A facile strategy to prepare fibrous and water resistant moist-electric generator with adjustable response speed

This work presents a polyvinyl alcohol (PVA) and cellulose nanofiber (CNF) based fiber structure moist-electric generator (FMEG), which demonstrates enhanced suitability for smart wearable electronics compared to traditional MEGs. The resulting PVA FMEG generated a relatively high output voltage of 0.50 V and a current of 4 μA per 2 cm fiber. The improved performance stems from the efficient directional ion movement enabled by the fiber structure (from outer to inner layers). Water resistance and response speed of FMEG were further improved by crosslinking PVA with boric acid (BA) and the introduction of CNF. After five washing cycles, the crosslinked FMEG retained 86 % of its initial weight. Additionally, the response time (time to reach 0.40 V) of the CNF-enhanced FMEG was reduced to 140 s, significantly shorter than that of pure PVA FMEG (600 s) and BA-crosslinked FMEG (1300 s). By tuning the crosslinking degree and CNF content, the response speed could be precisely regulated for applications such as breath sensing or powering a red LED bulb. This study demonstrates a promising FMEG with high output, water resistance, and tunable sensitivity, offering superior applicability for smart wearable devices compared to conventional MEGs.