Graphene Oxide-Modulated Nanocellulose/Polyacrylamide/Sodium Alginate Hierarchical Network Hydrogel for Flexible Sensing.

The application of hydrogels in flexible sensing has received increasing attention, but the simultaneous preparation of hydrogels with good structural stability, strain sensing sensitivity, freezing resistance, and drying resistance remains a challenge. Based on this, a GG-nanocellulose/sodium alginate/polyacrylamide composite hydrogel with a hierarchical network structure was constructed by one-step synthesis by incorporating graphene oxide (GO) and glycerol into the hydrogel. The hydrogel remained structurally intact after 100 compression cycles. In addition, the hydrogel was dried at 30 °C for 24 h. The mass retention rate was 48%, the melting peak was as low as -13.87 °C, and the hydrogel remained flexible and stable at low temperatures. GO modulated the network structure arrangement of the hydrogel through various mechanisms, thereby conferring to the hydrogel an excellent sensing performance, with a sensitivity (GF) of 2.21. In conclusion, this hierarchical network hydrogel has good drying, freezing, and sensing properties, which provides a new viable strategy for monitoring motion signals. Moreover, the hydrogel is predicted to function as a dressing, thereby facilitating the absorption of heat from the skin's surface, with the aim of alleviating the discomfort associated with joint and muscle injuries caused by strenuous exercise.