Ultrathin Cellulose Nanofiber-Reinforced Ti₃C₂T_x-Crosslinked Hydrogel for Multifunctional and Sensitive Sensors

Multifunctional strain sensors simultaneously satisfy all the requirements including flexibility, stretchability, biocompatibility, and high responsibility to external stimuli, which are always in high demand for wearable electronics. In this work, we introduced modified bacterial cellulose nanofibers (BCNF) as double-network hydrogel-reinforced substrates to prepare an MXene-based strain sensor (MPCB). The well-percolated BCNF play an important role in reinforcing the polymer skeleton and inducing the continuous MXene–MXene conductive paths. Consequently, the electrical conductivity was significantly improved and excellent mechanical properties were retained (with the elongation at break over 500%). The prepared hydrogel can act as a wearable sensor for human motion detection, including swallowing movements, finger bending, and wrist bending. It also exhibits promising applications with multiple characteristics, i.e., ideal EMI, adjustable flexibility, self-healing, and self-adhesive performance. Our work provides a simple and practical strategy for a generation of wearable electronic sensor devices.