Degenerate Si as an Electrode Material for Electrochemical Biosensors

Abstract

The use of degenerate (heavily doped) Si as an electrode material for electrochemical biosensors is demonstrated by a series of voltammetry and impedance studies. Cyclic voltammetry in solutions of and exhibits reversible electrochemistry without illumination, which to the best of the authors’ knowledge has not been previously reported for Si electrodes in an aqueous environment. The presence of prevents formation of the Si native oxide, while the use of a degenerate Si substrate makes its electrochemistry more like that of a metal. In addition, impedance detection of peanut protein Ara h 1 is demonstrated on a degenerate Si electrode following immobilization of the monoclonal mouse antibody to this protein. The variation in charge-transfer resistance with protein concentration is employed to estimate the dissociation constant of the surface-immobilized antibody-antigen complex as . The advantages of degenerate Si relative to n- and p-type Si include the lack of photoeffects, a simpler equivalent circuit, easier electrical connection to the working electrode, and knowledge that the applied potential applied is dropped within the electrical double layer, not within the semiconductor space-charge layer. Most important, degenerate Si electrodes are easily incorporated into Si-based semiconductor devices.