Thermo‐Switchable Bioadhesive Electrodes for Multimodal Electrophysiological Monitoring and Human‐Machine Interaction

ABSTRACT Conductive hydrogel‐based bioelectrodes, featuring superior biocompatibility and soft tissue‐conformal elasticity and adhesion, enable precise monitoring of subtle physiological signals while minimizing motion‐induced interference. However, persistent strong interfacial adhesion may cause tissue anaphylaxis and serious damage during peeling, especially in the practical scenarios requiring long‐time epidermal monitoring and possible intraoperative electrode reposition. Herein, we developed a smart hydrogel‐based electrode that integrates gelatin alongside an upper critical solution temperature (UCST)‐type polymer. Benefiting from a reversible temperature‐controlled phase‐transition, the hydrogel exhibits strong adhesion at body temperature and gentle detachment after cooling (e.g., with an ice bag for several seconds). This thermo‐switchable adhesion ensures robust interfacial contact that reduces electrode‐tissue impedance and enhances the signal‐to‐noise ratio, while allowing atraumatic removal from skin and subcutaneous tissues. The hydrogel electrode can accurately capture electromyography (EMG) signals of hand muscles, enabling high‐fidelity gesture recognition for non‐contact remote control of robotic devices. The electrode is suitable for high‐precision monitoring of deep subcutaneous muscle activity. Under simulated intraoperative conditions, it reliably recorded both spontaneous and evoked EMG signals from subcutaneous muscles. The proposed hydrogel‐based electrodes enables multimodal electrophysiological recording, including epidermal and subcutaneous healthcare sensing, thereby validating their promising application scenarios under wearable and implantable conditions.