Intrusion–Extrusion Triboelectric Nanogenerator converts mechanical energy into electricity using water confined in nanopores of silicon

https://www.eurekalert.org/news-releases/1102963

"pressure repeatedly forces water into/ out of nanoscale pores in water-repellent nanoporous silicon monolith... up to 9% energy conversion efficiency... friction electricity generated at solid silicon/ liquid water interface... no exotic materials... autonomous, maintenance-free sensor systems in applications such as water detection, smart garments for sports and health monitoring, and haptic robotics"