Impedance Biosensor Utilizing a Si Substrate Deposited by Wet Methods

We report an impedance biosensor utilizing a Si electrode created by wet chemical deposition atop Al alloy 6061. The sensor electrode is created by galvanic/electroless Si deposition from an electrolyte containing 10 mM HF and 20 mM Na2SiF6 in 80 wt% formic acid, followed by antibody immobilization. The impedance response of the sensor electrode to increasing concentrations of peanut protein Ara h 1, a common food allergen, can be fit to an equivalent circuit containing three RC loops. The circuit element most sensitive to antigen binding is the charge transfer resistance, yielding a detection limit of 4 ng/ml. (C) 2015 The Electrochemical Society. All rights reserved.