(591c) Degenerate Si As a Biosensor Substrate Material

We report the use of degenerate (heavily doped) Si as an electrode material for impedance detection of peanut protein Ara h 1, an allergenic food protein.  Following immobilization of the mouse monocloncal antibody onto degenerate Si by amide bond formation, detection limits in the pM range can be obtained.  Although p- and n-type Si have previously been reported as biosensor substrate materials, they typically form space charge layers that make electrochemical detection methods difficult.  One advantage of degenerate Si is much easier formation of ohmic contacts at both sides of the substrate material, which allows for “reversible” electrochemistry, as well as simpler equivalent circuits during impedance detection.  Other advantages of degenerate Si include easier incorporation of electrical biosensors into ULSI devices, and improved interfacial stability due to the strength (520 kJ/mole) of the Si-C bond.