Self‐Powered Flexible Electronics: Biomass Hydrogels for Integrated Sensing and Energy Harvesting

Biomass-derived hydrogels bridge the worlds of renewable natural sources and advanced electronics, offering a unique combination of biodegradability, biocompatibility, and highly tunable physicochemical characteristics. These features are pivotal for the development of next-generation self-powered flexible electronics. This review summarizes recent advances in structural and molecular design of biomass hydrogels, with emphasis on engineering strategies and composites that integrate sensing and energy conversion functions. We systematically examine how hierarchical architectural design facilitates precise modulation of mechanical, electrical, and biochemical properties, laying the material foundation for multifunctional applications. Furthermore, this review also highlights frontier applications in flexible sensing and energy systems, spanning physiological monitoring, triboelectric nanogenerators, supercapacitors, and biofuel cells for storage and conversion, and culminating in a dedicated discussion of their converging roles within self-powered platforms. By discussing the coupling of sensing and energy modules in unified hydrogel frameworks, we highlight how material innovation and structural engineering enable autonomous operation and reliable human-machine interfaces. Finally, we outline future directions toward intelligent and sustainable electronics, emphasizing the role of biomass hydrogels in developing eco-friendly and self-sufficient flexible systems.