Highly Adhesive and Stretchable Epidermal Electrode for Bimodal Recording Patch

For numerous biological and human-machine applications, it is critical to have a stable electrophysiological interface to obtain reliable signals. To achieve this, epidermal electrodes should possess conductivity, stretchability, and adhesiveness. However, limited types of materials can simultaneously satisfy these requirements to provide satisfying recording performance. Here, we present a dry electromyography (EMG) electrode based on conductive polymers and tea polyphenol (CPT), which offers adhesiveness (0.51 N/cm), stretchability (157%), and low impedance (14 kΩ cm² at 100 Hz). The adhesiveness of the electrode is attributed to the interaction between catechol groups and hydroxyls in the polymer blend. This adhesive electrode ensures stable EMG recording even in the presence of vibrations and provides signals with a high signal-to-noise ratio (>25 dB) for over 72 h. By integrating the CPT electrode with a liquid metal strain sensor, we have developed a bimodal rehabilitation monitoring patch (BRMP) for sports injuries. The patch utilizes Kinesio Tape as a substrate, which serves to accelerate rehabilitation. It also tackles the challenge of recording with knee braces by fitting snugly between the brace and the skin, due to its thin and stretchable design. CPT electrodes not only enable BRMP to assist clinicians in formulating effective rehabilitation plans and offer patients a more comfortable rehabilitation experience, but also hold promise for future applications in biological and human-machine interface domains.