Highly Stretchable and Self‐Healable MXene/Polyvinyl Alcohol Hydrogel Electrode for Wearable Capacitive Electronic Skin

Abstract Capacitive strain sensors could become an important component of electronic skin (E‐skin) due to their low hysteresis and high linearity. However, to fully mimic the functionality of human skin, a capacitive strain sensor should be stretchable and self‐healable. The development of such a sensor is limited by electrode materials which generally lack self‐healability and/or stretchability. A highly stretchable and self‐healing MXene (Ti 3 C 2 T x )/polyvinyl alcohol (PVA) hydrogel electrode is developed for use in capacitive strain sensors for E‐skin. The incorporation of MXene into the PVA enhances the conductivity and self‐healability of the hydrogel. The electrode exhibits high stretchability at break (≈1200%) and instantaneous self healing (healing time ≈ 0.15 s). A capacitive sensor based on these electrodes shows high linearity, up to 200%, low hysteresis, a sensitivity of ≈0.40, and good mechanical durability (a 5.8% reduction in relative capacitance change after 10 000 cycles). Moreover, this sensor maintains its performance after a self‐healing test, proving its potential for the monitoring of human motion.