Mussel-inspired Strong and Tough Hydrogel with Self-adhesive based on Dynamic Interactions for Flexible Wearable Electronics

Abstract

Emerging conductive hydrogels showcase profound potential for sophisticated manipulation and various sensing applications. However, it is still challenging to prepare conductive hydrogel materials with the integration of mechanically tough, reliable healability, and high adhesion strength for skin comfort. Inspired by the robust adhesive mechanisms of mussel proteins, we present an innovative adhesive hydrogel (PVA-DBA) with exceptional adhesive properties, elasticity, and self-healing capability, achieved through the integration of PVA-DOPA copolymer and Fe³⁺ ions within a PAM-PAA hydrogel. The DOPA groups confer strong interfacial adhesion, yielding an adhesion strength of 63.0 kPa on porcine skin (simulate human skin) under ambient conditions, with repeatable use across 6 cycles without residual interfacial traces. The catechol-carboxyl interactions, enhanced by Fe³⁺ coordination, impart the hydrogel with high tensile strength, stretchability, and toughness while accelerating gelation kinetics. The unique structural composition provides multiple functional groups (-NH₂, -COOH, and catechol), collectively reinforcing mechanical stability and self-healing performance, achieving an impressive strain self-repair rate of 81.2%. The resultant PVA-DBA hydrogel demonstrates both mechanical robustness and adhesive functionality, along with sensitive conductivity, making it highly suitable for integration into sensing devices that detect bodily motions such as finger, elbow, and knee bending, with a response time of 400 ms. Furthermore, this hydrogel shows potential in sports applications, effectively recording stretching and bending movements, marking a significant advancement in the development of intelligent and responsive material systems.