Gelatin/polyacrylamide ionic conductive hydrogel with skin temperature-triggered adhesion for human motion sensing and body heat harvesting

Flexible wearable devices based on hydrogels have attracted more and more attention, however, the preparation of hydrogels with high toughness, strong adhesion, on-demand debonding is still a challenge. Here, we report a gelatin/polyacrylamide double network ionic conductive hydrogel with skin temperature-triggered adhesion and low temperature-triggered detachment. The hydrogel has excellent stretchability, compressibility and conductivity. The strain sensor assembled by the hydrogel can realize the sensing of human movement, swallowing water and other behaviors. The thermoelectric generator assembled by the hydrogel has a Seebeck coefficient of 10.4 mV/K and output power of 2.26 μW/cm2 at 10 K temperature difference, showing the application potential in low-grade body heat harvesting. This work provides an intelligent hydrogel with skin temperature-triggered adhesion for flexible wearable devices such as human motion sensors and portable power supplies.