Mechanical tough, stretchable, and adhesive PEDOT:PSS-based hydrogel flexible electronics towards multi-modal wearable application

Conductive hydrogels based on poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) have emerged as promising candidate for wearable electronics due to their distinct conductivity and biocompatibility. However, these hydrogels often encounter limitations such as mismatched mechanical properties, poorly repeatable adhesion, inefficient self-healing capabilities, and insufficient resilience, thus hampering their seamless integration into daily life. Here, a conformally bioadhesive PEDOT:PSS based conductive hydrogel, featuring superior self-healing ability and tissue-like mechanical compliance, is fabricated by compositing and cross-linking multifunctional monomers in PEDOT:PSS dispersion in the presence of guar gum. The wellbalanced combination of PEDOT:PSS and guar gum, along with dynamically revisable noncovalent interactions inside the hydrogel network, lead to significant enhancements in fatigue resistance, conductivity, self-healing, and repeatable adhesion. Enabled by these properties, we further integrate the hydrogel into epidermal sensor with high strain sensitivity (gauge factor of 10.63, similar to 1200%), enabling real-time monitoring of human activities signals as well as high-quality recording of diverse electrophysiological signals with high signal-tonoise ratios (SNR). Moreover, an intelligent sign language recognition platform is constructed by collecting relative resistance change for machine learning and gesture recognition. This research provides a general and scalable strategy for the development of PDDOT:PSS based hydrogel with tailored functionalities to meet diverse wearable requirements.