joseph, J., Ma, B., Khuri-Yakub, B. T. 2022; 69 (2): 456-467

  Abstract

  Capacitive micromachined ultrasonic transducer (CMUT) was introduced as an alternative to the piezoelectric thick-film-based transducers in medical imaging applications. Gradually, CMUTs have been investigated in almost all the applications in acoustics due to their superior transduction properties. CMOS compatible process flow and limitless possibilities of miniaturization made CMUT a preferred choice for the ultrasound industry. This article comprehensively reviews all the applications in which CMUT was used until now. Such a complete review of the practical applications of CMUT has not been reported elsewhere. A topicwise presentation approach is adopted, and wherever possible, the necessary details of the device properties and experimental niceties were briefly covered.

  View details for DOI 10.1109/TUFFC.2021.3112917

  View details for Web of Science ID 000748372800004

  View details for PubMedID 34520356

• Giant Pressure Output Efficiency of Capacitive Micromachined Ultrasonic Transducers Using Nano-Silicon-Springs Kim, H., Kang, D., Shim, S., Seo, J., Khuri-Yakub, B. T., Lee, B., IEEE IEEE. 2022

  View details for DOI 10.1109/IUS54386.2022.9958066

  View details for Web of Science ID 000896080400302

• Comparison of Waveform Modulation Methods Used in Pattern Interference Radiation Force Neuromodulator Kim, Y., Kim, J., Park, K., Firouzi, K., Khuri-Yakub, B. T., IEEE IEEE. 2022

  View details for DOI 10.1109/IUS54386.2022.9957675

  View details for Web of Science ID 000896080400183

• Spike frequency-dependent inhibition and excitation of neural activity by high-frequency ultrasound. The Journal of general physiology Prieto, M. L., Firouzi, K., Khuri-Yakub, B. T., Madison, D. V., Maduke, M. 2020; 152 (11)

  Abstract

  Ultrasound can modulate action potential firing in vivo and in vitro, but the mechanistic basis of this phenomenon is not well understood. To address this problem, we used patch-clamp recording to quantify the effects of focused, high-frequency (43 MHz) ultrasound on evoked action potential firing in CA1 pyramidal neurons in acute rodent hippocampal brain slices. We find that ultrasound can either inhibit or potentiate firing in a spike frequency-dependent manner: at low (near-threshold) input currents and low firing frequencies, ultrasound inhibits firing, while at higher input currents and higher firing frequencies, ultrasound potentiates firing. The net result of these two competing effects is that ultrasound increases the threshold current for action potential firing, the slope of frequency-input curves, and the maximum firing frequency. In addition, ultrasound slightly hyperpolarizes the resting membrane potential, decreases action potential width, and increases the depth of the after-hyperpolarization. All of these results can be explained by the hypothesis that ultrasound activates a sustained potassium conductance. According to this hypothesis, increased outward potassium currents hyperpolarize the resting membrane potential and inhibit firing at near-threshold input currents but potentiate firing in response to higher-input currents by limiting inactivation of voltage-dependent sodium channels during the action potential. This latter effect is a consequence of faster action potential repolarization, which limits inactivation of voltage-dependent sodium channels, and deeper (more negative) after-hyperpolarization, which increases the rate of recovery from inactivation. Based on these results, we propose that ultrasound activates thermosensitive and mechanosensitive two-pore-domain potassium (K2P) channels through heating or mechanical effects of acoustic radiation force. Finite-element modeling of the effects of ultrasound on brain tissue suggests that the effects of ultrasound on firing frequency are caused by a small (<2°C) increase in temperature, with possible additional contributions from mechanical effects.

  View details for DOI 10.1085/jgp.202012672

  View details for PubMedID 33074301

• Toward rapid infectious disease diagnosis with advances in surface-enhanced Raman spectroscopy. The Journal of chemical physics Tadesse, L. F., Safir, F., Ho, C., Hasbach, X., Khuri-Yakub, B. P., Jeffrey, S. S., Saleh, A. A., Dionne, J. 2020; 152 (24): 240902

  Abstract

  In a pandemic era, rapid infectious disease diagnosis is essential. Surface-enhanced Raman spectroscopy (SERS) promises sensitive and specific diagnosis including rapid point-of-care detection and drug susceptibility testing. SERS utilizes inelastic light scattering arising from the interaction of incident photons with molecular vibrations, enhanced by orders of magnitude with resonant metallic or dielectric nanostructures. While SERS provides a spectral fingerprint of the sample, clinical translation is lagged due to challenges in consistency of spectral enhancement, complexity in spectral interpretation, insufficient specificity and sensitivity, and inefficient workflow from patient sample collection to spectral acquisition. Here, we highlight the recent, complementary advances that address these shortcomings, including (1) design of label-free SERS substrates and data processing algorithms that improve spectral signal and interpretability, essential for broad pathogen screening assays; (2) development of new capture and affinity agents, such as aptamers and polymers, critical for determining the presence or absence of particular pathogens; and (3) microfluidic and bioprinting platforms for efficient clinical sample processing. We also describe the development of low-cost, point-of-care, optical SERS hardware. Our paper focuses on SERS for viral and bacterial detection, in hopes of accelerating infectious disease diagnosis, monitoring, and vaccine development. With advances in SERS substrates, machine learning, and microfluidics and bioprinting, the specificity, sensitivity, and speed of SERS can be readily translated from laboratory bench to patient bedside, accelerating point-of-care diagnosis, personalized medicine, and precision health.

  View details for DOI 10.1063/1.5142767

  View details for PubMedID 32610995

• Wafer-scale Fabrication of Nanometer Silicon Posts for Capacitive Micromachined Ultrasonic Transducers with Substrate-Embedded Springs Kim, H., Kang, D., Kim, J., Khuri-Yakub, B. T., Lee, B., IEEE IEEE. 2020

  View details for Web of Science ID 000635688900225

• Wide Bandwidth and Low Driving Voltage Vented CMUTs for Airborne Applications. IEEE transactions on ultrasonics, ferroelectrics, and frequency control Ma, B., Firouzi, K., Brenner, K., Khuri-Yakub, B. T. 2019; 66 (11): 1777–85

  Abstract

  This paper presents a novel method to increase the bandwidth (BW) of airborne capacitive micromachined ultrasonic transducers (CMUTs). This method introduces a gaseous squeeze film as a damping mechanism, which induces a stiffening effect that lowers the pull-in voltage and improves the sensitivity. The optimal behavior of this stiffening effect versus the damping mechanism can be controlled by creating optimized fluidic trenches of various heights within the gap. The fractional BW can be controlled from 0.89% to 8.1% by adjusting the trench height while lowering the pull-in voltage to less than 54 V at the gap height of 1.0 [Formula: see text]. To achieve the largest sensitivity and lowest pull-in voltage at a given BW, we have developed a multi-parameter optimization method to adjust all combinations of design parameters. A novel multiple hard-mask process flow has been developed to enable fabrication of CMUTs with different cavity and trench heights on the same wafer. These devices provided an equivalent noise pressure level of 4.77 mu Pa/ Hz with 6.24-kHz BW for 7.6- [Formula: see text] deep fluidic trenches and 4.88 mu Pa/ Hz with 7.48-kHz BW for 14.3- [Formula: see text] deep fluidic trenches. This demonstration of the wide-BW CMUTs with high sensitivity and low pull-in voltage makes them applicable to medical and thermoacoustic imaging, nondestructive testing, and ultrasonic flow metering.

  View details for DOI 10.1109/TUFFC.2019.2928170

  View details for PubMedID 31329551

• A Microwave-Induced Thermoacoustic Imaging System With Non-Contact Ultrasound Detection IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Singhvi, A., Boyle, K. C., Fallahpour, M., Khuri-Yakub, B. T., Arbabian, A. 2019; 66 (10): 1587–99

  Abstract

  Portable and easy-to-use imaging systems are in high demand for medical, security screening, nondestructive testing, and sensing applications. We present a new microwave-induced thermoacoustic imaging system with non-contact, airborne ultrasound (US) detection. In this system, a 2.7 GHz microwave excitation causes differential heating at interfaces with dielectric contrast, and the resulting US signal via the thermoacoustic effect travels out of the sample to the detector in air at a standoff. The 65 dB interface loss due to the impedance mismatch at the air-sample boundary is overcome with high-sensitivity capacitive micromachined ultrasonic transducers with minimum detectable pressures (MDPs) as low as 278 μ Pa rms and we explore two different designs-one operating at a center frequency of 71 kHz and another at a center frequency of 910 kHz. We further demonstrate that the air-sample interface presents a tradeoff with the advantage of improved resolution, as the change in wave velocity at the interface creates a strong focusing effect alongside the attenuation, resulting in axial resolutions more than 10× smaller than that predicted by the traditional speed/bandwidth limit. A piecewise synthetic aperture radar (SAR) algorithm modified for US imaging and enhanced with signal processing techniques is used for image reconstruction, resulting in mm-scale lateral and axial image resolution. Finally, measurements are conducted to verify simulations and demonstrate successful system performance.

  View details for DOI 10.1109/TUFFC.2019.2925592

  View details for Web of Science ID 000489765500004

  View details for PubMedID 31251184

• Advances in Capacitive Micromachined Ultrasonic Transducers. Micromachines Brenner, K., Ergun, A. S., Firouzi, K., Rasmussen, M. F., Stedman, Q., Khuri-Yakub, B. P. 2019; 10 (2)

  Abstract

  Capacitive micromachined ultrasonic transducer (CMUT) technology has enjoyed rapid development in the last decade. Advancements both in fabrication and integration, coupled with improved modelling, has enabled CMUTs to make their way into mainstream ultrasound imaging systems and find commercial success. In this review paper, we touch upon recent advancements in CMUT technology at all levels of abstraction; modeling, fabrication, integration, and applications. Regarding applications, we discuss future trends for CMUTs and their impact within the broad field of biomedical imaging.

  View details for PubMedID 30813447

• Improved Interface Circuits for CMUT Chemical Sensors Stedman, Q., Fox, J. D., Khuri-Yakub, B. T., IEEE IEEE. 2019: 989–92

  View details for Web of Science ID 000510220100252

• Non-Contact Thermoacoustic Sensing and Characterization of Plant Root Traits Singhvi, A., Ma, B., Scharwies, J., Dinneny, J. R., Khuri-Yakub, B. T., Arbabian, A., IEEE IEEE. 2019: 1992–95

  View details for Web of Science ID 000510220100511

• High Sensitivity and Wide Bandwidth Airborne CMUTs with Low Driving Voltage Ma, B., Firouzi, K., Brenner, K., Khuri-Yakub, B. T., IEEE IEEE. 2019: 1201–4

  View details for Web of Science ID 000510220100306

• Compact Fast-Switching DC and Resonant RF Drivers for a Dual-Mode Imaging and HIFU 2D CMUT Array Stedman, Q., Gu, L., Pai, C., Rasmussen, M., Brenner, K., Ma, B., Ergun, A., Davila, J., Khuri-Yakub, B., IEEE IEEE. 2019: 1951–54

  View details for Web of Science ID 000510220100500

• Performance Parameters and Frequency Response of CMUTs in Transmit, Receive, and Pulse-Echo Operation Wygant, I., Khuri-Yakub, B. T., Kupnik, M., IEEE IEEE. 2019: 766–69

  View details for Web of Science ID 000510220100194

• Multiphase GaN Class-D Resonant Amplifier for High-Intensity Focused Ultrasound Gu, L., Stedman, Q., Rasmussen, M., Pai, C., Brenner, K., Ma, B., Ergun, A., Khuri-Yakub, B., Davila, J., IEEE IEEE. 2019

  View details for Web of Science ID 000493056900076

• High-Efficiency Output Pressure Performance Using Capacitive Micromachined Ultrasonic Transducers with Substrate-Embedded Springs SENSORS Lee, B., Nikoozadeh, A., Park, K., Khuri-Yakub, B. T. 2018; 18 (8)

  Abstract

  Capacitive micromachined ultrasonic transducers (CMUTs) with substrate-embedded springs offer highly efficient output pressure performance over conventional CMUTs, owing to their nonflexural parallel plate movement. The embedded silicon springs support thick Si piston plates, creating a large nonflexural average volume displacement efficiency in the operating frequency range from 1⁻3 MHz. Static and dynamic volume displacements of the nonflexural parallel plates were examined using white light interferometry and laser Doppler vibrometry. In addition, an output pressure measurement in immersion was performed using a hydrophone. The device showed a maximum transmission efficiency of 21 kPa/V, and an average volume displacement efficiency of 1.1 nm/V at 1.85 MHz with a low DC bias voltage of 55 V. The device element outperformed the lead zirconate titanate (PZT) ceramic HD3203, in the maximum transmission efficiency or the average volume displacement efficiency by 1.35 times. Furthermore, its average volume displacement efficiency reached almost 80% of the ideal state-of-the-art single-crystal relaxor ferroelectric materials PMN-0.33PT. Additionally, we confirmed that high-efficiency output pressure could be generated from the CMUT device, by quantitatively comparing the hydrophone measurement of a commercial PZT transducer.

  View details for PubMedID 30072601

• An Analytical Model for Capacitive Pressure Transducers With Circular Geometry JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Wygant, I. O., Kupnik, M., Khuri-Yakub, B. T. 2018; 27 (3): 448–56

  View details for DOI 10.1109/JMEMS.2018.2823200

  View details for Web of Science ID 000433954100011

• A Column-Row-Parallel Ultrasound Imaging Architecture for 3-D Plane-Wave Imaging and Tx Second-Order Harmonic Distortion Reduction IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Chen, K., Lee, B., Thomenius, K. E., Khuri-Yakub, B. T., Lee, H., Sodini, C. G. 2018; 65 (5): 828–43

  Abstract

  We propose a column-row-parallel imaging front-end architecture for integrated and low-power 3-D medical ultrasound imaging. The column-row-parallel architecture offers linear-scaling interconnection, acquisition, and programming time with row-by-row or column-by-column operations, while supporting volumetric imaging functionality and fault-tolerance against possible transducer element defects with per-element controls. The combination of column-parallel selection logic, row-parallel selection logic, and per-element selection logic reaches a balance between flexible imaging aperture definition and manageable imaging data/control interface to a 2-D array. A capacitive micromachined ultrasonic transducer (CMUT)-application-specific integrated circuit (ASIC) column-row-parallel prototype is fabricated and assembled with a flip-chip bonding process. It facilitates the 3-D plane-wave coherent compounding algorithm for volumetric imaging with a fast frame rate of 62.5 Hz and 46% improved lateral resolution with 10-angle compounding and a field of view volume of 2.3 mm in both azimuth and elevation, 8.5 mm in depth. At a hypothetically scaled up array size, the frame rate can still be kept at 31.2 Hz for a volume of 40 mm in both azimuth and elevation, 150 mm in depth. An interleaved checkerboard pattern with in-phase ( ) and quadrature ( ) excitations is also demonstrated for reducing CMUT second-harmonic distortion emission by up to 25 dB at the loss of 3-dB fundamental energy reduction. The method reduces nonlinear effects from both transducers and circuits and is a wide band technique that is applicable to arbitrary pulse shapes.

  View details for DOI 10.1109/TUFFC.2018.2811393

  View details for Web of Science ID 000431693800014

  View details for PubMedID 29733285

• Focused Ultrasound Activates Task Potassium Channels, Increases Membrane Capacitance, and Modulates Action Potential Waveform and Firing Properties in Hippocampal Brain Slices Prieto, M. L., Madison, D. V., Khuri-Yakub, B. T., Maduke, M. CELL PRESS. 2018: 669A

  View details for Web of Science ID 000430563300336

• Activation of Piezo1 but Not NaV1.2 Channels by Ultrasound at 43 MHz. Ultrasound in medicine & biology Prieto, M. L., Firouzi, K. n., Khuri-Yakub, B. T., Maduke, M. n. 2018

  Abstract

  Ultrasound (US) can modulate the electrical activity of the excitable tissues, but the mechanisms underlying this effect are not understood at the molecular level or in terms of the physical modality through which US exerts its effects. Here, we report an experimental system that allows for stable patch-clamp recording in the presence of US at 43 MHz, a frequency known to stimulate neural activity. We describe the effects of US on two ion channels proposed to be involved in the response of excitable cells to US: the mechanosensitive Piezo1 channel and the voltage-gated sodium channel NaV1.2. Our patch-clamp recordings, together with finite-element simulations of acoustic field parameters indicate that Piezo1 channels are activated by continuous wave US at 43 MHz and 50 or 90 W/cm2through cell membrane stress caused by acoustic streaming. NaV1.2 channels were not affected through this mechanism at these intensities, but their kinetics could be accelerated by US-induced heating.

  View details for PubMedID 29525457

• Localization of weak objects in reverberant fields using waveform inversion JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA Firouzi, K., Khuri-Yakub, B. T. 2017; 142 (2): 1088–97

  Abstract

  This paper presents an application of the Waveform inversion approach to localization of objects in reverberant fields and with limited spatial measurements. Reverberant fields in enclosures can potentially carry useful information, however, in an incoherent way. Incoherency comes from the consecutive reflections of the wave energy several times in the domain. This, along with diffraction and dispersion effects, can ultimately lead to mixing of the wave energy in a seemingly random way. However, spreading of the wave energy can lead to multiple interrogations of each point in the enclosure. Hence, any substructural changes in the enclosure can be sensed with sufficient information carried by the wave energy flow. Furthermore, the temporal information buried in the data makes it feasible to conduct only a few spatial measurements. The authors present a localization scheme that benefits from the reverberant field and can reduce the required number of spatial measurements.

  View details for PubMedID 28863571

• A k-Space Pseudospectral Method for Elastic Wave Propagation in Heterogeneous Anisotropic Media IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Firouzi, K., Khuri-Yakub, B. T. 2017; 64 (4): 749-760

  Abstract

  This paper presents the theory of the k -space method generalized to model elastic wave propagation in heterogeneous anisotropic media. The k -space methods are promising time integration techniques giving, in conjunction with collocation spectral methods, accurate and efficient numerical schemes for problems in heterogeneous media. In this paper, the k -space operator is derived in a spatially continuous form using the Fourier analysis of the displacement formalism of elastodynamics. An efficient numerical algorithm is then constructed by applying a Fourier collocation spectral method, leading to define the discrete k -space scheme. The proposed method is temporally exact for homogeneous media, unconditionally stable for heterogeneous media, and also allows larger time steps without loss of accuracy. Implementation of the method is discussed in detail. The method is validated through a set of numerical tests. The numerical results show the efficacy of the method compared with the conventional schemes.

  View details for DOI 10.1109/TUFFC.2017.2653063

  View details for Web of Science ID 000398974200011

  View details for PubMedID 28092534

• Capsule Ultrasound Device: Characterization and Testing Results Wang, J., Memon, F., Touma, G., Baltsavias, S., Jang, J., Chang, C., Rasmussen, M., Olcott, E., Jeffrey, R., Arbabian, A., Khuri-Yakub, B. T., IEEE IEEE. 2017

  View details for Web of Science ID 000416948401038

• An 8-Channel CMUT Chemical Sensor Array on a Single Chip Stedman, Q., Park, K., Khuri-Yakub, B. T., IEEE IEEE. 2017

  View details for Web of Science ID 000416948401144

• Multitouch Touchscreen using Reverberant Lamb Waves Firouzi, K., Nikoozadeh, A., Carver, T. E., Khuri-Yakub, B. T., IEEE IEEE. 2017

  View details for Web of Science ID 000416948401156

• Multi-Parameter Optimization of Vented CMUTs for Airborne Applications Ma, B., Chang, C., Oguz, H., Firouzi, K., Khuri-Yakub, B. T., IEEE IEEE. 2017

  View details for Web of Science ID 000416948400113

• A learning method for localizing objects in reverberant domains with limited measurements. journal of the Acoustical Society of America Firouzi, K., Khuri-Yakub, B. T. 2017; 141 (1): 104-?

  Abstract

  This article presents a learning (training)-based method for localizing objects in enclosures. Wave propagation in enclosures can lead to mixing of the wave energy, ultimately leading to incoherent spreading of information. This makes the localization problem challenging. However, spreading of the wave energy can lead to multiple interrogations of each point in the enclosure, which is in essence reminiscent of an ergodic or a closely ergodic behavior. Hence, any substructural changes in the enclosure can be sensed with sufficient information carried by the wave energy flow. Furthermore, temporal information buried in data makes it feasible to conduct only a few spatial measurements. A localization scheme is presented that benefits from the reverberant field and can reduce the required number of spatial measurements.

  View details for DOI 10.1121/1.4973807

  View details for PubMedID 28147585

• Integration of a Dual-Mode Catheter for Ultrasound Image Guidance and HIFU Ablation using a 2-D CMUT Array Jang, J., Chang, C., Rasmussen, M., Moini, A., Brenner, K., Stephens, D. N., Oralkan, O., Khuri-Yakub, B., IEEE IEEE. 2017

  View details for Web of Science ID 000416948400044

• Efficient Transcranial Ultrasound Delivery via Excitation of Lamb Waves: Concept and Preliminary Results Firouzi, K., Ghanouni, P., Khuri-Yakub, B. T., IEEE IEEE. 2017

  View details for Web of Science ID 000416948402016

• Ex Vivo HIFU Experiments Using a 32 x 32-Element CMUT Array IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Yoon, H., Chang, C., Jang, J. H., Bhuyan, A., Choe, J. W., Nikoozadeh, A., Watkins, R. D., Stephens, D. N., Pauly, K. B., Khuri-Yakub, B. T. 2016; 63 (12): 2150-2158

  Abstract

  High-intensity focused ultrasound (HIFU) has been used as noninvasive treatment for various diseases. For these therapeutic applications, capacitive micromachined ultrasonic transducers (CMUTs) have advantages that make them potentially preferred transducers over traditional piezoelectric transducers. In this paper, we present the design and the fabrication process of an 8 ×8 -mm (2) 32 ×32 -element 2-D CMUT array for HIFU applications. To reduce the system complexity for addressing the 1024 transducer elements, we propose to group the CMUT array elements into eight HIFU channels based on the phase delay from the CMUT element to the targeted focal point. Designed to focus at an 8-mm depth with a 5-MHz exciting frequency, this grouping scheme was realized using a custom application-specific integrated circuit. With a 40-V dc bias and a 60-V peak-to-peak ac excitation, the surface pressure was measured 1.2 MPa peak-to-peak and stayed stable for a long enough time to create a lesion. With this dc and ac voltage combination, the measured peak-to-peak output pressure at the focus was 8.5 MPa, which is expected to generate a lesion in a minute according to the temperature simulation. The following ex vivo tissue experiments successfully demonstrated its capability to make lesions in both bovine muscle and liver tissue.

  View details for DOI 10.1109/TUFFC.2016.2606126

  View details for Web of Science ID 000391550200014

  View details for PubMedCentralID PMC5241055

• Ex Vivo HIFU Experiments Using a $32 \times 32$ -Element CMUT Array. IEEE transactions on ultrasonics, ferroelectrics, and frequency control Yoon, H., Chang, C., Jang, J. H., Bhuyan, A., Choe, J. W., Nikoozadeh, A., Watkins, R. D., Stephens, D. N., Butts Pauly, K., Khuri-Yakub, B. T. 2016; 63 (12): 2150-2158

  Abstract

  High-intensity focused ultrasound (HIFU) has been used as noninvasive treatment for various diseases. For these therapeutic applications, capacitive micromachined ultrasonic transducers (CMUTs) have advantages that make them potentially preferred transducers over traditional piezoelectric transducers. In this paper, we present the design and the fabrication process of an 8 ×8 -mm (2) 32 ×32 -element 2-D CMUT array for HIFU applications. To reduce the system complexity for addressing the 1024 transducer elements, we propose to group the CMUT array elements into eight HIFU channels based on the phase delay from the CMUT element to the targeted focal point. Designed to focus at an 8-mm depth with a 5-MHz exciting frequency, this grouping scheme was realized using a custom application-specific integrated circuit. With a 40-V dc bias and a 60-V peak-to-peak ac excitation, the surface pressure was measured 1.2 MPa peak-to-peak and stayed stable for a long enough time to create a lesion. With this dc and ac voltage combination, the measured peak-to-peak output pressure at the focus was 8.5 MPa, which is expected to generate a lesion in a minute according to the temperature simulation. The following ex vivo tissue experiments successfully demonstrated its capability to make lesions in both bovine muscle and liver tissue.

  View details for PubMedID 27913330

• Lamb Wave Multitouch Ultrasonic Touchscreen IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Firouzi, K., Nikoozadeh, A., Carver, T. E., Khuri-Yakub, B. (. 2016; 63 (12): 2174-2186

  Abstract

  Touchscreen sensors are widely used in many devices such as smart phones, tablets, and laptops with diverse applications. We present the design, analysis, and implementation of an ultrasonic touchscreen system that utilizes the interaction of transient Lamb waves with objects in contact with the screen. It attempts to improve on the existing ultrasound technologies, with the potential of addressing some of the weaknesses of the dominant technologies, such as the capacitive or resistive ones. Compared with the existing ultrasonic and acoustic modalities, among other advantages, it provides the capability of detecting several simultaneous touch points and also a more robust performance. The localization algorithm, given the hardware design, can detect several touch points with a very limited number of measurements (one or two). This in turn can significantly reduce the manufacturing cost.

  View details for DOI 10.1109/TUFFC.2016.2608781

  View details for Web of Science ID 000391550200016

  View details for PubMedID 27913331

• Design of Tunable Ultrasonic Receivers for Efficient Powering of Implantable Medical Devices With Reconfigurable Power Loads IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Chang, T. C., Weber, M. J., Wang, M. L., Charthad, J., Khuri-Yakub, B. (., Arbabian, A. 2016; 63 (10): 1554-1562

  Abstract

  Miniaturized ultrasonic receivers are designed for efficient powering of implantable medical devices with reconfigurable power loads. Design parameters that affect the efficiency of these receivers under highly variable load conditions, including piezoelectric material, geometry, and operation frequency, are investigated. Measurements were performed to characterize electrical impedance and acoustic-to-electrical efficiency of ultrasonic receivers for off-resonance operation. Finally, we propose, analyze, and demonstrate adaptive matching and frequency tuning techniques using two different reconfigurable matching networks for typical implant loads from 10 [Formula: see text] to 1 mW. Both simulations and measurements show a significant increase in total implant efficiency (up to 50 percentage points) over this load power range when operating off-resonance with the proposed matching networks.

  View details for DOI 10.1109/TUFFC.2016.2606655

  View details for Web of Science ID 000385720000008

  View details for PubMedID 27623580

• <i>Ex-vivo</i> HIFU experiments using a 32×32-element CMUT array. IEEE transactions on ultrasonics, ferroelectrics, and frequency control Yoon, H., Chang, C., Jang, J. H., Bhuyan, A., Choe, J. W., Nikoozadeh, A., Watkins, R., Stephens, D., Butts Pauly, K., Khuri-Yakub, B. 2016

  Abstract

  High-intensity focused ultrasound (HIFU) has been used as noninvasive treatment for various diseases. For these therapeutic applications, capacitive micromachined ultrasonic transducers (CMUTs) have advantages that make them potentially preferred transducers over traditional piezoelectric transducers. In this paper, we present the design and the fabrication process of an 8×8-mm2, 32×32-element 2-D CMUT array for HIFU applications. To reduce the system complexity for addressing the 1024 transducer elements, we propose to group the CMUT array elements into eight HIFU channels based on the phase delay from the CMUT element to the targeted focal point. Designed to focus at an 8-mm depth with a 5-MHz exciting frequency, this grouping scheme was realized using a custom application-specific integrated circuit (ASIC). With a 40-V DC bias and a 60-V peak-to-peak AC excitation, the surface pressure was measured 1.2 MPa peak-to-peak and stayed stable for a long enough time to create a lesion. With this DC and AC voltage combination, the measured peak-to-peak output pressure at the focus was 8.5 MPa, which is expected to generate a lesion in a minute according to the temperature simulation. Following ex-vivo tissue experiments successfully demonstrated its capability to make lesions in both bovine muscle and liver tissue.

  View details for DOI 10.1109/TUFFC.2016.2606126

  View details for PubMedID 28113364

• Capsule Ultrasound Device: Further Developments Memon, F., Touma, G., Wang, J., Baltsavias, S., Moini, A., Chang, C., Rasmussen, M., Nikoozadeh, A., Choe, J., Olcott, E., Jeffrey, R., Arbabian, A., Khuri-Yakub, B. T., IEEE IEEE. 2016

  View details for Web of Science ID 000387497400478

• CMUT Chip with Integrated Temperature and Pressure Sensors Stedman, Q., Park, K., Khuri-Yakub, B. T., IEEE IEEE. 2016

  View details for Web of Science ID 000387497400323

• CMUT DESIGN EQUATIONS FOR OPTIMIZING NOISE FIGURE AND SOURCE PRESSURE Wygant, I. O., Kupnik, M., Khuri-Yakub, B. T., IEEE IEEE. 2016

  View details for Web of Science ID 000387497400446

• Standoff Tracking of Medical Interventional Devices using Non-Contact Microwave Thermoacoustic Detection Alexopoulos, G., Boyle, K. C., Dolatsha, N., Nan, H., Khuri-Yakub, B. T., Arbabian, A., IEEE IEEE. 2016

  View details for Web of Science ID 000390313200204

• Noncontact thermoacoustic detection of targets embedded in dispersive media Boyle, K. C., Nan, H., Khuri-Yakub, B. T., Arbabian, A., Kamerman, G., Steinvall, O. SPIE-INT SOC OPTICAL ENGINEERING. 2016

  View details for DOI 10.1117/12.2241941

  View details for Web of Science ID 000391299100014

• Ultrasound-guided delivery of microRNA loaded nanoparticles into cancer JOURNAL OF CONTROLLED RELEASE Wang, T., Choe, J. W., Pu, K., Devulapally, R., Bachawal, S., Machtaler, S., Chowdhury, S. M., Luong, R., Tian, L., Khuri-Yakub, B., Rao, J., Paulmurugan, R., Willmann, J. K. 2015; 203: 99-108

  Abstract

  Ultrasound induced microbubble cavitation can cause enhanced permeability across natural barriers of tumors such as vessel walls or cellular membranes, allowing for enhanced therapeutic delivery into the target tissues. While enhanced delivery of small (<1nm) molecules has been shown at acoustic pressures below 1MPa both in vitro and in vivo, the delivery efficiency of larger (>100nm) therapeutic carriers into cancer remains unclear and may require a higher pressure for sufficient delivery. Enhanced delivery of larger therapeutic carriers such as FDA approved pegylated poly(lactic-co-glycolic acid) nanoparticles (PLGA-PEG-NP) has significant clinical value because these nanoparticles have been shown to protect encapsulated drugs from degradation in the blood circulation and allow for slow and prolonged release of encapsulated drugs at the target location. In this study, various acoustic parameters were investigated to facilitate the successful delivery of two nanocarriers, a fluorescent semiconducting polymer model drug nanoparticle as well as PLGA-PEG-NP into human colon cancer xenografts in mice. We first measured the cavitation dose produced by various acoustic parameters (pressure, pulse length, and pulse repetition frequency) and microbubble concentration in a tissue mimicking phantom. Next, in vivo studies were performed to evaluate the penetration depth of nanocarriers using various acoustic pressures, ranging between 1.7 and 6.9MPa. Finally, a therapeutic microRNA, miR-122, was loaded into PLGA-PEG-NP and the amount of delivered miR-122 was assessed using quantitative RT-PCR. Our results show that acoustic pressures had the strongest effect on cavitation. An increase of the pressure from 0.8 to 6.9MPa resulted in a nearly 50-fold increase in cavitation in phantom experiments. In vivo, as the pressures increased from 1.7 to 6.9MPa, the amount of nanoparticles deposited in cancer xenografts was increased from 4- to 14-fold, and the median penetration depth of extravasated nanoparticles was increased from 1.3-fold to 3-fold, compared to control conditions without ultrasound, as examined on 3D confocal microscopy. When delivering miR-122 loaded PLGA-PEG-NP using optimal acoustic settings with minimum tissue damage, miR-122 delivery into tumors with ultrasound and microbubbles was 7.9-fold higher compared to treatment without ultrasound. This study demonstrates that ultrasound induced microbubble cavitation can be a useful tool for delivery of therapeutic miR loaded nanocarriers into cancer in vivo.

  View details for DOI 10.1016/j.jconrel.2015.02.018

  View details for Web of Science ID 000351696600011

  View details for PubMedID 25687306

• Non-contact thermoacoustic detection of embedded targets using airborne-capacitive micromachined ultrasonic transducers APPLIED PHYSICS LETTERS Nan, H., Boyle, K. C., Apte, N., Aliroteh, M. S., Bhuyan, A., Nikoozadeh, A., Khuri-Yakub, B. T., Arbabian, A. 2015; 106 (8)

  View details for DOI 10.1063/1.4909508

  View details for Web of Science ID 000350546600091

• Non-Contact Thermoacoustic Imaging of Tissue with Airborne Ultrasound Detection Boyle, K. C., Nan, H., Apte, N., Unlugedik, A., Aliroteh, M. S., Bhuyan, A., Nikoozadeh, A., Khuri-Yakub, B. T., Arbabian, A., IEEE IEEE. 2015

  View details for DOI 10.1109/ULTSYM.2015.0264

  View details for Web of Science ID 000366045700441

• FABRICATION, PACKAGING, AND CATHETER ASSEMBLY OF 2D CMUT ARRAYS FOR ENDOSCOPIC ULTRASOUND AND CARDIAC IMAGING Moini, A., Nikoozadeh, A., Choe, J., Khuri-Yakub, B. T., Chang, C., Stephens, D., Smith, L., Sahn, D., ASME AMER SOC MECHANICAL ENGINEERS. 2015

  View details for Web of Science ID 000373517400042

• CMUTS IN PERMANENT CONTACT OPERATION FOR HIGH OUTPUT PRESSURE Ho, M., Hoffmann, M., Unger, A., Park, K., Kupnik, M., Khuri-Yakub, B. T., ASME AMER SOC MECHANICAL ENGINEERS. 2015

  View details for Web of Science ID 000373517400046

• CMUTS WITH VENTED CAVITIES FOR AIRBORNE APPLICATIONS Apte, N., Nikoozadeh, A., Khuri-Yakub, B. T., Park, K., Crocker, M. J., Pawelczyk, M., Pedrielli, F., Carletti, E., Luzzi, S. INT INST ACOUSTICS & VIBRATION. 2015

  View details for Web of Science ID 000398997001122

• Experimental Study of Mutual Acoustic Coupling in CMUTs with Substrate-Embedded Springs Lee, B., Nikoozadeh, A., Park, K., Khuri-Yakub, B. T., IEEE IEEE. 2015

  View details for DOI 10.1109/ULTSYM.2015.0059

  View details for Web of Science ID 000366045700442

• Capsule Ultrasound Device Memon, F., Touma, G., Wang, J., Baltsavias, S., Moini, A., Chang, C., Rasmussen, M., Nikoozadeh, A., Choe, J., Arbabian, A., Jeffrey, R., Olcott, E., Khuri-Yakub, B. T., IEEE IEEE. 2015

  View details for DOI 10.1109/ULTSYM.2015.0168

  View details for Web of Science ID 000366045700461

• Dual-Mode Integrated Circuit for Imaging and HIFU With 2-D CMUT Arrays Jang, J., Rasmussen, M., Bhuyan, A., Yoon, H., Moini, A., Chang, C., Watkins, R. D., Choe, J., Nikoozadeh, A., Stephens, D., Oralkan, O., Pauly, K., Khuri-Yakub, B., IEEE IEEE. 2015

  View details for DOI 10.1109/ULTSYM.2015.0166

  View details for Web of Science ID 000366045700087

• A Multichannel Oscillator for a Resonant Chemical Sensor System IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS Lee, H. J., Park, K. K., Oralkan, O., Kupnik, M., Khuri-Yakub, B. T. 2014; 61 (10): 5632-5640

  View details for DOI 10.1109/TIE.2014.2300031

  View details for Web of Science ID 000336208200051

• Singulation for imaging ring arrays of capacitive micromachined ultrasonic transducers. Journal of micromechanics and microengineering : structures, devices, and systems Chang, C., Moini, A., Nikoozadeh, A., Sarioglu, A. F., Apte, N., Zhuang, X., Khuri-Yakub, B. T. 2014; 24 (10)

  Abstract

  Singulation of MEMS is a critical step in the transition from wafer-level to die-level devices. As is the case for capacitive micromachined ultrasound transducer (CMUT) ring arrays, an ideal singulation must protect the fragile membranes from the processing environment while maintaining a ring array geometry. The singulation process presented in this paper involves bonding a trench-patterned CMUT wafer onto a support wafer, deep reactive ion etching (DRIE) of the trenches, separating the CMUT wafer from the support wafer and de-tethering the CMUT device from the CMUT wafer. The CMUT arrays fabricated and singulated in this process were ring-shaped arrays, with inner and outer diameters of 5 mm and 10 mm, respectively. The fabricated CMUT ring arrays demonstrate the ability of this method to successfully and safely singulate the ring arrays and is applicable to any arbitrary 2D shaped MEMS device with uspended microstructures, taking advantage of the inherent planar attributes of DRIE.

  View details for PubMedID 27076702

• Singulation for imaging ring arrays of capacitive micromachined ultrasonic transducers 13th International Conference on Micro and Nano Technology for Power Generation and Energy Conversion Applications (PowerMEMS) Chang, C., Moini, A., Nikoozadeh, A., Sarioglu, A. F., Apte, N., Zhuang, X., Khuri-Yakub, B. T. IOP PUBLISHING LTD. 2014

  View details for DOI 10.1088/0960-1317/24/10/107002

  View details for Web of Science ID 000345262700021

• Acoustic lens for capacitive micromachined ultrasonic transducers 24th MicroMechanics and Microsystems Europe Conference (MME) Chang, C., Firouzi, K., Park, K. K., Sarioglu, A. F., Nikoozadeh, A., Yoon, H., Vaithilingam, S., Carver, T., Khuri-Yakub, B. T. IOP PUBLISHING LTD. 2014

  View details for DOI 10.1088/0960-1317/24/8/085007

  View details for Web of Science ID 000343413400012

• Distinguishing Chemicals Using CMUT Chemical Sensor Array and Artificial Neural Networks Stedman, Q., Park, K., Khuri-Yakub, B. T., IEEE IEEE. 2014: 162–65

  View details for DOI 10.1109/ULTSYM.2014.0041

  View details for Web of Science ID 000352792500041

• Bandwidth and Sensitivity Optimization in CMUTs for Airborne Applications IEEE International Ultrasonics Symposium (IUS) Apte, N., Park, K. K., Nikoozadeh, A., Khuri-Yakub, B. T. IEEE. 2014: 166–169

  View details for DOI 10.1109/ULTSYM.2014.0042

  View details for Web of Science ID 000352792500042

• Numerical Modeling of Ultrasonic Touchscreen Firouzi, K., Nikoozadeh, A., Khuri-Yakub, B. T., IEEE IEEE. 2014: 753–56

  View details for DOI 10.1109/ULTSYM.2014.0186

  View details for Web of Science ID 000352792500186

• Modeling Elastic Waves in Heterogeneous Anisotropic Media using a k-Space Method Firouzi, K., Nikoozadeh, A., Khuri-Yakub, B. T., IEEE IEEE. 2014: 1356–59

  View details for DOI 10.1109/ULTSYM.2014.0335

  View details for Web of Science ID 000352792500334

• A Column-Row-Parallel Ultrasound Imaging Architecture for 3D Plane-wave Imaging and Tx 2nd-Order Harmonic Distortion (HD2) Reduction Chen, K., Lee, B., Thomenius, K., Khuri-Yakub, B. T., Lee, H., Sodini, C. G., IEEE IEEE. 2014: 317–20

  View details for DOI 10.1109/ULTSYM.2014.0078

  View details for Web of Science ID 000352792500078

• Non- Flexural Parallel Piston Movement across CMUT with Substrate-Embedded Springs Lee, B., Nikoozadeh, A., Park, K., Khuri-Yakub, B. T., IEEE IEEE. 2014: 591–94

  View details for DOI 10.1109/ULTSYM.2014.0145

  View details for Web of Science ID 000352792500145

• Integrated Circuits for Volumetric Ultrasound Imaging With 2-D CMUT Arrays IEEE International Solid-State Circuits Flagship Conference of the IEEE Solid-State-Circuits-Society (ISSCC) Bhuyan, A., Choe, J. W., Lee, B. C., Wygant, I. O., Nikoozadeh, A., Oralkan, O., Khuri-Yakub, B. T. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. 2013: 796–804

  Abstract

  Real-time volumetric ultrasound imaging systems require transmit and receive circuitry to generate ultrasound beams and process received echo signals. The complexity of building such a system is high due to requirement of the front-end electronics needing to be very close to the transducer. A large number of elements also need to be interfaced to the back-end system and image processing of a large dataset could affect the imaging volume rate. In this work, we present a 3-D imaging system using capacitive micromachined ultrasonic transducer (CMUT) technology that addresses many of the challenges in building such a system. We demonstrate two approaches in integrating the transducer and the front-end electronics. The transducer is a 5-MHz CMUT array with an 8 mm × 8 mm aperture size. The aperture consists of 1024 elements (32 × 32) with an element pitch of 250 μ m. An integrated circuit (IC) consists of a transmit beamformer and receive circuitry to improve the noise performance of the overall system. The assembly was interfaced with an FPGA and a back-end system (comprising of a data acquisition system and PC). The FPGA provided the digital I/O signals for the IC and the back-end system was used to process the received RF echo data (from the IC) and reconstruct the volume image using a phased array imaging approach. Imaging experiments were performed using wire and spring targets, a ventricle model and a human prostrate. Real-time volumetric images were captured at 5 volumes per second and are presented in this paper.

  View details for DOI 10.1109/TBCAS.2014.2298197

  View details for Web of Science ID 000330230600007

  View details for PubMedID 24473544

• Dynamic Response of Model Lipid Membranes to Ultrasonic Radiation Force PLOS ONE Prieto, M. L., Oralkan, O., Khuri-Yakub, B. T., Maduke, M. C. 2013; 8 (10)

  Abstract

  Low-intensity ultrasound can modulate action potential firing in neurons in vitro and in vivo. It has been suggested that this effect is mediated by mechanical interactions of ultrasound with neural cell membranes. We investigated whether these proposed interactions could be reproduced for further study in a synthetic lipid bilayer system. We measured the response of protein-free model membranes to low-intensity ultrasound using electrophysiology and laser Doppler vibrometry. We find that ultrasonic radiation force causes oscillation and displacement of lipid membranes, resulting in small (<1%) changes in membrane area and capacitance. Under voltage-clamp, the changes in capacitance manifest as capacitive currents with an exponentially decaying sinusoidal time course. The membrane oscillation can be modeled as a fluid dynamic response to a step change in pressure caused by ultrasonic radiation force, which disrupts the balance of forces between bilayer tension and hydrostatic pressure. We also investigated the origin of the radiation force acting on the bilayer. Part of the radiation force results from the reflection of the ultrasound from the solution/air interface above the bilayer (an effect that is specific to our experimental configuration) but part appears to reflect a direct interaction of ultrasound with the bilayer, related to either acoustic streaming or scattering of sound by the bilayer. Based on these results, we conclude that synthetic lipid bilayers can be used to study the effects of ultrasound on cell membranes and membrane proteins.

  View details for DOI 10.1371/journal.pone.0077115

  View details for Web of Science ID 000326037000042

  View details for PubMedID 24194863

  View details for PubMedCentralID PMC3806737

• 3-D airborne ultrasound synthetic aperture imaging based on capacitive micromachined ultrasonic transducers ULTRASONICS Park, K. K., Khuri-Yakub, B. T. 2013; 53 (7): 1355-1362

  Abstract

  In this paper, we present an airborne 3-D volumetric imaging system based on capacitive micromachined ultrasonic transducers (CMUTs). For this purpose we fabricated 89-kHz CMUTs where each CMUT is made of a circular single-crystal silicon plate with a radius of 1mm and a thickness of 20μm, which is actuated by electrostatic force through a 20-μm vacuum gap. The measured transmit sensitivity at 300-V DC bias is 14.6Pa/V and 24.2Pa/V, when excited by a 30-cycle burst and a continuous wave, respectively. The measured receive sensitivity at 300-V DC bias is 16.6mV/Pa (-35.6dB re 1V/Pa) for a 30-cycle burst. A 26×26 2-D array was implemented by mechanical scanning a co-located transmitter and receiver using the classic synthetic aperture (CSA) method. The measurement of a 1.6λ-size target at a distance of 500mm presented a lateral resolution of 3.17° and also showed good agreement with the theoretical point spread function. The 3-D imaging of two plates at a distance of 350mm and 400mm was constructed to exhibit the capability of the imaging system. This study experimentally demonstrates that a 2-D CMUT array can be used for practical 3-D imaging applications in air, such as a human-machine interface.

  View details for DOI 10.1016/j.ultras.2013.04.003

  View details for Web of Science ID 000320598800018

  View details for PubMedID 23622768

• New technologies in clinical ultrasound. Seminars in roentgenology Kamaya, A., Machtaler, S., Safari Sanjani, S., Nikoozadeh, A., Graham Sommer, F., Pierre Khuri-Yakub, B. T., Willmann, J. K., Desser, T. S. 2013; 48 (3): 214-223

  View details for DOI 10.1053/j.ro.2013.03.009

  View details for PubMedID 23796372

• New Technologies in Clinical Ultrasound SEMINARS IN ROENTGENOLOGY Kamaya, A., Machtaler, S., Sanjani, S. S., Nikoozadeh, A., Sommer, F. G., Khuri-Yakub, B. T., Willmann, J. K., Desser, T. S. 2013; 48 (3): 214-223

  View details for DOI 10.1053/j.ro.2013.03.009

  View details for Web of Science ID 000321602300005

• Packaging and Modular Assembly of Large-Area and Fine-Pitch 2-D Ultrasonic Transducer Arrays IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Lin, D., Wodnicki, R., Zhuang, X., Woychik, C., Thomenius, K. E., Fisher, R. A., Mills, D. M., Byun, A. J., Burdick, W., Khuri-Yakub, P., Bonitz, B., Davies, T., Thomas, G., Otto, B., Toepper, M., Fritzsch, T., Ehrmann, O. 2013; 60 (7): 1356-1375

  View details for DOI 10.1109/TUFFC.2013.2709

  View details for Web of Science ID 000321629200007

• GPU-Based Real-Time Volumetric Ultrasound Image Reconstruction for a Ring Array IEEE TRANSACTIONS ON MEDICAL IMAGING Choe, J. W., Nikoozadeh, A., Oralkan, O., Khuri-Yakub, B. T. 2013; 32 (7): 1258-1264

  Abstract

  Synthetic phased array (SPA) beamforming with Hadamard coding and aperture weighting is an optimal option for real-time volumetric imaging with a ring array, a particularly attractive geometry in intracardiac and intravascular applications. However, the imaging frame rate of this method is limited by the immense computational load required in synthetic beamforming. For fast imaging with a ring array, we developed graphics processing unit (GPU)-based, real-time image reconstruction software that exploits massive data-level parallelism in beamforming operations. The GPU-based software reconstructs and displays three cross-sectional images at 45 frames per second (fps). This frame rate is 4.5 times higher than that for our previously-developed multi-core CPU-based software. In an alternative imaging mode, it shows one B-mode image rotating about the axis and its maximum intensity projection, processed at a rate of 104 fps . This paper describes the image reconstruction procedure on the GPU platform and presents the experimental images obtained using this software.

  View details for DOI 10.1109/TMI.2013.2253117

  View details for Web of Science ID 000321220300008

  View details for PubMedID 23529080

• Photoacoustic imaging of the bladder: a pilot study. Journal of ultrasound in medicine Kamaya, A., Vaithilingam, S., Chung, B. I., Oralkan, O., Khuri-Yakub, B. T. 2013; 32 (7): 1245-1250

  Abstract

  Photoacoustic imaging is a promising new technology that combines tissue optical characteristics with ultrasound transmission and can potentially visualize tumor depth in bladder cancer. We imaged simulated tumors in 5 fresh porcine bladders with conventional pulse-echo sonography and photoacoustic imaging. Isoechoic biomaterials of different optical qualities were used. In all 5 of the bladder specimens, photoacoustic imaging showed injected biomaterials, containing varying degrees of pigment, better than control pulse-echo sonography. Photoacoustic imaging may be complementary to diagnostic information obtained by cystoscopy and urine cytologic analysis and could potentially obviate the need for biopsy in some tumors before definitive treatment.

  View details for DOI 10.7863/ultra.32.7.1245

  View details for PubMedID 23804347

• A Comparison Between Conventional and Collapse-Mode Capacitive Micromachined Ultrasonic Transducers in 10-MHz 1-D Arrays IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Park, K. K., Oralkan, O., Khuri-Yakub, B. T. 2013; 60 (6): 1245-1255

  Abstract

  This paper presents a comprehensive comparison between a collapse-mode and a conventional-mode capacitive micromachined ultrasonic transducer (CMUT); both devices have a 1-μm-thick silicon plate and operate at 10 MHz when biased at 100 V. The radii of the circular plates and the gap heights are modified to meet the design specifications required for a fair comparison. Finite element analysis (FEA) shows that the collapse-mode CMUT has higher output pressure sensitivity (46.5 kPa/V) than the conventional CMUT (13.1 kPa/V), and achieves a 3-dB fractional bandwidth (FBW) of 124% compared with 128% for the conventional mode. These results were validated by experiments performed on devices fabricated in a 1-D phased array configuration using the local oxidation of silicon (LOCOS)/wafer-bonding process. The measured output pressure sensitivity and the FBW of the collapse-mode and the conventional CMUTs at 100 V were 26.4 kPa/V and 103% and 12.7 kPa/V and 111%, respectively. The maximum output pressure of the collapse-mode CMUT was 1.19 MPa at 10 MHz, which was much higher than the conventional CMUT (0.44 MPa). However, the second harmonic distortion (SHD) level of the collapse-mode CMUT is higher than the conventional CMUT at the same excitation condition. Even with higher electric field in the cavity, the collapse-mode CMUT was as stable as the conventional CMUT in a long-term test. A 30-h test with a total of 3.2 × 10(9) cycles of 30 V ac excitation resulted in no significant degradation in the performance of the collapse-mode devices.

  View details for DOI 10.1109/TUFFC.2013.2688

  View details for Web of Science ID 000319990800021

• A comparison between conventional and collapse-mode capacitive micromachined ultrasonic transducers in 10-MHz 1-D arrays. IEEE transactions on ultrasonics, ferroelectrics, and frequency control Kwan Kyu Park, Oralkan, O., Khuri-Yakub, B. T. 2013; 60 (6): 1245-1255

  Abstract

  This paper presents a comprehensive comparison between a collapse-mode and a conventional-mode capacitive micromachined ultrasonic transducer (CMUT); both devices have a 1-μm-thick silicon plate and operate at 10 MHz when biased at 100 V. The radii of the circular plates and the gap heights are modified to meet the design specifications required for a fair comparison. Finite element analysis (FEA) shows that the collapse-mode CMUT has higher output pressure sensitivity (46.5 kPa/V) than the conventional CMUT (13.1 kPa/V), and achieves a 3-dB fractional bandwidth (FBW) of 124% compared with 128% for the conventional mode. These results were validated by experiments performed on devices fabricated in a 1-D phased array configuration using the local oxidation of silicon (LOCOS)/wafer-bonding process. The measured output pressure sensitivity and the FBW of the collapse-mode and the conventional CMUTs at 100 V were 26.4 kPa/V and 103% and 12.7 kPa/V and 111%, respectively. The maximum output pressure of the collapse-mode CMUT was 1.19 MPa at 10 MHz, which was much higher than the conventional CMUT (0.44 MPa). However, the second harmonic distortion (SHD) level of the collapse-mode CMUT is higher than the conventional CMUT at the same excitation condition. Even with higher electric field in the cavity, the collapse-mode CMUT was as stable as the conventional CMUT in a long-term test. A 30-h test with a total of 3.2 × 10(9) cycles of 30 V ac excitation resulted in no significant degradation in the performance of the collapse-mode devices.

  View details for DOI 10.1109/TUFFC.2013.2688

  View details for PubMedID 25004488

• 3-D airborne ultrasound synthetic aperture imaging based on capacitive micromachined ultrasonic transducers Ultrasonics Park, K., K., Khuri-Yakub, B., T. 2013; 53: 1355-1362
• Dynamic response of model lipid membranes to ultrasonic radiation force. PloS one Prieto, M. L., Ömer, O., Khuri-Yakub, B. T., Maduke, M. C. 2013; 8 (10)

  Abstract

  Low-intensity ultrasound can modulate action potential firing in neurons in vitro and in vivo. It has been suggested that this effect is mediated by mechanical interactions of ultrasound with neural cell membranes. We investigated whether these proposed interactions could be reproduced for further study in a synthetic lipid bilayer system. We measured the response of protein-free model membranes to low-intensity ultrasound using electrophysiology and laser Doppler vibrometry. We find that ultrasonic radiation force causes oscillation and displacement of lipid membranes, resulting in small (<1%) changes in membrane area and capacitance. Under voltage-clamp, the changes in capacitance manifest as capacitive currents with an exponentially decaying sinusoidal time course. The membrane oscillation can be modeled as a fluid dynamic response to a step change in pressure caused by ultrasonic radiation force, which disrupts the balance of forces between bilayer tension and hydrostatic pressure. We also investigated the origin of the radiation force acting on the bilayer. Part of the radiation force results from the reflection of the ultrasound from the solution/air interface above the bilayer (an effect that is specific to our experimental configuration) but part appears to reflect a direct interaction of ultrasound with the bilayer, related to either acoustic streaming or scattering of sound by the bilayer. Based on these results, we conclude that synthetic lipid bilayers can be used to study the effects of ultrasound on cell membranes and membrane proteins.

  View details for DOI 10.1371/journal.pone.0077115

  View details for PubMedID 24194863

• 3D Volumetric Ultrasound Imaging with a 32x32 CMUT Array Integrated with Front-End ICs Using Flip-Chip Bonding Technology Bhuyan, A., Choe, J., Lee, B., Wygant, I., Nikoozadeh, A., Oralkan, O., Khuri-Yakub, B. T., IEEE IEEE. 2013: 396-+

  View details for Web of Science ID 000366612300168

• A 32x32 Integrated CMUT Array for Volumetric Ultrasound Imaging IEEE International Ultrasonics Symposium (IUS) Bhuyan, A., Chang, C., Choe, J. W., Lee, B. C., Nikoozadeh, A., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2013: 541–544

  View details for DOI 10.1109/ULTSYM.2013.0141

  View details for Web of Science ID 000336665300139

• VOLUMETRIC CHARACTERIZATION OF ULTRASONIC TRANSDUCERS FOR GAS FLOW METERING IEEE International Ultrasonics Symposium (IUS) Hoffmann, M., Unger, A., Ho, M., Park, K. K., Khuri-Yakub, B. T., Kupnik, M. IEEE. 2013: 1307–1310

  View details for DOI 10.1109/ULTSYM.2013.0336

  View details for Web of Science ID 000336665300333

• Experimental evaluation of CMUTs with vented cavities under varying pressure IEEE International Ultrasonics Symposium (IUS) Apte, N., Park, K. K., Khuri-Yakub, B. T. IEEE. 2013: 1724–1727

  View details for DOI 10.1109/ULTSYM.2013.0439

  View details for Web of Science ID 000336665300438

• FINITE ELEMENT ANALYSIS OF MECHANICALLY AMPLIFIED CMUTS IEEE International Ultrasonics Symposium (IUS) Unger, A., Hoffmann, M., Ho, M., Park, K. K., Khuri-Yakub, B. T., Kupnik, M. IEEE. 2013: 287–290

  View details for DOI 10.1109/ULTSYM.2013.0074

  View details for Web of Science ID 000336665300074

• Air-coupled CMUTs operating at ambient pressures ranging from 1 to 20 atm IEEE International Ultrasonics Symposium (IUS) Ho, M., Park, K. K., Eckhoff, K., Kupnik, M., Khuri-Yakub, B. T. IEEE. 2013: 1404–1407

  View details for DOI 10.1109/ULTSYM.2013.0358

  View details for Web of Science ID 000336665300355

• Fabrication of CMUTs with Substrate-embedded Springs IEEE International Ultrasonics Symposium (IUS) Lee, B. C., Nikoozadeh, A., Park, K. K., Khuri-Yakub, B. (. IEEE. 2013: 1733–1736

  View details for DOI 10.1109/ULTSYM.2013.0442

  View details for Web of Science ID 000336665300441

• GPU-Based Real-Time Imaging Software Suite for Medical Ultrasound IEEE International Ultrasonics Symposium (IUS) Choe, J. W., Nikoozadeh, A., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2013: 2057–2060

  View details for DOI 10.1109/ULTSYM.2013.0525

  View details for Web of Science ID 000336665300524

• A Comparison Between Conventional and Collapse-Mode Capacitive Micromachined Ultrasonic Transducers in 10-MHz 1-D Arrays Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on Park, K., K., Oralkan, O., Khuri-Yakub, B., T. 2013; 60 (6): 1245-1255
• Dynamic Response of Model Lipid Membranes to Ultrasonic Radiation Force PLOS ONE Prieto, M., L., Oralkan, O., Khuri-Yakub, B., T., Maduke, M., C. 2013; 8 (10)
• Precise Neural Stimulation in the Retina Using Focused Ultrasound J. Neuroscience Menz, M., D., Oralkan, O., Khuri-Yakub, P., T., Baccus, S., A. 2013; 33 (10): 4550-4560
• Functionalization layers for CO2 sensing using capacitive micromachined ultrasonic transducers SENSORS AND ACTUATORS B-CHEMICAL Lee, H. J., Park, K. K., Kupnik, M., Khuri-Yakub, B. T. 2012; 174: 87-93

  View details for DOI 10.1016/j.snb.2012.08.025

  View details for Web of Science ID 000311329000013

• Dynamic response of an array of flexural plates in acoustic medium JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA Park, K. K., Khuri-Yakub, B. T. 2012; 132 (4): 2292-2303

  Abstract

  The dynamic response of a transducer array made up of circular flexural plates in immersion is analytically calculated. The calculation method includes three steps: (1) the calculation of parallel resonant frequency and the velocity profile of each plate, (2) the calculation of mutual acoustic impedance between the plates, and (3) the calculation of velocity response, including the mechanical and acoustic impedance. The calculation method is validated by both finite element analysis and measurement results of a fabricated capacitive micromachined ultrasonic transducer. Based on the calculated velocity, the near-field pressure and the near-to-far field radiation patterns are presented. The flexural plate array in immersion displays two modes of operation. At low frequency, the mode shape of the transducer array is similar to that of a suspended plate and, at certain frequencies, two groups of plates move in opposite phase, which results in the cancellation of the average velocity. At high frequency, the mode shape is similar to that of a piston transducer; however, the near-field pressure distribution is similar to that of a resilient disk.

  View details for DOI 10.1121/1.4747613

  View details for Web of Science ID 000309650600035

  View details for PubMedID 23039426

  View details for PubMedCentralID PMC3477185

• Family of Enhanced Photoacoustic Imaging Agents for High-Sensitivity and Multiplexing Studies in Living Mice ACS NANO de la Zerda, A., Bodapati, S., Teed, R., May, S. Y., Tabakman, S. M., Liu, Z., Khuri-Yakub, B. T., Chen, X., Dai, H., Gambhir, S. S. 2012; 6 (6): 4694-4701

  Abstract

  Photoacoustic imaging is a unique modality that overcomes to a great extent the resolution and depth limitations of optical imaging while maintaining relatively high contrast. However, since many diseases will not manifest an endogenous photoacoustic contrast, it is essential to develop exogenous photoacoustic contrast agents that can target diseased tissue(s). Here we present a family of novel photoacoustic contrast agents that are based on the binding of small optical dyes to single-walled carbon nanotubes (SWNT-dye). We synthesized five different SWNT-dye contrast agents using different optical dyes, creating five "flavors" of SWNT-dye nanoparticles. In particular, SWNTs that were coated with either QSY(21) (SWNT-QSY) or indocyanine green (SWNT-ICG) exhibited over 100-times higher photoacoustic contrast in living animals compared to plain SWNTs, leading to subnanomolar sensitivities. We then conjugated the SWNT-dye conjugates with cyclic Arg-Gly-Asp peptides to molecularly target the α(v)β(3) integrin, which is associated with tumor angiogenesis. Intravenous administration of these tumor-targeted imaging agents to tumor-bearing mice showed significantly higher photoacoustic signal in the tumor than in mice injected with the untargeted contrast agent. Finally, we were able to spectrally separate the photoacoustic signals of SWNT-QSY and SWNT-ICG in living animals injected subcutaneously with both particles in the same location, opening the possibility for multiplexing in vivo studies.

  View details for DOI 10.1021/nn204352r

  View details for Web of Science ID 000305661300017

  View details for PubMedID 22607191

  View details for PubMedCentralID PMC3397693

• Volumetric Real-Time Imaging Using a CMUT Ring Array IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Choe, J. W., Oralkan, O., Nikoozadeh, A., Gencel, M., Stephens, D. N., O'Donnell, M., Sahn, D. J., Khuri-Yakub, B. T. 2012; 59 (6): 1201-1211

  Abstract

  A ring array provides a very suitable geometry for forward-looking volumetric intracardiac and intravascular ultrasound imaging. We fabricated an annular 64-element capacitive micromachined ultrasonic transducer (CMUT) array featuring a 10-MHz operating frequency and a 1.27-mm outer radius. A custom software suite was developed to run on a PC-based imaging system for real-time imaging using this device. This paper presents simulated and experimental imaging results for the described CMUT ring array. Three different imaging methods--flash, classic phased array (CPA), and synthetic phased array (SPA)--were used in the study. For SPA imaging, two techniques to improve the image quality--Hadamard coding and aperture weighting--were also applied. The results show that SPA with Hadamard coding and aperture weighting is a good option for ring-array imaging. Compared with CPA, it achieves better image resolution and comparable signal-to-noise ratio at a much faster image acquisition rate. Using this method, a fast frame rate of up to 463 volumes per second is achievable if limited only by the ultrasound time of flight; with the described system we reconstructed three cross-sectional images in real-time at 10 frames per second, which was limited by the computation time in synthetic beamforming.

  View details for DOI 10.1109/TUFFC.2012.2310

  View details for Web of Science ID 000305760000013

  View details for PubMedID 22718870

  View details for PubMedCentralID PMC3415797

• Deep Tissue Photoacoustic Imaging Using a Miniaturized 2-D Capacitive Micromachined Ultrasonic Transducer Array IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING Kothapalli, S., Ma, T., Vaithilingam, S., Oralkan, O., Khuri-Yakub, B. T., Gambhir, S. S. 2012; 59 (5): 1199-1204

  Abstract

  In this paper, we demonstrate 3-D photoacoustic imaging (PAI) of light absorbing objects embedded as deep as 5 cm inside strong optically scattering phantoms using a miniaturized (4 mm × 4 mm × 500 μm), 2-D capacitive micromachined ultrasonic transducer (CMUT) array of 16 × 16 elements with a center frequency of 5.5 MHz. Two-dimensional tomographic images and 3-D volumetric images of the objects placed at different depths are presented. In addition, we studied the sensitivity of CMUT-based PAI to the concentration of indocyanine green dye at 5 cm depth inside the phantom. Under optimized experimental conditions, the objects at 5 cm depth can be imaged with SNR of about 35 dB and a spatial resolution of approximately 500 μm. Results demonstrate that CMUTs with integrated front-end amplifier circuits are an attractive choice for achieving relatively high depth sensitivity for PAI.

  View details for DOI 10.1109/TBME.2012.2183593

  View details for Web of Science ID 000303201000001

  View details for PubMedID 22249594

• Mesoporous Thin-Film on Highly-Sensitive Resonant Chemical Sensor for Relative Humidity and CO2 Detection ANALYTICAL CHEMISTRY Lee, H. J., Park, K. K., Kupnik, M., Melosh, N. A., Khuri-Yakub, B. T. 2012; 84 (7): 3063-3066

  Abstract

  Distributed sensing of gas-phase chemicals is a promising application for mesoporous materials when combined with highly sensitive miniaturized gas sensors. We present a direct application of a mesoporous silica thin film on a highly sensitive miniaturized resonant chemical sensor with a mass sensitivity at the zeptogram scale for relative humidity and CO(2) detection. Using mesoporous silica thin-film, we report one of the lowest volume resolutions and a sensitive detection of 5.1 × 10(-4)% RH/Hz to water vapor in N(2), which is 70 times higher than a device with a nontemplated silica layer. In addition, a mesoporous thin-film that is functionalized with an amino-group is directly applied on the resonant sensor, which exhibits a volume sensitivity of 1.6 × 10(-4)%/Hz and a volume resolution of 1.82 × 10(-4)% to CO(2) in N(2).

  View details for DOI 10.1021/ac300225c

  View details for Web of Science ID 000302829800006

  View details for PubMedID 22372606

• First In Vivo Use of a Capacitive Micromachined Ultrasound Transducer Array-Based Imaging and Ablation Catheter JOURNAL OF ULTRASOUND IN MEDICINE Stephens, D. N., Truong, U. T., Nikoozadeh, A., Oralkan, O., Seo, C. H., Cannata, J., Dentinger, A., Thomenius, K., de la Rama, A., Nguyen, T., Lin, F., Khuri-Yakub, P., Mahajan, A., Shivkumar, K., O'Donnell, M., Sahn, D. J. 2012; 31 (2): 247-256

  Abstract

  The primary objective was to test in vivo for the first time the general operation of a new multifunctional intracardiac echocardiography (ICE) catheter constructed with a microlinear capacitive micromachined ultrasound transducer (ML-CMUT) imaging array. Secondarily, we examined the compatibility of this catheter with electroanatomic mapping (EAM) guidance and also as a radiofrequency ablation (RFA) catheter. Preliminary thermal strain imaging (TSI)-derived temperature data were obtained from within the endocardium simultaneously during RFA to show the feasibility of direct ablation guidance procedures.The new 9F forward-looking ICE catheter was constructed with 3 complementary technologies: a CMUT imaging array with a custom electronic array buffer, catheter surface electrodes for EAM guidance, and a special ablation tip, that permits simultaneous TSI and RFA. In vivo imaging studies of 5 anesthetized porcine models with 5 CMUT catheters were performed.The ML-CMUT ICE catheter provided high-resolution real-time wideband 2-dimensional (2D) images at greater than 8 MHz and is capable of both RFA and EAM guidance. Although the 24-element array aperture dimension is only 1.5 mm, the imaging depth of penetration is greater than 30 mm. The specially designed ultrasound-compatible metalized plastic tip allowed simultaneous imaging during ablation and direct acquisition of TSI data for tissue ablation temperatures. Postprocessing analysis showed a first-order correlation between TSI and temperature, permitting early development temperature-time relationships at specific myocardial ablation sites.Multifunctional forward-looking ML-CMUT ICE catheters, with simultaneous intracardiac guidance, ultrasound imaging, and RFA, may offer a new means to improve interventional ablation procedures.

  View details for Web of Science ID 000299717300010

  View details for PubMedID 22298868

  View details for PubMedCentralID PMC3420825

• Ultrasound-Induced Currents in Planar Lipid Blayers: Origins and Potential Physiological Significance Prieto, M. L., Oralkan, O., Khuri-Yakub, B. T., Maduke, M. C. CELL PRESS. 2012: 34A

  View details for DOI 10.1016/j.bpj.2011.11.212

  View details for Web of Science ID 000321561200170

• Large Area 1D CMUT Phased Arrays for Multi-Modality Ultrasound Imaging IEEE International Ultrasonics Symposium (IUS) Apte, N., Vaithilingam, S., Sarioglu, A. F., Kupnik, M., Khuri-Yakub, B. T. IEEE. 2012: 612–615

  View details for DOI 10.1109/ULTSYM.2011.0148

  View details for Web of Science ID 000309918400146

• Miniaturized, Wearable, Ultrasound Probe for On-Demand Ultrasound Screening IEEE International Ultrasonics Symposium (IUS) Bhuyan, A., Choe, J. W., Lee, B. C., Cristman, P., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2012: 1060–1063

  View details for DOI 10.1109/ULTSYM.2011.0260

  View details for Web of Science ID 000309918400243

• Finite Element Analysis of CMUTs with Pressurized Cavities IEEE International Ultrasonics Symposium (IUS) Apte, N., Park, K. K., Khuri-Yakub, B. T. IEEE. 2012: 979–982

  View details for DOI 10.1109/ULTSYM.2012.0245

  View details for Web of Science ID 000326960200202

• Long-term measurement results of pre-charged CMUTs with zero external bias operation IEEE International Ultrasonics Symposium (IUS) Ho, M., Kupnik, M., Park, K. K., Khuri-Yakub, B. T. IEEE. 2012: 89–92

  View details for DOI 10.1109/ULTSYM.2012.0022

  View details for Web of Science ID 000326960200019

• Fabrication and model validation for CMUTs operated in permanent contact mode IEEE International Ultrasonics Symposium (IUS) Ho, M., Kupnik, M., Vaithilingam, S., Khuri-Yakub, B. T. IEEE. 2012: 1016–1019

  View details for DOI 10.1109/ULTSYM.2011.0249

  View details for Web of Science ID 000309918400232

• CMUTS FOR AIR COUPLED ULTRASOUND WITH IMPROVED BANDWIDTH IEEE International Ultrasonics Symposium (IUS) Kupnik, M., Ho, M., Vaithilingam, S., Khuri-Yakub, B. T. IEEE. 2012: 592–595

  View details for DOI 10.1109/ULTSYM.2011.0143

  View details for Web of Science ID 000309918400141

• Wide pressure range operation of air-coupled CMUTs IEEE International Ultrasonics Symposium (IUS) Ho, M., Kupnik, M., Park, K. K., Eckhoff, K., Khuri-Yakub, B. T. IEEE. 2012: 93–96

  View details for DOI 10.1109/ULTSYM.2012.0023

  View details for Web of Science ID 000326960200020

• Real-Time Volumetric Imaging System for CMUT Arrays IEEE International Ultrasonics Symposium (IUS) Choe, J. W., Oralkan, O., Nikoozadeh, A., Bhuyan, A., Lee, B. C., Gencel, M., Khuri-Yakub, B. T. IEEE. 2012: 1064–1067

  View details for DOI 10.1109/ULTSYM.2011.0261

  View details for Web of Science ID 000309918400244

• Understanding CMUTs with Substrate-Embedded Springs IEEE International Ultrasonics Symposium (IUS) Lee, B. C., Nikoozadeh, A., Park, K., Khuri-Yakub, B. (. IEEE. 2012: 1008–1011

  View details for DOI 10.1109/ULTSYM.2011.0247

  View details for Web of Science ID 000309918400230

• Comparison of conventional and collapse-mode CMUT in 1-D array configuration IEEE International Ultrasonics Symposium (IUS) Park, K. K., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2012: 1000–1003

  View details for DOI 10.1109/ULTSYM.2011.0245

  View details for Web of Science ID 000309918400228

• Interdigitated Annular CMUT Arrays for Ultrasound Assisted Delivery of Fluorescent Contrast Agents IEEE International Ultrasonics Symposium (IUS) Cristman, P., Oralkan, O., Mandella, M., Solgaard, O., Contag, C., Khuri-Yakub, B. T. IEEE. 2012: 96–99

  View details for Web of Science ID 000309918400024

• Nanoscale Topography of Thermally-Grown Oxide Films at Right-Angled Convex Corners of Silicon JOURNAL OF THE ELECTROCHEMICAL SOCIETY Sarioglu, A. F., Kupnik, M., Vaithilingam, S., Khuri-Yakub, B. T. 2012; 159 (2): H79-H84

  View details for DOI 10.1149/2.005202jes

  View details for Web of Science ID 000298637500072

• Chemical Vapor Detection Using a Capacitive Micromachined Ultrasonic Transducer ANALYTICAL CHEMISTRY Lee, H. J., Park, K. K., Kupnik, M., Oralkan, O., Khuri-Yakub, B. T. 2011; 83 (24): 9314-9320

  Abstract

  Distributed sensing of gas-phase chemicals using highly sensitive and inexpensive sensors is of great interest for many defense and consumer applications. In this paper we present ppb-level detection of dimethyl methylphosphonate (DMMP), a common simulant for sarin gas, with a ppt-level resolution using an improved capacitive micromachined ultrasonic transducer (CMUT) as a resonant chemical sensor. The improved CMUT operates at a higher resonant frequency of 47.7 MHz and offers an improved mass sensitivity of 48.8 zg/Hz/μm(2) by a factor of 2.7 compared to the previous CMUT sensors developed. A low-noise oscillator using the CMUT resonant sensor as the frequency-selective device was developed for real-time sensing, which exhibits an Allan deviation of 1.65 Hz (3σ) in the presence of a gas flow; this translates into a mass resolution of 80.5 zg/μm(2). The CMUT resonant sensor is functionalized with a 50-nm thick DKAP polymer developed at Sandia National Laboratory for dimethyl methylphosphonate (DMMP) detection. To demonstrate ppb-level detection of the improved chemical sensor system, the sensor performance was tested at a certified lab (MIT Lincoln Laboratory), which is equipped with an experimental chemical setup that reliably and accurately delivers a wide range of low concentrations down to 10 ppb. We report a high volume sensitivity of 34.5 ± 0.79 pptv/Hz to DMMP and a good selectivity of the polymer to DMMP with respect to dodecane and 1-octanol.

  View details for DOI 10.1021/ac201626b

  View details for Web of Science ID 000297946900020

  View details for PubMedID 22124375

• Capacitive micromachined ultrasonic transducer (CMUT) as a chemical sensor for DMMP detection SENSORS AND ACTUATORS B-CHEMICAL Park, K. K., Lee, H., Kupnik, M., Oralkan, O., Ramseyer, J., Lang, H. P., Hegner, M., Gerber, C., Khuri-Yakub, B. T. 2011; 160 (1): 1120-1127

  View details for DOI 10.1016/j.snb.2011.09.036

  View details for Web of Science ID 000298768100154

• Capacitive micromachined ultrasonic transducers for medical imaging and therapy JOURNAL OF MICROMECHANICS AND MICROENGINEERING Khuri-Yakub, B. T., Oralkan, O. 2011; 21 (5)

  Abstract

  Capacitive micromachined ultrasonic transducers (CMUTs) have been subject to extensive research for the last two decades. Although they were initially developed for air-coupled applications, today their main application space is medical imaging and therapy. This paper first presents a brief description of CMUTs, their basic structure, and operating principles. Our progression of developing several generations of fabrication processes is discussed with an emphasis on the advantages and disadvantages of each process. Monolithic and hybrid approaches for integrating CMUTs with supporting integrated circuits are surveyed. Several prototype transducer arrays with integrated frontend electronic circuits we developed and their use for 2-D and 3-D, anatomical and functional imaging, and ablative therapies are described. The presented results prove the CMUT as a MEMS technology for many medical diagnostic and therapeutic applications.

  View details for DOI 10.1088/0960-1317/21/5/054004

  View details for Web of Science ID 000289986600005

  View details for PubMedCentralID PMC3158704

• Capacitive micromachined ultrasonic transducers for medical imaging and therapy. Journal of micromechanics and microengineering : structures, devices, and systems Khuri-Yakub, B. T., Oralkan, O. 2011; 21 (5): 54004-54014

  Abstract

  Capacitive micromachined ultrasonic transducers (CMUTs) have been subject to extensive research for the last two decades. Although they were initially developed for air-coupled applications, today their main application space is medical imaging and therapy. This paper first presents a brief description of CMUTs, their basic structure, and operating principles. Our progression of developing several generations of fabrication processes is discussed with an emphasis on the advantages and disadvantages of each process. Monolithic and hybrid approaches for integrating CMUTs with supporting integrated circuits are surveyed. Several prototype transducer arrays with integrated frontend electronic circuits we developed and their use for 2-D and 3-D, anatomical and functional imaging, and ablative therapies are described. The presented results prove the CMUT as a MEMS technology for many medical diagnostic and therapeutic applications.

  View details for DOI 10.1088/0960-1317/21/5/054004

  View details for PubMedID 21860542

  View details for PubMedCentralID PMC3158704

• Fabrication of Capacitive Micromachined Ultrasonic Transducers via Local Oxidation and Direct Wafer Bonding JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Park, K. K., Lee, H., Kupnik, M., Khuri-Yakub, B. T. 2011; 20 (1): 95-103

  View details for DOI 10.1109/JMEMS.2010.2093567

  View details for Web of Science ID 000286934900015

• The Feasibility of Using Thermal Strain Imaging to Regulate Energy Delivery During Intracardiac Radio-Frequency Ablation Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on Seo, C., H., Stephens, D., N., Cannata, J., Dentinger, A., Lin, F., Park, S., Khuri-Yakub, Butrus, T. 2011; 58 (7): 1406-16
• Fabrication of CMUT Cells with Gold Center Mass for Higher Output Pressure 10th International Symposium on Therapeutic Ultrasound Yoon, H., Ho, M., Apte, N., Cristman, P., Vaithilingam, S., Kupnik, M., Butts-Pauly, K., Khuri-Yakub, B. T. AMER INST PHYSICS. 2011: 183–188

  View details for DOI 10.1063/1.3607902

  View details for Web of Science ID 000295944900028

• Encapsulation of Capacitive Micromachined Ultrasonic Transducers Using Viscoelastic Polymer JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Lin, D., Zhuang, X., Wong, S. H., Kupnik, M., Khuri-Yakub, B. T. 2010; 19 (6): 1341-1351

  Abstract

  The packaging of a medical imaging or therapeutic ultrasound transducer should provide protective insulation while maintaining high performance. For a capacitive micromachined ultrasonic transducer (CMUT), an ideal encapsulation coating would therefore require a limited and predictable change on the static operation point and the dynamic performance, while insulating the high dc and dc actuation voltages from the environment. To fulfill these requirements, viscoelastic materials, such as polydimethylsiloxane (PDMS), were investigated for an encapsulation material. In addition, PDMS, with a glass-transition temperature below room temperature, provides a low Young's modulus that preserves the static behavior; at higher frequencies for ultrasonic operation, this material becomes stiffer and acoustically matches to water. In this paper, we demonstrate the modeling and implementation of the viscoelastic polymer as the encapsulation material. We introduce a finite element model (FEM) that addresses viscoelasticity. This enables us to correctly calculate both the static operation point and the dynamic behavior of the CMUT. CMUTs designed for medical imaging and therapeutic ultrasound were fabricated and encapsulated. Static and dynamic measurements were used to verify the FEM and show excellent agreement. This paper will help in the design process for optimizing the static and the dynamic behavior of viscoelastic-polymer-coated CMUTs.

  View details for DOI 10.1109/JMEMS.2010.2076786

  View details for Web of Science ID 000284875400008

  View details for PubMedCentralID PMC3002904

• Encapsulation of Capacitive Micromachined Ultrasonic Transducers Using Viscoelastic Polymer. Journal of microelectromechanical systems : a joint IEEE and ASME publication on microstructures, microactuators, microsensors, and microsystems Lin, D. S., Zhuang, X., Wong, S. H., Kupnik, M., Khuri-Yakub, B. T. 2010; 19 (6): 1341-1351

  Abstract

  The packaging of a medical imaging or therapeutic ultrasound transducer should provide protective insulation while maintaining high performance. For a capacitive micromachined ultrasonic transducer (CMUT), an ideal encapsulation coating would therefore require a limited and predictable change on the static operation point and the dynamic performance, while insulating the high dc and dc actuation voltages from the environment. To fulfill these requirements, viscoelastic materials, such as polydimethylsiloxane (PDMS), were investigated for an encapsulation material. In addition, PDMS, with a glass-transition temperature below room temperature, provides a low Young's modulus that preserves the static behavior; at higher frequencies for ultrasonic operation, this material becomes stiffer and acoustically matches to water. In this paper, we demonstrate the modeling and implementation of the viscoelastic polymer as the encapsulation material. We introduce a finite element model (FEM) that addresses viscoelasticity. This enables us to correctly calculate both the static operation point and the dynamic behavior of the CMUT. CMUTs designed for medical imaging and therapeutic ultrasound were fabricated and encapsulated. Static and dynamic measurements were used to verify the FEM and show excellent agreement. This paper will help in the design process for optimizing the static and the dynamic behavior of viscoelastic-polymer-coated CMUTs.

  View details for DOI 10.1109/JMEMS.2010.2076786

  View details for PubMedID 21170294

  View details for PubMedCentralID PMC3002904

• 3-D Deep Penetration Photoacoustic Imaging with a 2-D CMUT Array. Proceedings. IEEE Ultrasonics Symposium Ma, T., Kothapalli, S. R., Vaithilingam, S., Oralkan, O., Kamaya, A., Wygant, I. O., Zhuang, X., Gambhir, S. S., Jeffrey, R. B., Khuri-Yakub, B. T. 2010; 2010: 375-377

  Abstract

  In this work, we demonstrate 3-D photoacoustic imaging of optically absorbing targets embedded as deep as 5 cm inside a highly scattering background medium using a 2-D capacitive micromachined ultrasonic transducer (CMUT) array with a center frequency of 5.5 MHz. 3-D volumetric images and 2-D maximum intensity projection images are presented to show the objects imaged at different depths. Due to the close proximity of the CMUT to the integrated frontend circuits, the CMUT array imaging system has a low noise floor. This makes the CMUT a promising technology for deep tissue photoacoustic imaging.

  View details for PubMedID 22977296

• FEA of CMUTs Suitable for Wide Gas Pressure Range Applications. Proceedings. IEEE Ultrasonics Symposium Ho, M., Kupnik, M., Khuri-Yakub, B. T. 2010; 2010: 1234-1237

  Abstract

  The ability of ultrasound transducers to operate over a wide and varying pressure range is essential in applications such as ultrasonic flow metering (UFM) of flare gas. We propose a new operational mode for capacitive micromachined ultrasonic transducers (CMUTs), in which the plate is in permanent contact with the bottom of the cavity, even at zero DC bias and 1 atm pressure. Finite element analysis (FEA) software was used to investigate the performance of these CMUTs within the pressure range of 1 to 20 atm. First, we performed a static analysis to determine the plate deflection and, thus, the gap height. Further, from the static analysis, we obtained the static and free capacitances for calculating the coupling efficiency, and a modal analysis identified possible design geometries for frequencies lower than ~ 300 kHz. Our calculations show that conventionally operated CMUTs have huge changes in static operational point at different pressures, while our proposed mode exhibits an acceptable frequency range (73 - 340 kHz) over 1 - 20 atm pressure and an improved coupling efficiency at lower dc bias voltages. A donut shape partial electrode further allows us to tune the coupling efficiency, which translates into a better performance, especially at the higher pressure range. FEA shows that our proposed operation mode is a promising solution for flare gas metering applications.

  View details for PubMedID 21874100

• Modeling and Measuring the Effects of Mutual Impedance on Multi-Cell CMUT Configurations. Proceedings. IEEE Ultrasonics Symposium Park, K. K., Kupnik, M., Lee, H. J., Khuri-Yakub, B. T., Wygant, I. O. 2010; 2010: 431-434

  Abstract

  This paper presents a numerical method for calculating the frequency response of a CMUT with a large number of cells. In a multi-cell configuration, commonly found in CMUTs, each cell is affected by the acoustic loading from neighboring cells. Thus, for an accurate model of a multi-cell CMUT element it is better to consider the mutual acoustic impedance instead of the acoustic impedance of a single cell only. We calculate the velocity of every cell (plate movement) simultaneously, with the mutual impedance effects taken into account. The model predicts that the cells exhibit different frequency responses, based on their locations in the element. We used a laser interferometer to validate the model by measuring the displacement response of a CMUT immersed in vegetable oil. The device has 169 circular cells (single crystal silicon plates, 500 nm thick, 21 μm radii) placed in a hexagonal cell arrangement. The measurement results agree well with the numerical results. The computation time of our method is significantly shorter than finite element based calculations. Our model can be used for finding optimized cell configurations for CMUTs utilized in various applications such as medical imaging and therapeutic treatment.

  View details for PubMedID 21822364

• CMUT Fabrication Based On A Thick Buried Oxide Layer. Proceedings. IEEE Ultrasonics Symposium Kupnik, M., Vaithilingam, S., Torashima, K., Wygant, I. O., Khuri-Yakub, B. T. 2010; 2010: 547-550

  Abstract

  We introduce a versatile fabrication process for direct wafer-bonded CMUTs. The objective is a flexible fabrication platform for single element transducers, 1D and 2D arrays, and reconfigurable arrays. The main process features are: A low number of litho masks (five for a fully populated 2D array); a simple fabrication sequence on standard MEMS tools without complicated wafer handling (carrier wafers); an improved device reliability; a wide design space in terms of operation frequency and geometric parameters (cell diameter, gap height, effective insulation layer thickness); and a continuous front face of the transducer (CMUT plate) that is connected to ground (shielding for good SNR and human safety in medical applications). All of this is achieved by connecting the hot electrodes individually through a thick buried oxide layer, i.e. from the handle layer of an SOI substrate to silicon electrodes located in each CMUT cell built in the device layer. Vertical insulation trenches are used to isolate these silicon electrodes from the rest of the substrate. Thus, the high electric field is only present where required - in the evacuated gap region of the device and not in the insulation layer of the post region. Array elements (1D and 2D) are simply defined be etching insulation trenches into the handle wafer of the SOI substrate.

  View details for PubMedID 22685377

• Design, Synthesis, and Imaging of an Activatable Photoacoustic Probe JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Levi, J., Kothapalli, S. R., Ma, T., Hartman, K., Khuri-Yakub, B. T., Gambhir, S. S. 2010; 132 (32): 11264-11269

  Abstract

  Photoacoustic tomography is a rapidly growing imaging modality that can provide images of high spatial resolution and high contrast at depths up to 5 cm. We report here the design, synthesis, and evaluation of an activatable probe that shows great promise for enabling detection of the cleaved probe in the presence of high levels of nonactivated, uncleaved probe, a difficult task to attain in absorbance-based modality. Before the cleavage by its target, proteolytic enzyme MMP-2, the probe, an activatable cell-penetrating peptide, Ceeee[Ahx]PLGLAGrrrrrK, labeled with two chromophores, BHQ3 and Alexa750, shows photoacoustic signals of similar intensity at the two wavelengths corresponding to the absorption maxima of the chromophores, 675 and 750 nm. Subtraction of the images taken at these two wavelengths makes the probe effectively photoacoustically silent, as the signals at these two wavelengths essentially cancel out. After the cleavage, the dye associated with the cell-penetrating part of the probe, BHQ3, accumulates in the cells, while the other dye diffuses away, resulting in photoacoustic signal seen at only one of the wavelengths, 675 nm. Subtraction of the photoacoustic images at two wavelengths reveals the location of the cleaved (activated) probe. In the search for the chromophores that are best suited for photoacoustic imaging, we have investigated the photoacoustic signals of five chromophores absorbing in the near-infrared region. We have found that the photoacoustic signal did not correlate with the absorbance and fluorescence of the molecules, as the highest photoacoustic signal arose from the least absorbing quenchers, BHQ3 and QXL 680.

  View details for DOI 10.1021/0104000a

  View details for Web of Science ID 000280861300058

  View details for PubMedID 20698693

  View details for PubMedCentralID PMC2922742

• Ultrahigh Sensitivity Carbon Nanotube Agents for Photoacoustic Molecular Imaging in Living Mice NANO LETTERS de la Zerda, A., Liu, Z., Bodapati, S., Teed, R., Vaithilingam, S., Khuri-Yakub, B. T., Chen, X., Dai, H., Gambhir, S. S. 2010; 10 (6): 2168-2172

  Abstract

  Photoacoustic imaging is an emerging modality that overcomes to a great extent the resolution and depth limitations of optical imaging while maintaining relatively high-contrast. However, since many diseases will not manifest an endogenous photoacoustic contrast, it is essential to develop exogenous photoacoustic contrast agents that can target diseased tissue(s). Here we present a novel photoacoustic contrast agent, Indocyanine Green dye-enhanced single walled carbon nanotube (SWNT-ICG). We conjugated this contrast agent with cyclic Arg-Gly-Asp (RGD) peptides to molecularly target the alpha(v)beta(3) integrins, which are associated with tumor angiogenesis. Intravenous administration of this tumor-targeted contrast agent to tumor-bearing mice showed significantly higher photoacoustic signal in the tumor than in mice injected with the untargeted contrast agent. The new contrast agent gave a markedly 300 times higher photoacoustic contrast in living tissues than previously reported SWNTs, leading to subnanomolar sensitivities. Finally, we show that the new contrast agent can detect approximately 20 times fewer cancer cells than previously reported SWNTs.

  View details for DOI 10.1021/nl100890d

  View details for Web of Science ID 000278449200033

  View details for PubMedID 20499887

  View details for PubMedCentralID PMC2893026

• Photoacoustic ocular imaging OPTICS LETTERS de la Zerda, A., Paulus, Y. M., Teed, R., Bodapati, S., Dollberg, Y., Khuri-Yakub, B. T., Blumenkranz, M. S., Moshfeghi, D. M., Gambhir, S. S. 2010; 35 (3): 270-272

  Abstract

  We developed a photoacoustic ocular imaging device and demonstrated its utility in imaging the deeper layers of the eye including the retina, choroid, and optic nerve. Using safe laser intensity, the photoacoustic system was able to visualize the blood distribution of an enucleated pig's eye and an eye of a living rabbit. Ultrasound images, which were simultaneously acquired, were overlaid on the photoacoustic images to visualize the eye's anatomy. Such a system may be used in the future for early detection and improved management of neovascular ocular diseases, including wet age-related macular degeneration and proliferative diabetic retinopathy.

  View details for PubMedID 20125691

• Capacitive Micromachined Ultrasonic Transducers for Therapeutic Ultrasound Applications IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING Wong, S. H., Kupnik, M., Watkins, R. D., Butts-Pauly, K., Khuri-Yakub, B. T. 2010; 57 (1): 114-123

  Abstract

  Therapeutic ultrasound guided by MRI is a noninvasive treatment that potentially reduces mortality, lowers medical costs, and widens accessibility of treatments for patients. Recent developments in the design and fabrication of capacitive micromachined ultrasonic transducers (CMUTs) have made them competitive with piezoelectric transducers for use in therapeutic ultrasound applications. In this paper, we present the first designs and prototypes of an eight-element, concentric-ring, CMUT array to treat upper abdominal cancers. This array was simulated and designed to focus 30-50 mm into tissue, and ablate a 2- to 3-cm-diameter tumor within 1 h. Assuming a surface acoustic output pressure of 1 MPa peak-to-peak (8.5 W/cm (2)) at 2.5 MHz, we simulated an array that produced a focal intensity of 680 W/cm (2) when focusing to 35 mm. CMUT cells were then designed to meet these frequency and surface acoustic intensity specifications. These cell designs were fabricated as 2.5 mm x 2.5 mm test transducers and used to verify our models. The test transducers were shown to operate at 2.5 MHz with an output pressure of 1.4 MPa peak-to-peak (16.3 W/cm (2)). With this CMUT cell design, we fabricated a full eight-element array. Due to yield issues, we only developed electronics to focus the four center elements of the array. The beam profile of the measured array deviated from the simulated one because of the crosstalk effects; the beamwidth matched within 10% and sidelobes increased by two times, which caused the measured gain to be 16.6 compared to 27.4.

  View details for DOI 10.1109/TBME.2009.2026909

  View details for Web of Science ID 000273565600018

  View details for PubMedID 19628448

• Zero-Bias Resonant Sensor with an Oxide-Nitride Layer as Charge Trap 2010 IEEE Sensors Conference Park, K. K., Kupnik, M., Lee, H. J., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2010: 1024–1028

  View details for Web of Science ID 000287982100227

• PACKAGING OF LARGE AND LOW-PITCH SIZE 2D ULTRASONIC TRANSDUCER ARRAYS 23rd IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2010) Lin, D., Zhuang, X., Wodnicki, R., Woychik, C. G., Oralkan, O., Kupnik, M., Khuri-Yakub, B. T. IEEE. 2010: 508–511

  View details for Web of Science ID 000278416400125

• Highly Sensitive Detection of DMMP Using a CMUT-based Chemical Sensor 2010 IEEE Sensors Conference Lee, H. J., Park, K. K., Kupnik, M., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2010: 2122–2126

  View details for Web of Science ID 000287982100467

• Miniaturized Ultrasound Imaging Probes Enabled by CMUT Arrays with Integrated Frontend Electronic Circuits 32nd Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBC 10) Khuri-Yakub, B. (., Oralkan, O., Nikoozadeh, A., Wygant, I. O., Zhuang, S., Gencel, M., Choe, J. W., Stephens, D. N., de la Rama, A., Chen, P., Lin, F., Dentinger, A., Wildes, D., Thomenius, K., Shivkumar, K., Mahajan, A., Seo, C. H., O'Donnell, M., Uyen Truong, U., Sahn, D. J. IEEE. 2010: 5987–5990

  Abstract

  Capacitive micromachined ultrasonic transducer (CMUT) arrays are conveniently integrated with frontend integrated circuits either monolithically or in a hybrid multichip form. This integration helps with reducing the number of active data processing channels for 2D arrays. This approach also preserves the signal integrity for arrays with small elements. Therefore CMUT arrays integrated with electronic circuits are most suitable to implement miniaturized probes required for many intravascular, intracardiac, and endoscopic applications. This paper presents examples of miniaturized CMUT probes utilizing 1D, 2D, and ring arrays with integrated electronics.

  View details for Web of Science ID 000287964006097

  View details for PubMedID 21097106

• Three-Dimensional Photoacoustic Imaging Using a Two-Dimensional CMUT Array IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Vaithilingam, S., Ma, T., Furukawa, Y., Wygant, I. O., Zhuang, X., de la Zerda, A., Oralkan, O., Kamaya, A., Gambhir, S. S., Jeffrey, R. B., Khuri-Yakub, B. T. 2009; 56 (11): 2411-2419

  Abstract

  In this paper, we describe using a 2-D array of capacitive micromachined ultrasonic transducers (CMUTs) to perform 3-D photoacoustic and acoustic imaging. A tunable optical parametric oscillator laser system that generates nanosecond laser pulses was used to induce the photoacoustic signals. To demonstrate the feasibility of the system, 2 different phantoms were imaged. The first phantom consisted of alternating black and transparent fishing lines of 180 mum and 150 mum diameter, respectively. The second phantom comprised polyethylene tubes, embedded in chicken breast tissue, filled with liquids such as the dye indocyanine green, pig blood, and a mixture of the 2. The tubes were embedded at a depth of 0.8 cm inside the tissue and were at an overall distance of 1.8 cm from the CMUT array. Two-dimensional cross-sectional slices and 3-D volume rendered images of pulse-echo data as well as photoacoustic data are presented. The profile and beamwidths of the fishing line are analyzed and compared with a numerical simulation carried out using the Field II ultrasound simulation software. We investigated using a large aperture (64 x 64 element array) to perform photoacoustic and acoustic imaging by mechanically scanning a smaller CMUT array (16 x 16 elements). Two-dimensional transducer arrays overcome many of the limitations of a mechanically scanned system and enable volumetric imaging. Advantages of CMUT technology for photoacoustic imaging include the ease of integration with electronics, ability to fabricate large, fully populated 2-D arrays with arbitrary geometries, wide-bandwidth arrays and high-frequency arrays. A CMUT based photoacoustic system is proposed as a viable alternative to a piezoelectric transducer based photoacoustic systems.

  View details for DOI 10.1109/TUFFC.2009.1329

  View details for Web of Science ID 000271478600010

  View details for PubMedID 19942528

• An Integrated Circuit With Transmit Beamforming Flip-Chip Bonded to a 2-D CMUT Array for 3-D Ultrasound Imaging IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Wygant, I. O., Jamal, N. S., Lee, H. J., Nikoozadeh, A., Oralkan, O., Karaman, M., Khuri-Yakub, B. T. 2009; 56 (10): 2145-2156

  Abstract

  State-of-the-art 3-D medical ultrasound imaging requires transmitting and receiving ultrasound using a 2-D array of ultrasound transducers with hundreds or thousands of elements. A tight combination of the transducer array with integrated circuitry eliminates bulky cables connecting the elements of the transducer array to a separate system of electronics. Furthermore, preamplifiers located close to the array can lead to improved receive sensitivity. A combined IC and transducer array can lead to a portable, high-performance, and inexpensive 3-D ultrasound imaging system. This paper presents an IC flip-chip bonded to a 16 x 16-element capacitive micromachined ultrasonic transducer (CMUT) array for 3-D ultrasound imaging. The IC includes a transmit beamformer that generates 25-V unipolar pulses with programmable focusing delays to 224 of the 256 transducer elements. One-shot circuits allow adjustment of the pulse widths for different ultrasound transducer center frequencies. For receiving reflected ultrasound signals, the IC uses the 32-elements along the array diagonals. The IC provides each receiving element with a low-noise 25-MHz-bandwidth transimpedance amplifier. Using a field-programmable gate array (FPGA) clocked at 100 MHz to operate the IC, the IC generated properly timed transmit pulses with 5-ns accuracy. With the IC flip-chip bonded to a CMUT array, we show that the IC can produce steered and focused ultrasound beams. We present 2-D and 3-D images of a wire phantom and 2-D orthogonal cross-sectional images (Bscans) of a latex heart phantom.

  View details for DOI 10.1109/TUFFC.2009.1297

  View details for Web of Science ID 000270592000011

  View details for PubMedID 19942502

• Minimally Redundant 2-D Array Designs for 3-D Medical Ultrasound Imaging IEEE TRANSACTIONS ON MEDICAL IMAGING Karaman, M., Wygant, I. O., Oralkan, O., Khuri-Yakub, B. T. 2009; 28 (7): 1051-1061

  Abstract

  In real-time ultrasonic 3-D imaging, in addition to difficulties in fabricating and interconnecting 2-D transducer arrays with hundreds of elements, there are also challenges in acquiring and processing data from a large number of ultrasound channels. The coarray (spatial convolution of the transmit and receive arrays) can be used to find efficient array designs that capture all of the spatial frequency content (a transmit-receive element combination corresponds to a spatial frequency) with a reduced number of active channels and firing events. Eliminating the redundancies in the transmit-receive element combinations and firing events reduces the overall system complexity and improves the frame rate. Here we explore four reduced redundancy 2-D array configurations for miniature 3-D ultrasonic imaging systems. Our approach is based on 1) coarray design with reduced redundancy using different subsets of linear arrays constituting the 2-D transducer array, and 2) 3-D scanning using fan-beams (narrow in one dimension and broad in the other dimension) generated by the transmit linear arrays. We form the overall array response through coherent summation of the individual responses of each transmit-receive array pairs. We present theoretical and simulated point spread functions of the array configurations along with quantitative comparison in terms of the front-end complexity and image quality.

  View details for DOI 10.1109/TMI.2008.2010936

  View details for Web of Science ID 000267698100008

  View details for PubMedID 19131299

• Next-Gen Ultrasound IEEE SPECTRUM Khuri-Yakub, B. T., Oralkan, O., Kupnik, M. 2009; 46 (5): 44-?

  View details for Web of Science ID 000267714800023

• Experimental Studies With a 9F Forward-Looking Intracardiac Imaging and Ablation Catheter JOURNAL OF ULTRASOUND IN MEDICINE Stephens, D. N., O'Donnell, M., Thomenius, K., Dentinger, A., Wildes, D., Chen, P., Shung, K. K., Cannata, J., Khuri-Yakub, P., Oralkan, O., Mahajan, A., Shivkumar, K., Sahn, D. J. 2009; 28 (2): 207-215

  Abstract

  The purpose of this study was to develop a high-resolution, near-field-optimized 14-MHz, 24-element broad-bandwidth forward-looking array for integration on a steerable 9F electrophysiology (EP) catheter.Several generations of prototype imaging catheters with bidirectional steering, termed microlinear (ML), were built and tested as integrated catheter designs with EP sensing electrodes near the tip. The wide-bandwidth ultrasound array was mounted on the very tip, equipped with an aperture of only 1.2 by 1.58 mm. The array pulse echo performance was fully simulated, and its construction offered shielding from ablation noise. Both ex vivo and in vivo imaging with a porcine animal model were performed.The array pulse echo performance was concordant with Krimholtz-Leedom-Matthaei model simulation. Three generations of prototype devices were tested in the right atrium and ventricle in 4 acute pig studies for the following characteristics: (1) image quality, (2) anatomic identification, (3) visualization of other catheter devices, and (4) for a mechanism for stabilization when imaging ablation. The ML catheter is capable of both low-artifact ablation imaging on a standard clinical imaging system and high-frame rate myocardial wall strain rate imaging for detecting changes in cardiac mechanics associated with ablation.The imaging resolution performance of this very small array device, together with its penetration beyond 2 cm, is excellent considering its very small array aperture. The forward-looking intracardiac catheter has been adapted to work easily on an existing commercial imaging platform with very minor software modifications.

  View details for Web of Science ID 000266555700007

  View details for PubMedID 19168770

  View details for PubMedCentralID PMC2752346

• 50 kHz Capacitive Micromachined Ultrasonic Transducers for Generation of Highly Directional Sound with Parametric Arrays IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Wygant, I. O., Kupnik, M., Windsor, J. C., Wright, W. M., Wochner, M. S., Yaralioglu, G. G., Hamilton, M. F., Khuri-Yakub, B. T. 2009; 56 (1): 193-203

  Abstract

  In this study, we examine the use of capacitive micromachined ultrasonic transducers (CMUTs) with vacuum- sealed cavities for transmitting directional sound with parametric arrays. We used finite element modeling to design CMUTs with 40-microm- and 60-microm-thick membranes to have resonance frequencies of 46 kHz and 54 kHz, respectively. The wafer bonding approach used to fabricate the CMUTs provides good control over device properties and the capability to fabricate CMUTs with large diameter membranes and deep cavities. Each CMUT is 8 cm in diameter and consists of 284 circular membranes. Each membrane is 4 mm in diameter. Characterization of the fabricated CMUTs shows they have center frequencies of 46 kHz and 55 kHz and 3 dB bandwidths of 1.9 kHz and 5.3 kHz for the 40-microm- and 60-microm-thick membrane devices, respectively. With dc bias voltages of 380 V and 350 V and an ac excitation of 200 V peak-to-peak, the CMUTs generate average sound pressure levels, normalized to the device's surface, of 135 dB and 129 dB (re 20 microPa), respectively. When used to generate 5 kHz sound with a parametric array, we measured sound at 3 m with a 6 dB beamwidth of 8.7 degrees and a sound pressure level of 58 dB. To understand how detector nonlinearity (e.g., the nonlinearity of the microphone used to make the sound level measurements) affects the measured sound pressure level, we made measurements with and without an acoustic low-pass filter placed in front of the microphone; the measured sound levels agree with numerical simulations of the pressure field. The results presented in this paper demonstrate that large-area CMUTs, which produce high-intensity ultrasound, can be fabricated for transmitting directional sound with parametric arrays.

  View details for DOI 10.1109/TUFFC.2009.1019

  View details for Web of Science ID 000262561600022

  View details for PubMedID 19213646

• A LOW-NOISE OSCILLATOR BASED ON A MULTI-MEMBRANE CMUT FOR HIGH SENSITIVITY RESONANT CHEMICAL SENSORS 22nd International Conference on Micro Electro Mechanical Systems (MEMS) Lee, H. J., Park, K. K., Cristman, P., Oralkan, O., Kupnik, M., Khuri-Yakub, B. T. IEEE. 2009: 761–764

  View details for Web of Science ID 000341431500190

• Enhanced Sensitivity Carbon Nanotubes as Targeted Photoacoustic Molecular Imaging Agents Conference on Photons Plus Ultrasound - Imaging and Sensing 2009 de la Zerda, A., Liu, Z., Zavaleta, C., Bodapati, S., Teed, R., Vaithilingam, S., Ma, T., Oralkan, O., Chen, X., Khuri-Yakub, B. T., Dai, H., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2009

  View details for DOI 10.1117/12.809601

  View details for Web of Science ID 000285714100080

• Progress in Development of HIFU CMUTs for use under MR-guidance 8th International Symposium on Therapeutic Ultras Wong, S. H., Watkins, R. D., Kupnik, M., Pauly, K. B., Khuri-Yakub, B. T. AMER INST PHYSICS. 2009: 327–331

  View details for Web of Science ID 000266425300063

• Photoacoustic Molecular Imaging using Single Walled Carbon Nanotubes in Living Mice Conference on Photons Plus Ultrasound - Imaging and Sensing 2009 de la Zerda, A., Zavaleta, C., Keren, S., Vaithilingam, S., Bodapati, S., Teed, R., Liu, Z., Levi, J., Smith, B. R., Ma, T., Oralkan, O., Cheng, Z., Chen, X., Dai, H., Khuri-Yakub, B. T., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2009

  View details for DOI 10.1117/12.806497

  View details for Web of Science ID 000285714100066

• A Family of Intracardiac Ultrasound Imaging Devices Designed for Guidance of Electrophysiology Ablation Procedures Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society Sahn, D. J., Stephens, D. N., Cannata, J. M., Shung, K. K., Oralkan, O., Nikoozadeh, A., Khuri-Yakub, B. T., Nguyen, H., Chen, P., Dentinger, A. M., Wildes, D., Thomenius, K. E., Mahajan, A., Shivkumar, K., O'Donnell, M. IEEE. 2009: 1913–1917

  Abstract

  Our Bioengineering Research Partnership grant, -High Frequency Ultrasound Arrays for Cardiac Imaging", including the individuals cited at the end of this paper - Douglas N. Stephens (UC Davis), Matthew O'Donnell (UW Seattle), Kai Thomenius (GE Global Research), Aaron M. Dentinger (GE Global Research), Douglas Wildes (GE Global Research), Peter Chen (St. Jude Medical), K. Kirk Shung (University of Southern California), Jonathan M. Cannata (University of Southern California), Butrus (Pierre) T. Khuri-Yakub (Stanford University), Omer Oralkan (Stanford University), Aman Mahajan (UCLA School of Medicine), Kalyanam Shivkumar (UCLA School of Medicine) and David J. Sahn (Oregon Health & Science University) - is in its sixth year of NIH funding, having proposed to develop a family of high frequency miniaturized forward and side-looking ultrasound imaging devices equipped with electrophysiology mapping and localization sensors and eventually to include a family of capactive micromachined ultrasonic transducer (cMUT) devices - a forward-looking cMUT MicroLinear array and a ring array capable of 3-dimensional imaging and a 5Fr lumen large enough to admit an electrode and ablation devices.

  View details for PubMedID 19963529

• Wafer-Bonded 2-D CMUT Arrays Incorporating Through-Wafer Trench-Isolated Interconnects with a Supporting Frame IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Zhang, X., Wygant, I. O., Lin, D., Kupnik, M., Oralkan, O., Khuri-Yakub, B. T. 2009; 56 (1): 182-192

  Abstract

  This paper reports on wafer-bonded, fully populated 2-D capacitive micromachined ultrasonic transducer (CMUT) arrays. To date, no successful through-wafer via fabrication technique has been demonstrated that is compatible with the wafer-bonding method of making CMUT arrays. As an alternative to through-wafer vias, trench isolation with a supporting frame is incorporated into the 2-D arrays to provide through-wafer electrical connections. The CMUT arrays are built on a silicon-on-insulator (SOI) wafer, and all electrical connections to the array elements are brought to the back side of the wafer through the highly conductive silicon substrate. Neighboring array elements are separated by trenches on both the device layer and the bulk silicon. A mesh frame structure, providing mechanical support, is embedded between silicon pillars, which electrically connect to individual elements. We successfully fabricated a 16 x 16-element 2-D CMUT array using wafer bonding with a yield of 100%. Across the array, the pulse-echo amplitude distribution is uniform (rho = 6.6% of the mean amplitude). In one design, we measured a center frequency of 7.6 MHz, a peak-to-peak output pressure of 2.9 MPa at the transducer surface, and a 3-dB fractional bandwidth of 95%. Volumetric ultrasound imaging was demonstrated by chip-to-chip bonding one of the fabricated 2-D arrays to a custom-designed integrated circuit (IC). This study shows that through-wafer trench-isolation with a supporting frame is a viable solution for providing electrical interconnects to CMUT elements and that 2-D arrays fabricated using waferbonding deliver good performance.

  View details for DOI 10.1109/TUFFC.2009.1018

  View details for Web of Science ID 000262561600021

  View details for PubMedID 19213645

• Capacitive Micromachined Ultrasonic Transducers with Piston-Shaped Membranes: Fabrication and Experimental Characterization IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Huang, Y., Zhuang, X., Haeggstrom, E. O., Ergun, A. S., Cheng, C., Khuri-Yakub, B. T. 2009; 56 (1): 136-145

  Abstract

  Capacitive micromachined ultrasonic transducers (CMUTs) featuring piston-shaped membranes (piston CMUTs) were developed to improve device performance in terms of transmission efficiency, reception sensitivity, and fractional bandwidth (FBW). A piston CMUT has a relatively flat active moving surface whose membrane motion is closer to ideal piston-type motion compared with a CMUT with uniformly thick membranes (classical CMUT). Piston CMUTs with a more uniform surface displacement profile can achieve high output pressure with a relatively small electrode separation. The improved device capacitance and gap uniformity also enhance detection sensitivity. By adding a center mass to the membrane, a large ratio of second-order resonant frequency to first-order resonant frequency was achieved. This improved the FBW. Piston CMUTs featuring membranes of different geometric shapes were designed and fabricated using wafer bonding. Fabricating piston CMUTs is a more complex process than fabricating CMUTs with uniformly thick membranes. However, no yield loss was observed. These devices achieved ~100% improvement in transduction performance (transmission and reception) over classical CMUTs. For CMUTs with square and rectangular membranes, the FBW increased from ~110% to ~150% and from ~140% to ~175%, respectively, compared with classical CMUTs. The new devices produced a maximum output pressure exceeding 1 MPa at the transducer surface. Performance optimization using geometric membrane shape configurations was the same in both piston CMUTs and classical CMUTs.

  View details for DOI 10.1109/TUFFC.2009.1013

  View details for Web of Science ID 000262561600016

  View details for PubMedID 19213640

• Forward-Looking Intracardiac Ultrasound Imaging Using a 1-D CMUT Array Integrated With Custom Front-End Electronics IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Nikoozadeh, A., Wygant, I. O., Lin, D., Oralkan, O., Ergun, A. S., Stephens, D. N., Thomenius, K. E., Dentinger, A. M., Wildes, D., Akopyan, G., Shivkumar, K., Mahajan, A., Sahn, D. J., Khuri-Yakub, B. T. 2008; 55 (12): 2651-2660

  Abstract

  Minimally invasive catheter-based electrophysiological (EP) interventions are becoming a standard procedure in diagnosis and treatment of cardiac arrhythmias. As a result of technological advances that enable small feature sizes and a high level of integration, nonfluoroscopic intracardiac echocardiography (ICE) imaging catheters are attracting increasing attention. ICE catheters improve EP procedural guidance while reducing the undesirable use of fluoroscopy, which is currently the common catheter guidance method. Phased-array ICE catheters have been in use for several years now, although only for side-looking imaging. We are developing a forward-looking ICE catheter for improved visualization. In this effort, we fabricate a 24-element, fine-pitch 1-D array of capacitive micromachined ultrasonic transducers (CMUT), with a total footprint of 1.73 mm x 1.27 mm. We also design a custom integrated circuit (IC) composed of 24 identical blocks of transmit/ receive circuitry, measuring 2.1 mm x 2.1 mm. The transmit circuitry is capable of delivering 25-V unipolar pulses, and the receive circuitry includes a transimpedance preamplifier followed by an output buffer. The CMUT array and the custom IC are designed to be mounted at the tip of a 10-Fr catheter for high-frame-rate forward-looking intracardiac imaging. Through-wafer vias incorporated in the CMUT array provide access to individual array elements from the back side of the array. We successfully flip-chip bond a CMUT array to the custom IC with 100% yield. We coat the device with a layer of polydimethylsiloxane (PDMS) to electrically isolate the device for imaging in water and tissue. The pulse-echo in water from a total plane reflector has a center frequency of 9.2 MHz with a 96% fractional bandwidth. Finally, we demonstrate the imaging capability of the integrated device on commercial phantoms and on a beating ex vivo rabbit heart (Langendorff model) using a commercial ultrasound imaging system.

  View details for DOI 10.1109/TUFFC.2008.980

  View details for Web of Science ID 000262221800012

  View details for PubMedID 19126489

  View details for PubMedCentralID PMC2730563

• Evaluation of wafer bonded CMUTs with rectangular membranes featuring high fill factor IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Wong, S. H., Kupnik, M., Zhuang, X., Lin, D., Butts-Pauly, K., Khuri-Yakub, B. T. 2008; 55 (9): 2053-2065

  Abstract

  Increasing fill factor is one design approach used to increase average output displacement, output pressure, and sensitivity of capacitive micromachined ultrasonic transducers (CMUTs). For rectangular cells, the cell-to-cell spacing and the aspect ratio determine the fill factor. In this paper, we explore the effects of these parameters on performance, in particular the nonuniformity of collapse voltage between neighboring cells and presence of higher order modes in air or immersed operation. We used a white light interferometer to measure nonuniformity in deflection between neighboring cells. We found that reducing the cell-to-cell spacing could cause bending of the center support post, which amplifies nonuniformities in collapse voltage to 18.4% between neighboring cells. Using a 2-D finite element model (FEM), we found that for our designs, increasing the support post width to 1.67 times the membrane thickness alleviated the post bending problem. Using impedance and interferometer measurements to observe the effects of aspect ratio on higher order modes, we found that the (1,3) modal frequency approached the (1,1) modal frequency as the aspect ratio of the rectangles increased. In air operation, under continuous wave (CW) excitation at the center frequency, the rectangular cells behaved in the (1,1) mode. In immersion, because of dispersive guided modes, these cells operated in a higher order mode when excited with a CW signal at the center frequency. This contributed to a loss of output pressure; for this reason our rectangular design was unsuitable for CW operation in immersion.

  View details for DOI 10.1109/TUFFC.897

  View details for Web of Science ID 000258912800020

  View details for PubMedID 18986902

  View details for PubMedCentralID PMC2766518

• Carbon nanotubes as photoacoustic molecular imaging agents in living mice NATURE NANOTECHNOLOGY de la Zerda, A., Zavaleta, C., Keren, S., Vaithilingam, S., Bodapati, S., Liu, Z., Levi, J., Smith, B. R., Ma, T., Oralkan, O., Cheng, Z., Chen, X., Dai, H., Khuri-Yakub, B. T., Gambhir, S. S. 2008; 3 (9): 557-562

  Abstract

  Photoacoustic imaging of living subjects offers higher spatial resolution and allows deeper tissues to be imaged compared with most optical imaging techniques. As many diseases do not exhibit a natural photoacoustic contrast, especially in their early stages, it is necessary to administer a photoacoustic contrast agent. A number of contrast agents for photoacoustic imaging have been suggested previously, but most were not shown to target a diseased site in living subjects. Here we show that single-walled carbon nanotubes conjugated with cyclic Arg-Gly-Asp (RGD) peptides can be used as a contrast agent for photoacoustic imaging of tumours. Intravenous administration of these targeted nanotubes to mice bearing tumours showed eight times greater photoacoustic signal in the tumour than mice injected with non-targeted nanotubes. These results were verified ex vivo using Raman microscopy. Photoacoustic imaging of targeted single-walled carbon nanotubes may contribute to non-invasive cancer imaging and monitoring of nanotherapeutics in living subjects.

  View details for DOI 10.1038/nnano.2008.231

  View details for Web of Science ID 000259013100014

  View details for PubMedID 18772918

  View details for PubMedCentralID PMC2562547

• Multifunctional catheters combining intracardiac ultrasound imaging and electrophysiology sensing IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Stephens, D. N., Cannata, J., Liu, R., Zhao, J. Z., Shung, K. K., Nguyen, H., Chia, R., Dentinger, A., Wildes, D., Thomenius, K. E., Mahajan, A., Shivkumar, K., Kim, K., O'Donnell, M., Nikoozadeh, A., Oralkan, O., Khuri-Yakub, P. T., Sahn, D. J. 2008; 55 (7): 1570-1581

  Abstract

  A family of 3 multifunctional intracardiac imaging and electrophysiology (EP) mapping catheters has been in development to help guide diagnostic and therapeutic intracardiac EP procedures. The catheter tip on the first device includes a 7.5 MHz, 64-element, side-looking phased array for high resolution sector scanning. The second device is a forward-looking catheter with a 24-element 14 MHz phased array. Both of these catheters operate on a commercial imaging system with standard software. Multiple EP mapping sensors were mounted as ring electrodes near the arrays for electrocardiographic synchronization of ultrasound images and used for unique integration with EP mapping technologies. To help establish the catheters' ability for integration with EP interventional procedures, tests were performed in vivo in a porcine animal model to demonstrate both useful intracardiac echocardiographic (ICE) visualization and simultaneous 3-D positional information using integrated electroanatomical mapping techniques. The catheters also performed well in high frame rate imaging, color flow imaging, and strain rate imaging of atrial and ventricular structures. The companion paper of this work discusses the catheter design of the side-looking catheter with special attention to acoustic lens design. The third device in development is a 10 MHz forward-looking ring array that is to be mounted at the distal tip of a 9F catheter to permit use of the available catheter lumen for adjunctive therapy tools.

  View details for DOI 10.1109/TUFFC.2008.834

  View details for Web of Science ID 000257386000020

  View details for PubMedID 18986948

• Feasibility of MR-temperature mapping of ultrasonic heating from a CMUT IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Wong, S. H., Watkins, R. D., Kupnik, M., Pauly, K. B., Khuri-Yakub, B. T. 2008; 55 (4): 811-818

  Abstract

  In the last decade, high intensity focused ultrasound (HIFU) has gained popularity as a minimally invasive and noninvasive therapeutic tool for treatment of cancers, arrhythmias, and other medical conditions. HIFU therapy is often guided by magnetic resonance imaging (MRI), which provides anatomical images for therapeutic device placement, temperature maps for treatment guidance, and postoperative evaluation of the region of interest. While piezoelectric transducers are dominantly used for MR-guided HIFU, capacitive micromachined ultrasonic transducers (CMUTs) show competitive advantages, such as ease of fabrication, integration with electronics, improved efficiency, and reduction of self-heating. In this paper, we will show our first results of an unfocused CMUT transducer monitored by MR-temperature maps. This 2.51 mm by 2.32 mm, unfocused CMUT heated a HIFU phantom by 14 degrees C in 2.5 min. This temperature rise was successfully monitored by MR thermometry in a 3.0 T General Electric scanner.

  View details for DOI 10.1109/TUFFC.2008.71.5

  View details for Web of Science ID 000254783100007

  View details for PubMedID 18467225

• Fabrication of flexible transducer arrays with through-wafer electrical interconnects based on trench refilling with PDMS JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Zhuang, X., Lin, D., Oralkan, O., Khuri-Yakub, B. T. 2008; 17 (2): 446-452

  View details for DOI 10.1109/JMEMS.2008.918381

  View details for Web of Science ID 000258996600021

• Capacitive micromachined ultrasonic transducers (CMUTs) with isolation posts ULTRASONICS Huang, Y., Zhuang, X., Haeggstrom, E. O., Ergun, A. S., Cheng, C., Khuri-Yakub, B. T. 2008; 48 (1): 74-81

  Abstract

  In this paper, an improved design of a capacitive micromachined ultrasonic transducer (CMUT) is presented. The design improvement aims to address the reliability issues of a CMUT and to extend the device operation beyond the contact (collapse) voltage. The major design novelty is the isolation posts in the vacuum cavities of the CMUT cells instead of full-coverage insulation layers in conventional CMUTs. This eliminates the contact voltage drifting due to charging caused by the insulation layer, and enables repeatable CMUT operation in the post-contact regime. Ultrasonic tests of the CMUTs with isolation posts (PostCMUTs) in air (electrical input impedance and capacitance vs. bias voltage) and immersion (transmission and reception) indicate acoustic performance similar to that obtained from conventional CMUTs while no undesired side effects of this new design is observed.

  View details for DOI 10.1016/j.ultras.2007.11.006

  View details for Web of Science ID 000254854000009

  View details for PubMedID 18207212

• Integration of 2D CMUT arrays with front-end electronics for volumetric ultrasound imaging IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Wygant, I. O., Zhuang, X., Yeh, D. T., Oralkan, O., Ergun, A. S., Karaman, M., Khuri-Yakub, B. T. 2008; 55 (2): 327-342

  Abstract

  For three-dimensional (3D) ultrasound imaging, connecting elements of a two-dimensional (2D) transducer array to the imaging system's front-end electronics is a challenge because of the large number of array elements and the small element size. To compactly connect the transducer array with electronics, we flip-chip bond a 2D 16 x 16-element capacitive micromachined ultrasonic transducer (CMUT) array to a custom-designed integrated circuit (IC). Through-wafer interconnects are used to connect the CMUT elements on the top side of the array with flip-chip bond pads on the back side. The IC provides a 25-V pulser and a transimpedance preamplifier to each element of the array. For each of three characterized devices, the element yield is excellent (99 to 100% of the elements are functional). Center frequencies range from 2.6 MHz to 5.1 MHz. For pulse echo operation, the average - 6-dB fractional bandwidth is as high as 125%. Transmit pressures normalized to the face of the transducer are as high as 339 kPa and input-referred receiver noise is typically 1.2 to 2.1 mPa/pHz. The flip-chip bonded devices were used to acquire 3D synthetic aperture images of a wire-target phantom. Combining the transducer array and IC, as shown in this paper, allows for better utilization of large arrays, improves receive sensitivity, and may lead to new imaging techniques that depend on transducer arrays that are closely coupled to IC electronics.

  View details for DOI 10.1109/TUFFC.2008.652

  View details for Web of Science ID 000253358700008

  View details for PubMedID 18334340

• Investigating Large 2D Arrays for Photoacoustic and Acoustic Imaging using CMUT Technology IEEE Ultrasonics Symposium Vaithilingam, S., Ma, T., Furukawa, Y., Oralkan, O., Kamaya, A., Torashima, K., Kupnik, M., Wygant, I. O., Zhuang, X., Jeffrey, R. B., Khuri-Yakub, B. T. IEEE. 2008: 1238–1241

  View details for Web of Science ID 000268845800299

• Analytically Calculating Membrane Displacement and the Equivalent Circuit Model of a Circular CMUT Cell IEEE Ultrasonics Symposium Wygant, I. O., Kupnik, M., Khuri-Yakub, B. T. IEEE. 2008: 2111–2114

  View details for Web of Science ID 000268845801113

• FINITE ELEMENT ANALYSIS OF STRESS STIFFENING EFFECTS IN CMUTs IEEE Ultrasonics Symposium Kupnik, M., Wygant, I. O., Khuri-Yakub, B. T. IEEE. 2008: 487–490

  View details for Web of Science ID 000268845800119

• The Design and Characterization of Capacitive Micromachined Ultrasonic Transducers (CMUTs) for Generating High-Intensity Ultrasound for Transmission of Directional Audio IEEE Ultrasonics Symposium Wygant, I. O., Kupnik, M., Khuri-Yakub, B. T., Wochner, M. S., Wright, W. M., Hamilton, M. F. IEEE. 2008: 2100–2102

  View details for Web of Science ID 000268845801110

• The effect of parallelism of CMUT cells on phase noise for chem/bio sensor applications IEEE Ultrasonics Symposium Lee, H. J., Park, K. K., Cristman, P., Oralkan, O., Kupnik, M., Khuri-Yakub, B. T. IEEE. 2008: 1951–1954

  View details for Web of Science ID 000268845801072

• CMUT as a Chemical Sensor for DMMP Detection IEEE International Frequency Control Symposium Lee, H. J., Park, K. K., Oralkan, O., Kupnik, M., Khuri-Yakub, B. T. IEEE. 2008: 434–439

  View details for Web of Science ID 000261285400089

• Development of Nanoparticle-Based Gold Contrast Agent for Photoacoustic Tomography Nanotechnology Conference and Trade Show (Nanotech 2008) Yang, Y., Vaithilingam, S., Ma, H. T., Salehi-Had, S., Oralkan, O., Khuri-Yakub, B. (., Guccione, S. CRC PRESS-TAYLOR & FRANCIS GROUP. 2008: 708–711

  View details for Web of Science ID 000272169500185

• Optimum design of circular CMUT membranes for high quality factor in air IEEE Ultrasonics Symposium Park, K. K., Lee, H. J., CRISMAN, P., Kupnik, M., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2008: 504–507

  View details for Web of Science ID 000268845800123

• Progress in CMUTs for HIFU ablation of upper abdominal cancer IEEE Ultrasonics Symposium Wong, S. H., Kupnik, M., Khuri-Yakub, B. T., Watkins, R. D., Pauly, K. B. IEEE. 2008: 2068–2071

  View details for Web of Science ID 000268845801102

• Fabricating capacitive micromachined ultrasonic transducers with direct wafer-bonding and locos technology 21st IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2008) Park, K. K., Lee, H. J., Kupnik, M., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2008: 339–342

  View details for Web of Science ID 000253356900085

• Capacitive micromachined ultrasonic transducers for chemical detection in nitrogen APPLIED PHYSICS LETTERS Park, K. K., Lee, H. J., Yaralioglu, G. G., Ergun, A. S., Oralkan, O., Kupnik, M., Quate, C. F., Khuri-Yakub, B. T., Braun, T., Ramseyer, J., Lang, H. P., Hegner, M., Gerber, C., Gimzewski, J. K. 2007; 91 (9)

  View details for DOI 10.1063/1.2776348

  View details for Web of Science ID 000249156100148

• Integration of trench-isolated through-wafer interconnects with 2d capacitive micromachined ultrasonic transducer arrays SENSORS AND ACTUATORS A-PHYSICAL Zhuang, X., Ergun, A. S., Huang, Y., Wygant, I. O., Oralkan, O., Khuri-Yakub, B. T. 2007; 138 (1): 221-229

  Abstract

  This paper presents a method to provide electrical connection to a 2D capacitive micromachined ultrasonic transducer (CMUT) array. The interconnects are processed after the CMUTs are fabricated on the front side of a silicon wafer. Connections to array elements are made from the back side of the substrate via highly conductive silicon pillars that result from a deep reactive ion etching (DRIE) process. Flip-chip bonding is used to integrate the CMUT array with an integrated circuit (IC) that comprises the front-end circuits for the transducer and provides mechanical support for the trench-isolated array elements. Design, fabrication process and characterization results are presented. The advantages when compared to other through-wafer interconnect techniques are discussed.

  View details for DOI 10.1016/j.sna.2007.04.008

  View details for Web of Science ID 000248296900028

  View details for PubMedCentralID PMC2084216

• Integration of Trench-Isolated Through-Wafer Interconnects with 2D Capacitive Micromachined Ultrasonic Transducer Arrays. Sensors and actuators. A, Physical Zhuang, X., Ergun, A. S., Huang, Y., Wygant, I. O., Oralkan, O., Khuri-Yakub, B. T. 2007; 138 (1): 221-229

  Abstract

  This paper presents a method to provide electrical connection to a 2D capacitive micromachined ultrasonic transducer (CMUT) array. The interconnects are processed after the CMUTs are fabricated on the front side of a silicon wafer. Connections to array elements are made from the back side of the substrate via highly conductive silicon pillars that result from a deep reactive ion etching (DRIE) process. Flip-chip bonding is used to integrate the CMUT array with an integrated circuit (IC) that comprises the front-end circuits for the transducer and provides mechanical support for the trench-isolated array elements. Design, fabrication process and characterization results are presented. The advantages when compared to other through-wafer interconnect techniques are discussed.

  View details for DOI 10.1016/j.sna.2007.04.008

  View details for PubMedID 18037982

  View details for PubMedCentralID PMC2084216

• Biocompatible coatings for CMUTs in a harsh, aqueous environment JOURNAL OF MICROMECHANICS AND MICROENGINEERING Zhuang, X., Nikoozadeh, A., Beasley, M. A., Yaralioglu, G. G., Khuri-Yakub, B. T., Pruitt, B. L. 2007; 17 (5): 994-1001

  View details for DOI 10.1088/0960-1317/17/5/020

  View details for Web of Science ID 000246551600022

• Finite element modeling and experimental characterization of crosstalk in 1-D CMUT arrays IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Bayram, B., Kupnik, M., Yaralioglu, C. G., Oralkan, O., Ergun, A. S., Lin, D., Wong, S. H., Khuri-Yakub, B. T. 2007; 54 (2): 418-430

  Abstract

  Crosstalk is the coupling of energy between the elements of an ultrasonic transducer array. This coupling degrades the performance of transducers in applications such as medical imaging and therapeutics. In this paper, we present an experimental demonstration of guided interface waves in capacitive micromachined ultrasonic transducers (CMUTs). We compare the experimental results to finite element calculations using a commercial package (LS-DYNA) for a 1-D CMUT array operating in the conventional and collapsed modes. An element in the middle of the array was excited with a unipolar voltage pulse, and the displacements were measured using a laser interferometer along the center line of the array elements immersed in soybean oil. We repeated the measurements for an identical CMUT array covered with a 4.5-microm polydimethylsiloxane (PDMS) layer. The main crosstalk mechanism is the dispersive guided modes propagating in the fluid-solid interface. Although the transmitter element had a center frequency of 5.8 MHz with a 130% fractional bandwidth in the conventional operation, the dispersive guided mode was observed with the maximum amplitude at a frequency of 2.1 MHz, and had a cut-off frequency of 4 MHz. In the collapsed operation, the dispersive guided mode was observed with the maximum amplitude at a frequency of 4.0 MHz, and had a cut-off frequency of 10 MHz. Crosstalk level was lower in the collapsed operation (-39 dB) than in the conventional operation (-24.4 dB). The coverage of the PDMS did not significantly affect the crosstalk level, but reduced the phase velocity for both operation modes. Lamb wave modes, A0 and S0, were also observed with crosstalk levels of -40 dB and -65 dB, respectively. We observed excellent agreement between the finite element and the experimental results.

  View details for DOI 10.1109/TUFFC.2007.256

  View details for Web of Science ID 000243920900022

  View details for PubMedID 17328339

• A co-axial scanning acoustic and. photoacoustic microscope IEEE Ultrasonics Symposium Vaithilingam, S., Ma, T., Furukawa, Y., de la Zerda, A., Oralkan, O., Kamaya, A., Keren, S., Gambhir, S. S., Jeffrey, R. B., Khuri-Yakub, B. T. IEEE. 2007: 2413–2416

  View details for Web of Science ID 000254281802104

• Extended insulation layer structure for CMUTs IEEE Ultrasonics Symposium Kupnik, M., Ergun, A. S., Huang, Y., Khuri-Yakub, B. T. IEEE. 2007: 511–514

  View details for Web of Science ID 000254281800120

• Flexible transducer arrays with through-wafer electrical interconnects based on trench refilling with PDMS 20th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2007) Zhuang, X., Lin, D., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2007: 264–267

  View details for Web of Science ID 000255867800066

• The capactive micromachined ultrasonic transducer (CMUT) as a Chem/Bio sensor IEEE Ultrasonics Symposium Khuri-Yakub, B. T., Park, K. K., Lee, H. J., Yaralioglu, G. G., Ergun, S., Oralkan, O., Kupnik, M., Quate, C. F., Braun, T., Lang, H. P., Hegner, M., Ramseyer, J., Gerber, C., Gimzewski, J. IEEE. 2007: 472–475

  View details for Web of Science ID 000254281800112

• Trench-isolated CMUT Arrays with a supporting frame: Characterization and Imaging results IEEE Ultrasonics Symposium Zhuang, X., Wygant, I. O., Lin, D., Kupnik, M., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2007: 507–510

  View details for Web of Science ID 000254281800119

• An integrated circuit with transmit beamforming and parallel receive channels for 3D ultrasound imaging: Testing and characterization IEEE Ultrasonics Symposium Wygant, I. O., Jamal, N., Lee, H. J., Nikoozadeh, A., Zhuang, X., Oralkan, O., Ergun, A. S., Karaman, M., Khuri-Yakub, B. T. IEEE. 2007: 25–28

  View details for Web of Science ID 000254281800005

• 50-kHz capacitive micromachined ultrasonic transducers for generating highly directional sound with parametric arrays IEEE Ultrasonics Symposium Wygant, I. O., Kupnik, M., Yaralioglu, G., Khuri-Yakub, B. T., Windsor, J. C., Wright, W. M., Wochner, M. S., Hamilton, M. F. IEEE. 2007: 519–522

  View details for Web of Science ID 000254281800122

• Design of HIFUCMUT arrays for treatment of liver and renal cancer 6th International Symposium on Therapeutic Ultrasound Wong, S. H., Ergun, A. S., Yaralioglu, G. G., Oralkan, O., Kupnik, M., Pauly, K. B., Khuri-Yakub, B. T. AMER INST PHYSICS. 2007: 54–60

  View details for Web of Science ID 000247342200009

• Characterization of fabrication related gap-height variations in capacitive micromachined ultrasonic transducers IEEE Ultrasonics Symposium Lin, D., Zhuang, X., Wong, S. H., Ergun, A. S., Kupnik, M., Khuri-Yakub, B. T. IEEE. 2007: 523–526

  View details for Web of Science ID 000254281800123

• Advantages of capacitive micromachined ultrasonics transducers (CMUTs) for high intensity focused ultrasound (HIFU) IEEE Ultrasonics Symposium Wong, S. H., Kupnik, M., Butts-Pauly, K., Khuri-Yakub, B. T. IEEE. 2007: 1313–1316

  View details for Web of Science ID 000254281801078

• Feasibility of noncontact intracardiac ultrasound ablation and Imaging catheter for treatment of atrial fibrillation IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Wong, S. H., Scott, G. C., Conolly, S. M., Narayan, G., Liang, D. H. 2006; 53 (12): 2394-2405

  Abstract

  Atrial fibrillation (AF) affects 1% of the population and results in a cost of 2.8 billion dollars from hospitalizations alone. Treatments that electrically isolate portions of the atria are clinically effective in curing AF. However, such minimally invasive catheter treatments face difficulties in mechanically positioning the catheter tip and visualizing the anatomy of the region. We propose a noncontact, intracardiac transducer that can ablate tissue and provide rudimentary imaging to guide therapy. Our design consists of a high-power, 20 mm by 2 mm, 128-element, transducer array placed on the side of 7-French catheter. The transducer will be used in imaging mode to locate the atrial wall; then, by focusing at that location, a lesion can be formed. Imaging of previously formed lesions could potentially guide placement of subsequent lesions. Successive rotations of the catheter will potentially enable a contiguous circular lesion to be created around the pulmonary vein. The challenge of intracardiac-sized transducers is achieving high intensities (300-5000 W/cm2) needed to raise the temperature of the tissue above 43 degrees C. In this paper, we demonstrate the feasibility of an intracardiac-sized transducer for treatment of atrial fibrillation. In simulations and proof-of-concept experiments, we show a 37 degrees C temperature rise in the lesion location and demonstrate the possibility of lesion imaging.

  View details for DOI 10.1109/TUFFC.2006.188

  View details for Web of Science ID 000242390900022

  View details for PubMedID 17186922

• Comparison of conventional and collapsed region operation of capacitive micromachined ultrasonic transducers IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Huang, Y., Haeggstrom, E., Bayram, B., Zhuang, X., Ergun, A. S., Cheng, C., Khuri-Yakub, B. T. 2006; 53 (10): 1918-1933

  Abstract

  We report experimental results from a comparative study on collapsed region and conventional region operation of capacitive micromachined ultrasonic transducers (CMUTs) fabricated with a wafer bonding technique. Using ultrasonic pulse-echo and pitch-catch measurements, we characterized single elements of 1-D CMUT arrays operating in oil. The experimental results from this study agreed with the simulation results: a CMUT operating in the collapsed region produced a higher maximum output pressure than a CMUT operated in the conventional region at 90% of its collapse voltage (3 kPa/V vs. 16.1 kPa/V at 2.3 MHz). While the pulse-echo fractional bandwidth (126%) was higher in the collapsed region operation than in the conventional operation (117%), the pulse-echo amplitude in collapsed region operation was 11 dB higher than in conventional region operation. Furthermore, within the range of tested bias voltages, the output pressure monotonously increased with increased bias during collapsed region operation. It was also found that in the conventional mode, short AC pulses (larger than the collapse voltage) could be applied without collapsing the membranes. Finally, while no significant difference was observed in reflectivity of the CMUT face between the two regions of operation, hysteretic behavior of the devices was identified in the collapsed region operation.

  View details for DOI 10.1109/TUFFC.2006.125

  View details for Web of Science ID 000240860200023

  View details for PubMedID 17036801

• Experimental measurements of mechanical dissipation associated with dielectric coatings formed using SiO2, Ta2O5 and Al2O3 CLASSICAL AND QUANTUM GRAVITY Crooks, D. R., Cagnoli, G., Fejer, M. M., Harry, G., Hough, J., Khuri-Yakub, B. T., Penn, S., Route, R., Rowan, S., Sneddon, P. H., Wygant, I. O., Yaralioglu, G. G. 2006; 23 (15): 4953-4965

  View details for DOI 10.1088/0264-9381/23/15/014

  View details for Web of Science ID 000239416800014

• Experimental characterization of collapse-mode CMUT operation IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Oralkan, O., Bayram, B., Yaralioglu, G. G., Ergun, A. S., Kupnik, M., Yeh, D. T., Wygant, I. O., Khuri-Yakub, B. T. 2006; 53 (8): 1513-1523

  Abstract

  This paper reports on the experimental characterization of collapse-mode operation of capacitive micromachined ultrasonic transducers (CMUTs). CMUTs are conventionally operated by applying a direct current (DC) bias voltage less than the collapse voltage of the membrane, so that the membrane is deflected toward the bottom electrode. In the conventional regime, there is no contact between the membrane and the substrate; the maximum alternating current (AC) displacement occurs at the center of the membrane. In collapse-mode operation, the DC bias voltage is first increased beyond the collapse voltage, then reduced without releasing the collapsed membrane. In collapse-mode operation, the center of the membrane is always in contact with the substrate. In the case of a circular membrane, the maximum AC displacement occurs along the ring formed between the center and the edge of the membrane. The experimental characterization presented in this paper includes impedance measurements in air, pulse-echo experiments in immersion, and one-way optical displacement measurements in immersion for both conventional and collapse-mode operations. A 205-microm x 205-microm 2-D CMUT array element composed of circular silicon nitride membranes is used in the experiments. In pulse-echo experiments, a custom integrated circuit (IC) comprising a pulse driver, a transmit/receive switch, a wideband low-noise preamplifier, and a line driver is used. By reducing the parasitic capacitance, the use of a custom IC enables pulse-echo measurements at high frequencies with a very small transducer. By comparing frequency response and efficiency of the transducer in conventional and collapse regimes, experimental results show that a collapsed membrane can be used to generate and detect ultrasound more efficiently than a membrane operated in the conventional mode. Furthermore, the center frequency of the collapsed membrane can be changed by varying the applied DC voltage. In this study, the center frequency of a collapsed transducer in immersion is shown to vary from 20 MHz to 28 MHz with applied DC bias; the same transducer operates at 10 MHz in the conventional mode. In conventional mode, the maximum peak-to-peak pressure is 370 kPa on the transducer surface for a 40-ns, 25-V unipolar pulse excitation. In collapse mode, a 25-ns, 25-V unipolar pulse generates 590 kPa pressure at the surface of the transducer.

  View details for Web of Science ID 000239405700015

  View details for PubMedID 16921904

• 3-D ultrasound imaging using a forward-looking CMUT ring array for intravascular/intracardiac applications IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Yeh, D. T., Oralkan, O., Wygant, I. O., O'Donnell, M., Khuri-Yakub, B. T. 2006; 53 (6): 1202-1211

  Abstract

  Forward-viewing ring arrays can enable new applications in intravascular and intracardiac ultrasound. This work presents compelling, full-synthetic, phased-array volumetric images from a forward-viewing capacitive micromachined ultrasonic transducer (CMUT) ring array wire bonded to a custom integrated circuit front end. The CMUT ring array has a diameter of 2 mm and 64 elements each 100 microm x 100 microm in size. In conventional mode, echo signals received from a plane reflector at 5 mm had 70% fractional bandwidth around a center frequency of 8.3 MHz. In collapse mode, 69% fractional bandwidth is measured around 19 MHz. Measured signal-to-noise ratio (SNR) of the echo averaged 16 times was 29 dB for conventional operation and 35 dB for collapse mode. B-scans were generated of a target consisting of steel wires 0.3 mm in diameter to determine resolution performance. The 6 dB axial and lateral resolutions for the B-scan of the wire target are 189 microm and 0.112 radians for 8 MHz, and 78 microm and 0.051 radians for 19 MHz. A reduced firing set suitable for real-time, intravascular applications was generated and shown to produce acceptable images. Rendered three-dimensional (3-D) images of a Palmaz-Schatz stent also are shown, demonstrating that the imaging quality is sufficient for practical applications.

  View details for Web of Science ID 000238493000013

  View details for PubMedID 16846153

• CAPACITIVE MICROMACHINED ULTRASONIC TRANSDUCERS FOR HIGH INTENSITY FOCUSED ABLATION OF UPPER ABDOMINAL TUMORS IEEE Ultrasonics Symposium Wong, S. H., Ergun, A. S., Yaralioglu, G. G., Kupnik, M., Zhuang, X., Oralkan, O., Butts-Pauly, K., Khuri-Yakub, B. T. IEEE. 2006: 841–844

  View details for Web of Science ID 000260407800202

• Beamforming and hardware design for a multichannel front-end integrated circuit for real-time 3D catheter-based ultrasonic imaging. Medical Imaging 2006 Conference Wygant, I. O., Karaman, M., Oralkan, O., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 2006

  View details for DOI 10.1117/12.673786

  View details for Web of Science ID 000238041300010

• An Integrated Circuit with Transmit Beamforming and Parallel Receive Channels for Real-Time Three-Dimensional Ultrasound Imaging IEEE Ultrasonics Symposium Wygant, I., Lee, H., Nikoozadeh, A., Yeh, D. T., Oralkan, O., Karaman, M., Khuri-Yakub, B. T. IEEE. 2006: 2186–2189

  View details for Web of Science ID 000260407801158

• FINITE ELEMENT ANALYSIS OF CMUTs: CONVENTIONAL VS. COLLAPSE OPERATION MODES IEEE Ultrasonics Symposium Yaralioglu, G. G., Bayram, B., Khuri-Yakub, B. T. IEEE. 2006: 586–589

  View details for Web of Science ID 000260407800139

• FINITE ELEMENT ANALYSIS OF FABRICATION RELATED THERMAL EFFECTS IN CAPACITIVE MICROMACHINED ULTRASONIC TRANSDUCERS IEEE Ultrasonics Symposium Kupnik, M., Ergun, A. S., Yaralioglu, G. G., Bayram, B., Oralkan, O., Wong, S. H., Lin, D., Khuri-Yakub, B. T. IEEE. 2006: 942–945

  View details for Web of Science ID 000260407800227

• Capacitive micromachined ultrasonic transducer arrays for integrated diagnostic/therapeutic catheters 5th International Symposium on Therapeutic Ultrasound Wong, S. H., Wygant, I. O., Yeh, D. T., Zhuang, X., Bayram, B., Kupnik, M., Oralkan, O., Ergun, A. S., Yaralioglu, G. G., Khuri-Yakub, B. T. AMER INST PHYSICS. 2006: 395–399

  View details for Web of Science ID 000238329700078

• Capacitive micromachined ultrasonic transducers (CMUTs) for photoacoustic imaging 7th Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-Optics Vaithilingam, S., Wygant, I. O., Kuo, P. S., Zhuang, X., Oralkan, O., Olcott, P. D., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 2006

  View details for DOI 10.1117/12.659459

  View details for Web of Science ID 000237084900002

• ACOUSTIC CROSSTALK REDUCTION METHOD FOR CMUT ARRAYS IEEE Ultrasonics Symposium Bayram, B., Yaralioglu, G. G., Kupnik, M., Khuri-Yakub, B. T. IEEE. 2006: 590–593

  View details for Web of Science ID 000260407800140

• Trench-Isolated CMUT Arrays with a Supporting Frame IEEE Ultrasonics Symposium Zhuang, X., Lin, D., Ergun, A. S., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2006: 1955–1958

  View details for Web of Science ID 000260407801101

• Adaptive pulse repetition frequency technique for an ultrasonic transit-time gas flowmeter for hot pulsating gases Sensors Journal, IEEE Khuri-Yakub, B., T., Kupnik, M., Schroder, A., O'Leary, P., Benes, E., Groeschl, M. 2006; 6 (4): 906-915
• Tomographic Photoacoustic Imaging Using Capacitive Micromachined Ultrasonic Transducer (CMUT) Technology IEEE Ultrasonics Symposium Vaithilingam, S., Wygant, I. O., Sifferman, S., Zhuang, X., Furukawa, Y., Oralkan, O., Keren, S., Gambhir, S. S., Khuri-Yakub, B. T. IEEE. 2006: 397–400

  View details for Web of Science ID 000260407800095

• Volumetric Imaging Using Fan-Beam Scanning with Reduced Redundancy 2D Arrays IEEE Ultrasonics Symposium Wygant, I., Karaman, M., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2006: 2190–2193

  View details for Web of Science ID 000260407801159

• Interconnection and packaging for 2D capacitive micromachined ultrasonic transducer arrays based on through-wafer trench isolation 19th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2006) Zhuang, X. F., Ergun, A. S., Oralkan, O., Wygant, I. O., Khuri-Yakub, B. T. IEEE. 2006: 270–273

  View details for Web of Science ID 000236994500068

• Capacitive micromachined ultrasonic transducers: Fabrication technology IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Ergun, A. S., Huang, Y. L., Zhuang, X. F., Oralkan, O., Yaralioglu, G. G., Khuri-Yakub, B. T. 2005; 52 (12): 2242-2258

  Abstract

  Capacitive micromachined ultrasonic transducer (cMUT) technology is a prime candidate for next generation imaging systems. Medical and underwater imaging and the nondestructive evaluation (NDE) societies have expressed growing interest in cMUTs over the years. Capacitive micromachined ultrasonic transducer technology is expected to make a strong impact on imaging technologies, especially volumetric imaging, and to appear in commercial products in the near future. This paper focuses on fabrication technologies for cMUTs and reviews and compares variations in the production processes. We have developed two main approaches to the fabrication of cMUTs: the sacrificial release process and the recently introduced wafer-bonding method. This paper gives a thorough review of the sacrificial release processes, and it describes the new wafer-bonding method in detail. Process variations are compared qualitatively and quantitatively whenever possible. Through these comparisons, it was concluded that wafer-bonded cMUT technology was superior in terms of process control, yield, and uniformity. Because the number of steps and consequent process time were reduced (from six-mask process to four-mask process), turn-around time was improved significantly.

  View details for Web of Science ID 000234398700009

  View details for PubMedID 16463490

• Introduction to the special issue on micromachined ultrasonic transducers IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Khuri-Yakub, B. T. 2005; 52 (12): 2162-2162

  View details for Web of Science ID 000234398700001

• Dynamic analysis of capacitive micromachined ultrasonic transducers IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Bayram, B., Yaralioglu, G. G., Kupnik, M., Ergun, A. S., Oralkan, O., Nikoozadeh, A., Khuri-Yakub, B. T. 2005; 52 (12): 2270-2275

  Abstract

  Electrostatic transducers are usually operated under a DC bias below their collapse voltage. The same scheme has been adopted for capacitive micromachined ultrasonic transducers (cMUTs). DC bias deflects the cMUT membranes toward the substrate, so that their centers are free to move during both receive and transmit operations. In this paper, we present time-domain, finite element calculations for cMUTs using LS-DYNA, a commercially available finite element package. In addition to this DC bias mode, other new cMUT operations (collapse and collapse-snapback) have recently been demonstrated. Because cMUT membranes make contact with the substrate in these new operations, modeling of these cMUTs should include contact analysis. Our model was a cMUT transducer consisting of many hexagonal membranes; because it was symmetrical, we modeled only one-sixth of a hexagonal cell loaded with a fluid medium. The finite element results for both conventional and collapse modes were compared to measurements made by an optical interferometer; a good match was observed. Thus, the model is useful for designing cMUTs that operate in regimes where membranes make contact with the substrate.

  View details for Web of Science ID 000234398700011

  View details for PubMedID 16463492

• Finite-element analysis of capacitive micromachined ultrasonic transducers IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Yaralioglu, C. G., Ergun, A. S., Khuri-Yakub, B. T. 2005; 52 (12): 2185-2198

  Abstract

  In this paper, we present the results of finite-element analysis performed to investigate capacitive micromachined ultrasonic transducers (CMUTs). Both three-dimensional (3-D) and 2-D models were developed using a commercially available finite-element modeling (FEM) software. Depending on the dimensionality of the model, the membranes were constructed using plane or shell elements. The electrostatic gap was modeled using many parallel plate transducers. An axisymmetric model for a single membrane was built; the electrical input impedance of the device then was calculated in vacuum to investigate series and parallel resonant frequencies, where the input impedance has a minimum and a maximum, respectively. A method for decomposing the membrane capacitance into parasitic and active parts was demonstrated, and it was shown that the parallel resonant frequency shifted down with increased biased voltage. Calculations then were performed for immersion transducers. Acoustic wave propagation was simulated in the immersion medium, using appropriate elements in a 3-D model. Absorbing boundaries were implemented to avoid the reflections at the end of the medium mesh. One row of an array element, modeled with appropriate boundary conditions, was used to calculate the output pressure. The results were compared with a simpler model: a single membrane in immersion, with symmetry boundary conditions on the sidewalls that cause the calculations to reflect the properties of an infinitely large array. A 2-D model then was developed to demonstrate the effect of membrane dimensions on the output pressure and bandwidth. Our calculations revealed that the small signal transmit pressure was inversely proportional to the square root of gap height. We also compared FEM results with analytical and experimental results.

  View details for Web of Science ID 000234398700004

  View details for PubMedID 16463485

• Femtoliter to picoliter droplet generation for organic polymer deposition using single reservoir ejector arrays IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING Demirci, U., Yaralioglu, G. G., Haeggstrom, E., Khuri-Yakub, B. T. 2005; 18 (4): 709-715

  View details for DOI 10.1109/TSM.2005.858500

  View details for Web of Science ID 000233379400031

• A new design and manufacturing process for embedded Lamb waves interdigital transducers based on piezopolymer film 18th European Conference on Solid-State Transducers Bellan, F., Bulletti, A., Capineri, L., Masotti, L., Yaralioglu, G. G., Degertekin, F. L., Khuri-Yakub, B. T., Guasti, F., Rosi, E. ELSEVIER SCIENCE SA. 2005: 379–387

  View details for DOI 10.1016/j.sna.2005.05.013

  View details for Web of Science ID 000232321800059

• Microfluidic sonicator for real-time disruption of eukaryotic cells and bacterial spores for DNA analysis ULTRASOUND IN MEDICINE AND BIOLOGY Marentis, T. C., Kusler, B., Yaralioglu, G. G., Liu, S. J., Haeggstrom, E. O., Khuri-Yakub, B. T. 2005; 31 (9): 1265-1277

  Abstract

  Biologic agent screening is a three-step process: lysis of host cell membranes or walls to release their DNA, polymerase chain reaction to amplify the genetic material and screening for distinguishing genetic signatures. Macrofluidic devices commonly use sonication as a lysis method. Here, we present a piezoelectric microfluidic minisonicator and test its performance. Eukaryotic human leukemia HL-60 cells and Bacillus subtilis bacterial spores were lysed as they passed through a microfluidic channel at 50 microL/min and 5 microL/min, respectively, in the absence of any chemical denaturants, enzymes or microparticles. We used fluorescence-activated cell sorting and hematocytometry to measure 80% lysis of HL-60 cells after 3 s of sonication. Real-time polymerase chain reaction indicated 50% lysis of B. subtilis spores with 30 s of sonication. Advantages of the minisonicator over macrofluidic implementations include a small sample volume (2.5 microL), reduced energy consumption and compatibility with other microfluidic blocks. These features make this device an attractive option for "lab-on-a-chip" and portable applications.

  View details for DOI 10.1016/j.ultrasmedbio.2005.05.005

  View details for Web of Science ID 000232083800013

  View details for PubMedID 16176793

• Capacitive micromachined ultrasonic transducer design for high power transmission IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Bayram, B., Oralkan, O., Ergun, A. S., Haeggstrom, E. 2005; 52 (2): 326–39

  Abstract

  Capacitive micromachined ultrasonic transducers (cMUTs) were developed to meet the demands of the ultrasonic industry. To achieve maximum efficiency, the conventional operation of the cMUT requires a bias voltage close to the collapse voltage. Total acoustic output pressure is limited by the efficiency of the cMUT and the maximum-allowed pulse voltage on the membrane. In this paper, we propose the collapse-snapback operation of the cMUT: the membrane is collapsed onto the substrate in the collapsing cycle, and released in the snapback cycle. The collapse-snapback operation overcomes the above-mentioned limitations of the conventional operation. The collapse-snapback operation utilizes a larger range of membrane deflection profiles (both collapsed and released profiles) and generates higher acoustic output pressures. The static finite element calculations were performed to design cMUTs with specific collapse and snapback voltages by changing the electrode parameters (radius (re), position (de), and thickness (te)). These designs were refined for optimum average displacement per cycle. An electrode radius greater than 60% of the membrane radius significantly improved the displacement per volt. Moderately thick membranes (te approximately 0.2 microm) were preferred, as thicker membranes reduced the displacement per volt. Under proper bias conditions, the collapse-snapback operation, designed for high-power transmission, allowed the application of pulse voltages larger than the difference of collapse and snapback voltages. Dynamic finite element calculations of an infinite cMUT array on the substrate loaded with acoustic fluid medium were performed to determine the dynamic response of the cMUT. Commercially available FEM packages ANSYS and LS-DYNA were used for static and dynamic calculations, respectively. The cMUTs were fabricated for optimal performance in the collapse-snapback operation. The transmit experiments were performed on a 2-D cMUT array using a calibrated hydrophone. Taking into account the attenuation and diffraction losses, the pressure on the cMUT surface was extracted. The cMUT generated 0.47 MPa (6 kPa/V) and 1.04 MPa (11 kPa/V) in the conventional and collapse-snapback operations, respectively. Therefore, collapse-snapback operation of the cMUTs was superior for high-power transmission.

  View details for PubMedID 15801320

• 3-D ultrasound imaging using forward viewing CMUT ring arrays for intravascular and intracardiac applications IEEE International Ultrasonics Symposium Yeh, D. T., Oralkan, O., Wygant, I. O., O'Donnell, M., Khuri-Yakub, B. T. IEEE. 2005: 783–786

  View details for Web of Science ID 000236090701018

• Reconfigurable Arrays for portable ultrasound IEEE International Ultrasonics Symposium Fisher, R., Thomenius, K., WODNICKI, R., Thomas, R., Khuri-Yakub, B., Ergun, A., Yaralioglu, G. IEEE. 2005: 495–499

  View details for Web of Science ID 000236090700118

• An endoscopic imaging system based on a two-dimensional CMUT array: Real-time imaging results IEEE International Ultrasonics Symposium Wygant, I. O., Zhuang, X., Yeh, D. T., Vaithilingam, S., Nikoozadeh, A., Oralkan, O., Ergun, A. S., Karaman, M., Khuri-Yakub, B. T. IEEE. 2005: 792–795

  View details for Web of Science ID 000236090701020

• High-frequency CMUT arrays for high-resolution medical imaging Medical Imaging 2005 Conference Yeh, D. T., Oralkan, O., Ergun, A. S., Zhuang, X. F., Wygant, I. O., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 2005: 87–98

  View details for DOI 10.1117/12.595918

  View details for Web of Science ID 000229069500010

• Photoacoustic imaging using a two-dimensional CMUT array IEEE International Ultrasonics Symposium Wygant, I. O., Zhuang, X., Kuo, P. S., Yeh, D. T., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2005: 1921–1924

  View details for Web of Science ID 000236090703013

• Characterization of cross-coupling in capacitive micromachined ultrasonic transducers IEEE International Ultrasonics Symposium Bayram, B., Kupnik, M., Yaralioglu, G. G., Oralkan, O., Lin, D. S., Zhuang, X. F., Ergun, A. S., Sarioglu, A. F., Wong, S. H., Khuri-Yakub, B. T. IEEE. 2005: 601–604

  View details for Web of Science ID 000236090700143

• A miniature real-time volumetric ultrasound imaging system Medical Imaging 2005 Conference Wygant, I. O., Yeh, D. T., Zhuang, X. F., Nikoozadeh, A., Oralkan, O., Ergun, A. S., Karaman, M., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 2005: 26–36

  View details for DOI 10.1117/12.596019

  View details for Web of Science ID 000229069500004

• Finite element modeling of capacitive micromachined ultrasonic transducers Medical Imaging 2005 Conference Yaralioglu, G. G., Bayram, B., Nikoozadeh, A., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 2005: 77–86

  View details for DOI 10.1117/12.595619

  View details for Web of Science ID 000229069500009

• Capacitive micromachined ultrasonic transducer technology for medical ultrasound imaging Medical Imaging 2005 Conference Ergun, A. S., Zhuang, X., Huang, Y., Oralkan, O., Yaralioglu, G. G., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 2005: 58–68

  View details for DOI 10.1117/12.595692

  View details for Web of Science ID 000229069500007

• Two-dimensional capacitive micromachined ultrasonic transducer (CMUT) arrays for a miniature integrated volumetric ultrasonic imaging system Medical Imaging 2005 Conference Zhuang, X., Wygant, I. O., Yeh, D. T., Nikoozadeh, A., Oralkan, O., Ergun, A. S., Cheng, C. H., Huang, Y., Yaralioglu, G. G., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 2005: 37–46

  View details for DOI 10.1117/12.594702

  View details for Web of Science ID 000229069500005

• Capacitive micromachined ultrasonic transducer design for high power transmission Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on Bayram, B., Oralkan, O., Ergun, A., S., Haeggstrom, E., Yaralioglu, G., G., Khuri-Yakub, B., T. 2005; 52 (2): 326-339
• Coherent array imaging using phased subarmys. Part II: Simulations and experimental results IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Johnson, J. A., Oralkan, O., Ergun, S., Demirci, U., Karaman, M., Khuri-Yakub, B. T. 2005; 52 (1): 51-64

  Abstract

  The basic principles and theory of phased subarray (PSA) imaging imaging provides the flexibility of reducing the number of front-end hardware channels between that of classical synthetic aperture (CSA) imaging--which uses only one element per firing event--and full-phased array (FPA) imaging-which uses all elements for each firing. The performance of PSA generally ranges between that obtained by CSA and FPA using the same array, and depends on the amount of hardware complexity reduction. For the work described in this paper, we performed FPA, CSA, and PSA imaging of a resolution phantom using both simulated and experimental data from a 3-MHz, 3.2-cm, 128-element capacitive micromachined ultrasound transducer (CMUT) array. The simulated system point responses in the spatial and frequency domains are presented as a means of studying the effects of signal bandwidth, reconstruction filter size, and subsampling rate on the PSA system performance. The PSA and FPA sector-scanned images were reconstructed using the wideband experimental data with 80% fractional bandwidth, with seven 32-element subarrays used for PSA imaging. The measurements on the experimental sector images indicate that, at the transmit focal zone, the PSA method provides a 10% improvement in the 6-dB lateral resolution, and the axial point resolution of PSA imaging is identical to that of FPA imaging. The signal-to-noise ratio (SNR) of PSA image was 58.3 dB, 4.9 dB below that of the FPA image, and the contrast-to-noise ratio (CNR) is reduced by 10%. The simulated and experimental test results presented in this paper validate theoretical expectations and illustrate the flexibility of PSA imaging as a way to exchange SNR and frame rate for simplified front-end hardware.

  View details for Web of Science ID 000226812800007

  View details for PubMedID 15742562

• Coherent-array imaging using phased subarmys. Part I: Basic principles IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Johnson, J. A., Karaman, M., Khuri-Yakub, B. T. 2005; 52 (1): 37-50

  Abstract

  The front-end hardware complexity of a coherent array imaging system scales with the number of active array elements that are simultaneously used for transmission or reception of signals. Different imaging methods use different numbers of active channels and data collection strategies. Conventional full phased array (FPA) imaging produces the best image quality using all elements for both transmission and reception, and it has high front-end hardware complexity. In contrast, classical synthetic aperture (CSA) imaging only transmits on and receives from a single element at a time, minimizing the hardware complexity but achieving poor image quality. We propose a new coherent array imaging method--phased subarray (PSA) imaging--that performs partial transmit and receive beam-forming using a subset of adjacent elements at each firing step. This method reduces the number of active channels to the number of subarray elements; these channels are multiplexed across the full array and a reduced number of beams are acquired from each subarray. The low-resolution subarray images are laterally upsampled, interpolated, weighted, and coherently summed to form the final high-resolution PSA image. The PSA imaging reduces the complexity of the front-end hardware while achieving image quality approaching that of FPA imaging.

  View details for Web of Science ID 000226812800006

  View details for PubMedID 15742561

• Integrated ultrasound imaging systems based on capacitive micromachined ultrasonic transducer arrays 4th IEEE Conference on Sensors Wygant, I. O., Yeh, D. T., Zhuang, X. F., Vaithilingam, S., Nikoozadeh, A., Oralkan, O., Ergun, A. S., Yaralioglu, G. G., Khuri-Yakub, B. T. IEEE. 2005: 704–707

  View details for Web of Science ID 000237003500175

• Capacitive micromachined ultrasonic transducers (CMUTs) with piston-shaped membranes IEEE International Ultrasonics Symposium Huang, Y. L., Heaggstrom, E. O., Zhuang, X. F., Ergun, A. S., Khuri-Yakub, B. T. IEEE. 2005: 589–592

  View details for Web of Science ID 000236090700140

• High-resolution imaging with high-frequency 1-D linear CMUT arrays IEEE International Ultrasonics Symposium Yeh, D. T., Oralkan, O., Wygant, I. O., Ergun, A. S., Wong, J. H., Khuri-Yakub, B. T. IEEE. 2005: 665–668

  View details for Web of Science ID 000236090700159

• Acoustically actuated flextensional SixNy and single-crystal silicon 2-D micromachined ejector arrays IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING Demirci, U., Yaralioglu, G. G., Haeggstrom, E., Percin, G., Ergun, S., Khuri-Yakub, B. T. 2004; 17 (4): 517-524

  View details for DOI 10.1109/tsm.2004.835714

  View details for Web of Science ID 000224995800007

• Wideband micromachined capacitive microphones with radio frequency detection JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA Hansen, S. T., Ergun, A. S., Liou, W., Auld, B. A., Khuri-Yakub, B. T. 2004; 116 (2): 828-842

  View details for DOI 10.1121/1.1771617

  View details for Web of Science ID 000223281800019

• Forward-viewing CMUT arrays for medical Imaging IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Demirci, U., Ergun, A. S., Oralkan, O., Karaman, M., Khuri-Yakub, B. T. 2004; 51 (7): 887-895

  Abstract

  This paper reports the design and testing of forward-viewing annular arrays fabricated using capacitive micromachined ultrasonic transducer (CMUT) technology. Recent research studies have shown that CMUTs have broad frequency bandwidth and high-transduction efficiency. One- and two-dimensional CMUT arrays of various sizes already have been fabricated, and their viability for medical imaging applications has been demonstrated. We fabricated 64-element, forward-viewing annular arrays using the standard CMUT fabrication process and carried out experiments to measure the operating frequency, bandwidth, and transmit/receive efficiency of the array elements. The annular array elements, designed for imaging applications in the 20 MHz range, had a resonance frequency of 13.5 MHz in air. The immersion pulse-echo data collected from a plane reflector showed that the devices operate in the 5-26 MHz range with a fractional bandwidth of 135%. The output pressure at the surface of the transducer was measured to be 24 kPa/V. These values translate into a dynamic range of 131.5 dB for 1-V excitation in 1-Hz bandwidth with a commercial low noise receiving circuitry. The designed, forward-viewing annular CMUT array is suitable for mounting on the front surface of a cylindrical catheter probe and can provide Doppler information for measurement of blood flow and guiding information for navigation through blood vessels in intravascular ultrasound imaging.

  View details for Web of Science ID 000222678000018

  View details for PubMedID 15301009

• Ultrasonic mixing in microfluidic channels using integrated transducers ANALYTICAL CHEMISTRY Yaralioglu, G. G., Wygant, I. O., Marentis, T. C., Khuri-Yakub, B. T. 2004; 76 (13): 3694-3698

  Abstract

  This paper presents a microfluidic mixer that uses acoustic stirring created by ultrasonic waves. The ultrasound is introduced into the channel by integrated piezoelectric transducers. The transducers are made of a zinc oxide thin film, which is deposited on the bottom surface of a quartz substrate. The poly(dimethylsiloxane) channel is aligned to the transducers on the top surface of the substrate. The transducers are designed for operation around 450 MHz. The main mechanism of the mixing is the acoustic stirring of the fluid perpendicular to the flow direction. The radiation pressure that is generated by the transducer causes the stirring inside the microfluidic channel. The performance of the mixer is characterized by mixing phenolphthalein solution and sodium hydroxide dissolved in ethyl alcohol. Flow rates on the order of 1-100 microL/min are used. The transducers are driven by 1.2 V(rms) sinusoidal voltages at 450 MHz.

  View details for DOI 10.1021/ac035220k

  View details for Web of Science ID 000222418300038

  View details for PubMedID 15228343

• Capacitive micromachined ultrasonic transducers (CMUTS) with isolation posts IEEE Ultrasonics Symposium Huang, Y. L., Haeggstrom, E. O., Zhuang, X. F., Ergun, A. S., Khuri-Yakub, B. T. IEEE. 2004: 2223–2226

  View details for Web of Science ID 000228557202162

• CMUT ring arays for forward-looking intravascular imaging IEEE Ultrasonics Symposium Oralkan, O., Hansen, S. T., Bayram, B., Yaralioglu, G. G., Ergun, A. S., Khuri-Yakub, B. T. IEEE. 2004: 403–406

  View details for Web of Science ID 000228557207096

• Integrated ultrasonic imaging systems based on CMUT arrays: Recent progress IEEE Ultrasonics Symposium Wygant, I. O., Zhuang, X., Yeh, D. T., Nikoozadeh, A., Oralkan, O., Ergun, A. S., Karaman, M., Khuri-Yakub, B. T. IEEE. 2004: 391–394

  View details for Web of Science ID 000228557207093

• Analytical calculation of collapse voltage of CMUT membrane IEEE Ultrasonics Symposium Nikoozadeh, A., Bayram, B., Yaralioglu, G. G., Khuri-Yakub, B. T. IEEE. 2004: 256–259

  View details for Web of Science ID 000228557207063

• Micromachined ultrasonic transducers and their use for 2D and 3D imaging 27th International Symposium on Acoustical Imaging Khuri-Yakub, B. T., Ergun, A. S., Huang, Y., Cheng, C. H., Oralkan, O., Johnson, J., Yaralioglu, G. G., Karaman, M. SPRINGER. 2004: 1–9

  View details for Web of Science ID 000226549200001

• Dynamic FEM analysis of multiple cMUT cells in immersion IEEE Ultrasonics Symposium Bayram, B., Yaralioglu, G. G., Ergun, A. S., Oralkan, O., Khuri-Yakub, B. T. IEEE. 2004: 252–255

  View details for Web of Science ID 000228557207062

• Optimized membrane configuration improves CMUT performance IEEE Ultrasonics Symposium Huang, Y. L., Haeggstrom, E. O., Zhuang, X. F., Ergun, A. S., Khuri-Yakub, B. T. IEEE. 2004: 505–508

  View details for Web of Science ID 000228557207121

• Volumetric ultrasound Imaging using 2-D CMUT arrays IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Oralkan, O., Ergun, A. S., Cheng, C. H., Johnson, J. A., Karaman, M., Lee, T. H., Khuri-Yakub, B. T. 2003; 50 (11): 1581-1594

  Abstract

  Recently, capacitive micromachined ultrasonic transducers (CMUTs) have emerged as a candidate to overcome the difficulties in the realization of 2-D arrays for real-time 3-D imaging. In this paper, we present the first volumetric images obtained using a 2-D CMUT array. We have fabricated a 128 x 128-element 2-D CMUT array with through-wafer via interconnects and a 420-microm element pitch. As an experimental prototype, a 32 x 64-element portion of the 128 x 128-element array was diced and flip-chip bonded onto a glass fanout chip. This chip provides individual leads from a central 16 x 16-element portion of the array to surrounding bondpads. An 8 x 16-element portion of the array was used in the experiments along with a 128-channel data acquisition system. For imaging phantoms, we used a 2.37-mm diameter steel sphere located 10 mm from the array center and two 12-mm-thick Plexiglas plates located 20 mm and 60 mm from the array. A 4 x 4 group of elements in the middle of the 8 x 16-element array was used in transmit, and the remaining elements were used to receive the echo signals. The echo signal obtained from the spherical target presented a frequency spectrum centered at 4.37 MHz with a 100% fractional bandwidth, whereas the frequency spectrum for the echo signal from the parallel plate phantom was centered at 3.44 MHz with a 91% fractional bandwidth. The images were reconstructed by using RF beamforming and synthetic phased array approaches and visualized by surface rendering and multiplanar slicing techniques. The image of the spherical target has been used to approximate the point spread function of the system and is compared with theoretical expectations. This study experimentally demonstrates that 2-D CMUT arrays can be fabricated with high yield using silicon IC-fabrication processes, individual electrical connections can be provided using through-wafer vias, and flip-chip bonding can be used to integrate these dense 2-D arrays with electronic circuits for practical 3-D imaging applications.

  View details for Web of Science ID 000187162500021

  View details for PubMedID 14682642

• A new regime for operating capacitive micromachined ultrasonic transducers IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Bayram, B., Haeggstrom, E., Yaralioglu, G. G., Khuri-Yakub, B. T. 2003; 50 (9): 1184-1190

  Abstract

  We report on a new operation regime for capacitive micromachined ultrasonic transducers (cMUTs). Traditionally, cMUTs are operated at a bias voltage lower than the collapse voltage of their membranes. In the new proposed operation regime, first the cMUT is biased past the collapse voltage. Second, the bias voltage applied to the collapsed membrane is reduced without releasing the membrane. Third, the cMUT is excited with an ac signal at the bias point, keeping the total applied voltage between the collapse and snapback voltages. In this operation regime, the center of the membrane is always in contact with the substrate. Our finite element methods (FEM) calculations reveal that a cMUT operating in this new regime, between collapse and snapback voltages, possesses a coupling efficiency (k(T)2) higher than a cMUT operating in the conventional regime below its collapse voltage. This paper compares the simulation results of the coupling efficiencies of cMUTs operating in conventional and new operation regimes.

  View details for Web of Science ID 000185519100010

  View details for PubMedID 14561034

• Capacitive micromachined ultrasonic lamb wave transducers using rectangular membranes IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Badi, M. H., Yaralioglu, G. G., Ergun, A. S., Hansen, S. T., Wong, E. J., Khuri-Yakub, B. T. 2003; 50 (9): 1191-1203

  Abstract

  This paper details the theory, fabrication, and characterization of a new Lamb wave device. Built using capacitive micromachined ultrasonic transducers (CMUTs), the structure described uses rectangular membranes to excite and receive Lamb waves on a silicon substrate. An equivalent circuit model for the transducer is proposed that produces results, which match well with those observed by experiment. During the derivation of this model, emphasis is placed on the resistance presented to the transducer membranes by the Lamb wave modes. Finite element analysis performed in this effort shows that the dominant propagating mode in the device is the lowest order antisymmetric flexural wave (A0). Furthermore, most of the power that couples into the Lamb wave is due to energy in the vibrating membrane that is transferred to the substrate through the supporting posts of the device. The manufacturing process of the structure, which relies solely on fundamental IC-fabrication techniques, is also discussed. The resulting device has an 18-microm-thick substrate that is almost entirely made up of crystalline silicon and operates at a frequency of 2.1 MHz. The characterization of this device includes S-parameter and laser vibrometer measurements as well as delay-line transmission data. The insertion loss, as determined by both S-parameter and delay-line transmission measurements, is 20 dB at 2.1 MHz. When configured as a delay-line oscillator, the device functions well as a sensor with sensitivity to changes in the mass loading of its substrate.

  View details for Web of Science ID 000185519100011

  View details for PubMedID 14561035

• Photoresist deposition without spinning IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING Percin, G., Khuri-Yakub, B. T. 2003; 16 (3): 452-459

  View details for DOI 10.1109/TSM.2003.815197

  View details for Web of Science ID 000184695600017

• Fabricating capacitive micromachined ultrasonic transducers with wafer-bonding technology JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Huang, Y. L., Ergun, A. S., Haeggstrom, E., Badi, M. H., Khuri-Yakub, B. T. 2003; 12 (2): 128-137

  View details for DOI 10.1109/JMEMS.2003.809968

  View details for Web of Science ID 000182054900002

• Capacitive micromachined ultrasonic transducers: Theory and technology JOURNAL OF AEROSPACE ENGINEERING Ergun, A. S., Yaralioglu, G. G., Khuri-Yakub, B. T. 2003; 16 (2): 76-84

  View details for DOI 10.1061/(ASCE)0893-1321(2003)16:2(76)

  View details for Web of Science ID 000181846200005

• Calculation and measurement of electromechanical coupling coefficient of capacitive micromachined ultrasonic transducers IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Yaralioglu, G. G., Ergun, A. S., Bayram, B., Haeggstrom, E., Khuri-Yakub, B. T. 2003; 50 (4): 449-456

  Abstract

  The electromechanical coupling coefficient is an important figure of merit of ultrasonic transducers. The transducer bandwidth is determined by the electromechanical coupling efficiency. The coupling coefficient is, by definition, the ratio of delivered mechanical energy to the stored total energy in the transducer. In this paper, we present the calculation and measurement of coupling coefficient for capacitive micromachined ultrasonic transducers (CMUTs). The finite element method (FEM) is used for our calculations, and the FEM results are compared with the analytical results obtained with parallel plate approximation. The effect of series and parallel capacitances in the CMUT also is investigated. The FEM calculations of the CMUT indicate that the electromechanical coupling coefficient is independent of any series capacitance that may exist in the structure. The series capacitance, however, alters the collapse voltage of the membrane. The parallel parasitic capacitance that may exist in a CMUT or is external to the transducer reduces the coupling coefficient at a given bias voltage. At the collapse, regardless of the parasitics, the coupling coefficient reaches unity. Our experimental measurements confirm a coupling coefficient of 0.85 before collapse, and measurements are in agreement with theory.

  View details for Web of Science ID 000182674700012

  View details for PubMedID 12744401

• Piezoelectric droplet ejector for ink-jet printing of fluids and solid particles REVIEW OF SCIENTIFIC INSTRUMENTS Percin, G., Khuri-Yakub, B. T. 2003; 74 (2): 1120-1127

  View details for DOI 10.1063/1.1532839

  View details for Web of Science ID 000180579500030

• An implementation of a microfluidic mixer and switch using micromachined acoustic transducers 16th IEEE Annual International Conference on Micro Electro Mechanical Systems Jagannathan, H., Yaralioglu, G. G., Ergun, A. S., Khuri-Yakub, B. T. IEEE. 2003: 104–107

  View details for Web of Science ID 000182405500027

• Ultrasonic temperature control and measurement in micro-fluidic channels Conference on Microfluidics, BioMEMS, and Medical Microsystems Jagannathan, H., Yaralioglu, G. G., Ergun, A. S., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 2003: 243–247

  View details for Web of Science ID 000181864600031

• Wideband micromachined acoustic sensors with radio frequency detection Conference on Unattended Ground Sensor Technologies and Applications V Hansen, S. T., Ergun, A. S., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 2003: 42–50

  View details for Web of Science ID 000186054400005

• Improved modeling and fabrication techniques for capacitive micromachined ultrasonic lamb wave transducers IEEE International Ultrasonics Symposium Badi, M. H., Yaralioglu, G. G., Ergun, A. S., Huang, Y. L., Khuri-Yakub, B. T. IEEE. 2003: 585–588

  View details for Web of Science ID 000189492100127

• Micromachined fluid ejector arrays for biotechnological and biomedical applications 20th IEEE International Conference on Robotics and Automation (ICRA) Percin, G., Yaralioglu, G. G., Khuri-Yakub, B. T. IEEE. 2003: 2892–2894

  View details for Web of Science ID 000187419900464

• 2D acoustically actuated micromachined droplet ejector array IEEE International Ultrasonics Symposium Demirci, U., Yaralioglu, G. G., Haeggstrom, E., Percin, G., Khuri-Yakub, B. T. IEEE. 2003: 1983–1986

  View details for Web of Science ID 000189492100460

• Phased subarray imaging for low-cost, wideband coherent array imaging IEEE International Ultrasonics Symposium Johnson, J. A., Oralkan, O., Ergun, A. S., Demirci, U., Karaman, M., Khuri-Yakub, B. T. IEEE. 2003: 1875–1878

  View details for Web of Science ID 000189492100435

• Improved equivalent circuit and finite element method modeling of capacitive micromachined ultrasonic transducers IEEE International Ultrasonics Symposium Yaralioglu, G. G., Badi, M. H., Ergun, A. S., Khuri-Yakub, B. T., GINZTON, E. L. IEEE. 2003: 469–472

  View details for Web of Science ID 000189492100102

• Dynamic analysis of CMUTs in different regimes of operation IEEE International Ultrasonics Symposium Bayram, B., Haeggstrom, E., Ergun, A. S., Yaralioglu, G. G., Khuri-Yakub, B. T. IEEE. 2003: 481–484

  View details for Web of Science ID 000189492100105

• Capacitive micromachined ultrasonic transducers for robotic sensing applications IEEE/RSJ International Conference on Intelligent Robots and Systems Yaralioglu, G. G., Ergun, A. S., Huang, Y., Khuri-Yakub, B. T. IEEE. 2003: 2347–2352

  View details for Web of Science ID 000187883300380

• New fabrication process for capacitive micromachined ultrasonic transducers 16th IEEE Annual International Conference on Micro Electro Mechanical Systems Huang, Y., Ergun, A. S., Haeggstrom, E., Khuri-Yakub, B. T. IEEE. 2003: 522–525

  View details for Web of Science ID 000182405500130

• Acoustic heating and thermometry in microfluidic channels 16th IEEE Annual International Conference on Micro Electro Mechanical Systems Jagannathan, H., Yaralioglu, G. G., Ergun, A. S., Khuri-Yakub, B. T. IEEE. 2003: 474–477

  View details for Web of Science ID 000182405500118

• Collapsed regime operation of capacitive micromachined ultrasonic transducers based on wafer-bonding technique IEEE International Ultrasonics Symposium Huang, Y., Haeggstrom, E., Bayram, B., Zhuang, X., Ergun, A. S., Cheng, C. H., Khuri-Yakub, B. T. IEEE. 2003: 1161–1164

  View details for Web of Science ID 000189492100262

• Micromachined droplet ejector arrays REVIEW OF SCIENTIFIC INSTRUMENTS Percin, G., Yaralioglu, G. G., Khuri-Yakub, B. T. 2002; 73 (12): 4385-4389

  View details for DOI 10.1063/1.1517145

  View details for Web of Science ID 000179393200042

• Capacitive micromachined ultrasonic transducers: Next-generation arrays for acoustic imaging? IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Oralkan, O., Ergun, A. S., Johnson, J. A., Karaman, M., Demirci, U., Kaviani, K., Lee, T. H., Khuri-Yakub, B. T. 2002; 49 (11): 1596-1610

  Abstract

  Piezoelectric materials have dominated the ultrasonic transducer technology. Recently, capacitive micromachined ultrasonic transducers (CMUTs) have emerged as an alternative technology offering advantages such as wide bandwidth, ease of fabricating large arrays, and potential for integration with electronics. The aim of this paper is to demonstrate the viability of CMUTs for ultrasound imaging. We present the first pulse-echo phased array B-scan sector images using a 128-element, one-dimensional (1-D) linear CMUT array. We fabricated 64- and 128-element 1-D CMUT arrays with 100% yield and uniform element response across the arrays. These arrays have been operated in immersion with no failure or degradation in performance over the time. For imaging experiments, we built a resolution test phantom roughly mimicking the attenuation properties of soft tissue. We used a PC-based experimental system, including custom-designed electronic circuits to acquire the complete set of 128 x 128 RF A-scans from all transmit-receive element combinations. We obtained the pulse-echo frequency response by analyzing the echo signals from wire targets. These echo signals presented an 80% fractional bandwidth around 3 MHz, including the effect of attenuation in the propagating medium. We reconstructed the B-scan images with a sector angle of 90 degrees and an image depth of 210 mm through offline processing by using RF beamforming and synthetic phased array approaches. The measured 6-dB lateral and axial resolutions at 135 mm depth were 0.0144 radians and 0.3 mm, respectively. The electronic noise floor of the image was more than 50 dB below the maximum mainlobe magnitude. We also performed preliminary investigations on the effects of crosstalk among array elements on the image quality. In the near field, some artifacts were observable extending out from the array to a depth of 2 cm. A tail also was observed in the point spread function (PSF) in the axial direction, indicating the existence of crosstalk. The relative amplitude of this tail with respect to the mainlobe was less than -20 dB.

  View details for Web of Science ID 000179224100016

  View details for PubMedID 12484483

• Piezoelectrically actuated flextensional micromachined ultrasound droplet ejectors IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Percin, G., Khuri-Yakub, B. T. 2002; 49 (6): 756-766

  Abstract

  This paper reports a variation on the design of the flextensional transducer for use in ejecting liquids. The transducer is constructed by depositing a piezoelectric thin film to a thin, edge-clamped, circular annular plate. By placing a fluid behind one face of a vibrating compound plate that has an orifice at its center, we achieve continuous or drop-on-demand ejection of the fluid. We present results of ejection of water and isopropanol. The ejector is harmless to sensitive fluids and can be used to eject fuels as well as chemical and biological samples. Micromachined two-dimensional array piezoelectrically actuated flextensional droplet ejectors were realized using planar silicon micromachining techniques. Typical resonant frequency of the micromachined device ranges from 400 kHz to 4.5 MHz. The ejection of water thru a 5-microm diameter orifice at 3.5 MHz was demonstrated by using the developed micromachined two-dimensional array ejectors.

  View details for Web of Science ID 000176055500008

  View details for PubMedID 12075968

• Piezoelectrically actuated flextensional micromachined ultrasound transducers - I: Theory IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Percin, G., Khuri-Yakub, B. T. 2002; 49 (5): 573-584

  Abstract

  This series of two papers considers piezoelectrically actuated flextensional micromachined ultrasound transducers (PAFMUTs) and consists of theory, fabrication, and experimental parts. The theory presented in this paper is developed for an ultrasound transducer application presented in the second part. In the absence of analytical expressions for the equivalent circuit parameters of a flextensional transducer, it is difficult to calculate its optimal parameters and dimensions and difficult to choose suitable materials. The influence of coupling between flexural and extensional deformation and that of coupling between the structure and the acoustic volume on the dynamic response of piezoelectrically actuated flextensional transducer are analyzed using two analytical methods: classical thin (Kirchhoff) plate theory and Mindlin plate theory. Classical thin plate theory and Mindlin plate theory are applied to derive two-dimensional plate equations for the transducer and to calculate the coupled electromechanical field variables such as mechanical displacement and electrical input impedance. In these methods, the variations across the thickness direction vanish by using the bending moments per unit length or stress resultants. Thus, two-dimensional plate equations for a step-wise laminated circular plate are obtained as well as two different solutions to the corresponding systems. An equivalent circuit of the transducer is also obtained from these solutions.

  View details for Web of Science ID 000175662600005

  View details for PubMedID 12046933

• Piezoelectrically actuated flextensional micromachined ultrasound transducers - II: Fabrication and experiments IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Percin, G., Khuri-Yakub, B. T. 2002; 49 (5): 585-595

  Abstract

  This paper presents novel micromachined two-dimensional array piezoelectrically actuated flextensional transducers that can be used to generate sound in air or water. Micromachining techniques to fabricate these devices are also presented. Individual unimorph array elements consist of a thin piezoelectric annular disk and a thin, fully clamped, circular plate. We manufacture the transducer in two-dimensional arrays using planar silicon micromachining and demonstrate ultrasound transmission in air at 2.85 MHz with 0.15 microm/V peak displacement. The devices have a range of operating resonance frequencies starting from 450 kHz to 4.5 MHz. Such an array could be combined with on-board driving and addressing circuitry for different applications.

  View details for Web of Science ID 000175662600006

  View details for PubMedID 12046934

• Micromachined droplet ejector arrays for controlled ink-jet printing and deposition REVIEW OF SCIENTIFIC INSTRUMENTS Percin, G., Khuri-Yakub, B. T. 2002; 73 (5): 2193-2196

  View details for DOI 10.1063/1.1468684

  View details for Web of Science ID 000175194200035

• Piezoelectrically actuated flextensional micromachined ultrasound transducers 1st Ultrasonics International Conference Percin, G., Khuri-Yakub, B. T. ELSEVIER SCIENCE BV. 2002: 441–48

  Abstract

  This paper presents novel micromachined two-dimensional array piezoelectrically actuated flextensional transducers that can be used to generate sound in air or water. Micromachining techniques to fabricate these devices are also presented. Individual unimorph array elements consist of a thin piezoelectric annular disk and a thin, fully clamped, circular plate. We manufacture the transducer in two-dimensional arrays using planar silicon micromachining and demonstrate ultrasound transmission in air at 2.85 MHz with 0.15 microm/V peak displacement. The devices have a range of operating resonance frequencies starting from 450 kHz up to 4.5 MHz. Such an array could be combined with on-board driving and addressing circuitry for different applications.

  View details for Web of Science ID 000176648000079

  View details for PubMedID 12159981

• Finite element analysis of underwater capacitor micromachined ultrasonic transducers IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Roh, Y., Khuri-Yakub, B. T. 2002; 49 (3): 293-298

  Abstract

  A simple electro-mechanical equivalent circuit model is used to predict the behavior of capacitive micromachined ultrasonic transducers (cMUT). Most often, cMUTs are made in silicon and glass plates that are in the 0.5 mm to 1 mm range in thickness. The equivalent circuit model of the cMUT lacks important features such as coupling to the substrate and the ability to predict cross-talk between elements of an array of transducers. To overcome these deficiencies, a flnite element model of the cMUT is constructed using the commercial code ANSYS. Calculation results of the complex load impedance seen by single capacitor cells are presented, then followed by a calculation of the plane wave real load impedance seen by a parallel combination of many cells that are used to make a transducer. Cross-talk between 1-D array elements is found to be due to two main sources: coupling through a Stoneley wave propagating at the transducer-water interface and coupling through Lamb waves propagating in the substrate. To reduce the cross-talk level, the effect of structural variations of the substrate are investigated, which includes a change of its thickness and etched trenches or polymer walls between array elements.

  View details for Web of Science ID 000174440200002

  View details for PubMedID 12322877

• Underwater acoustic imaging using capacitive micromachined ultrasonic transducer arrays MTS/IEEE Oceans 2002 Conference Oralkan, O., Ergun, A. S., Cheng, C. H., Johnson, J. A., Karaman, M., Khuri-Yakub, B. T. IEEE. 2002: 2354–2360

  View details for Web of Science ID 000182293200370

• Fabrication of capacitive micromachined ultrasonic transducers (CMUTs) using wafer bonding technology for low frequency (10 kHz-150 kHz) sonar applications MTS/IEEE Oceans 2002 Conference Huang, Y., Ergun, A. S., Haeggstrom, E., Khuri-Yakub, B. T. IEEE. 2002: 2322–2327

  View details for Web of Science ID 000182293200365

• Fabrication and characterization of 1-dimensional and 2-dimensional capacitive micromachined ultrasonic transducer (CMUT) arrays for 2-dimensional and volumetric ultrasonic imaging MTS/IEEE Oceans 2002 Conference Ergun, A. S., Cheng, C. H., Demirci, U., Khuri-Yakub, B. T. IEEE. 2002: 2361–2367

  View details for Web of Science ID 000182293200371

• Phased subarray processing for underwater 3D acoustic imaging MTS/IEEE Oceans 2002 Conference Johnson, J. A., Karaman, M., Khuri-Yakub, B. T. IEEE. 2002: 2145–2151

  View details for Web of Science ID 000182293200336

• Medical imaging using capacitive micromachined ultrasonic transducerarrays Ultrasonics Johnson, J., A., Oralkan, O., Demirci, U., Ergun, S., Karaman, M., Khuri-Yakub, B., T. 2002; 40: 471-476
• Medical imaging using capacitive micromachined ultrasonic transducerarrays Ultrasonics Johnson, J., A., Oralkan, O., Demirci, U., Ergun, S., Karaman, M., Khuri-Yakub, B., T. 2002; 40: 471-476
• Piezoelectrically actuated flextensional micromachined ultrasonic transducers Ultrasonics Percin, G., Khuri-Yakub, B., T. 2002; 40: 441-448
• Volumetric imaging using 2D capacitive Micromachined Ultrasonic Transducer Arrays (CMUTs): Initial results IEEE International Ultrasonic Symposium Oralkan, O., Ergun, A. S., Cheng, C. H., Johnson, J. A., Karaman, M., Lee, T. H., Khuri-Yakub, B. T. IEEE. 2002: 1083–1086

  View details for Web of Science ID 000182111700242

• Lamb wave devices based on Capacitive Micromachined Ultrasonic Transducers IEEE International Ultrasonic Symposium Badi, M. H., Yaralioglu, G. G., Ergun, A. S., Hansen, S. T., Khuri-Yakub, B. T. IEEE. 2002: 1031–1034

  View details for Web of Science ID 000182111700230

• Electrical through-wafer interconnects with sub-picofarad parasitic capacitance Microelectromechanical Systems Conference Cheng, C. H., Ergun, A. S., Khuri-Yakub, B. T. IEEE. 2002: 18–21

  View details for Web of Science ID 000175725000006

• Broadband capacitive micromachined ultrasonic transducers ranging from 10 kHz to 60 mHz for imaging arrays and more IEEE International Ultrasonic Symposium Ergun, A. S., Huang, Y., Cheng, C. H., Oralkan, O., Johnson, J., Jagannathan, H., Demirci, U., Yaralioglu, G. G., Karaman, M., Khuri-Yakub, B. T. IEEE. 2002: 1039–1043

  View details for Web of Science ID 000182111700232

• Characterization of one-dimensional capacitive micromachined ultrasonic immersion transducer arrays IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Jin, X. C., Oralkan, O., Degertekin, F. L., Khuri-Yakub, B. T. 2001; 48 (3): 750-760

  Abstract

  In this paper, we report on the characterization of 1-D arrays of capacitive micromachined ultrasonic transducers (cMUT). A 275- x 5600-micron 1-D CMUT array element is experimentally characterized, and the results are found to be in agreement with theoretical predictions. As a receiver, the transducer has a 0.28-fm/square root of Hz displacement sensitivity, and, as a transmitter, it produces 5 kPa/V of output pressure at the transducer surface at 3 MHz with a DC bias of 35 V. The transducer has more than 100% fractional bandwidth around 3 MHz, which makes it suitable for ultrasound imaging. The radiation pattern of isolated single elements, as well as those of array elements are measured, and two major sources of acoustical cross talk are identified. A weakly dispersive non-leaky interface wave (Stoneley wave) is observed to be propagating at the silicon substrate-fluid interface at a speed close to the speed of sound in the fluid. This wave causes internal reflections, spurious resonance, and radiation from the edges of the silicon substrate. The large lateral component of the particle velocity generated by the membranes at the edge of the cMUT array elements is found to be the source of this interface wave. Lowest order Lamb waves in the silicon substrate are also found to contribute to the cross talk between elements. These waves are excited at the edges of individual vibrating membranes, where they are anchored to the substrate, and result in a narrowing of the beam profile of the array elements. Several methods, such as trench isolation and wafer thinning, are proposed and implemented to modify the acoustical cross coupling between array elements.

  View details for Web of Science ID 000168589400015

  View details for PubMedID 11381699

• Capacitive micromachined ultrasonic transducer arrays for medical imaging: Experimental results IEEE International Ultrasonic Symposium Demirci, U., Oralkan, O., Johnson, J. A., Ergun, A. S., Karaman, M., Khuri-Yakub, B. T. IEEE. 2001: 957–960

  View details for Web of Science ID 000176890800203

• Micromachined piezoelectrically actuated flextensional transducers for high resolution printing and imaging IEEE International Ultrasonic Symposium Percin, G., Khuri-Yakub, B. T. IEEE. 2001: 921–924

  View details for Web of Science ID 000176890800195

• Micromachined piezoelectrically actuated flextensional transducers for high resolution printing International Conference on Digital Printing Technologies Percin, G., Khuri-Yakub, B. T. SOCIETY IMAGING SCIENCE TECHNOLOGY. 2001: 673–676

  View details for Web of Science ID 000183952700156

• Acoustic sensing using radio micromachined frequency detection and capacitive ultrasonic transducers IEEE MTT-S International Microwave Symposium Hansen, S. T., Ergun, A. S., Khuri-Yakub, B. T. IEEE. 2001: 2243–2246

  View details for Web of Science ID 000175125500528

• Piezoelectrically actuated flextensional MUTs IEEE International Ultrasonic Symposium Percin, G., Khuri-Yakub, B. T. IEEE. 2001: 903–906

  View details for Web of Science ID 000176890800191

• Influence of the electrode size and location on the performance of a CMUT IEEE International Ultrasonic Symposium Bayram, B., Yaralioglu, G. G., Ergun, A. S., Khuri-Yakub, B. T. IEEE. 2001: 949–952

  View details for Web of Science ID 000176890800201

• Residual stress and Young's modulus measurement of capacitive micromachined ultrasonic transducer membranes IEEE International Ultrasonic Symposium Yaralioglu, G. G., Ergun, A. S., Bayram, B., Marentis, T., Khuri-Yakub, B. T. IEEE. 2001: 953–956

  View details for Web of Science ID 000176890800202

• Micro-fluidic channels with integrated ultrasonic transducers IEEE International Ultrasonic Symposium Jagannathan, H., Yaralioglu, G. G., Ergun, A. S., Degertekin, F. L., Khuri-Yakub, B. T. IEEE. 2001: 859–862

  View details for Web of Science ID 000176890800181

• Lamb wave devices using capacitive micromachined ultrasonic transducers APPLIED PHYSICS LETTERS Yaralioglu, G. G., Badi, M. H., Ergun, A. S., Cheng, C. H., Khuri-Yakub, B. T., Degertekin, F. L. 2001; 78 (1): 111-113

  View details for Web of Science ID 000166122000038

• Improved modeling and design of microphones using radio frequency detection with capacitive micromachined ultrasonic transducers IEEE International Ultrasonic Symposium Hansen, S. T., Ergun, A. S., Khuri-Yakub, B. T. IEEE. 2001: 961–964

  View details for Web of Science ID 000176890800204

• A novel parametric-effect MEMS amplifier JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Raskin, J. P., Brown, A. R., Khuri-Yakub, B. T., Rebeiz, G. M. 2000; 9 (4): 528-537

  View details for Web of Science ID 000166597800015

• Silicon micromachined ultrasonic transducers 20th Memorial Symposium on Ultrasonic Electronics (USE 99) Khuri-Yakub, B. T., Cheng, C. H., Degertekin, F. L., Ergun, S., Hansen, S., Jin, X. C., Oralkan, O. JAPAN SOC APPLIED PHYSICS. 2000: 2883–87

  View details for Web of Science ID 000088909800002

• RF detection for low frequency cMUTS and its comparison to traditional detection IEEE Ultrasonics Symposium Ergun, A. S., Hansen, S. T., Khuri-Yakub, B. T. IEEE. 2000: 935–938

  View details for Web of Science ID 000171881300200

• Finite element method and normal mode modeling of capacitive micromachined SAW and Lamb wave transducers IEEE Ultrasonics Symposium Yaralioglu, G. G., Degertekin, F. L., Badi, M. H., Auld, B. A., Khuri-Yakub, B. T. IEEE. 2000: 129–132

  View details for Web of Science ID 000171881300030

• Finite element modeling of capacitor micromachined ultrasonic transducers IEEE Ultrasonics Symposium Roh, Y., Khuri-Yakub, B. T. IEEE. 2000: 905–908

  View details for Web of Science ID 000171881300194

• Characterization of capacitive micromachined ultrasonic transducers in air using optical measurements IEEE Ultrasonics Symposium Hansen, S. T., Turo, A., Degertekin, F. L., Khuri-Yakub, B. T. IEEE. 2000: 947–950

  View details for Web of Science ID 000171881300203

• A first experimental verification of micromachined capacitive lamb wave transducers IEEE Ultrasonics Symposium Badi, M. H., Yaralioglu, G. G., Ergun, A. S., Degertekin, F. L., Cheng, C. H., Khuri-Yakub, B. T. IEEE. 2000: 311–314

  View details for Web of Science ID 000171881300067

• An efficient electrical addressing method using through-wafer vias for two-dimensional ultrasonic arrays IEEE Ultrasonics Symposium Cheng, C. H., Chow, E. M., Jin, X. C., Ergun, S., Khuri-Yakub, B. T. IEEE. 2000: 1179–1182

  View details for Web of Science ID 000171881300255

• Initial pulse-echo imaging results with one-dimensional capacitive micromachined ultrasonic transducer arrays IEEE Ultrasonics Symposium Oralkan, O., Jin, X. C., Kaviani, K., Ergun, A. S., Degertekin, F. L., Karaman, M., Khuri-Yakub, B. T. IEEE. 2000: 959–962

  View details for Web of Science ID 000171881300206

• Micromachined piezoelectrically actuated flextensional transducers for high resolution printing International Conference on Digital Printing Technologies Percin, G., Khuri-Yakub, B. T. SOCIETY IMAGING SCIENCE TECHNOLOGY. 2000: 68–68

  View details for Web of Science ID 000183951600014

• Theory and analysis of electrode size optimization for capacitive microfabricated ultrasonic transducers IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Bozkurt, A., Ladabaum, I., Atalar, A., Khuri-Yakub, B. T. 1999; 46 (6): 1364-1374

  Abstract

  Theoretical analysis and computer simulations of capacitive microfabricated ultrasonic transducers indicate that device performance can be optimized through judicious patterning of electrodes. The conceptual basis of the analysis is that electrostatic force should be applied only where it is most effective, such as at the center of a circular membrane. If breakdown mechanisms are ignored, an infinitesimally small electrode with an infinite bias voltage results in the optimal transducer. A more realistic design example compares the 3-dB bandwidths of a fully metalized transducer and a partially metalized transducer, each tuned with a lossless Butterworth network. It is found that the bandwidth of the optimally metalized device is twice that of the fully metalized device.

  View details for Web of Science ID 000084029700005

  View details for PubMedID 18244332

• Ultrasonic sensor for photoresist process monitoring IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING Morton, S. L., Degertekin, F. L., Khuri-Yakub, B. T. 1999; 12 (3): 332-339

  View details for Web of Science ID 000081882200009

• Controlled ink-jet printing and deposition of organic polymers and solid particles (vol 19, pg 2375, 1998) APPLIED PHYSICS LETTERS Percin, G., Lundgren, T. S., Khuri-Yakub, B. T. 1999; 74 (10): 1498-1498

  View details for Web of Science ID 000079011500050

• Fabrication and characterization of surface micromachined capacitive ultrasonic immersion transducers JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Jin, X. C., Ladabaum, I., Degertekin, F. L., Calmes, S., Khuri-Yakub, B. T. 1999; 8 (1): 100-114

  View details for Web of Science ID 000079038600014

• Simulation and experimental characterization of a 2-D, 3-MHZ capacitive micromachined ultrasonic transducer (CMUT) array element 1999 IEEE Ultrasonics International Symposium Oralkan, O., Jin, X. C., Degertekin, F. L., Khuri-Yakub, B. T. IEEE. 1999: 1141–1144

  View details for Web of Science ID 000088356000245

• Air-coupled nondestructive evaluation using micromachined ultrasonic transducers 1999 IEEE Ultrasonics International Symposium Hansen, S. T., Mossawir, B. J., Ergun, A. S., Degertekin, F. L., Khuri-Yakub, B. T. IEEE. 1999: 1037–1040

  View details for Web of Science ID 000088356000222

• Micromachined ultrasonic transducers for air-coupled non-destructive evaluation Conference on Nondestructive Evaluation of Aging Aircraft, Airports, and Aerospace Hardware III Hansen, S. T., Degertekin, F. L., Khuri-Yakub, B. T. SPIE - INT SOC OPTICAL ENGINEERING. 1999: 310–318

  View details for Web of Science ID 000079846700033

• Highly integrated 2-D capacitive micromachined ultrasonic transducers 1999 IEEE Ultrasonics International Symposium Calmes, S., Cheng, C. H., Degertekin, F. L., Jin, X. C., Ergun, S., Khuri-Yakub, B. T. IEEE. 1999: 1163–1166

  View details for Web of Science ID 000088356000249

• Ultrasonic monitoring of photoresist processing Conference on Metrology, Inspection, and Process Control for Microlithography XIII Morton, S. L., Degertekin, F. L., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 1999: 340–347

  View details for Web of Science ID 000081633500034

• Recent progress in capacitive micromachined ultrasonic immersion transducer array 8th International Symposium on Integrated Circuits, Devices and Systems (ISIC-99) Jin, X. C., Cheng, C. H., Oralkan, O., Calmes, S., Degertekin, F. L., Khuri-Yakub, B. T. NANYANG TECHNOLOGICAL UNIV. 1999: 159–162

  View details for Web of Science ID 000083413600043

• Controlled ink-jet printing and deposition of organic polymers and solid particles APPLIED PHYSICS LETTERS Percin, G., Lundgren, T. S., Khuri-Yakub, B. T. 1998; 73 (16): 2375-2377

  View details for Web of Science ID 000076427800049

• In situ ultrasonic monitoring of photoresist development APPLIED PHYSICS LETTERS Morton, S. L., Degertekin, F. L., Khuri-Yakub, B. T. 1998; 73 (15): 2215-2217

  View details for Web of Science ID 000076427700050

• The microfabrication of capacitive ultrasonic transducers JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Jin, X. C., Ladabaum, I., Khuri-Yakub, B. T. 1998; 7 (3): 295-302

  View details for Web of Science ID 000075535300003

• Micromachinable ultrasonic leaky wave air transducers APPLIED PHYSICS LETTERS Degertekin, F. L., Atalar, A., Khuri-Yakub, B. T. 1998; 73 (6): 741-743

  View details for Web of Science ID 000075303400013

• In situ ultrasonic measurement of photoresist glass transition temperature APPLIED PHYSICS LETTERS Morton, S. L., Degertekin, F. L., Khuri-Yakub, B. T. 1998; 72 (19): 2457-2459

  View details for Web of Science ID 000073540600035

• Surface micromachined capacitive ultrasonic transducers IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Ladabaum, I., Jin, X. C., Soh, H. T., Atalar, A., Khuri-Yakub, B. T. 1998; 45 (3): 678-690

  Abstract

  The current state of novel technology, surface microfabricated ultrasonic transducers, is reported. Experiments demonstrating both air and water transmission are presented. Air-coupled longitudinal wave transmission through aluminum is demonstrated, implying a 110 dB dynamic range for transducers at 2.3 MHz in air. Water transmission experiments from 1 to 20 MHz are performed, with a measured 60 dB SNR at 3 MHz. A theoretical model is proposed that agrees well with observed transducer behavior. Most significantly, the model is used to demonstrate that microfabricated ultrasonic transducers constitute an attractive alternative to piezoelectric transducers in many applications.

  View details for Web of Science ID 000073912500016

  View details for PubMedID 18244219

• Micromachined two-dimensional array piezoelectrically actuated transducers APPLIED PHYSICS LETTERS Percin, G., Atalar, A., Degertekin, F. L., Khuri-Yakub, B. T. 1998; 72 (11): 1397-1399

  View details for Web of Science ID 000072566000046

• Miniature drumheads: microfabricated ultrasonic transducers 17th Ultrasonics International Conference (UI 97) Ladabaum, I., Jin, X. C., Khuri-Yakub, B. T. ELSEVIER SCIENCE BV. 1998: 25–29

  View details for Web of Science ID 000073685400006

• Recent progress in surface micromachined capacitive ultrasonic transducers 5th International Conference on Solid-State and Integrated Circuit Technology Jin, X. C., Ladabaum, I., Degertekin, F. L., Calmes, S., Khuri-Yakub, B. T. IEEE. 1998: 880–883

  View details for Web of Science ID 000080928800237

• Silicon micromachined ultrasonic transducers 1998 IEEE Ultrasonics Symposium Khuri-Yakub, B. T., Degertekin, F. L., Jin, X. C., Calmes, S., Ladabaum, I., Hansen, S., Zhang, X. J. IEEE. 1998: 985–991

  View details for Web of Science ID 000079968900216

• Ultrasonic cure and temperature monitoring of photoresist during pre-exposure bake process Conference on Metrology, Inspection, and Process Control for Microlithography XII Morton, S. L., Degertekin, F. L., Khuri-Yakub, B. T. SPIE - INT SOC OPTICAL ENGINEERING. 1998: 254–261

  View details for Web of Science ID 000075068300026

• Micromachined capacitive immersion ultrasonic transducers Conference on Ultrasonic Transducer Engineering - Medical Imaging 1998 Khuri-Yakub, B. T., Jin, X. C., Ladabaum, I., Degertekin, F. L. SPIE - INT SOC OPTICAL ENGINEERING. 1998: 237–241

  View details for Web of Science ID 000074538600021

• Defect imaging by micromachined ultrasonic air transducers 1998 IEEE Ultrasonics Symposium Hansen, S., Irani, N., Degertekin, F. L., Ladabaum, I., Khuri-Yakub, B. T. IEEE. 1998: 1003–1006

  View details for Web of Science ID 000079968900219

• Analytic modeling of loss and cross-coupling in capacitive micromachined ultrasonic transducers 1998 IEEE Ultrasonics Symposium Bozkurt, A., Degertekin, F. L., Atalar, A., Khuri-Yakub, B. T. IEEE. 1998: 1025–1028

  View details for Web of Science ID 000079968900224

• Surface micromachined capacitive ultrasonic immersion transducers 11th Annual International Workshop on Micro Electro Mechanical Systems Jin, X. C., Ladabaum, I., Khuri-Yakub, B. T. IEEE. 1998: 649–654

  View details for Web of Science ID 000073380900116

• Resist deposition without spinning by using novel inkjet technology and direct lithography for MEMS 15th Annual SPIE Conference on Advances in Resist Technology and Processing Percin, G., Sob, T. H., Khuri-Yakub, B. T., GINZTON, E. L. SPIE-INT SOC OPTICAL ENGINEERING. 1998: 1382–1389

  View details for Web of Science ID 000075444000134

• Micromachined capacitive ultrasonic immersion transducer for medical imaging 10th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society Jin, X. C., Khuri-Yakub, B. T., Degertekin, F. L., Ladabaum, I., Calmes, S. IEEE. 1998: 779–782

  View details for Web of Science ID 000079210400212

• Micromachined capacitive transducer arrays for medical ultrasound imaging 1998 IEEE Ultrasonics Symposium Jin, X. C., Degertekin, F. L., Calmes, S., Zhang, X. J., Ladabaum, I., Khuri-Yakub, B. T. IEEE. 1998: 1877–1880

  View details for Web of Science ID 000079968900419

• Micromachined 2-D array piezoelectrically actuated flextensional transducers: New designs Micromachined Devices amd Components IV Percin, G., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 1998: 411–414

  View details for Web of Science ID 000076796500043

• Control of a drop-ejector used as photo-resist dispenser SPIE Conference on Mathematics and Control in Smart Structures Roche, P. E., Hansson, A., Khuri-Yakub, B. T. SPIE-INT SOC OPTICAL ENGINEERING. 1998: 446–454

  View details for Web of Science ID 000075786300041

• Piezoelectrically actuated droplet ejector REVIEW OF SCIENTIFIC INSTRUMENTS Percin, G., Levin, L., Khuri-Yakub, B. T. 1997; 68 (12): 4561-4563

  View details for Web of Science ID 000071054200042

• Controlled two-step solid-phase crystallization for high-performance polysilicon TFT's IEEE ELECTRON DEVICE LETTERS Subramanian, V., Dankoski, P., Degertekin, L., KHURIYAKUB, B. T., Saraswat, K. C. 1997; 18 (8): 378-381

  View details for Web of Science ID A1997XM44100004

• Lamb wave excitation by Hertzian contacts with applications in NDE IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Degertekin, F. L., KHURIYAKUB, B. T. 1997; 44 (4): 769-779

  View details for Web of Science ID A1997XL86900006

• In situ monitoring of crystallinity and temperature during rapid thermal crystallization of silicon on glass JOURNAL OF THE ELECTROCHEMICAL SOCIETY Subramanian, V., Degertekin, F. L., Dankoski, P., KHURIYAKUB, B. T., Saraswat, K. C. 1997; 144 (6): 2216-2221

  View details for Web of Science ID A1997XH82800070

• Air coupled through transmission of aluminum and other recent results using MUTs 1997 IEEE Ultrasonics Symposium Ladabaum, I., Jin, X. C., Khuri-Yakub, B. T. I E E E. 1997: 983–986

  View details for Web of Science ID 000072927100207

• Non-linear dynamics of flexural disc transducers 1997 IEEE Ultrasonics Symposium Roche, P. M., Khuri-Yakub, B. T. I E E E. 1997: 971–974

  View details for Web of Science ID 000072927100204

• Micromachinable leaky wave air transducers 1997 IEEE Ultrasonics Symposium Degertekin, L., Atalar, A., Khuri-Yakub, B. T. I E E E. 1997: 975–978

  View details for Web of Science ID 000072927100205

• The microfabrication of capacitive ultrasonic transducers 9th International Conference on Solid-State Sensors and Actuators Jin, X. C., Ladabaum, I., KHURIYAKUB, B. T. IEEE. 1997: 437–440

  View details for Web of Science ID A1997BJ35B00109

• Ultrasonic cure monitoring of photoresist during pre-exposure bake process 1997 IEEE Ultrasonics Symposium Morton, S. L., Degertekin, F. L., Khuri-Yakub, B. T. I E E E. 1997: 837–840

  View details for Web of Science ID 000072927100175

• Plate thickness and transducer distance dual inversion with dry contact ultrasonic Lamb wave transducers 1997 IEEE Ultrasonics Symposium Pei, J., Khuri-Yakub, B. T. I E E E. 1997: 1021–1024

  View details for Web of Science ID 000072927100216

• A novel technique for in-situ monitoring of crystallinity and temperature during rapid thermal annealing of thin Si/Si-Ge films on quartz/glass Symposium on Flat Panel Display Materials II, at the 1996 MRS Spring Meeting Subramanian, V., Degertekin, F. L., Dankoski, P., KHURIYAKUB, B. T., Saraswat, K. C. MATERIALS RESEARCH SOCIETY. 1997: 267–272

  View details for Web of Science ID A1997BH30A00041

• Controlled two-step solid-phase crystallization for high-performance polysilicon TFT's Electron Device Letters, IEEE Subramanian, V., Dankoski, P., Degertekin, L., Khuri-Yakub, B., T., Saraswat, K., C. 1997; 18 (8): 378-381
• Lamb wave excitation by Hertzian contacts with applications in NDE Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on Degertekin, F., L., Khuri-Yakub, B., T. 1997; 44 (4): 769-779
• In Situ Monitoring of Crystallinity and Temperature During Rapid Thermal Crystallization of Silicon on Glass J. Electrochem. Soc. Subramanian, V., Degertekin, F., L., Dankoski, P., Khuri-Yakub, B., T., Saraswat, K., C. 1997; 144: 2216-2221
• Analysis of micro machinable piezoelectrically driven one dimensional flexural transducers 1997 IEEE Ultrasonics Symposium RONNEKLEIV, A., Roche, P. E., Khuri-Yakub, B. T. I E E E. 1997: 1061–1065

  View details for Web of Science ID 000072927100225

• Dry contact ultrasonic sensors for structural monitoring International Workshop on Structural Health Monitoring Khuri-Yakub, B. T., Degertekin, F. L., Pei, J. TECHNOMIC PUBL CO INC. 1997: 481–491

  View details for Web of Science ID 000086581600040

• Micromachined 2-D array piezoelectricallly actuated flextensional transducers 1997 IEEE Ultrasonics Symposium Percin, G., Khuri-Yakub, B. T. I E E E. 1997: 959–962

  View details for Web of Science ID 000072927100201

• An improved circuit model of MUTs 1997 IEEE Ultrasonics Symposium RONNEKLEIV, A., Ladabaum, I., Jin, X. C., Khuri-Yakub, B. T. I E E E. 1997: 395–399

  View details for Web of Science ID 000072927100080

• Silicon micromachined ultrasonic immersion transducers APPLIED PHYSICS LETTERS Soh, H. T., Ladabaum, I., Atalar, A., Quate, C. F., KHURIYAKUB, B. T. 1996; 69 (24): 3674-3676

  View details for Web of Science ID A1996VW75000018

• Single mode lamb wave excitation in thin plates by Hertzian contacts APPLIED PHYSICS LETTERS Degertekin, F. L., KHURIYAKUB, B. T. 1996; 69 (2): 146-148

  View details for Web of Science ID A1996UW17200003

• Temperature measurement in rapid thermal processing using the acoustic temperature sensor IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING Lee, Y. J., KHURIYAKUB, B. T., Saraswat, K. 1996; 9 (1): 115-121

  View details for Web of Science ID A1996TW65900017

• Modeling, measurement and control of rapid thermal processing 1st Meeting on Transient Thermal Processing Techniques in Electronic Materials at the 1996 TMS Annual Meeting Saraswat, K. C., Chen, Y. H., Khuri-Yakub, B. T. MINERALS, METALS & MATERIALS SOC. 1996: 3–10

  View details for Web of Science ID 000078837100001

• Ultrasonic monitoring of photoresist prebake using TOF measurement 1996 IEEE Ultrasonic Symposium Morton, S. L., Hansson, A., KHURIYAKUB, B. T. I E E E. 1996: 1013–1016

  View details for Web of Science ID A1996BH56C00211

• Piezoelectrically actuated transducer and droplet ejector 1996 IEEE Ultrasonic Symposium Percin, G., Levin, L., KHURIYAKUB, B. T. I E E E. 1996: 913–916

  View details for Web of Science ID A1996BH56C00190

• Application of surface impedance approach to ultrasonic wave propagation in layered anisotropic media 1996 IEEE Ultrasonic Symposium Degertekin, F. L., HONEIN, B. V., KHURIYAKUB, B. T. I E E E. 1996: 559–562

  View details for Web of Science ID A1996BH56C00116

• In situ simultaneous measurement of temperature and thin film thickness with ultrasonic techniques 1996 IEEE Ultrasonic Symposium Pei, J., KHURIYAKUB, B. T., Degertekin, F. L., HONEIN, B. V., STANKE, F. E., Saraswat, K. C. I E E E. 1996: 1039–1042

  View details for Web of Science ID A1996BH56C00216

• Erosion/corrosion monitoring with dry contact ultrasonic lamb wave transducers Conference on Nondestructive Evaluation of Aging Aircraft, Airports, and Aerospace Hardware Pei, J., Degertekin, F. L., HONEIN, B. V., KHURIYAKUB, B. T. SPIE - INT SOC OPTICAL ENGINEERING. 1996: 428–435

  View details for Web of Science ID A1996BG82A00045

• In situ simultaneous measurement of temperature and thin film thickness with ultrasonic techniques Conference on Nondestructive Evaluation for Process Control in Manufacturing KHURIYAKUB, B. T., Pei, J., Degertekin, F. L., Saraswat, K. C. SPIE - INT SOC OPTICAL ENGINEERING. 1996: 131–135

  View details for Web of Science ID A1996BG84R00014

• Microfabricated ultrasonic transducers: Towards robust models and immersion devices 1996 IEEE Ultrasonic Symposium Ladabaum, I., Jin, X., Soh, H. T., Pierre, F., Atalar, A., KHURIYAKUB, B. T. I E E E. 1996: 335–338

  View details for Web of Science ID A1996BH56C00068

• Hertzian contact transducers for nondestructive evaluation JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA Degertekin, F. L., KHURIYAKUB, B. T. 1996; 99 (1): 299-308

  View details for Web of Science ID A1996TQ78700031

• A surface micromachined electrostatic ultrasonic air transducer IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL HALLER, M. I., KHURIYAKUB, B. T. 1996; 43 (1): 1-6

  View details for Web of Science ID A1996TQ35100001

• Lamb wave tomography and its application in pipe erosion/corrosion monitoring RESEARCH IN NONDESTRUCTIVE EVALUATION Pei, J., Yousuf, M. I., Degertekin, F. L., HONEIN, B. V., KHURIYAKUB, B. T. 1996; 8 (4): 189-197

  View details for Web of Science ID A1996WD82100001

• A surface micromachined electrostatic ultrasonic air transducer Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on Haller, M., I., Khuri-Yakub, B., T. 1996; 43 (1): 1-6
• Single mode lamb wave excitation in thin plates by hertzian contacts Appl. Phys. Lett. Degertekin, F., L., Khuri-Yakub, B., T. 1996; 69: 146-148
• Micromachined ultrasonic air-transducers (MUTs) International Conference on Micro-Engineering and Nano-Engineering 1995 (MNE 95) Spoliansky, D., Ladabaum, I., KHURIYAKUB, B. T. ELSEVIER SCIENCE BV. 1996: 535–38

  View details for Web of Science ID A1996TV40000121

• Point Contact Ultrasonic Transducer of Waveguiding Structure for High-Freq. Operation Appl. Phys. Lett. Yamada, K., Khuri-Yakub, B., T. 1996; 68: 1335-1337
• Hertzian contact transducers for nondestructive evaluation J. Acoustical Society of America Degertekin, F., L., Khuri-Yakub, B., T. 1996; 99: 299-308
• Micromachined ultrasonic transducers: 11.4 MHz transmission in air and more APPLIED PHYSICS LETTERS Ladabaum, I., KHURIYAKUB, B. T., Spoliansky, D. 1996; 68 (1): 7-9

  View details for Web of Science ID A1996TM84700003

• Plate tomography with dry contact lamb wave transducers 22nd International Symposium on Acoustical Imaging Pei, J., Yousuf, M. I., Degertekin, F. L., HONEIN, B. V., KHURIYAKUB, B. T. PLENUM PRESS DIV PLENUM PUBLISHING CORP. 1996: 725–730

  View details for Web of Science ID A1996BF85N00118

• IN-SITU THIN-FILM THICKNESS MEASUREMENT WITH ACOUSTIC LAMB WAVES APPLIED PHYSICS LETTERS Pei, J., Degertekin, F. L., KHURIYAKUB, B. T., Saraswat, K. C. 1995; 66 (17): 2177-2179

  View details for Web of Science ID A1995QU40600009

• A new flexible rapid thermal processing system 1995 MRS Spring Meeting on Rapid Thermal and Integrated Processing Saraswat, K. C., Chen, Y., Degertekin, L., KHURIYAKUB, B. T. MATERIALS RESEARCH SOC. 1995: 35–47

  View details for Web of Science ID A1995BE31M00005

• Efficient excitation and detection of lamb waves for process monitoring and NDE 1995 IEEE Ultrasonics Symposium Degertekin, F. L., HONEIN, B. V., KHURIYAKUB, B. T. IEEE. 1995: 787–790

  View details for Web of Science ID A1995BF57F00154

• Lamb wave tomography and its application in pipe erosion/corrosion monitoring 1995 IEEE Ultrasonics Symposium Pei, J., Yousuf, M. I., Degertekin, F. L., HONEIN, B. V., KHURIYAKUB, B. T. IEEE. 1995: 795–798

  View details for Web of Science ID A1995BF57F00156

• Micromachined ultrasonic transducers (MUTs) 1995 IEEE Ultrasonics Symposium Ladabaum, I., KHURIYAKUB, B. T., Spoliansky, D., HALLER, M. I. IEEE. 1995: 501–504

  View details for Web of Science ID A1995BF57F00097

• In-situ thin film thickness measurement with acoustic lamb waves Appl. Phys. Lett. Pei, J., Degertekin, F., L., Khuri-Yakub, B., T., Saraswat, K., C. 1995; 66: 2177-2179
• A new flexible rapid thermal processing system Materials-Research-Society Symposium on Modeling and Simulation of Thin-Film Processing Saraswat, K. C., Chen, Y., Degertekin, L., KHURIYAKUB, B. T. MATERIALS RESEARCH SOC. 1995: 307–319

  View details for Web of Science ID A1995BE11P00043

• MICROMACHINED 1-3 COMPOSITES FOR ULTRASONIC AIR TRANSDUCERS REVIEW OF SCIENTIFIC INSTRUMENTS HALLER, M. I., KHURIYAKUB, B. T. 1994; 65 (6): 2095-2098

  View details for Web of Science ID A1994NU85400044

• RAPID THERMAL MULTIPROCESSING FOR A PROGRAMMABLE FACTORY FOR ADAPTABLE MANUFACTURING OF ICS IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING Saraswat, K. C., Apte, P. P., Booth, L., CHEN, Y. Z., DANKOSKI, P. C., Degertekin, F. L., Franklin, G. F., KHURIYAKUB, B. T., Moslehi, M. M., Schaper, C., GYUGYI, P. J., Lee, Y. J., Pei, J., Wood, S. C. 1994; 7 (2): 159-175

  View details for Web of Science ID A1994NR23100008

• TEMPERATURE-MEASUREMENT IN RAPID THERMAL-PROCESSING USING ACOUSTIC TECHNIQUES REVIEW OF SCIENTIFIC INSTRUMENTS Lee, Y. J., KHURIYAKUB, B. T., Saraswat, K. C. 1994; 65 (4): 974-976

  View details for Web of Science ID A1994NG49400031

• IN-SITU ACOUSTIC TEMPERATURE TOMOGRAPHY OF SEMICONDUCTOR WAFERS APPLIED PHYSICS LETTERS Degertekin, F. L., Pei, J., KHURIYAKUB, B. T., Saraswat, K. C. 1994; 64 (11): 1338-1340

  View details for Web of Science ID A1994NA49600009

• INSITU THIN FILM THICKNESS MEASUREMENT USING ULTRASONICS WAVES 1994 IEEE Ultrasonics Symposium Pei, J., Degertekin, F. L., HONEIN, B. V., KHURIYAKUB, B. T., Saraswat, K. C. I E E E. 1994: 1237–1240

  View details for Web of Science ID A1994BC66H00248

• PROPAGATION IN FINITE ANISOTROPIC PLATES OF DIFFRACTING SCALAR WAVES 1994 IEEE Ultrasonics Symposium ROCHE, P. E., KHURIYAKUB, B. T. I E E E. 1994: 679–682

  View details for Web of Science ID A1994BC66H00135

• A SURFACE MICROMACHINED ELECTROSTATIC ULTRASONIC AIR TRANSDUCER 1994 IEEE Ultrasonics Symposium HALLER, M. I., KHURIYAKUB, B. T. I E E E. 1994: 1241–1244

  View details for Web of Science ID A1994BC66H00249

• 3D MODELING OF RAPID THERMAL PROCESSORS FOR DESIGN OPTIMIZATION OF A NEW FLEXIBLE RTP SYSTEM 1994 IEEE International Electron Devices Meeting CHEN, Y. Z., Booth, L., Schaper, C., KHURIYAKUB, B. T., Saraswat, K. C. IEEE. 1994: 545–548

  View details for Web of Science ID A1994BC55U00124

• TILTED SAMPLE ACOUSTIC MICROSCOPY FOR ANISOTROPY MEASUREMENT 1994 IEEE Ultrasonics Symposium Degertekin, F. L., HONEIN, B. V., KHURIYAKUB, B. T. I E E E. 1994: 1433–1436

  View details for Web of Science ID A1994BC66H00288

• THIN FILM EFFECTS IN ULTRASONIC WAFER THERMOMETRY 1994 IEEE Ultrasonics Symposium Degertekin, F. L., Pei, J., HONEIN, B. V., KHURIYAKUB, B. T., Saraswat, K. C. I E E E. 1994: 1337–1341

  View details for Web of Science ID A1994BC66H00268

• EFFECT OF SURFACE-TENSION ON THE ACOUSTIC RADIATION PRESSURE-INDUCED MOTION OF THE WATER AIR INTERFACE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA CINBIS, C., Mansour, N. N., KHURIYAKUB, B. T. 1993; 94 (4): 2365-2372

  View details for Web of Science ID A1993MB55200045

• SCANNING ACOUSTIC MICROSCOPY ULTRASONICS KHURIYAKUB, B. T. 1993; 31 (5): 361-372

  View details for Web of Science ID A1993LV11800010

• ONE-POINT CONTACT MEASUREMENT OF SPHERICAL RESONANCES APPLIED PHYSICS LETTERS Hsieh, C. P., KHURIYAKUB, B. Y. 1993; 62 (24): 3091-3093

  View details for Web of Science ID A1993LF99000010

• IN-SITU ULTRASONIC THERMOMETRY OF SEMICONDUCTOR WAFERS IEEE 1993 Ultrasonics Symposium Degertekin, F. L., Pei, J., Lee, Y. J., KHURIYAKUB, B. T., Saraswat, K. C. I E E E. 1993: 375–377

  View details for Web of Science ID A1993BA31N00069

• OPTICAL PROBING OF SPHERICAL RESONANCE APPLIED TO SURFACE DEFECT INSPECTION 19TH ANNUAL REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION Hsieh, C. P., KHURIYAKUB, B. T. PLENUM PRESS DIV PLENUM PUBLISHING CORP. 1993: 1093–1098

  View details for Web of Science ID A1993BY59R00140

• HIGH-EFFICIENCY FRESNEL ACOUSTIC LENSES IEEE 1993 Ultrasonics Symposium Hadimioglu, B., RAWSON, E. G., Lujan, R., Lim, M., ZESCH, J. C., KHURIYAKUB, B. T., Quate, C. F. I E E E. 1993: 579–582

  View details for Web of Science ID A1993BA31N00108

• HIGH-FREQUENCY ULTRASONIC TECHNIQUES Ultrasonics International Conference Hadimioglu, B., KHURIYAKUB, B. T. BUTTERWORTH-HEINEMANN. 1993: 559–562

  View details for Web of Science ID A1993BA27D00133

• IN-SITU TEMPERATURE MONITORING IN RTP BY ACOUSTICAL TECHNIQUES SYMP ON RAPID THERMAL AND INTEGRATED PROCESSING 2, AT THE 1993 SPRING MEETING OF THE MATERIALS RESEARCH SOC Degertekin, F. L., Pei, J., Lee, Y. J., KHURIYAKUB, B. T., Saraswat, K. C. MATERIALS RESEARCH SOC. 1993: 133–138

  View details for Web of Science ID A1993BY84M00020

• Effect of surface tension on the acoustic radiation pressure-induced motion of the water-air interface Journal of the Acoustical Society of America Cinbis, C., Mansour, N., N., Khuri-Yakub, B., T. 1993; 94 (4): 2365-72
• Effect of surface tension on the acoustic radiation pressure-induced motion of the water-air interface Journal of the Acoustical Society of America Cinbis, C., Mansour, N., N., Khuri-Yakub, B., T. 1993; 94 (4): 2365-72
• MATERIAL CHARACTERIZATION USING HERTZIAN POINT-CONTACT TRANSDUCERS IEEE 1993 Ultrasonics Symposium Degertekin, F. L., Pei, J., KHURIYAKUB, B. T. I E E E. 1993: 297–299

  View details for Web of Science ID A1993BA31N00054

• TAPERED ACOUSTIC MATCHING LAYERS IEEE 1993 Ultrasonics Symposium HALLER, M. I., KHURIYAKUB, B. T. I E E E. 1993: 505–508

  View details for Web of Science ID A1993BA31N00094

• COMPUTATION OF RIPPLE WAVE PARAMETERS - A COMPARISON OF METHODS JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS Fernandez, D. M., Vesecky, J. F., NAPOLITANO, D. J., KHURIYAKUB, B. T., Mann, J. A. 1992; 97 (C4): 5207-5213

  View details for Web of Science ID A1992HQ25600002

• SURFACE DEFECT INSPECTION OF SPHERICAL OBJECTS BY THE RESONANT SPHERE TECHNIQUE APPLIED PHYSICS LETTERS Hsieh, C. P., KHURIYAKUB, B. T. 1992; 60 (15): 1815-1817

  View details for Web of Science ID A1992HN48100015

• A NONCONTACTING TECHNIQUE FOR MEASURING SURFACE-TENSION OF LIQUIDS REVIEW OF SCIENTIFIC INSTRUMENTS CINBIS, C., KHURIYAKUB, B. T. 1992; 63 (3): 2048-2050

  View details for Web of Science ID A1992HG44900035

• A noncontacting technique for measuring surface tension of liquids Review of Scientific Instruments Cinbis, C., Khuri-Yakub, B., T. 1992; 63 (3): 2048-2050
• MICROMACHINED ACOUSTIC MATCHING LAYERS CONF ON NEW DEVELOPMENTS IN ULTRASONIC TRANSDUCERS AND TRANSDUCER SYSTEMS HALLER, M. I., KHURIYAKUB, B. T. SPIE - INT SOC OPTICAL ENGINEERING. 1992: 72–77

  View details for Web of Science ID A1992BX17C00006

• NEAR-FIELD ACOUSTIC MICROSCOPY CONF ON SCANNING MICROSCOPY INSTRUMENTATION KHURIYAKUB, B. T., Akamine, S., Hadimioglu, B., YAMADA, H., Quate, C. F. SPIE - INT SOC OPTICAL ENGINEERING. 1992: 30–39

  View details for Web of Science ID A1992BV26R00004

• ACOUSTIC INK PRINTING IEEE 1992 ULTRASONIC SYMP Hadimioglu, B., Elrod, S. A., STEINMETZ, D. L., Lim, M., ZESCH, J. C., KHURIYAKUB, B. T., RAWSON, E. G., Quate, C. F. I E E E. 1992: 929–935

  View details for Web of Science ID A1992BY55S00183

• 1-3 COMPOSITES FOR ULTRASONIC AIR TRANSDUCERS IEEE 1992 ULTRASONIC SYMP HALLER, M. I., KHURIYAKUB, B. T. I E E E. 1992: 937–939

  View details for Web of Science ID A1992BY55S00184

• ACOUSTIC INK PRINTING - PRINTING BY ULTRASONIC INK EJECTION 8TH INTERNATIONAL CONGRESS ON ADVANCES IN NON-IMPACT PRINTING TECHNOLOGIES Hadimioglu, B., Elrod, S. A., Lim, M., STEINMETZ, D. L., ZESCH, J. C., KHURIYAKUB, B. T., RAWSON, E. G., Quate, C. F. SOC IMAGING SCIENCE & TECHNOLOGY. 1992: 411–415

  View details for Web of Science ID A1992BZ19M00102

• SINGLE-POINT CONTACT MEASUREMENTS OF MECHANICAL RESONANCES IEEE 1992 ULTRASONIC SYMP Hsieh, C. P., KHURIYAKUB, B. T. I E E E. 1992: 787–789

  View details for Web of Science ID A1992BY55S00155

• A noncontacting technique for measuring surface tension of liquids Review of Scientific Instruments Cinbis, C., Khuri-Yakub, B., T. 1992; 63 (3): 2048-2050
• IMAGE-PROCESSING FOR A SCANNING ACOUSTIC MICROSCOPE THAT MEASURES AMPLITUDE AND PHASE IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL REINHOLDTSEN, P. A., KHURIYAKUB, B. T. 1991; 38 (2): 141-147

  Abstract

  Several image-processing techniques for a low-frequency (3 to 10 MHz) scanning acoustic microscope (SAM) that measures amplitude and phase are described. This microscope is capable of measuring both the amplitude and phase of the reflected and transmitted signals, in contrast with most earlier implementations that only measure the amplitude. By measuring phase, the authors can carry out quantitative nondestructive evaluation (NDE) and image processing that cannot be done with amplitude or phase alone. The effective 2-D point spread function of the microscope is modified by spatial filtering of the digitized complex images. In various images, the transverse resolution is improved by about 20%, aberration of images of subsurface features is corrected, and surface features are numerically defocused. The last process is used to remove the obscuring effect of surface roughness from images of subsurface features.

  View details for Web of Science ID A1991EY70100008

  View details for PubMedID 18267568

• Image processing for a scanning acoustic microscope that measures amplitude and phase Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on Reinholdtsen, P., A., Khuri-Yakub, B., T. 1991; 38 (2): 141-147
• HIGH-FREQUENCY ULTRASONIC INSPECTION OF GREEN AND HIPPED SILICON-NITRIDE CYLINDRICAL SAMPLES SYMP ON NONDESTRUCTIVE EVALUATION AND MATERIAL PROPERTIES OF ADVANCED MATERIALS, AT THE 1991 ANNUAL MEETING OF THE MINERALS, METALS AND MATERIALS SOC Fraser, J. D., Amin, K. E., KHURIYAKUB, B. T. MINERALS, METALS & MATERIALS SOC. 1991: 1–4

  View details for Web of Science ID A1991BW52G00001

• MICROMACHINED ULTRASONIC MATERIALS 1991 ULTRASONICS SYMP HALLER, M. I., KHURIYAKUB, B. T. I E E E. 1991: 403–405

  View details for Web of Science ID A1991BW50L00076

• DEPOSITION OF HIGHLY ORIENTED LOW-STRESS ZNO FILMS 1991 ULTRASONICS SYMP ZESCH, J. C., Hadimioglu, B., KHURIYAKUB, B. T., Lim, M., Lujan, R., Ho, J., Akamine, S., Steinmetz, D., Quate, C. F., RAWSON, E. G. I E E E. 1991: 445–448

  View details for Web of Science ID A1991BW50L00085

• NOVEL TECHNIQUE OF NDE IN CERAMIC BEARING BALLS 1991 ULTRASONICS SYMP Hsieh, C. P., Chou, C. H., KHURIYAKUB, B. T. I E E E. 1991: 891–894

  View details for Web of Science ID A1991BW50L00170

• NONCONTACTING ACOUSTICS-BASED TEMPERATURE-MEASUREMENT TECHNIQUES IN RAPID THERMAL-PROCESSING CONF ON RAPID THERMAL AND RELATED PROCESSING TECHNIQUES Lee, Y. J., Chou, C. H., KHURIYAKUB, B. T., Saraswat, K. C. SPIE - INT SOC OPTICAL ENGINEERING. 1991: 366–371

  View details for Web of Science ID A1991BT22H00030

• INSITU FILM THICKNESS AND TEMPERATURE MONITORING USING A 2 GHZ ACOUSTIC PHASE MEASUREMENT SYSTEM 1991 ULTRASONICS SYMP Bhardwaj, S., Mohan, S. S., DROZD, R. J., KHURIYAKUB, B. T., Saraswat, K. C. I E E E. 1991: 965–967

  View details for Web of Science ID A1991BW50L00187

• NONINVASIVE SWITCHABLE ACOUSTOOPTIC TAPS FOR OPTICAL FIBER OPTICAL FIBER COMMUNICATIONS CONF ( OFC 90 ) Patterson, D. B., Howell, M. D., Digonnet, M., Kino, G. S., KHURIYAKUB, B. T. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. 1990: 1304–12

  View details for Web of Science ID A1990DU74200010

• AMPLITUDE AND PHASE ACOUSTIC MICROSCOPE USING DIGITAL HETERODYNING REVIEW OF SCIENTIFIC INSTRUMENTS REINHOLDTSEN, P. A., KHURIYAKUB, B. T. 1990; 61 (4): 1236-1242

  View details for Web of Science ID A1990CX70400011

• TEMPERATURE-MEASUREMENT OF SILICON-WAFERS USING PHOTOACOUSTIC TECHNIQUES 1989 ANNUAL REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION Lee, Y. J., Chou, C. H., KHURIYAKUB, B. T., Saraswat, K., MOSLEHI, M. PLENUM PRESS DIV PLENUM PUBLISHING CORP. 1990: 1109–1114

  View details for Web of Science ID A1990BR09J00141

• HIGH-FREQUENCY ACOUSTOOPTIC MODE LOCKER FOR PICOSECOND PULSE GENERATION OPTICS LETTERS Keller, U., Li, K. D., KHURIYAKUB, B. T., Bloom, D. M., Weingarten, K. J., Gerstenberger, D. C. 1990; 15 (1): 45-47

  Abstract

  We modeled, designed, and built a 500-MHz acousto-optic mode locker with a diffraction efficiency of 28% per 1 W drive power. The transducer is zinc oxide sputtered onto a sapphire substrate. A new figure of merit is defined for the mode-locker design, which indicates that sapphire is a good substrate material. Pulse widths of less than 10 psec with an average power of 150 mW were achieved from a 500-MHz pulse-rate, diode-pumped, cw mode-locked Nd:YLF laser using a pump power of 700 mW.

  View details for Web of Science ID A1990CH36900016

  View details for PubMedID 19759706

• SELECTIVE RATE ENHANCEMENT OF ETCHING PROCESSES BY ACOUSTIC AGITATION IEEE 1990 ULTRASONICS SYMP Howell, M. D., KHURIYAKUB, B. T., Kino, G. S. I E E E. 1990: 861–863

  View details for Web of Science ID A1990BT34L00167

• FREQUENCY-SHIFTING IN OPTICAL FIBER USING A SAW HORN IEEE 1990 ULTRASONICS SYMP Patterson, D. B., Digonnet, M. J., Liu, A. C., KHURIYAKUB, B. T., Kino, G. S. I E E E. 1990: 617–620

  View details for Web of Science ID A1990BT34L00121

• AMPLITUDE AND PHASE ACOUSTIC MICROSCOPY FOR CERAMIC BEARING BALL INSPECTIONS IEEE 1990 ULTRASONICS SYMP Chou, C. H., Hsieh, C. P., KHURIYAKUB, B. T. I E E E. 1990: 887–890

  View details for Web of Science ID A1990BT34L00172

• POLYMER-FILMS AS ACOUSTIC MATCHING LAYERS IEEE 1990 ULTRASONICS SYMP Hadimioglu, B., KHURIYAKUB, B. T. I E E E. 1990: 1337–1340

  View details for Web of Science ID A1990BT34L00262

• ND-3+ DOPED FIBER LASER WITH INTEGRATED ACOUSTOOPTIC MODE-LOCKING CONF ON FIBER LASER SOURCES AND AMPLIFIERS Howell, M. D., Patterson, D. B., Kino, G. S., KHURIYAKUB, B. T., Digonnet, M. J. SPIE - INT SOC OPTICAL ENGINEERING. 1990: 309–315

  View details for Web of Science ID A1990BQ49D00030

• PROCESS MONITORING TECHNIQUES USING ACOUSTIC-WAVES IEEE 1990 ULTRASONICS SYMP Bhardwaj, S., KHURIYAKUB, B. T., Saraswat, K. C. I E E E. 1990: 367–369

  View details for Web of Science ID A1990BT34L00073

• RAPID THERMAL MULTIPROCESSING FOR MICRO FACTORIES CONF ON RAPID ISOTHERMAL PROCESSING Saraswat, K. C., Booth, L., GROSSMAN, D. D., KHURIYAKUB, B. T., Lee, Y. J., Moslehi, M. M., Wood, S. SPIE - INT SOC OPTICAL ENGINEERING. 1990: 2–14

  View details for Web of Science ID A1990BQ91R00001

• Switchable acoustooptic tap for optical fibers Technical Digest Series Patterson, D., B., Howell, M., D., Digonnet, M., Kino, G., S., Khuri-Yakub, B., T. 1990: 98
• High-frequency acousto-optic mode locker for picosecond pulse generation Optics Letters Keller, U., Li, K., D., Khuri-Yakub, B., T., Bloom, D., M., Weingarten, K., J., Gerstenberger, D., C. 1990; 15 (1): 45-7
• A SAM BEARING BALL INSPECTION SYSTEM 1989 ANNUAL REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION Chou, C. H., Parent, P., KHURIYAKUB, B. T. PLENUM PRESS DIV PLENUM PUBLISHING CORP. 1990: 2091–2096

  View details for Web of Science ID A1990BR09J00269

• NOVEL HIGH-FREQUENCY AIR TRANSDUCERS 1989 ANNUAL REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION Schiller, S., Hsieh, C. K., Chou, C. H., KHURIYAKUB, B. T. PLENUM PRESS DIV PLENUM PUBLISHING CORP. 1990: 795–798

  View details for Web of Science ID A1990BR09J00100

• PHOTOTHERMAL MEASUREMENTS OF HIGH-TC SUPERCONDUCTORS 6TH INTERNATIONAL TOPICAL MEETING ON PHOTOACOUSTIC AND PHOTOTHERMAL PHENOMENA FANTON, J. T., Kapitulnik, A., Mitzi, D. B., KHURIYAKUB, B. T., Kino, G. S. SPRINGER-VERLAG BERLIN. 1990: 202–204

  View details for Web of Science ID A1990BQ96Y00051

• PHOTOTHERMAL MEASUREMENTS OF HIGH-TC SUPERCONDUCTORS APPLIED PHYSICS LETTERS FANTON, J. T., Mitzi, D. B., Kapitulnik, A., KHURIYAKUB, B. T., Kino, G. S., Gazit, D., Feigelson, R. S. 1989; 55 (6): 598-599

  View details for Web of Science ID A1989AJ91500029

• NOZZLELESS DROPLET FORMATION WITH FOCUSED ACOUSTIC BEAMS JOURNAL OF APPLIED PHYSICS Elrod, S. A., Hadimioglu, B., KHURIYAKUB, B. T., RAWSON, E. G., Richley, E., Quate, C. F., Mansour, N. N., Lundgren, T. S. 1989; 65 (9): 3441-3447

  View details for Web of Science ID A1989U244800022

• DESIGN AND IMPLEMENTATION OF MIXED-MODE TRANSDUCERS IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Chou, C. H., KHURIYAKUB, B. T. 1989; 36 (3): 337-341

  Abstract

  In order to design a mixed-mode transducer with high efficiency and broad bandwidth for both longitudinal and shear wave modes, a theory is developed to determine the properties of this transducer with arbitrary acoustic loads at both ends of the piezoelectric element. Several Y-cut lithium niobate (LiNbO(3)) transducers were made on both [110] single-crystal bismuth germanium oxide (Bi(12)GeO(20)) and fused quartz. The piezoelectric plates were attached to indium bonding and later polished to operate in the 100-MHz frequency range. The experimental data of round-trip insertion loss for both longitudinal and shear modes showed an excellent agreement with theoretical predictions.

  View details for Web of Science ID A1989U111900008

  View details for PubMedID 18284988

• DETACHABLE 400-MHZ ACOUSTOOPTIC PHASE MODULATOR FOR A SINGLE-MODE OPTICAL FIBER OPTICS LETTERS Patterson, D. B., Godil, A. A., Kino, G. S., KHURIYAKUB, B. T. 1989; 14 (4): 248-250

  Abstract

  A single-mode-fiber phase modulator was constructed by contacting the fiber with a lapped glass capillary tube. The capillary's inner surface provides a long, effectively semicircular contact region to the fiber, allowing throughput of acoustic waves launched from a thin-film ZnO transducer fabricated directly onto the capillary's other lapped face. The device operated at a center frequency of 416 MHz with a FWHM bandwidth of 14 MHz. The maximum phase shift was 0.033 rad/ radicalmw, with a largest measured value of 1.2 rad at 1.3-W input electrical power.

  View details for Web of Science ID A1989T289900020

  View details for PubMedID 19749885

• PHOTOACOUSTIC MEASUREMENTS OF SILICON-WAFER PROCESSING TEMPERATURES 1989 SYMP OF THE INST OF ELECTRICAL AND ELECTRONICS ENGINEERS ON ULTRASONICS Lee, Y. J., Chou, C. H., KHURIYAKUB, B. T., Saraswat, K., MOSLEHI, M. I E E E. 1989: 535–538

  View details for Web of Science ID A1989BQ92K00095

• NEAR-FIELD SCANNING ACOUSTIC MICROSCOPE 1989 SYMP OF THE INST OF ELECTRICAL AND ELECTRONICS ENGINEERS ON ULTRASONICS KHURIYAKUB, B. T., CINBIS, C., Chou, C. H., REINHOLDTSEN, P. A. I E E E. 1989: 805–807

  View details for Web of Science ID A1989BQ92K00151

• NOZZLELESS DROPLET FORMATION WITH FOCUSED ACOUSTIC BEAMS 3RD INTERNATIONAL COLLOQUIUM ON DROPS AND BUBBLES Elrod, S. A., Hadimioglu, B., KHURIYAKUB, B. T., RAWSON, E. G., Quate, C. F., Mansour, N. N., Lundgren, T. S. AIP PRESS. 1989: 49–57

  View details for Web of Science ID A1989BQ25T00006

• ALL-FIBER ACOUSTOOPTIC PHASE MODULATORS USING ZINC-OXIDE FILMS ON GLASS-FIBER JOURNAL OF LIGHTWAVE TECHNOLOGY Godil, A. A., Patterson, D. B., HEFFNER, B. L., Kino, G. S., KHURIYAKUB, B. T. 1988; 6 (10): 1586-1590

  View details for Web of Science ID A1988Q257400022

• LENS DESIGN FOR ACOUSTIC MICROSCOPY IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Chou, C. H., KHURIYAKUB, B. T., Kino, G. S. 1988; 35 (4): 464-469

  Abstract

  Design criteria for acoustic microscope lenses are examined with respect to their intended application. Aside from buffer rod material and F-number, the factors influencing the lens design are the critical angle for surface wave excitation, lens illumination, and leak rate of the surface wave on the sample. It is found that the design criteria are different for surface and subsurface examination and that for different applications and materials, different lenses are required for optimum imaging performance. A formalism for evaluating the performance of an acoustic microscope by considering its response in the time domain, both theoretically and experimentally, is presented.

  View details for Web of Science ID A1988P539100005

  View details for PubMedID 18290175

• ULTRASONIC EXCITATION AND DETECTION OF CAPILLARY WAVES FOR THE MEASUREMENT OF SURFACE-FILM PROPERTIES APPLIED PHYSICS LETTERS KHURIYAKUB, B. T., REINHOLDTSEN, P. A., Chou, C. H., Vesecky, J. F., Teague, C. C. 1988; 52 (19): 1571-1572

  View details for Web of Science ID A1988N237900008

• GENERATION OF 7.8 PS ELECTRICAL TRANSIENTS ON A MONOLITHIC NONLINEAR TRANSMISSION-LINE ELECTRONICS LETTERS Rodwell, M. J., Madden, C. J., KHURIYAKUB, B. T., Bloom, D. M., Pao, Y. C., GABRIEL, N. S., Swierkowski, S. P. 1988; 24 (2): 100-102

  View details for Web of Science ID A1988M171400017

• HIGH-EFFICIENCY, MULTIPLE LAYER ZNO ACOUSTIC TRANSDUCERS AT MILLIMETER-WAVE FREQUENCIES APPLIED PHYSICS LETTERS Hadimioglu, B., LACOMB, L. J., Wright, D. R., KHURIYAKUB, B. T., Quate, C. F. 1987; 50 (23): 1642-1644

  View details for Web of Science ID A1987H673100009

• TUNABLE OPTICAL FILTER IN FIBEROPTIC FORM OPTICS LETTERS Risk, W. P., Kino, G. S., KHURIYAKUB, B. T. 1986; 11 (9): 578-580

  Abstract

  Light can be coupled between the two principal polarizations of birefringent fiber by using a traveling acoustic wave to produce a spatially periodic stress in the fiber. For a fixed acoustic frequency, maximum coupling occurs when the input optical wavelength is such that the beat length of the fiber equals the acoustic wavelength. By changing the acoustic frequency, the wavelength at which peak coupling occurs can be tuned. A prototype device has a passband 5 nm wide with a peak optical wavelength that can be tuned from 570 to 630 nm by changing the acoustic frequency from 2.85 to 2.55 MHz.

  View details for Web of Science ID A1986D799200010

  View details for PubMedID 19738694

• SWITCHABLE FIBEROPTIC TAP USING THE ACOUSTOOPTIC BRAGG INTERACTION OPTICS LETTERS HEFFNER, B. L., Kino, G. S., KHURIYAKUB, B. T., Risk, W. P. 1986; 11 (7): 476-478

  Abstract

  A new type of electronically switchable optical-fiber tap using acousto-optic Bragg diffraction is demonstrated. An acoustic transducer on a wedge launches an acoustic beam through a Hertzian contact into a D-shaped optical fiber, diffracting light out through the side of the fiber. The bandwidth of the tap is greater than 1 GHz centered at 3.5 GHz, with a tap efficiency of 0.01% per watt of rf power. The tap does not damage the fiber and is completely reversible, so its location on the fiber can easily be adjusted.

  View details for Web of Science ID A1986C992500024

  View details for PubMedID 19730669

• DEPOSITION OF ORIENTED ZINC-OXIDE ON AN OPTICAL FIBER APPLIED PHYSICS LETTERS HEFFNER, B. L., KHURIYAKUB, B. T. 1986; 48 (21): 1422-1423

  View details for Web of Science ID A1986C456700004

• PRECISE PHASE MEASUREMENTS WITH THE ACOUSTIC MICROSCOPE IEEE TRANSACTIONS ON SONICS AND ULTRASONICS Liang, K. K., Bennett, S. D., KHURIYAKUB, B. T., Kino, G. S. 1985; 32 (2): 266-273

  View details for Web of Science ID A1985AHN4400016

• MATERIAL CHARACTERIZATION BY THE INVERSION OF V(Z) IEEE TRANSACTIONS ON SONICS AND ULTRASONICS Liang, K. K., Kino, G. S., KHURIYAKUB, B. T. 1985; 32 (2): 213-224

  View details for Web of Science ID A1985AHN4400010

• ACOUSTIC MICROSCOPY IN AIR AT 2 MHZ APPLIED PHYSICS LETTERS Fox, J. D., Kino, G. S., KHURIYAKUB, B. T. 1985; 47 (5): 465-467

  View details for Web of Science ID A1985APH9900012

• ACOUSTIC RESONATOR TRANSDUCER FOR OPERATION IN AIR ELECTRONICS LETTERS Fox, J. D., KHURIYAKUB, B. T., Kino, G. S. 1985; 21 (16): 695-696

  View details for Web of Science ID A1985ART4600022

• 7-GHZ ACOUSTIC TRANSMISSION THROUGH A HERTZIAN CONTACT APPLIED PHYSICS LETTERS HEFFNER, B. L., Kino, G. S., KHURIYAKUB, B. T. 1985; 47 (1): 17-18

  View details for Web of Science ID A1985AKE5600007

• MEASUREMENT OF NORMAL SURFACE DISPLACEMENTS FOR THE CHARACTERIZATION OF RECTANGULAR ACOUSTIC ARRAY ELEMENTS JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA Jungerman, R. L., Bennett, P., Selfridge, A. R., KHURIYAKUB, B. T., Kino, G. S. 1984; 76 (2): 516-524

  View details for Web of Science ID A1984TF80500022

• EFFECT OF PHOTOCARRIERS ON ACOUSTIC-WAVE PROPAGATION FOR MEASURING EXCESS CARRIER DENSITY AND LIFETIMES IN SILICON APPLIED PHYSICS LETTERS STEARNS, R. G., KHURIYAKUB, B. T., Kino, G. S. 1984; 45 (11): 1181-1183

  View details for Web of Science ID A1984TV54500010

• CHARACTERIZATION OF SURFACE-DEFECTS USING A PULSED ACOUSTIC LASER PROBE APPLIED PHYSICS LETTERS Jungerman, R. L., KHURIYAKUB, B. T., Kino, G. S. 1984; 44 (4): 392-393

  View details for Web of Science ID A1984SD34900015

• MEASUREMENTS OF ADHERENCE OF RESIDUALLY STRESSED THIN-FILMS BY INDENTATION .2. EXPERIMENTS WITH ZNO/SI JOURNAL OF APPLIED PHYSICS Rossington, C., Evans, A. G., Marshall, D. B., KHURIYAKUB, B. T. 1984; 56 (10): 2639-2644

  View details for Web of Science ID A1984TT18800003

• OPTICAL-DETECTION OF ACOUSTIC DISPLACEMENTS FOR THE CHARACTERIZATION OF SURFACE-DEFECTS MATERIALS EVALUATION Jungerman, R. L., KHURIYAKUB, B. T., Kino, G. S. 1984; 42 (4): 444-450

  View details for Web of Science ID A1984SN03300070

• BROAD-BAND OPTICAL CAVITIES FOR INFRARED FREE-ELECTRON LASERS - ANALYSIS AND PRELIMINARY EXPERIMENTAL RESULTS APPLIED OPTICS Cutolo, A., KHURIYAKUB, B. T., Madey, J. M. 1984; 23 (17): 2935-2943

  View details for Web of Science ID A1984TG74300021

  View details for PubMedID 18213099

• OPTICAL PROBING OF ACOUSTIC-WAVES ON ROUGH SURFACES JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA Jungerman, R. L., KHURIYAKUB, B. T., Kino, G. S. 1983; 73 (5): 1838-1841

  View details for Web of Science ID A1983QP90900052

• CONICAL TRANSDUCER FOR GENERATION OF ACOUSTIC-WAVES IN FLUIDS APPLIED PHYSICS LETTERS Baer, R. L., KHURIYAKUB, B. T., Kino, G. S. 1983; 42 (7): 573-574

  View details for Web of Science ID A1983QJ27000009

• A NEW TYPE OF LASER PROBE APPLIED PHYSICS LETTERS STEARNS, R. G., Kino, G. S., KHURIYAKUB, B. T. 1983; 42 (8): 659-661

  View details for Web of Science ID A1983QK94000012

• MEASUREMENT OF PERIODIC SURFACE HEATING USING SURFACE ACOUSTIC-WAVES APPLIED PHYSICS LETTERS STEARNS, R. G., KHURIYAKUB, B. T., Kino, G. S. 1983; 43 (8): 748-750

  View details for Web of Science ID A1983RL77400016

• PRECISION-MEASUREMENT OF RAYLEIGH-WAVE VELOCITY PERTURBATION APPLIED PHYSICS LETTERS Liang, K., Bennett, S. D., KHURIYAKUB, B. T., Kino, G. S. 1982; 41 (12): 1124-1126

  View details for Web of Science ID A1982PU24700006

• EFFECT OF NONUNIFORM PIEZOELECTRIC FILMS ON MONOLITHIC SURFACE ACOUSTIC-WAVE DEVICES APPLIED PHYSICS LETTERS Bowers, J. E., Thornton, R. L., KHURIYAKUB, B. T., Jungerman, R. L., Kino, G. S. 1982; 41 (9): 805-807

  View details for Web of Science ID A1982PM95600011

• REACTIVE MAGNETRON SPUTTERING OF ZNO JOURNAL OF APPLIED PHYSICS KHURIYAKUB, B. T., Smits, J. G., Barbee, T. 1981; 52 (7): 4772-4774

  View details for Web of Science ID A1981MC30900069

• ACOUSTIC SURFACE-WAVE MEASUREMENTS OF SURFACE CRACKS IN CERAMICS JOURNAL OF THE AMERICAN CERAMIC SOCIETY KHURIYAKUB, B. T., Kino, G. S., Evans, A. G. 1980; 63 (1-2): 65-71

  View details for Web of Science ID A1980JJ02100018

• BROAD-BAND EFFICIENT THIN-FILM SEZAWA WAVE INTERDIGITAL TRANSDUCERS APPLIED PHYSICS LETTERS Bowers, J. E., KHURIYAKUB, B. T., Kino, G. S. 1980; 36 (10): 806-807

  View details for Web of Science ID A1980JT24300010

• GENERATION AND DETECTION OF UNIPOLAR STRESS PULSES APPLIED PHYSICS LETTERS Yu, F., LLIC, D. B., KHURIYAKUB, B. T., Kino, G. S. 1980; 36 (7): 553-555

  View details for Web of Science ID A1980JP15000027

• SHEAR-WAVE EXCITATION IN A SOLID BY LONGITUDINAL-WAVE CONTACT TRANSDUCERS JOURNAL OF APPLIED PHYSICS Chou, C. H., Liang, K., KHURIYAKUB, B. T., Kino, G. S. 1980; 51 (10): 5257-5259

  View details for Web of Science ID A1980KM67100031

• A THEORY FOR THE RADIATION-PATTERN OF A NARROW-STRIP ACOUSTIC TRANSDUCER APPLIED PHYSICS LETTERS Selfridge, A. R., Kino, G. S., KHURIYAKUB, B. T. 1980; 37 (1): 35-36

  View details for Web of Science ID A1980KA77200015

• EDGE-BONDED SURFACE-ACOUSTIC-WAVE TRANSDUCER ARRAY APPLIED PHYSICS LETTERS TUAN, H. C., Kino, G. S., KHURIYAKUB, B. T., Selfridge, A. R. 1979; 35 (4): 320-321

  View details for Web of Science ID A1979HH96600009

• ACOUSTIC MEASUREMENT OF STRESS INTENSITY FACTORS APPLIED PHYSICS LETTERS RESCH, M. T., KHURIYAKUB, B. T., Kino, G. S., SHYNE, J. C. 1979; 34 (3): 182-184

  View details for Web of Science ID A1979GK77300002

• ULTRASONIC-ATTENUATION OF PIEZOELECTRIC PVF2 FILMS AT HIGH-FREQUENCIES ELECTRONICS LETTERS KHURIYAKUB, B. T., Chou, C. H. 1979; 15 (11): 308-309

  View details for Web of Science ID A1979HH82500004

• APPLICATION OF WIENER FILTERING TO NONDESTRUCTIVE EVALUATION APPLIED PHYSICS LETTERS Murakami, Y., KHURIYAKUB, B. T., Kino, G. S., Richardson, J. M., Evans, A. G. 1978; 33 (8): 685-687

  View details for Web of Science ID A1978FU58600001

• NEW TECHNIQUE FOR EXCITATION OF SURFACE AND SHEAR ACOUSTIC-WAVES ON NONPIEZOELECTRIC MATERIALS APPLIED PHYSICS LETTERS KHURIYAKUB, B. T., Kino, G. S. 1978; 32 (9): 513-514

  View details for Web of Science ID A1978EV73800002

• LENGTH AND DEPTH RESONANCES OF SURFACE CRACKS AND THEIR USE FOR CRACK SIZE ESTIMATION APPLIED PHYSICS LETTERS DOMARKAS, V., KHURIYAKUB, B. T., Kino, G. S. 1978; 33 (7): 557-559

  View details for Web of Science ID A1978FT14000002

• ULTRASONIC-ATTENUATION IN CERAMICS JOURNAL OF APPLIED PHYSICS Evans, A. G., Tittmann, B. R., Kino, G. S., Ahlberg, L., KHURIYAKUB, B. T. 1978; 49 (5): 2669-2679

  View details for Web of Science ID A1978EX43500012

• DESIGN OF EFFICIENT BROAD-BAND WEDGE TRANSDUCERS APPLIED PHYSICS LETTERS Fraser, J., KHURIYAKUB, B. T., Kino, G. S. 1978; 32 (11): 698-700

  View details for Web of Science ID A1978EZ05600003

• ACOUSTIC PULSE ECHO MEASUREMENTS AT 200 MHZ APPLIED PHYSICS LETTERS KHURIYAKUB, B. T., Kino, G. S. 1977; 30 (2): 78-80

  View details for Web of Science ID A1977CR48500003

• DETAILED THEORY OF MONOLITHIC ZINC-OXIDE ON SILICON CONVOLVER IEEE TRANSACTIONS ON SONICS AND ULTRASONICS KHURIYAKUB, B. T., Kino, G. S. 1977; 24 (1): 34-43

  View details for Web of Science ID A1977CR40600005

• MONOLITHIC WAVEGUIDE ZINC-OXIDE-ON-SILICON CONVOLVER ELECTRONICS LETTERS KHURIYAKUB, B. T., Kino, G. S. 1976; 12 (11): 271-272

  View details for Web of Science ID A1976BS55600006

• NEW METHOD FOR WIDEBAND EXCITATION OF INTERDIGITAL SURFACE-WAVE TRANSDUCERS ELECTRONICS LETTERS KHURIYAKUB, B. T., JOLY, R. L. 1976; 12 (11): 266-267

  View details for Web of Science ID A1976BS55600002

• STUDIES OF OPTIMUM CONDITIONS FOR GROWTH OF RF-SPUTTERED ZNO FILMS JOURNAL OF APPLIED PHYSICS KHURIYAKUB, B. T., Kino, G. S., Galle, P. 1975; 46 (8): 3266-3272

  View details for Web of Science ID A1975AK66800008