Bio


Ada was born and raised in Hong Kong. She received her B.Eng degree from the EEE department at the University of Hong Kong and her Ph.D. degree from the EECS department at the University of California at Berkeley in 2004. Her dissertation attempted to connect information theory with electromagnetic theory so as to better understand the fundamental limit of wireless channels. Upon graduation, she spent one year at Intel as a senior research scientist building reconfigurable baseband processors for flexible radios. Afterwards, she joined her advisor’s startup company, SiBeam Inc., architecting Gigabit wireless transceivers leveraging 60 GHz CMOS and MIMO antenna systems. After two years in industries, she returned to academic and joined the faculty of the ECE department at the University of Illinois, Urbana-Champaign. Since then, she has changed her research direction from wireless communications to integrated biomedical systems. In 2008, she moved back to California and joined the faculty of the Department of Electrical Engineering at Stanford University.

Academic Appointments


Honors & Awards


  • CZ Biohub Investigator, Chan Zuckerberg Biohub (2017)
  • CAREER Award, NSF (2013)
  • Research Grant recipient, Okawa Foundation (2010)
  • Terman Fellow, Stanford (2008)

Professional Education


  • PhD, UC Berkeley, Electrical Engineering (2004)
  • MS, UC Berkeley, Electrical Engineering (1999)
  • MPhil, University of Hong Kong, Electrical and Electronic Engineering (1997)
  • BEng, University of Hong Kong, Electrical and Electronic Engineering (1996)

Current Research and Scholarly Interests


Our research focuses on providing theoretical foundations and engineering platforms for realizing electronics that seamlessly integrate with the body. Such systems will allow precise recording or modulation of physiological activity, for advancing basic scientific discovery and for restoring or augmenting biological functions for clinical applications. To build these integrated biomedical systems, our research program emphasizes a vertical integration of diverse fields ranging from physics, wireless technologies, and low-power integrated circuits. In close collaboration with biologists and clinical specialists, we validate our systems in animal models and prepare the testing of the systems in humans.

Projects


  • Memory recovery device for Alzheimer’s disease and other dementias

    In US, one in 10 people age 65 and older has Alzheimer’s disease (AD). This number increases to one in 3 people age 85 and older. Loss of memory and reasoning badly rob the quality of life and dignity of the elderly. Unfortunately, AD cannot be prevented, cured, or even slowed. Instead of waiting for a pharmaceutical breakthrough, we propose a radical solution to develop a redundant electronic memory system that would progressively replace degenerated neurons and hence reversing effects of neurodegeneration in AD and other dementias.

    Location

    Stanford, CA

  • Wireless neuromodulation platforms, Stanford University

    Optical or electrical stimulation of neural circuits in mice during natural behavior is an important paradigm for studying brain function. Conventional systems for optogenetics and electrical stimulation require tethers or large head-mounted devices that disrupt animal behavior. Our research focuses on developing new wireless tools for activity modulation and recording in both the brain and the periphery. Targeted technologies include wireless platforms for experiments in freely-moving animals and tiny, fully-implantable devices for controlled delivery of light or electrical pulses.

    Location

    Stanford, CA

    Collaborators

    • Scott Delp, James H. Clark Professor in the School of Engineering, Professor of Bioengineering, of Mechanical Engineering and, by courtesy, of Orthopaedic Surgery, Stanford University
    • Karl Deisseroth, Professor, Stanford University
  • Wireless power transfer to microimplants, Stanford University

    Medical electronics are capable of precisely monitoring or modulating activity in the human body, and thus hold promise for treating a broad range of diseases. To implant electronic devices in the body, they need to be miniaturized and powered wirelessly across complex biological tissue. We are developing a new method of electromagnetic energy transfer, termed midfield powering, to power devices at the scale of a millimeter or less anywhere in the body, including the heart and the brain. Our approach spans fundamental studies of wave-tissue interactions, development of new electromagnetic structures, and experiments in both computational and animal tissue models.

    Location

    Stanford, CA

    Collaborators

    • Ramin Beygui, Professor of Cardiothoracic Surgery, Stanford University
  • Low-power biomedical integrated circuits, Stanford University

    Advances in integrated circuit technology have enabled electronic systems that can augment or even replace physiological functions. While the processing capabilities of these devices are virtually unlimited, the available energy is highly constrained. Our research combines low-power architectures with innovations in circuit design techniques to design biomedical electronics capable of ultra-low-power operation in the human body.

    Location

    Stanford University

  • Metasurfaces, Stanford University

    The solid immersion lens is a powerful optical tool that allows light entering material from air or vacuum to focus to a spot much smaller than the free-space wavelength. Conventionally, however, they rely on semispherical topographies and are non-planar and bulky, which limits their integration in many applications. Recently, there has been considerable interest in using planar structures, referred to as metasurfaces, to construct flat optical components for manipulating light in unusual ways. Here, we propose and demonstrate the concept of a planar immersion lens based on metasurfaces. The resulting planar device, when placed near an interface between air and dielectric material, can focus electromagnetic radiation incident from air to a spot in material smaller than the free-space wavelength.

    Location

    Stanford, CA

    Collaborators

    • Shanhui Fan, Professor of Electrical Engineering and, by courtesy, of Applied Physics, Stanford University

Stanford Advisees


All Publications


  • An RF-Powered FDD Radio for Neural Microimplants IEEE JOURNAL OF SOLID-STATE CIRCUITS Rajavi, Y., Taghivand, M., Aggarwal, K., Ma, A., Poon, A. S. 2017; 52 (5): 1221-1229
  • A Millimeter-Wave Digital Link for Wireless MRI IEEE TRANSACTIONS ON MEDICAL IMAGING Aggarwal, K., Joshi, K. R., Rajavi, Y., Taghivand, M., Pauly, J. M., Poon, A. S., Scott, G. 2017; 36 (2): 574-583

    Abstract

    A millimeter (mm) wave radio is presented in this work to support wireless MRI data transmission. High path loss and availability of wide bandwidth make mm-waves an ideal candidate for short range, high data rata communication required for wireless MRI. The proposed system uses a custom designed integrated chip (IC) mm-wave radio with 60 GHz as radio frequency carrier. In this work, we assess performance in a 1.5 T MRI field, with the addition of optical links between the console room and magnet. The system uses ON-OFF keying (OOK) modulation for data transmission and supports data rates from 200 Mb/s to 2.5 Gb/s for distances up-to 65 cm. The presence of highly directional, linearly polarized, on-chip dipole antennas on the mm-wave radio along with the time division multiplexing (TDM) circuitry allows multiple wireless links to be created simultaneously with minimal inter-channel interference. This leads to a highly scalable solution for wireless MRI.

    View details for DOI 10.1109/TMI.2016.2622251

    View details for Web of Science ID 000396115800021

    View details for PubMedCentralID PMC5709036

  • High-performance wireless powering for peripheral nerve neuromodulation systems. PloS one Tanabe, Y., Ho, J. S., Liu, J., Liao, S. Y., Zhen, Z., Hsu, S., Shuto, C., Zhu, Z. Y., Ma, A., Vassos, C., Chen, P., Tse, H. F., Poon, A. S. 2017; 12 (10): e0186698

    Abstract

    Neuromodulation of peripheral nerves with bioelectronic devices is a promising approach for treating a wide range of disorders. Wireless powering could enable long-term operation of these devices, but achieving high performance for miniaturized and deeply placed devices remains a technological challenge. We report the miniaturized integration of a wireless powering system in soft neuromodulation device (15 mm length, 2.7 mm diameter) and demonstrate high performance (about 10%) during in vivo wireless stimulation of the vagus nerve in a porcine animal model. The increased performance is enabled by the generation of a focused and circularly polarized field that enhances efficiency and provides immunity to polarization misalignment. These performance characteristics establish the clinical potential of wireless powering for emerging therapies based on neuromodulation.

    View details for DOI 10.1371/journal.pone.0186698

    View details for PubMedID 29065141

    View details for PubMedCentralID PMC5655495

  • Micrometer-scale magnetic-resonance-coupled radio-frequency identification and transceivers for wireless sensors in cells Physical Review Applied Hu, X., Aggarwal, K., Yang, M., Parizi, K., Xu, X., Akin, D., Poon, A., Wong, H. 2017
  • Conformal phased surfaces for wireless powering of bioelectronic microdevices. Nature biomedical engineering Agrawal, D. R., Tanabe, Y., Weng, D., Ma, A., Hsu, S., Liao, S. Y., Zhen, Z., Zhu, Z. Y., Sun, C., Dong, Z., Yang, F., Tse, H. F., Poon, A. S., Ho, J. S. 2017; 1

    Abstract

    Wireless powering could enable the long-term operation of advanced bioelectronic devices within the human body. Although both enhanced powering depth and device miniaturization can be achieved by shaping the field pattern within the body, existing electromagnetic structures do not provide the spatial phase control required to synthesize such patterns. Here, we describe the design and operation of conformal electromagnetic structures, termed phased surfaces, that interface with non-planar body surfaces and optimally modulate the phase response to enhance the performance of wireless powering. We demonstrate that the phased surfaces can wirelessly transfer energy across anatomically heterogeneous tissues in large animal models, powering miniaturized semiconductor devices (<12 mm3) deep within the body (>4 cm). As an illustration ofin vivooperation, we wirelessly regulated cardiac rhythm by powering miniaturized stimulators at multiple endocardial sites in a porcine animal model.

    View details for DOI 10.1038/s41551-017-0043

    View details for PubMedID 29226018

    View details for PubMedCentralID PMC5722470

  • A NEW KIND OF WIRELESS MOUSE IEEE SPECTRUM Poon, A. 2016; 53 (12): 26-U37
  • Wirelessly powered, fully internal optogenetics for brain, spinal and peripheral circuits in mice. Nature methods Montgomery, K. L., Yeh, A. J., Ho, J. S., Tsao, V., Mohan Iyer, S., Grosenick, L., Ferenczi, E. A., Tanabe, Y., Deisseroth, K., Delp, S. L., Poon, A. S. 2015; 12 (10): 969-974

    Abstract

    To enable sophisticated optogenetic manipulation of neural circuits throughout the nervous system with limited disruption of animal behavior, light-delivery systems beyond fiber optic tethering and large, head-mounted wireless receivers are desirable. We report the development of an easy-to-construct, implantable wireless optogenetic device. Our smallest version (20 mg, 10 mm(3)) is two orders of magnitude smaller than previously reported wireless optogenetic systems, allowing the entire device to be implanted subcutaneously. With a radio-frequency (RF) power source and controller, this implant produces sufficient light power for optogenetic stimulation with minimal tissue heating (<1 °C). We show how three adaptations of the implant allow for untethered optogenetic control throughout the nervous system (brain, spinal cord and peripheral nerve endings) of behaving mice. This technology opens the door for optogenetic experiments in which animals are able to behave naturally with optogenetic manipulation of both central and peripheral targets.

    View details for DOI 10.1038/nmeth.3536

    View details for PubMedID 26280330

  • Self-Tracking Energy Transfer for Neural Stimulation in Untethered Mice PHYSICAL REVIEW APPLIED Ho, J. S., Tanabe, Y., Iyer, S. M., Christensen, A. J., Grosenick, L., Deisseroth, K., Delp, S. L., Poon, A. S. 2015; 4 (2)
  • An Energy Harvesting 2 x 2 60 GHz Transceiver With Scalable Data Rate of 38-2450 Mb/s for Near-Range Communication IEEE JOURNAL OF SOLID-STATE CIRCUITS Taghivand, M., Aggarwal, K., Rajavi, Y., Poon, A. S. 2015; 50 (8): 1889-1902
  • Planar immersion lens with metasurfaces PHYSICAL REVIEW B Ho, J. S., Qiu, B., Tanabe, Y., Yeh, A. J., Fan, S., Poon, A. S. 2015; 91 (12)
  • Midfield Wireless Power Transfer for Bioelectronics IEEE CIRCUITS AND SYSTEMS MAGAZINE Ma, A., Poon, A. S. 2015; 15 (2): 54-60
  • Wireless power transfer to deep-tissue microimplants PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Ho, J. S., Yeh, A. J., Neofytou, E., Kim, S., Tanabe, Y., Patlolla, B., Beygui, R. E., Poon, A. S. 2014; 111 (22): 7974-7979

    Abstract

    The ability to implant electronic systems in the human body has led to many medical advances. Progress in semiconductor technology paved the way for devices at the scale of a millimeter or less ("microimplants"), but the miniaturization of the power source remains challenging. Although wireless powering has been demonstrated, energy transfer beyond superficial depths in tissue has so far been limited by large coils (at least a centimeter in diameter) unsuitable for a microimplant. Here, we show that this limitation can be overcome by a method, termed midfield powering, to create a high-energy density region deep in tissue inside of which the power-harvesting structure can be made extremely small. Unlike conventional near-field (inductively coupled) coils, for which coupling is limited by exponential field decay, a patterned metal plate is used to induce spatially confined and adaptive energy transport through propagating modes in tissue. We use this method to power a microimplant (2 mm, 70 mg) capable of closed-chest wireless control of the heart that is orders of magnitude smaller than conventional pacemakers. With exposure levels below human safety thresholds, milliwatt levels of power can be transferred to a deep-tissue (>5 cm) microimplant for both complex electronic function and physiological stimulation. The approach developed here should enable new generations of implantable systems that can be integrated into the body at minimal cost and risk.

    View details for DOI 10.1073/pnas.1403002111

    View details for Web of Science ID 000336687900037

    View details for PubMedID 24843161

    View details for PubMedCentralID PMC4050616

  • Wirelessly powering miniature implants for optogenetic stimulation APPLIED PHYSICS LETTERS Yeh, A. J., Ho, J. S., Tanabe, Y., Neofytou, E., Beygui, R. E., Poon, A. S. 2013; 103 (16)

    View details for DOI 10.1063/1.4825272

    View details for Web of Science ID 000326148700092

  • Midfield Wireless Powering for Implantable Systems PROCEEDINGS OF THE IEEE Ho, J. S., Kim, S., Poon, A. S. 2013; 101 (6): 1369-1378
  • Midfield Wireless Powering of Subwavelength Autonomous Devices PHYSICAL REVIEW LETTERS Kim, S., Ho, J. S., Poon, A. S. 2013; 110 (20)

    Abstract

    We obtain an analytical bound on the efficiency of wireless power transfer to a weakly coupled device. The optimal source is solved for a multilayer geometry in terms of a representation based on the field equivalence principle. The theory reveals that optimal power transfer exploits the properties of the midfield to achieve efficiencies far greater than conventional coil-based designs. As a physical realization of the source, we present a slot array structure whose performance closely approaches the theoretical bound.

    View details for DOI 10.1103/PhysRevLett.110.203905

    View details for Web of Science ID 000319214800003

  • Wireless power transfer to a cardiac implant APPLIED PHYSICS LETTERS Kim, S., Ho, J. S., Chen, L. Y., Poon, A. S. 2012; 101 (7)

    View details for DOI 10.1063/1.4745600

    View details for Web of Science ID 000308263100081

  • Supporting and Enabling Circuits for Antenna Arrays in Wireless Communications PROCEEDINGS OF THE IEEE Poon, A. S., Taghivand, M. 2012; 100 (7): 2207-2218
  • Degree-of-Freedom Gain From Using Polarimetric Antenna Elements IEEE TRANSACTIONS ON INFORMATION THEORY Poon, A. S., Tse, D. N. 2011; 57 (9): 5695-5709
  • Optimal Frequency for Wireless Power Transmission Into Dispersive Tissue IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION Poon, A. S., O'Driscoll, S., Meng, T. H. 2010; 58 (5): 1739-1750
  • Degrees of freedom in multiple-antenna channels: a signal space approach IEEE Trans. Information Theory Poon, A., S. Y., Brodersen, R., W., Tse, D., N. C. 2005; 51 (2): 523–536
  • A mm-sized implantable power receiver with adaptive link compensation IEEE International Solid-State Circuits Conference (ISSCC) O'Driscoll, S., Poon, A., Meng, T. H.
  • Successive AoA estimation: revealing the second path for 60 GHz communication system 49th Annual Allerton Conference on Communication, Control, and Computing Tsang, Y. M., Poon, A.
  • A mm-sized implantable wireless power receiver IEEE Engineering in Medicine and Biology Society Annual International Conference (EMBC) Poon, A.
  • A multi-agent approach to the deregulation and restructuring of power industry Hawaii International Conference on System Sciences Poon, A., Wu, F. F., Yeung, C., Yen, J.
  • Future implantable systems IEEE Technology Time Machine Symposium (TTM) Poon, A.
  • Fast beam training for mmWave communication system: from algorithm to circuits ACM international workshop on mmWave communications: from circuits to networks Tsang, Y. M., Lin, S., Poon, A.
  • Multiple-antenna channels from a combined physical and networking perspective Asilomar Conference on Signals, Systems, and Computers Poon, A., Tse, D., Brodersen, R. W.
  • A 60GHz digitally controlled RF beamforming array in 65nm CMOS with off-chip antennas IEEE RFIC Symposium Lin, S., Ng, K., Wong, H., Luk, L., Wong, S. S., Poon, A.
  • Trade-offs of performance and single chip implementation of indoor wireless multi-access receivers IEEE Wireless Communications and Networking Conference Zhang, N., Poon, A., Tse, D., Brodersen, R. W., Verdu, S.
  • The signal dimensions in multiple-antenna channels IEEE Global Telecommunications Conference (GLOBECOM) Poon, A., Tse, D., Brodersen, R. W.
  • Beam focused slot antenna for microstrip implants International Symposium on Antennas and Propagation (ISAP) Tanabe, Y., Wong, H., Kim, S., Ho, J., Poon, A.
  • An inherently linear phase-oversampling vector modulator in 90-nm CMOS IEEE Asian Solid-State Circuits Conference (ASSCC) Tseng, R., Li, H., Kwon, D., Poon, A., Chun, Y.
  • Measuring abdominal fatness using principle of Salisbury screen ELECTRONICS LETTERS Park, J., Lee, J., Lee, B., Poon, A. Y., Lee, S., Kim, S. 2017; 53 (14): 908–9
  • Non-Coil, Optimal Sources for Wireless Powering of Sub-Millimeter Implantable Devices PROGRESS IN ELECTROMAGNETICS RESEARCH-PIER Kim, S., Ho, J. S., Poon, A. Y. 2017; 158: 99–108
  • Conformal Microwave Lens for Focusing Across Inhomogenous Tissue Ho, J. S., Poon, A. Y., IEEE IEEE. 2016: 881–82
  • An Energy Harvested Ultra-Low Power Transceiver for Internet of Medical Things Rajavi, Y., Taghivand, M., Aggarwal, K., Ma, A., Poon, A. Y., IEEE IEEE. 2016: 133–36
  • INDUCTIVE POWER TRANSFER AND FAR-FIELD RADIATION WITH SMALL DUAL-BAND ANTENNAS MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Chang, T., Tanabe, Y., Tan, B., Poon, A. 2015; 57 (5)

    View details for DOI 10.1002/mop.29014

    View details for Web of Science ID 000351835800008

  • Miniaturized Biomedical Implantable Devices IMPLANTABLE BIOELECTRONICS Poon, A. Y., Katz, E. 2014: 45–64
  • Energy Transfer for Implantable Electronics in the Electromagnetic Midfield PROGRESS IN ELECTROMAGNETICS RESEARCH-PIER Ho, J. S., Poon, A. S. 2014; 148: 151-158
  • A General Solution to Wireless Power Transfer between Two Circular Loops PROGRESS IN ELECTROMAGNETICS RESEARCH-PIER Poon, A. S. 2014; 148: 171-182
  • An Energy Harvesting 2x2 60GHz Transceiver with Scalable Data Rate of 38-to-2450Mb/s for Near Range Communication 36th Annual IEEE Custom Integrated Circuits Conference (CICC) - The Showcase for Integrated Circuit Design in the Heart of Silicon Valley Taghivand, M., Rajavi, Y., Aggarwal, K., Poon, A. S. IEEE. 2014
  • A Small Dual-Band Asymmetric Dipole Antenna for 13.56 MHz Power and 2.45 GHz Data Transmission IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS Tanabe, Y., Chang, T., Yeh, A. J., Poon, A. S. 2014; 13: 1120-1123
  • Mass fabrication and delivery of 3D multilayer mu Tags into living cells SCIENTIFIC REPORTS Chen, L. Y., Parizi, K. B., Kosuge, H., Milaninia, K. M., McConnell, M. V., Wong, H. P., Poon, A. S. 2013; 3

    Abstract

    Continuous monitoring of in vivo biological processes and their evolution at the cellular level would enable major advances in our understanding of biology and disease. As a stepping stone towards chronic cellular monitoring, we demonstrate massively parallel fabrication and delivery of 3D multilayer micro-Tags (μTags) into living cells. Both 10 μm × 10 μm × 1.5 μm and 18 μm × 7 μm × 1.5 μm devices containing inductive and capacitive structures were designed and fabricated as potential passive radio-frequency identification tags. We show cellular internalization and persistence of μTags over a 5-day period. Our results represent a promising advance in technologies for studying biology and disease at the cellular level.

    View details for DOI 10.1038/srep02295

    View details for Web of Science ID 000322308900002

    View details for PubMedID 23887586

    View details for PubMedCentralID PMC3724179

  • Emerging wireless applications in biomedicine 5th IEEE International Workshop on Advances in Sensors and Interfaces (IWASI) Poon, A. IEEE. 2013: 35–35
  • A 11 mu W Sub-pJ/bit Reconfigurable Transceiver for mm-Sized Wireless Implants 35th Annual IEEE Custom Integrated Circuits Conference (CICC) - The Showcase for Circuit Design in the Heart of Silicon Valley Yakovlev, A., Jang, J., Pivonka, D., Poon, A. IEEE. 2013
  • A mm-Sized Wirelessly Powered and Remotely Controlled Locomotive Implant IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS Pivonka, D., Yakovlev, A., Poon, A. S., Meng, T. 2012; 6 (6): 523-532

    Abstract

    A wirelessly powered and controlled implantable device capable of locomotion in a fluid medium is presented. Two scalable low-power propulsion methods are described that achieve roughly an order of magnitude better performance than existing methods in terms of thrust conversion efficiency. The wireless prototype occupies 0.6 mm × 1 mm in 65 nm CMOS with an external 2 mm × 2 mm receive antenna. The IC consists of a matching network, a rectifier, a bandgap reference, a regulator, a demodulator, a digital controller, and high-current drivers that interface directly with the propulsion system. It receives 500 μW from a 2 W 1.86 GHz power signal at a distance of 5 cm. Asynchronous pulse-width modulation on the carrier allows for data rates from 2.5-25 Mbps with energy efficiency of 0.5 pJ/b at 10 Mbps. The received data configures the propulsion system drivers, which are capable of driving up to 2 mA at 0.2 V and can achieve speed of 0.53 cm/sec in a 0.06 T magnetic field.

    View details for DOI 10.1109/TBCAS.2012.2232665

    View details for Web of Science ID 000313907800002

  • Wireless Power Transfer to Miniature Implants: Transmitter Optimization IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION Kim, S., Ho, J. S., Poon, A. S. 2012; 60 (10): 4838-4845
  • Implantable Biomedical Devices: Wireless Powering and Communication IEEE COMMUNICATIONS MAGAZINE Yakovlev, A., Kim, S., Poon, A. 2012; 50 (4): 152-159
  • Electromagnetic field focusing for short-range wireless power transmission IEEE Radio and Wireless Symposium (RWS) Poon, A. 2012
  • A mm-sized wireless powered and remotely controlled locomotive implant IEEE Trans. Biomedical Circuits and Systems Pivonka, D., Yakovlev, A., Poon, A., Meng, T. 2012; 6 (6): 523-532
  • Wireless Powering of Microchip Implants by a Cross-Slot Antenna Asia-Pacific Microwave Conference (APMC) Tanabe, Y., Ho, J. S., Wong, H., Poon, A. S. IEEE. 2012: 418–420
  • Exceeding Nernst Limit (59mV/pH): CMOS-Based pH Sensor for Autonomous Applications IEEE International Electron Devices Meeting (IEDM) Parizi, K. B., Yeh, A. J., Poon, A. S., Wong, H. S. IEEE. 2012
  • Detecting Human Blockage and Device Movement in mmWave Communication System 54th Annual IEEE Global Telecommunications Conference (GLOBECOM) Tsang, Y. M., Poon, A. S. IEEE. 2011
  • Wireless communication device using adaptive beamforming Poon, A., S. Y. 2011
  • Coding the Beams: Improving Beamforming Training in mmWave Communication System 54th Annual IEEE Global Telecommunications Conference (GLOBECOM) Tsang, Y. M., Poon, A. S., Addepalli, S. IEEE. 2011
  • Optimal Transmit Dimension for Wireless Powering of Miniature Implants IEEE International Symposium on Antennas and Propagation (APSURSI)/USNC/URSI National Radio Science Meeting Kim, S., Poon, A. S. IEEE. 2011: 408–411
  • A Four-Channel Beamforming Down-Converter in 90-nm CMOS Utilizing Phase-Oversampling IEEE Asian Solid-State Circuits Conference (A-SSCC) Tseng, R., Li, H., Kwon, D. H., Chiu, Y., Poon, A. S. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. 2010: 2262–72
  • Degree-of-Freedom Gain from Polarimetric Antenna Elements 2010 IEEE International Symposium Antennas and Propagation/CNC-USNC/URSI Radio Science Meeting Poon, A. S. IEEE. 2010
  • Optimizations of Source Distribution in Wireless Power Transmission for Implantable Devices 2010 IEEE International Symposium Antennas and Propagation/CNC-USNC/URSI Radio Science Meeting Kim, S., Poon, A. S. IEEE. 2010
  • Translating Electromagnetic Torque into Controlled Motion for use in Medical Implants 32nd Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBC 10) Pivonka, D., Meng, T., Poon, A. IEEE. 2010: 6433–6436

    Abstract

    A new propulsion method for sub-millimeter implants is presented that achieves high power to thrust conversion efficiency with a simple implementation. Previous research has shown that electromagnetic forces are a promising micro-scale propulsion mechanism; however the actual implementation is challenging due to the inherent symmetry of these forces. The presented technique translates torque into controlled motion via asymmetries in resistance forces, such as fluid drag. For a 1-mm sized object using this technique, the initial analysis predicts that speeds of 1 cm/sec can be achieved with approximately 100 µW of power, which is about 10 times more efficient than existing methods. In addition to better performance, this method is easily controllable and has favorable scalability.

    View details for Web of Science ID 000287964006208

    View details for PubMedID 21096711

  • Miniaturization of Implantable Wireless Power Receiver Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society Poon, A. S. IEEE. 2009: 3217–3220

    Abstract

    Implantable medical devices will play an important role in modern medicine. To reduce the risk of wire snapping, and replacement and corrosion of embedded batteries, wireless delivery of energy to these devices is desirable. However, current autonomous implants remain large in scale due to the operation at very low frequency and the use of unwieldy size of antennas. This paper will show that the optimal frequency is about 2 orders of magnitude higher than the conventional wisdom; and thereby the power receiving coils can be reduced by more than 100 fold without sacrificing either power efficiency or range. We will show that a mm-sized implant can receive 100's microW of power under safety constraints. This level of power transfer is sufficient to enable many functionalities into the micro-implants for clinical applications.

    View details for Web of Science ID 000280543602168

    View details for PubMedID 19964059

  • An Inherently Linear Phase-Oversampling Vector Modulator in 90-nm CMOS Tseng, R., Li, H., Kwon, D., Poon, A. Y., Chiu, Y., IEEE IEEE. 2009: 257–60
  • Locomotive Micro-Implant with Active Electromagnetic Propulsion Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society Pivonka, D., Poon, A. S., Meng, T. H. IEEE. 2009: 6404–6407

    Abstract

    An active locomotive technique requiring only an external power source and a static magnetic field is presented, and its operation is analyzed and simulated. For a modest static MRI magnetic field of 1 T, the results show that a 1-mm cube achieves roughly 3 cm/sec of lateral motion using less than 20.4 microW of power. Current-carrying wires generate the forces, resulting in highly controllable motion. Existing solutions trade off size and power: passive solutions are small but impractical, and mechanical solutions are inefficient and large. The presented solution captures the advantages of both systems, and has much better scalability.

    View details for Web of Science ID 000280543605057

    View details for PubMedID 19964695

  • A mixed-signal vector modulator for eigen-beamforming receivers IEEE Trans. Circuits and Systems II Tseng, R., Poon, A., Chiu, Y. 2008; 55 (5): 479–483
  • Polarization degrees of freedom Poon, A., S. Y., Tse, D., N. C. 2008
  • Non-robustness of statistics-based beamformer design in correlated design in correlated MIMO channels Raghavan, V., Poon, A., Veeravalli, V. 2008
  • Angular domain processing for MIMO wireless systems with non-uniform antenna arrays Huang, D., Raghavan, V., Poon, A., Veeravalli, V. 2008
  • A mixed-signal MIMO beamforming receiver Tseng, R., Poon, A., S. Y., Chiu, Y. 2008
  • Optimal operating frequency in wireless power transmission for implantable devices 29th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society Poon, A. S., O'Driscoll, S., Meng, T. H. IEEE. 2007: 5674–5679

    Abstract

    This paper examines short-range wireless powering for implantable devices and shows that existing analysis techniques are not adequate to conclude the characteristics of power transfer efficiency over a wide frequency range. It shows, theoretically and experimentally, that the optimal frequency for power transmission in biological media can be in the GHz-range while existing solutions exclusively focus on the MHz-range. This implies that the size of the receive coil can be reduced by 10(4) times which enables the realization of fully integrated implantable devices.

    View details for Web of Science ID 000253467004156

    View details for PubMedID 18003300

  • An energy-efficient reconfigurable baseband processor for wireless communications IEEE Trans. VLSI Systems Poon, A., S. Y. 2007; 15 (3): 319–327
  • Angular domain signal processing techniques Poon, A., S. Y. 2007
  • MIMO systems with arbitrary antenna array architectures: channel modeling, capacity, and low-complexity signaling Raghavan, V., Poon, A., Veeravalli, V. 2007
  • Closed loop feedback in MIMO systems Poon, A., S. Y. 2006
  • An energy-efficient reconfigurable baseband processor for flexible radios Poon, A., S. Y. 2006
  • Technique to increase a code rate in a MIMO system using virtual channels Poon, A., S. Y. 2006
  • Method and system for closed loop transmit beamforming in MIMO systems with limited feedback Poon, A., S. Y. 2006
  • Link adaptation for MIMO transmission schemes Poon, A., S. Y. 2006
  • Code rate adaptation in a MIMO system using virtual channels Poon, A., S. Y. 2006
  • Bit distributor for multicarrier communication systems employing adaptive bit loading for multiple spatial streams and methods Poon, A., S. Y. 2006
  • Apparatus and method to form a transform Poon, A., S. Y. 2006
  • Adaptive bit loading for multicarrier communication system Poon, A., S. Y. 2006
  • Deterministic spatial power allocation and bit loading for closed loop MIMO Poon, A., S. Y. 2006
  • Impact of scattering on the capacity, diversity, and propagation range of multiple-antenna channels IEEE Trans. Information Theory Poon, A., Tse, D., Brodersen, R. W. 2006; 52 (3): 1087–1100
  • Determining spatial power allocation and bit loading for a MIMO OFDM system without feedback information about the channel Poon, A., S. Y. 2006
  • Closed loop MIMO systems using codebooks for feedback Poon, A., S. Y. 2006
  • Spatial puncturing apparatus, method, and system Poon, A., S. Y. 2005
  • Compact feedback for closed loop MIMO systems Poon, A., S. Y. 2005
  • Spatial channel models for multiple-antenna systems Poon, A., S. Y., Tse, D., N. C., Brodersen, R., W. 2004
  • Indoor multiple-antenna channel characterization from 2 to 8 GHz Poon, A. S., Ho, M., IEEE, IEEE, IEEE IEEE. 2003: 3519–23
  • An adaptive multi-antenna transceiver for slowly flat-fading channels IEEE Trans. Communications Poon, A., S. Y., Tse, D., N. C., Brodersen, R., W. 2003; 51 (11): 1820–1827
  • Game theoretical multi-agent modelling of coalition formation for multilateral trades IEEE TRANSACTIONS ON POWER SYSTEMS Yeung, C. S., Poon, A. S., Wu, F. F. 1999; 14 (3): 929-934