A top-electrode-based liquid-solid triboelectric nanogenerator for energy harvesting and ethanol detection

Liquid-solid triboelectric nanogenerators (LS-TENGs) offer a promising avenue for self-powered energy harvesting and sensing by exploiting contact electrification at fluid-dielectric interfaces, where droplet dynamics drive charge separation for electrical output without external power. In this work, a top-electrode LS-TENG was fabricated using a polytetrafluoroethylene (PTFE) film on a PMMA substrate with deionised water droplets, achieving an open-circuit voltage of ‒3.4 V, short-circuit current of 3.6 μA, and peak power of 1.48 nW at 100 MΩ under optimised conditions of 2 cm drop height, 45° tilt, and 50 μL volume. Performance scaled with droplet kinetics and volume due to enhanced contact area and charge transfer, while stability persisted over repeated cycles, and ethanol-water mixtures distinctly modulated outputs via reduced permittivity and wettability, enabling sensitive, battery-free detection for practical applications in environmental monitoring.