Impact of size and shape for textile surface electromyography electrodes: a study of the biceps brachii muscle

Electromyography is a technique to record and analyze signals from muscle tissue. Commonly, gel-based (Ag/AgCl) electrodes are used to detect muscle action potentials. Current gel-based electrode designs, however, do not perform well under constant movement and therefore are less suitable to monitor muscle behavior under everyday activities. Textile electrodes do well under movement and extended use, but produce weaker signals than their gel-based counterparts. This work points towards a reduction of this performance gap when the textile electrodes are designed to fit the target muscle. Four textile electrodes of different sizes and shapes are tested on the biceps brachii of 13 subjects. Signal parameters such as the signal-to-noise ratio and voltage root-mean-square are used to determine the quality of the myoelectric signals generated by these electrodes. Results with statistically significant differences show that the electrode area and alignment to the muscle fibers affect signal quality and strength. These results indicate that target muscle characteristics should dictate the electrode dimensional parameters to optimize surface electromyography signal acquisition.