Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 109, Issue 24, Pages 9304-9308Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1203749109
Keywords
label-free detection; genome sequencing; cantilever; spring-softening; critical-point sensors
Categories
Funding
- National Institutes of Health (NIH) [R01-CA20003]
- Materials, Structures and Devices (MSD) Focus Center
- PRISM center
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In this article, we propose a Flexure-FET (flexure sensitive field effect transistor) ultrasensitive biosensor that utilizes the nonlinear electromechanical coupling to overcome the fundamental sensitivity limits of classical electrical or mechanical nanoscale biosensors. The stiffness of the suspended gate of Flexure-FET changes with the capture of the target biomolecules, and the corresponding change in the gate shape or deflection is reflected in the drain current of FET. The Flexure-FET is configured to operate such that the gate is biased near pull-in instability, and the FET-channel is biased in the subthreshold regime. In this coupled nonlinear operating mode, the sensitivity (S) of Flexure-FET with respect to the captured molecule density (N-s) is shown to be exponentially higher than that of any other electrical or mechanical biosensor. In other words, while S-Flexure similar to e((gamma 1 root Ns-gamma 2Ns)), classical electrical or mechanical biosensors are limited to S-classical similar to gamma N-3(S) or gamma(4) ln(N-S), where gamma(i) are sensor-specific constants. In addition, the proposed sensor can detect both charged and charge-neutral biomolecules, without requiring a reference electrode or any sophisticated instrumentation, making it a potential candidate for various low-cost, point-of-care applications.
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