Testing the Need for Carbon in Salt/Adhesive Electrodes for Surface Electromyography Measurements: Preliminary Results

Abstract

We compared previously carbon/salt/adhesive (CSA) electrodes with Ag/AgCl electrodes for surface electromyography (sEMG) signals collection. We found no differences in amplitude, but CSA electrodes exhibited a significantly better response to noise and motion artifacts. However, the carbon component may not be needed, and the salt/adhesive (SA) mixture might be as good as CSA for such a task. Either CSA or SA mixtures have the potential to provide the unique advantages of having longer (theoretically infinite) shelf life and potentially lower cost, compared to the gold standard Ag/AgCl hydrogel electrodes. In order to determine if carbon contribution is necessary for effective sEMG measuring capabilities the mixture, the functionality of SA electrodes utilizing different levels of salt concentration were compared to the capabilities of CSA electrodes. The levels consisted of 10%, 15%, and 25% salt concentration. Six subjects have been recruited so far to collect simultaneous recordings of sEMG signals using CSA and SA electrodes, side-by-side on triceps brachii, tibial anterior muscles, biceps brachii and quadriceps femoris. For all three levels of salt concentration in the SA electrodes, high correlation was found to the CSA electrodes on the estimated linear envelopes, RMS envelope and power spectrum density. Furthermore, no significant differences in amplitude, compared to CSA electrodes, were found for the three concentrations. Based on signal-to-noise and signal-to-motion measures on the preliminary data set, it seems like adding carbon to the mixture improves the response to motion, but impairs the noise corruption of the sEMG signals.