Skin-Conformal Wearable System for Electromyographic Analysis of Palm Muscles During Baseball Pitching

Surface electromyography (sEMG) is a valuable tool for analyzing human movements, including athletic activities like baseball pitching, where precise muscle control plays a critical role. The muscles of the palm are particularly crucial for accurate ball release, yet conventional wearable sEMG devices are often rigid and bulky, hindering natural movements and accurate muscle recordings. To overcome these challenges, we have developed a novel skin-conformal patch device featuring ultra-thin (~300 nm) conductive polymer nanosheet bioelectrodes and stretchable wiring based on kirigami design principles, addressing the mechanical mismatch between skin and electronics. The device incorporates a mechanical gradient structure that transitions from the nanosheet bioelectrodes interfacing with the palm to a robust amplifier/Bluetooth module on the forearm, reducing mechanical stress during arm and wrist movements. This system successfully captured sEMG signals from the abductor pollicis brevis muscle (APBM) of a baseball player, differentiating between fastball and curveball pitches. In addition to enabling detailed analysis of previously underexplored muscles in the palm, fingers, and soles, the system enhances understanding of muscular activity across various sports and complex movements. This technology promises to improve the accuracy and comfort of sEMG recordings, with broad potential applications in sports science and biomechanics.