Tough and super-stretchable conductive double network hydrogels with multiple sensations and moisture-electric generation

The rapid development of artificial skin, flexible sensors, and soft robotics proposes more requirements on conductive hydrogels, which should integrate more functions. However, it remains a great challenge to develop an integrated conductive hydrogel combining multiple sensations and self-powered properties. Herein, we develop a conductive MXene-cellulose nanocrystals (CNCs)-tamarind gum (TG)-polyacrylamide (PAM) hydrogel containing conductive ions by a facile fabrication process. A unique double network structure in the composite hydrogel was assembled by employing TG with an ionically cross-linked network and PAM with a UV photoinitiated cross-linked network, which imparted this hydrogel with toughness (38.8 KJ/m2) and high stretchability (2000% strain). The hydrogel also possessed high sensitivity (gauge factor = 5.23, 248% strain) due to the introduction of MXene and mobile ions, thus exhibiting multiple sensations towards pressure, strain, humidity, and temperature. More importantly, the hydrogel is self-powered and can generate an open-circuit-voltage of up to 164 mV from moisture flow in a very short time (18 s). We believe that the hydrogel not only shows great potential applications in artificial skin, flexible sensors, and soft robotics, but also contributes to the development of next-generation artificial intelligence.