Highly stretchable, adhesive and self-healing hydrogel electronics for human motion detection and electrophysiological signal monitoring

Hydrogels have emerged as an ideal platform for wearable sensors due to their exceptional biocompatibility and flexibility, enabling seamless integration into multifunctional daily applications. Nevertheless, concurrently achieving hydrogels-based sensors with robust adhesion, efficient self-healing, high sensitivity, and broad strain detection range via a straightforward fabrication methodology remains a significant challenge. Here, we present a highly stretchable, adhesive and self-healing conductive Polyvinyl alcohol-Borax-Polypyrrole (PVA-B-PPy, PBP) hydrogel through in-situ polymerization and freeze-thaw treatment. The multi-synergistic dynamic interaction of reversible borate ester bonds, extensive hydrogen bonding and physically crosslinked PVA microcrystalline domains endows PBP hydrogel exceptional mechanical properties, tissue-mimetic softness, robust adhesion and autonomous self-healing (97.4 % mechanical efficiency, instantaneous electrical recovery). The PBP hydrogel-based strain sensor with a high sensitivity (GF = 2.48) and an extensive monitoring range (360 % strain) is capable to accurately and timely monitor various human movements. Furthermore, the PBP hydrogel enables long-term electrophysiological monitoring via skin-adhesive bioelectrodes and serves as human-machine interfaces through flexible pressure-sensor arrays and hydrogel touchscreen pens for smartphone operation. This research provides a promising strategy for designing hydrogels with tailored functionalities for wearable electronics that satisfy diverse requirements of practical applications in personalized healthcare monitoring, soft robotics, and interactive devices.