Assessment of Single Use Dry Epidermal Electrodes for Surface Electromyography Recordings

Alternatives to conventional wet Silver/Silver Chloride (Ag/AgCl) hydrogel electrodes could greatly improve the ability to record long-term surface electromyography (sEMG). This paper presents preliminary evaluation of dry epidermal electronic system (EES) electrodes over 8 days measurements. We tested 3 subjects and recorded sEMG signals of right rectus femoris during static and dynamic tasks from epidermal electrodes and traditional Ag/AgCl electrodes. For epidermal electrodes that remained intact and maintained adhesion to the skin, signal-to-noise ratio (SNR) values were greater than 16.9 dB and signal-to-motion ratio (SMR) values were greater than 13.1 dB, which were both above the accepted thresholds for good signal quality (SNR > 15 dB and SMR > 12dB). We also developed a new metric, the Signal Quality Index, SQI to help determine whether higher SNR or higher SMR were necessarily indicative of better EMG signal quality. Our results indicated that the single use dry epidermal electrodes were able to maintain high signal quality over 8 days and suggested that dry epidermal electrodes have the potential ability for long-term sEMG recording.