Highly tough, crack‐resistant and self‐healable piezo‐ionic skin enabled by dynamic hard domains with mechanosensitive ionic channel

Abstract Robust and reliable piezo‐ionic materials that are both crack resistant and self‐healable like biological skin hold great promise for applications inflexible electronics and intelligent systems with prolonged service lives. However, such a combination of high toughness, superior crack resistance, autonomous self‐healing and effective control of ion dynamics is rarely seen in artificial iontronic skin because these features are seemingly incompatible in materials design. Here, we resolve this perennial mismatch through a molecularly engineered strategy of implanting carboxyl‐functionalized groups into the dynamic hard domain structure of synthesized poly(urethane‐urea). This design provides an ultra‐high fracture energy of 211.27 kJ m −2 that is over 123.54 times that of tough human skin, while maintaining skin‐like stretchability, elasticity, and autonomous self‐healing with a 96.40% healing efficiency. Moreover, the carboxyl anion group allows the dynamic confinement of ionic fluids though electrostatic interaction, thereby ensuring a remarkable pressure sensitivity of 7.03 kPa −1 for the tactile sensors. As such, we successfully demonstrated the enormous potential ability of this skin‐like piezo‐ionic sensor for biomedical monitoring and robotic item identification, which indicates promising future uses in flexible electronics and human–machine interactions.