Soak Your PCB: a Design Activity for Hands-On Learning of the Electrochemical Interface Impedance

A newly introduced laboratory experience addressing the practical understanding of the impedance of the non-Faradaic electrochemical interface, within a bioelectronics class, is presented. The project is carried out by teams of M.Sc. students (3 to 5 persons) of mixed backgrounds (electronics and biomedical engineering). It comprises two phases. First, a design phase, in which a PCB hosting planar gold coated electrodes, to be sized in order to properly measure the ionic resistance of the solution (below 10 MHz), and a low-noise transimpedance stage to interface to a USB network analyzer are designed. Then, during the experimental activity impedance spectroscopy is performed with the electrodes in saline solution, coupled to microfluidics, and data are analyzed to estimate the solution conductivity and compared with simulations.