On the function and robustness of skin-electrode interfaces for high-density electromyography: Towards ubiquitous integration with robotics devices

Abstract

High-density electromyography is a technique to infer muscle activity from large numbers of electrodes placed over the muscle just a few millimetres apart. Due to the spatial density of electrode arrays, novel recommendations regarding skin-electrode interfaces are required, noting inconsistencies throughout literature. In addition, for HD-EMG to become a viable option for interfacing with wearable robotics, various pressure effects on performance must be investigated. 11 subjects were recruited to analyse the function and robustness of common and novel conductive materials including gel, viscous gel, conductive paint, z-tape and dry configurations by comparing skin resistances and connectivity. The gel conditions led to the lowest skin resistance with an overall median of 65.72kΩ. Viscous gel resulted in improved connectivity to the skin in comparison to the standard gel interface. Pressure effects on resistance, as applied by an exoskeleton strapped over the electrode grid, were diminished using a double-sided adhesive foam tape. Test-retest evaluations revealed rather low reliability with ICCs ≤ 0.22. Viscous gel might provide advantages over pure gel in HD-EMG set-ups as channels are less prone to short-circuit.