Self-healing, sensitive and antifreezing biomass nanocomposite hydrogels based on hydroxypropyl guar gum and application in flexible sensors.

In this manuscript, self-healing, highly flexible hydrogels based on hydroxypropyl guar gum (HPG) were prepared by adding dopamine-coated reduced-graphene oxide (rGO@PDA). The multiple reversible dynamic networks were simultaneously constructed by boron-oxygen and metal-ligand interactions. These multiple networks significantly improve the self-healing efficiency and mechanical strength of the biomass hydrogels. It is noteworthy that rGO@PDA can enhance conductivity and flexibility properties. Impressively, flexible sensor with these self-healing hydrogels have a large strain range (728%), high sensitivity (GF = 11.30) and fast response time (210 ms). The obtained flexible sensors can also detect human motion (such as sound vibrations and pulse rates) to large scales (such as knee flexion) over a wide temperature range (-20-30 °C). The signals of sensors have superior stability and repeatability, which show potential application prospect in the field of flexible wearable devices.