Honors & Awards


  • Bruce and Elizabeth BioX SIGF Fellow, BioX SIGF
  • NSF Graduate Research Fellow, NSF

Professional Education


  • Doctor of Philosophy, Stanford University, BIOE-PHD (2019)
  • Bachelor of Science, University of Texas Austin, Biomedical Engineering (2013)
  • Master of Science, Stanford University, BIOE-MS (2015)

Stanford Advisors


All Publications


  • Diagnostics for SARS-CoV-2 detection: A comprehensive review of the FDA-EUA COVID-19 testing landscape. Biosensors & bioelectronics Ravi, N., Cortade, D. L., Ng, E., Wang, S. X. 2020; 165: 112454

    Abstract

    The rapidly spreading outbreak of COVID-19 disease is caused by the SARS-CoV-2 virus, first reported in December 2019 in Wuhan, China. As of June 17, 2020, this virus has infected over 8.2 million people but ranges in symptom severity, making it difficult to assess its overall infection rate. There is a need for rapid and accurate diagnostics to better monitor and prevent the spread of COVID-19. In this review, we present and evaluate two main types of diagnostics with FDA-EUA status for COVID-19: nucleic acid testing for detection of SARS-CoV-2 RNA, and serological assays for detection of SARS-CoV-2 specific IgG and IgM patient antibodies, along with the necessary sample preparation for accurate diagnoses. In particular, we cover and compare tests such as the CDC 2019-nCoV RT-PCR Diagnostic Panel, Cellex's qSARS-CoV-2 IgG/IgM Rapid Test, and point-of-care tests such as Abbott's ID NOW COVID-19 Test. Antibody testing is especially important in understanding the prevalence of the virus in the community and to identify those who have gained immunity. We conclude by highlighting the future of COVID-19 diagnostics, which include the need for quantitative testing and the development of emerging biosensors as point-of-care tests.

    View details for DOI 10.1016/j.bios.2020.112454

    View details for PubMedID 32729549

  • Early multiplexed detection of cirrhosis by giant magnetoresistive biosensors with protein biomarkers. ACS sensors Ng, E. n., Le, A. K., Nguyen, M. H., Wang, S. X. 2020

    Abstract

    Liver cirrhosis is one of the leading causes of death in adults worldwide. It is highly prevalent in developing countries and is growing in prevalence in developed countries mostly due to chronic liver diseases, such as chronic hepatitis B and C, and alcoholic and nonalcoholic fatty liver disease. However, the prevalence of cirrhosis may be highly underestimated because early stages are asymptomatic and current early detection methods are inadequate. Here, we evaluate the potential of a set of novel cirrhotic protein biomarkers, including soluble intercellular adhesion molecule-1 (sICAM-1) and mac-2 binding protein glycosylation isomer (M2BPGi), for early detection of cirrhosis in a multiplexed assay using our giant magnetoresistive (GMR) sensor arrays. We evaluated the diagnostic performance of the biomarkers, individually and in combination, using multivariate logistic regression and random forest in a blinded proof-of-concept retrospective case-controlled study. The biomarkers in combination exhibited high diagnostic performance in both logistic regression and random forest models, with area under the curve (AUC) of 0.98 (0.94 - 1.00). In addition, the combination of biomarkers resulted in high sensitivity of 0.97 (0.95 - 1.00) and high specificity of 1.00. We showed that the diagnostic performance of our novel set of cirrhotic protein biomarkers on our multiplexed GMR sensor arrays is higher than the performance of currently used clinical biomarkers and factors (i.e. age, sex, alanine aminotransferase (ALT), aspartate aminotransferase (AST), etc.). With this combination of novel biomarkers and the GMR technology, we could potentially boost the diagnostic power of early cirrhosis detection.

    View details for DOI 10.1021/acssensors.0c00232

    View details for PubMedID 32896123

  • Magneto-nanosensor smartphone platform for the detection of HIV and leukocytosis at point-of-care NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE Ng, E., Yao, C., Shultz, T. O., Ross-Howe, S., Wang, S. X. 2019; 16: 10–19
  • An Automated, Quantitative, and Multiplexed Assay Suitable for Point-of-Care Hepatitis B Virus Diagnostics. Scientific reports Gani, A. W., Wei, W. n., Shi, R. Z., Ng, E. n., Nguyen, M. n., Chua, M. S., So, S. n., Wang, S. X. 2019; 9 (1): 15615

    Abstract

    Hepatitis B virus (HBV) infection has a global reach with high prevalence in resource-limited areas like China and Africa. HBV patients in these areas have limited access to the currently used, costly HBV assays, which are performed in centralized clinical laboratories using single-plexed assays with bulky and expensive instruments. We aim to overcome these limitations by developing a simple and affordable HBV diagnostic platform to allow for timelier diagnosis and intervention of HBV infection. Using giant magnetoresistive (GMR) biosensor chips, we developed an automated and multiplexed quantitative platform for the measurement of a panel of HBV serology markers, including HBV "e" antigen (HBeAg), HBV surface antigen (HBsAg), and the antibody against HBsAg (anti-HBs). Our assay platform was able to detect each HBV marker with high specificity and sensitivity (with three orders of magnitude in dynamic range for each marker). Blinded analysis of HBV patient sera showed excellent correlation between our multiplexed quantitative HBsAg results and the qualitative results obtained using FDA-approved immunoassays, as well as those obtained using quantitative, single-plexed, enzyme-linked immunosorbent assays (ELISAs). The portable, automated, multiplexed, quantitative HBV serology assay platform we designed shows great promise as a more accessible alternative for HBV screening, diagnosis, and treatment monitoring.

    View details for DOI 10.1038/s41598-019-52147-z

    View details for PubMedID 31666635

  • Magneto-nanosensor Smartphone Platform for the Detection of HIV and Leukocytosis at Point-of-Care. Nanomedicine : nanotechnology, biology, and medicine Ng, E., Yao, C., Shultz, T. O., Ross-Howe, S., Wang, S. X. 2018

    Abstract

    The advent of personalized medicine has brought an increased interest in personal health among general consumers. As a result, there is a great need for user-centric point-of-care (POC) health devices. Such devices are equally pertinent in developing countries or resource-limited settings for performing diagnostic tests. However, current POC tests for diseases such as human immunodeficiency virus (HIV) or leukocytosis, do not provide adequate levels of sensitivity or do not exist at all. Here, we extend our mobile magneto-nanosensor platform to point-of-care HIV and leukocytosis detection. The platform can be multiplexed, and the circuitry enables portability and sensitivity in the POC setting. A smartphone application simplifies operation and provides guidance to facilitate self-testing. Commercially available POC test kits typically provide only qualitative or semi-quantitative results of a single analyte. The magneto-nanosensor platform can provide users with pleasant user-experience while demonstrating robust sensitive and specific multiplexed quantification and detection of common diseases.

    View details for PubMedID 30502420

  • Giant magnetoresistive sensor array for sensitive and specific multiplexed food allergen detection. Biosensors & bioelectronics Ng, E., Nadeau, K. C., Wang, S. X. 2016; 80: 359-365

    Abstract

    Current common allergen detection methods, including enzyme-linked immunosorbent assays (ELISAs) and dip-stick methods, do not provide adequate levels of sensitivity and specificity for at-risk allergic patients. A method for performing highly sensitive and specific detection of multiple food allergens is thus imperative as food allergies are becoming increasingly recognized as a major healthcare concern, affecting an estimated 4% of the total population. We demonstrate first instance of sensitive and specific multiplexed detection of major peanut allergens Ara h 1 and Ara h 2, and wheat allergen Gliadin using giant magnetoresistive (GMR) sensor arrays. Commercialized ELISA kits for Ara h 1 and Ara h 2 report limits of detection (LODs) at 31.5 ng/mL and 0.2 ng/mL, respectively. In addition, the 96-well-based ELISA developed in-house for Gliadin was found to have a LOD of 40 ng/mL. Our multiplexed GMR-based assay demonstrates the ability to perform all three assays on the same chip specifically and with sensitivities at LODs about an order of magnitude lower than those of 96-well-based ELISAs. LODs of GMR-based assays developed for Ara h 1, Ara h 2, and Gliadin were 7.0 ng/mL, 0.2 ng/mL, and 1.5 ng/mL, respectively, with little to no cross-reactivity. These LODs are clinically important as some patients could react strongly against such low allergen levels. Given the limitations of current industrial detection technology, multiplexed GMR-based assays provide a method for highly sensitive and specific simultaneous detection of any combination of food-product allergens, thus protecting allergic patients from life-threatening events, including anaphylaxis, by unintentional consumption.

    View details for DOI 10.1016/j.bios.2016.02.002

    View details for PubMedID 26859787

  • Multi-Dimensional Nanostructures for Microfluidic Screening of Biomarkers: From Molecular Separation to Cancer Cell Detection ANNALS OF BIOMEDICAL ENGINEERING Ng, E., Chen, K., Hang, A., Syed, A., Zhang, J. X. 2016; 44 (4): 847-862

    Abstract

    Rapid screening of biomarkers, with high specificity and accuracy, is critical for many point-of-care diagnostics. Microfluidics, the use of microscale channels to manipulate small liquid samples and carry reactions in parallel, offers tremendous opportunities to address fundamental questions in biology and provide a fast growing set of clinical tools for medicine. Emerging multi-dimensional nanostructures, when coupled with microfluidics, enable effective and efficient screening with high specificity and sensitivity, both of which are important aspects of biological detection systems. In this review, we provide an overview of current research and technologies that utilize nanostructures to facilitate biological separation in microfluidic channels. Various important physical parameters and theoretical equations that characterize and govern flow in nanostructure-integrated microfluidic channels will be introduced and discussed. The application of multi-dimensional nanostructures, including nanoparticles, nanopillars, and nanoporous layers, integrated with microfluidic channels in molecular and cellular separation will also be reviewed. Finally, we will close with insights on the future of nanostructure-integrated microfluidic platforms and their role in biological and biomedical applications.

    View details for DOI 10.1007/s10439-015-1521-2

    View details for Web of Science ID 000373741800002

    View details for PubMedID 26692080

    View details for PubMedCentralID PMC4828292

  • Magneto-nanosensor platform for probing low-affinity protein-protein interactions and identification of a low-affinity PD-L1/PD-L2 interaction. Nature communications Lee, J., Bechstein, D. J., Ooi, C. C., Patel, A., Gaster, R. S., Ng, E., Gonzalez, L. C., Wang, S. X. 2016; 7: 12220-?

    Abstract

    Substantial efforts have been made to understand the interactions between immune checkpoint receptors and their ligands targeted in immunotherapies against cancer. To carefully characterize the complete network of interactions involved and the binding affinities between their extracellular domains, an improved kinetic assay is needed to overcome limitations with surface plasmon resonance (SPR). Here, we present a magneto-nanosensor platform integrated with a microfluidic chip that allows measurement of dissociation constants in the micromolar-range. High-density conjugation of magnetic nanoparticles with prey proteins allows multivalent receptor interactions with sensor-immobilized bait proteins, more closely mimicking natural-receptor clustering on cells. The platform has advantages over traditional SPR in terms of insensitivity of signal responses to pH and salinity, less consumption of proteins and better sensitivities. Using this platform, we characterized the binding affinities of the PD-1-PD-L1/PD-L2 co-inhibitory receptor system, and discovered an unexpected interaction between the two known PD-1 ligands, PD-L1 and PD-L2.

    View details for DOI 10.1038/ncomms12220

    View details for PubMedID 27447090

  • Microfluidic multiplexed partitioning enables flexible and effective utilization of magnetic sensor arrays. Lab on a chip Bechstein, D. J., Ng, E., Lee, J., Cone, S. G., Gaster, R. S., Osterfeld, S. J., Hall, D. A., Weaver, J. A., Wilson, R. J., Wang, S. X. 2015; 15 (22): 4273-4276

    Abstract

    We demonstrate microfluidic partitioning of a giant magnetoresistive sensor array into individually addressable compartments that enhances its effective use. Using different samples and reagents in each compartment enables measuring of cross-reactive species and wide dynamic ranges on a single chip. This compartmentalization technique motivates the employment of high density sensor arrays for highly parallelized measurements in lab-on-a-chip devices.

    View details for DOI 10.1039/c5lc00953g

    View details for PubMedID 26395039

  • Micro Patterned Quantum Dots Excitation for Cellular Microarray Imaging Conference on Bioinspired, Biointegrated, Bioengineered Photonic Devices III Bhave, G., Ng, E., Lee, Y., Zhang, J. X. SPIE-INT SOC OPTICAL ENGINEERING. 2015

    View details for DOI 10.1117/12.2083645

    View details for Web of Science ID 000353890300001

  • Microfluidic multiplexed partitioning enables flexible and effective utilization of magnetic sensor arrays LAB ON A CHIP Bechstein, D. J., Ng, E., Lee, J., Cone, S. G., Gaster, R. S., Osterfeld, S. J., Hall, D. A., Weaver, J. A., Wilson, R. J., Wang, S. X. 2015; 15 (22): 4273-4276

    Abstract

    We demonstrate microfluidic partitioning of a giant magnetoresistive sensor array into individually addressable compartments that enhances its effective use. Using different samples and reagents in each compartment enables measuring of cross-reactive species and wide dynamic ranges on a single chip. This compartmentalization technique motivates the employment of high density sensor arrays for highly parallelized measurements in lab-on-a-chip devices.

    View details for DOI 10.1039/c5lc00953g

    View details for Web of Science ID 000364072300003

    View details for PubMedID 26395039

  • Microfluidic immunodetection of cancer cells via site-specific microcontact printing of antibodies on nanoporous surface. Methods (San Diego, Calif.) Ng, E. n., Hoshino, K. n., Zhang, X. n. 2013; 63 (3): 266–75

    Abstract

    We demonstrate an efficient method for cancer cell capture via cell line-specific protein deposition on nanoporous surface in microfluidic channels. Specifically, anti-epithelial cell adhesion molecules (EpCAM) were microcontact printed onto nanoporous silica substrate with optimal pore size of 4 nm, porosity of 52.4 ± 0.2%, and thin film thickness of 130 ± 0.5 nm. SkBr3, Colo205, and MDA-MB-435 cancer cells suspended in buffer solution were captured on the stamped nanoporous silica substrate. The method demonstrated significantly higher numbers of captured EpCAM-positive cancer cells within anti-EpCAM stamped areas. For site-selective cell capture, grooved microfluidic channels were designed to investigate effects of local confinement due to the laminar flows. Both theoretical modeling and experiments show that the integration of the microfluidic channels greatly enhances cell capture. Patterning of anti-EpCAM in areas of downward flow (optimal regions for cell capture), generated by grooves of the microchannel, enables higher capture numbers than that of stamped areas of upward flow (non-optimal). Fluorescence microscopy images were acquired for captured SkBr3 and Colo205 cells using anti-EpCAM on the nanoporous silica substrate. It was shown that higher numbers of cells were captured across all EpCAM-positive cell lines in optimal areas versus non-optimal areas. Spatial control and large scale patterning of proteins enable novel designs and productions of cost effective, high throughput, and integrated detection and analysis systems. Site-selective detection provides the capability of defining optimal locations for cell capture based on various channel geometries and flow profile. The demonstrated method shows great potential for point-of-care cancer diagnostic tools to quantify the progression and status of the disease.

    View details for PubMedID 24012763