Design and Fabrication of Printed Human Skin Model Equivalent Circuit: A Tool for Testing Biomedical Electrodes without Human Trials

Within the efforts of developing a new generation of biomedical electrodes with embedded switching logics, developing safe and simple procedures for testing these novel systems is tackled. The development and demonstration of an all-printed flexible testbed for automated validation and testing of multi pad systems is presented. The system is based on a Human model equivalent circuit (HMEC), which, when connected to the electrical stimulation system, mirrors the electrical behavior of biomedical electrodes and their specific interface material as if they are placed on a human subject. A simulation model of the electrical stimulation system components was developed based on the experimental data, in order to optimize printed electronic components' characteristics and design. The testbed is composed of five layers of different conductive and dielectric materials screen-printed on a flexible poly(ethylene terephthalate) (PET) substrate. The system was prototyped with the characteristic values of the HMEC matching the average experimental data acquired from human subjects. Thus, it is demonstrated that an all printed flexible HMEC is a feasible approach to enabling the functional testing of transcutaneous electrical stimulation devices required for their fabrication, evaluation and optimization, reducing the need for tests on human subjects in the development phase of new systems.