Amperometric instrumentation system with on-chip electrode array for biosensor application

Abstract

An integrated amperometric instrumentation system with on-chip electrodes for biosensor arrays is presented. The mixed-signal integrated circuit supports a variety of electrochemical measurement techniques including linear sweep, constant potential, cyclic and pulse voltammetry. Implemented in 0.5 μm CMOS, the 3×3 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> chip dissipates 22.5 mW for a 200 kHz clock. The highly programmable chip provides a wide range of user-controlled rate and amplitude parameters with a maximum scan range of 2 V and scan rate ranging between 1mV/sec to 400V/sec. The amperometric readout circuit provides ± 0.5 pA linear resolution and supports inputs up to 100μA. A 2×2 array gold electrode electrochemical cells was fabricated on the surface of the CMOS instrumentation chip. An all-parylene packaging scheme was developed for compatibility with liquid test environments as well as harsh piranha electrode cleaning processes. The chip was tested using cyclic voltammetry of 0.1M potassium ferrocyanide, and results were comparable to measurements using commercial instruments.