Highly stretchable and autonomously healable epidermal sensor based on multi-functional hydrogel frameworks

A highly sensitive sensor platform is significant for human-machine interactions and healthcare applications due to its instantaneous monitoring of human physiological activities. However, current flexible sensors are confronted with liability to rupture, malfunction under subzero temperatures and deficient recyclability, posing great challenges to long-term implementation. Herein, a highly stretchable and healable somatosensory platform with excellent low temperature tolerance was demonstrated by adopting self-healing hydrogels as building blocks. Both metal-coordinated bonds and tetrahedral borate interactions within the binary-networked frameworks account for the satisfactory stretchability (∼550%), remarkable healed strain (∼497% after 6 h) and high healing efficiency (∼90.4%). Self-remolding capacity to regain the mechanical performance is also presented, showing superb malleability. Low temperature (-25 °C) tolerance of the sensor is favorable for all-weather applications. In addition, the piezoresistive sensor has negligible electrical hysteresis, fast response (∼31 ms) and electrically self-healable behavior. Various human motions (e.g., finger bending, phonation, and limb activity) can be differentiated by this hydrogel-based sensor.