A Compact Embedded System for Time-Based Electrochemical Impedance Spectroscopy of Gas Sensors

In this work, a compact embedded system for time-based EIS of gas sensors is presented. Differently from other works, which rely mostly on laboratory instrumentation, the proposed system proves that fast EIS measurements can be implemented on reduced size hardware with minimal employment of on-board components. These goals are achieved thanks to the implementation of the MLS-based measurement technique on a programmable system-on-chip (PSoC) device. In particular, the IR of the sensor is measured by driving it with an MLS excitation signal, thus performing the digital cross-correlation between the input and the output. The selected PSoC device allows the implementation of the digital circuits, the microcontroller and the analog front-end in the same device. As a benefit, the bill of onboard components is extremely reduced. The system architecture and operation are presented in detail and the experimental measurements, obtained by testing a parallel RC as sensor circuit model, are shown. The accuracy between different measurements is evaluated by computing the Pearson's correlation coefficient for each measured IR.