Nanogap biosensors for electrical and label-free detection of biomolecular interactions

Abstract

We demonstrate nanogap biosensors for electrical and label-free detection of biomolecularinteractions. Parallel fabrication of nanometer distance gaps has been achieved using asilicon anisotropic wet etching technique on a silicon-on-insulator (SOI) wafer with a finelycontrollable silicon device layer. Since silicon anisotropic wet etching resulted in atrapezoid-shaped structure whose end became narrower during the etching, the nanogapstructure was simply fabricated on the device layer of a SOI wafer. The nanogap deviceswere individually addressable and a gap size of less than 60 nm was obtained. Wedemonstrate that the nanogap biosensors can electrically detect biomolecular interactionssuch as biotin/streptavidin and antigen/antibody pairs. The nanogap devices show acurrent increase when the proteins are bound to the surface. The current increasesproportionally depending upon the concentrations of the molecules in the range of 100 fg ml−1–100 ng ml−1 at 1 V bias. It is expected that the nanogap developed here could be a highly sensitivebiosensor platform for label-free detection of biomolecular interactions.