Integrated VLSI potentiostat for cyclic voltammetry in electrolytic reactions

This paper describes a CMOS integrated potentiostatic control circuit. The design maintains a constant bias potential between the reference and working electrodes for an amperometric chemical sensor. A technique of converting input currents into time for amperometric measurements is proposed. Redox currents ranging from 1pA to 200nA can be measured with a maximum non-linearity of ±0.1% over this range. The design can be used to generate a cyclic voltammogram for an electrochemical reaction by sweeping the voltages across the range specified by the user. Analog inputs are processed and digital outputs are generated without requiring a power-hungry A/D converter. A prototype chip has been fabricated in the 0.5μm AMI CMOS process. Experimental results are reported showing the performance of the circuit as a chemical sensor.