Multifunctional MXene/PAA organohydrogel as a flexible strain sensor for wearable human–machine interaction

Flexible strain sensors play a critical role in wearable human–machine interaction (HMI), allowing for natural and intuitive communication between humans and machines. Conductive hydrogels are promising candidates for flexible sensor materials due to their flexibility, sensitivity, and biocompatibility. However, the conventional hydrogels tend to freeze at subzero temperatures or lose water at room temperature, resulting in decreased electrical conductivity and mechanical flexibility, and thus poor long-term stability. Herein, a multifunctional MXene/polyacrylic acid (PAA) organohydrogel with high toughness and self-healing, self-adhesive, antifreeze, and long-term moisturizing ability was prepared using a facile solvent replacement method. It has a high sensitivity (gauge factor ∼10.96), wide detection range (0–1304%), and stable signal output for 500 cycles, making it an ideal flexible strain sensor for monitoring human joint movements, subtle expression changes, and pronunciation in real time. This work provides a new paradigm for wearable artificial intelligence and human–machine interactions in complex environments.