A fully differential CMOS potentiostat

A CMOS potentiostat for chemical sensing in a noisy environment is presented. The potentiostat measures bidirectional electrochemical redox currents proportional to the concentration of a chemical down to pico-ampere range. The fully differential architecture with differential recording electrodes suppresses the common mode interference. A 200 mumtimes200 mum prototype was fabricated in a standard 0.35 mum standard CMOS technology and yields a 70 dB dynamic range. The in-channel analog-to-digital converter (ADC) performs 16-bit current-to-frequency quantization. The integrated potentiostat functionality is validated in electrical and electrochemical experiments.