A highly stretchable, self-adhesive, anti-freezing, and highly sensitive dual-network conductive hydrogel sensor for multifunctional electronic skin

Hydrogel-based wearable sensors have received great attention owing to their potential applications in human health detection and identification of wearable devices. However, it is still a great challenge to integrate all the key functions (such as high stretchability, self-adhesive properties, excellent anti-freezing properties, and high conductivity) into a single hydrogel. In this study, MXene@cellulose nanofibers (MXene@CNFs) were added to polyacrylamide/gelatin (PG) dual-network hydrogels. Afterward, the hydrogels were immersed in different solutions for further crosslinking to explore the effect of different solutions and different immersion times on the degree of crosslinking. Finally, the PG/MXene@CNF/CaCl2 composite hydrogel sensor exhibited an excellent stretchability of >1600%, a high strain sensitivity of 19.95 over a wide strain range, strong adhesion (17.4 kPa), excellent anti-freeze resistance, a fast response time of 150 ms, and high electromagnetic shielding capability. The hydrogel-based wearable sensor could accurately monitor various body movements, vocal cord articulation, letter recognition, heat source location, and human-computer interaction and had a wide range of applications for developing wearable electronic devices, intelligent soft robots, electronic skins, and human-computer interfaces.