Design of a voltammetry potentiostat with wide dynamic current range measurement

In this paper, we design a voltammetry potentiostat chip with wide range current measurement for the signal processing of electrochemical biosensors. In this design, the current of biosensors will be detected and divided into four regions, and then be diminished in accordance with corresponding current scaling ratio. All the ranges of the biosensor´s current will be diminished to a proper current range (≤ 2.5 μA) and then be converted into frequency-modulated pulses by a sigma-delta modulator in a fixed conversion time. The aim of this design is to deal with the large dynamic current range of signal processing for different biosensors in applications. The measured results of proposed potentiostat can be digitized by a microprocessor without using a high resolution ADC. The proposed potentiostat is fabricated by 0.35 μm CMOS technology, and the chip layout core area is 0.31 mm². The function of the proposed potentiostat has been tested and measured in our laboratory, and the measurement results show that the dynamic range of signal processing, from 1 nA to 2 mA, is 126 dB. The power consumption under normal operation is 10 mW.