Sean Fischer

From Murmann Mixed-Signal Group

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BSEE, University of Connecticut, 2013
Email: seanrf@stanford.edu

Quantum Biomolecular Transducers

The detection of a target analyte in a biological sample is a common problem in scientific research. Traditionally, analytes are sensed indirectly through interactions with matched antibodies and molecular labels. Labeled detection methods are time consuming, expensive, and immobile, since the combinatorial process requires many reactions, access to a variety of chemicals, and a stable environment. Label-free detection, which is based on identifying the vibrational modes of the target analyte through photonic or electronic means, eliminates the overhead required by labeled detection. Photon-based approaches such as infrared spectroscopy and raman imaging have proven difficult to scale, but electron-based transduction may be possible to integrate on a single chip. One such method, called inelastic electron tunneling spectroscopy (IETS), is based on measuring a vibrationally assisted tunneling current through the target analyte as the potential across the analyte is varied. The resolution of IETS measurements relies on tightly controlled electron energy distributions, which is traditionally achieved by thermally cooling the analyte to impractically low temperatures. However, it has been hypothesized that the analyte may be effectively cooled by electronically reducing the noise present in the system, a method referred to as noise cooling. A circuit demonstrating this noise cooling hypothesis has been used to study the vibrational modes of solvated analytes in electrochemical systems [1, 2]. The goal of this research is to integrate the sensors, interfacing electronics, and data processing required to detect target analytes using this noise cooling technique into a single lab on a chip. This mobile system will quickly detect traces of the target analyte with high reliability at low cost. Such a system will accelerate scientific research in biological and chemical disciplines and provide an essential tool for bio-threat detection in defense applications.
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References

[1] C. Gupta, R. M. Walker, R. Gharpuray, M. M. Shulaker, Z. Zhang, M. Javanmard, R.W. Davis, B. Murmann, and R. T. Howe, “Electrochemical quantum tunneling for electronic detection and characterization of biological toxins,” Proceedings of SPIE, vol. 8373, p. 837303 (14pp), 2012.

[2] R. M. Walker, “Interface electronics for emerging sensor systems,” Ph.D. dissertation, Dept. Elect. Eng., Stanford Univ., Stanford, CA, 2013.

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