Highly tough, crack-resistant and self-healable piezo-ionic skin enabled by dynamic hard domains with...

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.