Multifunctional hydrogel with self-healing and recyclability based on self-catalytic Fe/TA system for sustainable E-skin application.

Hydrogel-based materials for e-skin applications have aroused tremendous attention due to their ability to simulate human skin's sensory capabilities and possess mechanical properties comparable to those of skin. When used as sensors attached to the skin, hydrogels are inevitably subject to damage, highlighting the need for self-healing properties. Furthermore, the lack of recyclability in traditional hydrogel sensors is detrimental to sustainability. To address this issue, we developed a hydrogel based on multiple noncovalent bonds and ferric ion/tannic acid redox system, combined with polyvinyl alcohol as a reinforcing skeleton and low polymerization of polyacrylic acid. This design endows the hydrogel with excellent self-healing properties, easy recyclability and enhanced mechanical properties. Additionally, as a strain sensor, it exhibits competitive performance including high sensitivity, rapid response time and excellent sensing stability. With these remarkable characteristics, the hydrogel demonstrates significant potential as a sensor for sustainable e-skin applications.