High-performance droplet-driven electrification for self-powered real-time nitrate monitoring in agricultural water systems

This study presents a high-performance liquid–solid contact triboelectric nanogenerator (L-S TENG) designed for efficient harvesting of water-droplet energy and for self-powered water-quality monitoring. A critical focus of this work is the systematic investigation of electrode configuration dependence, in which top-, bottom-, and dual-electrode architectures were rigorously compared. In addition, the work reports systematic analyses of the effects of droplet height, volume, falling frequency, and substrate tilt on the device output when utilising a polytetrafluoroethylene (PTFE) surface in conjunction with deionised water. The dual-electrode layout produced the strongest electrical response among the three electrode configurations. An open-circuit voltage ( V oc ) of −52 V and a short-circuit current ( I sc ) of 31 μA were obtained through experimental optimization at a substrate tilt of 55° and a water drop height of 1.5 cm. Furthermore, capacitors were charged by the electrical output of the L-S TENG. Beyond energy harvesting, the device was successfully demonstrated as a self-powered environmental sensor capable of detecting nitrate (fertiliser) contamination. The sensor exhibited high sensitivity to changes in ionic concentration, distinguishing between deionised water and potassium nitrate solutions at varying concentrations. These findings demonstrate that the proposed L-S TENG is a sustainable, cost-effective solution for real-time agricultural water quality assessment and distributed energy harvesting.