ABSTRACT
Label-free bioaffinity sensors directly detect changes in the inherent property of the analyte, receptor or the molecular aggregates formed upon binding. This chapter introduces a label-free biosensor that utilizes a two-dimensional planar thin-film as the gate of a field effect transistor (FET). The direct label-free detection of biomolecules by the FET is based on the change of conductance due to the depletion or accumulation of carriers within the transistor structures when the charged biomolecules bind to the gate. The selectivity and sensitivity of the FET can be improved by modifying the gate of the FET with bioreceptors molecules such as antibodies, antigens, and oligonucleotides. Performance and sensitivity are further improved by fabricating the FETs from 1D nanostructured materials (e.g. conducting polymer nanowires). Improvements using 1D conducting nanowires include large conductance changes, real-time monitoring because the binding between the receptor and the target is reversible, direct conversion of chemical information into an electronic signal, and the development of high-density arrays due to the very small size of the nanostructures.
