Optimizing Silver Nanowires on-Skin Electrode Shape for Improved Electromyography Signal Quality in Detecting Adjacent Muscles

The monitoring of the electrophysiological signals of the human body has drawn a lot of interest in recent decades. The electromyography (EMG) signals, in particular, are frequently used in a variety of applications involving human-machine interfaces (HMI) because they can represent the activation of human muscles. Nevertheless, the commercial Ag/AgCl electrodes for monitoring EP signals have no stretchability with a large size.As a result, it is challenging to keep the conformal contact with skin under deformation for Ag/AgCl electrodes, and capture signals from dense muscles. Therefore, a soft and thin on-skin electrode was developed in this work, with a conductive layer fabricated by silver nanowires (AgNWs) and a polydimethylsiloxane (PDMS) substrate. The AgNW electrode has a high conductivity of ~0.48 Ω/sq with only 300 μm thickness. Besides, a differential strip AgNW electrode with a spacing of 10 mm was created and put perpendicular to the muscle fibers in order to further reduce the crosstalk from nearby muscles when detecting EMG signals from the human body part with densely distributed human muscles. The obtained EMG signals had a higher signal-to-noise ratio (SNR) than the round electrode under the same experimental circumstances. In addition, the ability of the strip AgNW electrode to reduce crosstalk in the acquisition of multichannel EMG signals under various gestures was demonstrated, which can help improve the gesture classification accuracy and employ the potential in human-machine intelligence (HMI) applications.