A compact signal generation and acquisition circuit for electrochemical impedance spectroscopy

In this paper, a circuit for signal stimulus generation and response signal acquisition for electrochemical impedance spectroscopy (EIS) is presented. The circuit is capable of generating a stimulus signal consisting of 32 frequencies with a 2 Hz (low band) and a 62 Hz (medium band) step from 2 Hz to 2 kHz. A composite signal was generated from the circuit for one band at a time. Such composite signal provides a compact representation of the desired signal spectrum with 0.3% error. The response signal acquisition is accomplished with signal amplification followed by an ADC. An average error of 2.14% in measured impedance was achieved. The limit of detection of 9.2 Ohms was obtained. The design was implemented on a 2-layer PCB board with a total footprint of 75.26 cm².