Wearable, agricultural and environmental sensors increasingly require power sources that operate in humid settings without frequent battery replacement, particularly for skin-mounted patches and remote nodes that are difficult to retrieve. Moisture-enabled electric generators (MEGs) can convert ambient and physiological moisture into electricity, but many systems rely on persistent polymers or complex architectures that complicate scalable, environmentally responsible deployment. Here we report a biodegradable and recyclable MEG fabricated by a single water-based process from food-grade gelatin, sodium chloride and activated carbon. During casting and drying, the composite undergoes self-stratification into an asymmetric layered architecture consisting of a hydrophilic gelatin–salt layer and an activated-carbon layer, sustaining moisture uptake/evaporation cycles that drive directional ion transport and stable output. Single devices deliver open-circuit voltages approaching 1 V and peak current densities up to 1.36 mA cm -2 , maintaining ~1 V output for over one month under controlled conditions. Modular integration scales output to 90 V and 5.08 mA, enabling capacitor charging and low-power demonstrations. Beyond energy harvesting, the films function as self-powered sensors for respiration and speech monitoring, skin-hydration tracking and touchless human–machine interaction. Finally, we demonstrate rapid biodegradation in soil within weeks, and water-based recycling without performance loss, reducing end-of-life burdens for disposable patches and distributed electronics. • A fully biobased MEG platform using only food-grade components, demonstrating that high-performance moisture-powered devices do not need to rely on persistent synthetic polymers or hazardous materials. • The spontaneous formation of an asymmetric layered structure during a single-step water-based casting process represents a scalable fabrication approach that simplifies manufacturing while maintaining device functionality. • Demonstration of simultaneous energy harvesting and physiological sensing capabilities, expanding the utility of MEG technology beyond power generation alone. • Verified dual end-of-life pathways (biodegradation and recycling) that are matched to application contexts, addressing a critical gap in sustainable electronics.
Dong et al. (Fri,) studied this question.