Experimental Characterization of a Water Droplet Energy Harvester

This paper is aimed at experimentally investigating the performance of a Water Droplet Energy Harvester (WDEH) as a function of the main harvester characteristics. A prototype of a WDEH composed of two electrodes and a PolyTetraFluoroEthylene (PTFE) layer is implemented and tested. The PTFE is placed between an upper electrode (a simple conductive terminal) and a lower electrode (a conductive layer). A fundamental characteristic for the operation of the WDEH is the very good charge storage capability and stability of the PTFE. In particular, by means of a continuous water droplets impingement on the PTFE surface, negative charges are stored on it. In this way, a pre-charged variable capacitance is formed during the flowing of droplets over the upper electrode, and a current flow is obtained when the upper and lower electrodes are connected to an electrical load. The experimental tests that are presented and discussed in this paper are aimed at highlighting the variation of the performance of the considered WDEH prototype as a function of the characteristics of the source of energy, of the device structure and of the electrical load.