Transparent, highly stretchable, fully self-recoverable ionic hydrogel for flexible ultra-sensitive sensors

Up to now, a variety of hydrogels have been explored for strain sensors, but simultaneous accomplishment of high stretchability, rapid full self-recovery, favourable transparency and excellent sensing properties through employing inexpensive raw materials and simple synthesis approach remains challenging. Herein, AlCl3·6H2O aqueous solution, as a sort of solvent, was utilized to facilely manufacture high performance hydrogel ionic conductors with novel one-pot dual ionic cross-linking approach. The resulting model hydrogel sensors manifested favorable transparency (>84%), excellent stretchability (1400%), good mechanical strength (421.2 kPa), outstanding rapid self-recovery (nearly full recover) and good anti-fatigue. Furthermore, our ionic hydrogel sensors demonstrated brilliant stretching sensitivity (gage factor as high as 9.6), and it displayed stable sensing performance for repeatedly real-time monitoring of both large and subtle deformations. Hence, the hydrogel sensors successfully achieved critical features combination and could serve as wearable devices to sense various human motions.