Bipolar Concentric Ring Microneedle Array (BCRMA): An Electrical Stimulation Electrode for Precise Movement Control

Functional electrical stimulation (FES) has played a vital role in exercise rehabilitation, and focused electric field distribution can achieve precise and efficient selective stimulation. In this work, we introduce an electrical stimulation method for precise muscle movement control utilizing a bipolar concentric ring microneedle array (BCRMA) electrode. Microneedle array and surface-modified conductive polymer PEDOT: PSS effectively reduce the electrode-skin contact impedance and increase the charge injection capacity. Due to the bipolar concentric ring structure of BCRMA and the low contact impedance, a concentrated electric field can be formed when a relatively low voltage is applied, which is proved by the electric field and current density simulation results. According to the biological electrical stimulation experiment, the proposed BCRMA can achieve precise control of rat forelimb movements. After electrical stimulation, there is no obvious skin damage, and pinholes left by microneedles can be healed within 20 minutes.