Semiconductor Electronic Label-Free Assay with Novel Nanowire Field-Effect Transistor Biosensors

Abstract: Biomolecular assays are biochemical tests used for quantitative measurement of target biomolecular analytes from specimens. This is usually achieved with labelling techniques where target biomolecules were conjugated with labels for signal readout. Label-free assay provides an alternative route to detect target biomolecules without secondary label conjugation. The technique enables high-throughput and real-time measurements of analyte samples which is of primary significance in many biological applications (e.g. drug screening, point-of-care diagnosis). One promising candidate for real-time label-free biomolecular detection is using field-effect transistor (FET) biosensors. A FET without a gate electrode is designed to detect immunological antigen-antibody binding reactions. Charged target biomolecules specifically are bound onto biological receptors anchored on the oxide dielectric surface. The induced electric field mitigated by oxide dielectric is directly translated into current change without any labeling. Nanowire FET (nwFET) biosensors have been demonstrated to have exceptional biomolecule sensitivity with lower limit of detection (LLOD) down to sub-picomolar range. However, the inherently low output-signal levels are impractical for their use outside of the research lab. In addition, variability issues originated from device fabrication, system integration and during sensing experiment prohibit reliable quantitations of target biomolecules in the scenarios of interest. As a result, label-free biomolecular assays have not been meaningfully adopted and impacted the biomedical and pharmaceutical industry even after decades of intense research.

To boost output signal level of FET sensors, we previously proposed a novel T-shape nwFET (T-nwFET) structure containing integrated sensor-amplifier to amplify output signals at close proximity. However, the concept of T-nwFET as a biosensor has not been implemented in biomolecular detections. In this work, we first understood and improved the sensitivity of T-nwFET biosensors using a signal-to-noise ratio metric, and validated the performance in practical settings. We also investigated theoretical and practical approaches to improve selectivity, which is crucial to the accuracy of assays. We proposed a novel per-sensor based calibration scheme to eliminate potential test-to-test variability. The T-nwFET was then developed into a holistic biomolecular assay platform, SELFA, and its performance was evaluated by implementations in predictive toxicology and clinical studies.

Biography: Yufei Mao is currently a Ph.D. candidate at University of California, Los Angeles (UCLA) under the mentorship of Prof. Chi On Chui. He received the B.S. degree in Electrical Engineering from Beihang University, China, in 2010. He joined Nanostructure and Device Technology Lab in 2010 and received his M.S. degree from Department of Electrical Engineering in UCLA. His research interests include field-effect transistor (FET) based biosensing and biosensors, optoelectronic tweezers for bioelectronics applications.

For more information, contact Prof. Chi On Chui (chui@ee.ucla.edu)

Date/Time:
Date(s) - Jun 10, 2016
11:00 am - 1:00 pm

Location:
E-IV Maxwell Room #57-124
420 Westwood Plaza - 5th Flr. , Los Angeles CA 90095