New CMOS potentiostat as ASIC for several electrochemical microsensors construction

The purpose of this paper is to design and create the potentiostat that can be integrated and encapsulated within a microelectrode as a low-cost electrochemical sensor. Recently, microsystems on sensors or lab on a chip using electrochemical detection of substances matters are pushing forward into the area of analysis. For providing electrochemical analysis, the microsystem has to be equipped with an integrated potentiostat. The integrated potentiostat with four current ranges (from 1 uA to 1 mA) was designed in the CADENCE software environment using the AMIS CMOS 0.7um technology and fabricated under the Europractice program. Memory cells of 48 bytes were implemented with the potentiostat using VERILOG. The characteristics of integrated potentiostat are strictly linear; the measured results confirm the simulated values. The potentiostat measurements error is about 1.5 percent and very low offsets are reached by the offset-zeroing circuitry. The detection limit of the current at the lowest range with respect to S/N ratio is about 10 nA. The integrated potentiostat is embedded on a screen-printed sensor and its characteristics are successfully verified. Lower range of 100 nA can be implemented on a new microchip as well as rail to rail output circuitry would increase the voltage dynamic range.