Capacitance Affinity Biosensors

Abstract

In the 1980s work began on the development of a new type of biosensor, where changes in the dielectric properties, between electrodes or at an electrode surface, were monitored. In this way a biorecognition event, where a biomolecule (analyte) in solution binding to a capture layer immobilised on an electrode surface or between electrodes, could be detected directly without the need for labels or indicators. Initial work in this field tended to focus on enzymatic or antibody antigen sensing as a replacement for immunoassay formats. However, with the current interest in elucidating the human genome there has been a rise in DNA-based sensing systems. In this chapter an introduction to the principle of capacitance-based transduction will be given. The electrode/electrolyte interface for metal electrodes and semiconductors will be described and a simple model of these interfaces outlined. An overview of capacitance-based sensors using metal and semiconductor electrodes will be given.