A CMOS potentiostat for amperometric chemical sensors

A simple CMOS integrated potentiostatic control circuit is described. The circuit maintains a constant bias potential between the reference and working electrodes. Chemical concentration signals are converted amperometrically to an output voltage with a slope of approximately 60 mV/μA. Redox currents from 0.1 to 3.5 μA can be measured with a maximum nonlinearity of ±2% over this range. This design also provides the capability of performing differential measurements in order to null the effect of spurious background current. The total power consumption is less than 2 mW. Experimental results are reported showing the performance of the circuit as a chemical sensor control system.