A highly stretchable, self-adhesive, anti-freezing dual-network conductive carboxymethyl chitosan based hydrogel for flexible wearable strain sensor.

Achieving the integration of multiple properties in a single hydrogel system faces significant challenges. This research presents a simple approach to developing a multifunctional conductive hydrogel with high stretchability (>740 %), electrical conductivity, frost resistance and self-adhesiveness. It serves as a wearable, flexible electronic material, it remains functional even in low-temperature environments. The hydrogel is synthesized by incorporating a uniformly mixed solution of carboxymethyl cellulose (CMC) and aminated carbon nanotubes (NH-CNTs) into a polyacrylamide (PAM)/gelatin dual-network hydrogel. By adjusting the CMC mass fraction, the optimal composite hydrogel is obtained within a specified gradient. After cross-linking modification with a calcium chloride (CaCl) solution, enhances its mechanical properties, resulting in a final hydrogel with excellent stretchability (strain = 749 %), strong adhesion, frost resistance, moisture retention, and conductivity. Additionally, this research explores the hydrogel's potential for anti-counterfeiting and salt ion monitoring by analyzing changes in mechanical properties and transparency. The hydrogel exhibits high sensitivity to external strains and effectively monitors human signals such as finger bending, head movement, and speech, even at low temperatures. This research provides new insights into flexible electronic skin, wearable sensors and human-computer interaction, expanding the potential applications of multifunctional conductive hydrogels.