A Biodegradable Gelatin-Based Hydrogel Polymer Electrolyte for Integrated Multimodal Physiological Signal Sensing and...

The growing demand for wearable bioelectronics and energy devices requires reliable energy solutions with sustainable features, multimodal responsiveness, and improved electrochemical performance. Natural biomass-derived hydrogel polymer electrolytes are ideal candidates due to their high conductivity, safety, and environmental friendliness. Herein, we propose a biodegradable gelatin-based hydrogel polymer electrolyte (GBHPE) synthesized via one-pot free-radical polymerization of gelatin, acrylic acid, and acrylamide, followed by ZnO/KOH solution immersion for polyelectrolyte functionalization. The GBHPE exhibits excellent conductivity, stretchability, optical transparency, adhesion, moisture retention, biocompatibility, and biodegradability. Meanwhile, GBHPE shows high multimodal responsiveness and sensitivity for on-skin bioelectronics as a sensor to diverse pH, temperature, stress-strain, and bioelectric signals, effectively enabling human movement detection, temperature early warning, and underwater emergency Morse code communication. These results enhance GBHPE's practicality in flexible/wearable electronics and energy devices. Notably, the GBHPE performs exceptionally well in rechargeable zinc-air batteries (ZABs), delivering a prolonged cycling lifetime of 563.38 h, achieving a high specific capacity of 859.43 mAh·g^-1, and demonstrating outstanding rate performance. Additionally, in Zn||Zn symmetric cells, it exhibits a 459.33 h deposition/stripping cycle life, reduced polarization, and effective dendrite suppression. Overall, this work provides a robust strategy for high-performance hydrogel polymer electrolytes, promising for integrated wearable bioelectronics and rechargeable ZABs.