A High-Efficiency Discrete Current Mode Output Stage Potentiostat Instrumentation for Self-Powered Electrochemical Devices

Power usage reduction and efficiency enhancement of measurement devices are a major challenge in self-powered wireless sensor nodes and also sensors implanted in the human body. Such instruments should he usually operated using the limited environmental energy resources. Electrochemical sensors and potentiostats are extensively used in this context for the measurement of chemical components. In these cases, a lot of research has focused on internal processing blocks power reduction of the potentiostat circuit. In this paper, a discrete current mode (DCM) switching potentiostat is presented, which can significantly reduce the static power usage at the output stage of the potentiostat compared with linear output stage counterparts. Using time-domain analyses, the unexpected oscillatory behavior of a continuous current mode (CCM) output stage switching potentiostat is investigated. Consecutively, it is shown that in current fabrication processes, this configuration will consume more power than the DCM topology. The correctness of the designs and analyses are shown using both simulation and experimental results. The simulated 0.18-mu m CMOS DCM output stage potentiostat has an efficiency of 95% at an output load of 12 mu A, while the long-channel MOSFET-based prototype implementation shows an efficiency of 64%.