Raccoon-paw-inspired porous hydrogel electronic skin for self-powered fused perception.

Wearable gel electronics require soft material platforms capable of supporting autonomous tactile sensing and physiological monitoring within a compact system. Here, we report a raccoon-paw-inspired porous hydrogel electronic skin for self-powered slip perception and artificial sweat fingerprint recognition. A sacrificial sucrose-template strategy was used to construct an interconnected porous hydrogel network with low volume density, high compressibility, rapid liquid uptake, and continuous ionic transport. After loading with the [Fe(CN)6]3-/4- redox couple, the hydrogel generates a thermogalvanic output under a temperature difference. Benefiting from the active piezoresistive effect based on thermoelectricity, the electronic skin enables self-powered pressure sensing with a sensitivity of 161.3 kPa-1, a detection limit of 2.5 Pa, and response and recovery times of 65 and 75 ms, respectively. It is further coupled with a honeycomb-structured contact layer to capture sliding-induced current signals for surface texture perception, achieving 95.23% accuracy in recognizing nine surface textures. In addition, the hydrogel network converts ion-dependent diffusion dynamics of mixed sweat electrolytes into time-resolved sweat fingerprints, allowing eight artificial sweat compositions to be identified with 95.0% accuracy. The recognized compositions are further mapped to three electrolyte-status levels for electrochromic visual feedback. This porous hydrogel platform provides a simple strategy for integrating self-powered tactile perception with artificial sweat classification in wearable electronics.