Properties of Dry and Non-contact Electrodes for Wearable Physiological Sensors

Dry and non-contact electrodes are an important part of building user-friendly wearable body sensor networks for physiological (ECG, EEG, EMG) recording. This paper presents the theory and characterization of several inexpensive and non-irritating electrode materials that implement dry and non-contact sensors, including lead-free PCB solder finish, latex, cotton, silver cloth and solder mask. The noise spectra of the electrodes were measured on a live subject to fully mode all the effects of biological and chemical noise processes at the skin- electrode interface. In addition, exemplary ECG physiological measurements are also presented and compared against the signal from reference clinical wet Ag/AgCl electrodes. Results show that PCB finish can function as a general purpose, low-noise dry electrode. Latex and solder mask also work well as insulated electrodes.