Design of a supersoft, ultra-stretchable, and 3D printable hydrogel electrical bioadhesive interface for electromyography monitoring

• PEDOT:PSS-PAA-PAAm hydrogel is designed for electrical bioadhesive interface. • The high sensitivity of EMG monitoring is attributed to the hydrogel's excellent mechanical compatibility. • The tissue-like softness of the hydrogel reaches 5-8.5 kPa (Young's modulus). • The hydrogel achieves ultra-stretchability with a strain of 1,175%. • The PEDOT:PSS-based hydrogel EBI has a higher signal-to-noise ratio (SNR) compared to commercial electrodes. Electromyography (EMG) monitoring has been extensively employed for critical applications in medicine, sports science, and rehabilitation. However, the mechanical mismatch between conventional EMG electrodes and the skin can lead to electrode detachment upon significant skin deformation. To address this limitation, we develop a PEDOT:PSS-based hydrogel electrical bioadhesive interface (EBI) that incorporates molecular doping and robust adhesion strategies to achieve excellent mechanical compatibility with biological tissues. This hydrogel EBI is fabricated using direct writing of printable inks followed by in-situ thermal initiation, enabling the creation of customizable patterns with high shape fidelity. The resultant 3D-printed PEDOT:PSS-based hydrogel EBI exhibits supersoft properties (Young's modulus 5-8.5 kPa), ultra-stretchability (1,175% strain), robust adhesion (>133 kPa), and outstanding electrochemical performance (CIC reduction by 0.45% over 100,000 cycles). Additionally, we further develop a PEDOT:PSS-based hydrogel electrode specifically for stable EMG signal recording. This electrode outperforms superior signal-to-noise ratio (SNR) performance compared to commercial electrodes in EMG monitoring.