(Invited) Why Are Nanowire BioFETs More Sensitive than Their Large-Scale Counterparts?

Abstract

We have studied the electrostatics of nanowire bioFETs as their channel widths vary. It is commonly believed that smaller bioFET channel widths and heights result in better sensitivity, which is attributed to increased surface-area-to-volume ratios of the bioFET channels. The simulations and analytical arguments presented here show that this reasoning is flawed. Instead, our work suggests that the local curvature of the bioFET surface, especially the corners, affects the electrostatic potential that results from the captured target analytes. Nanowires of any width have the same number of corners, but as the nanowire width shrinks, the beneficial concave corners contain a larger fraction of the total surface area, and their relative importance increases, leading to a slight increase in the bioFET signal.