Lignin-Derived Flexible Polyurethane Triboelectric Nanogenerator for Smart Underwater Sensing

With the deepening of marine resource development and marine science research, developing devices capable of underwater sensing and self-powering has become a significant challenge. Moreover, there is a growing demand for the environmental sustainability of the substrate materials used in the device. Herein, we have synthesized a lignin-based polyurethane foam with a high biobased content (HBLPUF) by the reaction of pentamethylene diisocyanate (PDI) with lignin polyol. The conductive polyaniline (PANI) was grown in situ on the surface of HBLPUF, serving as the substrate, and assembled with a polytetrafluoroethylene (PTFE) film to form a vertical contact-separation triboelectric nanogenerator. It was additionally encapsulated with polydimethylsiloxane (PDMS) to ensure stable performance underwater. A voltage of up to 148 V and a current output of 1.8 μA were achieved, successfully overcoming the challenge of the underwater power supply. The excellent fatigue resistance of the foam substrate allowed it to maintain stable output even after 10,000 impact tests. The sensor could detect various movements in both conventional and underwater environments, including twisting, finger bending, and wrist flexion. This study introduced a novel approach for fabricating a lignin-based underwater triboelectric nanogenerator, which holds significant implications for advancing the application of polyurethane foam and the development of underwater sensing technologies.