NIR light-triggered mechanically mutable mussel-inspired hydrogels for developing smart wearable sensing

Emerging light-driven mechanically mutable soft matters showcase profound potential for sophisticated manipulation and various applications. However, the realization of a versatile and straightforward fabrication technique has been absent in photoresponsive hydrogel. Inspired by mussel adhesive protein and boronic ester-based dynamic covalent bonds, near-infrared (NIR) light-triggered adhesive hydrogels (PBD gel) with the permanent mechanical characters reconfiguration capability are prepared. The hydrogel consists of catechol-based polymer as adhesive units and thermal responsive boronic ester as physical cross-linking junctions, which combines their covalent character to achieve stiffness and their dynamic nature for fast and reversible transition to soft elastics. Taking advantage of the catechol-B(OH) 4 - coordination, the adhesive behavior and permanent mechanical performances of the PBD gel could be reconfigured. On the basis of the light switchable transformation between stiffness and elasticity at room temperature, we demonstrated precise control over nonplanar substrates especially adaptable in multidimensional structures designed for tasks such as wearable sports sensors on the human skin and intelligent robots grabbing objects. When it is assembled into an electronic device, it can transmit information and recognize sign language via Morse code. Overall, we report the hydrogel here advances user-friendly and versatile light control technologies, unlocking new possibilities for various applications, promoting the development of intelligent soft photonic and electronic sensing technologies.