Advancements in Thermoelectric Hydrogels: Structural Design and Material Innovation for Biomedical and Wearable Applications

Abstract

Thermoelectrics (TEs), enabling the direct conversion between heat and electrical energy, have demonstrated extensive application potential in wearable and biomedical fields. Among numerous thermoelectric materials, flexible hydrogels have garnered significant research attention in thermal-electricity systems owing to their unique properties, including a porous network structure, large specific surface area, high water content, and low thermal conductivity, which facilitate efficient charge transport and provide abundant reaction sites for effective or assisted energy conversion efficiency. Despite being an ideal material, the design of advanced thermoelectric and multifunctional hydrogel systems remains an active area of exploration. This review covers the most recent advances in thermoelectric hydrogel research and development, ranging from mechanism design to device performance, with a main focus on the structural design of excellent thermoelectric hydrogels to enhance multifunctional properties. Meanwhile, performance-influencing key factors such as humidity control, crystallinity regulation, ion loading, and temperature optimization are systematically analyzed to provide a comprehensive understanding of material optimization. Finally, the review paper concludes by highlighting the existing challenge and outlook of thermoelectric hydrogel. Altogether, a well-grasped overview and potential strategies extended from the overall analysis of the structure and performance of thermoelectric hydrogels are offered to lift advancement in developing futuristic materials for biomedical and wearable applications.