Ultra-stretchable and self-healable hydrogel driven by sorbitol for flexible strain sensors with anti-freezing and self-adhesive

The hydrogel-based strain sensors have increasingly attracted attention for its flexibility, high transparency and excellent sensitivity. However, poor environmental adaptability (e.g. low temperature) and lack of self-healing limited the scope of the application, resulting reducing practical value. Herein, a Polyacrylamide / Chitosan / D-Sorbitol (PCS) conductive hydrogel that integrated multiple properties has been developed by a facile free radical polymerization. The PCS hydrogel not only possessed high transparency, large fracture strain (2600%) and excellent toughness (1.75 MJ m−3), but also adhesive ability to various interfaces without extra assistance. Furthermore, the crystallization peak of PCS hydrogel was at −25.53 °C by introducing sorbitol as cryoprotectant and it also could respond to stimuli of 1% strain after 24 h at −10 °C. Benefitting from reversible hydrogen bonding interactions, the crack with a knife can be fully repaired in 10 min. Similarly, when assembled into a strain sensor with a high GF of 8.224, it was competent to precisely monitor and recognize both drastic human joint movement and subtle pronunciation signals. This work provided a novel idea for developing flexible electronics with multi-performance.