Moisture-Enabled Electric Generator Based on Crosslinked PVA/SA Bilayer Nanofiber Membrane With Enhanced Hygroscopic Cycling Performance and Biostability

Abstract

Moisture-enabled electric generators (MEGs) harvest environmental moisture for energy generation and environmental monitoring, showing promise in wearable electronics. Electrospinning nanofiber membranes, favored for their large surface area, micro-nano channel networks, material versatility, and facile fabrication, serve as ideal platforms for MEGs. Although sodium alginate (SA), a natural polymer rich in hydrophilic groups, is suitable for humidity-driven energy harvesting, challenges persist in its direct electrospinnability and in balancing sustained hygroscopic power output with structural stability under humid conditions. This work designed an antibacterial bilayer nanofiber membrane with a distinct hydrophilic hierarchical structure using polyvinyl alcohol (PVA), SA, and silver nanoparticles (AgNPs), cross–linked with glutaraldehyde (GA) to enhance durability. The bilayer structure, with an upper layer of PVA/SA/AgNPs and a lower layer of PVA/AgNPs, both cross–linked with 2 wt.% GA, achieved a 0.415 V open-circuit voltage, retaining 93.2% performance after 25 cycles. It exhibited 99.83% and 99.57% inhibition against S. aureus and E. coli, respectively, ensuring biostability in humid environments. These MEGs enable multifunctional integration for real-time moisture detection, respiratory health monitoring, activity tracking, and energy harvesting in self-powered wearable systems.