DC Output Water Droplet Energy Harvester Enhanced by the Triboelectric Effect

The rising of liquid–solid triboelectric nanogenerator has shed light on droplet energy harvesting technologies which is an important part of realizing high-entropy energy harvesting. However, the output of conventional triboelectric approach still needs to be further increased to meet the requirement of practical applications. Here, we report a DC output water droplet energy harvester (DC-WDEH) enhanced by the triboelectric effect. Instead of generating current through electrostatic induction as the traditional triboelectric nanogenerator, the proposed DC-WDEH combines the triboelectric effect and the salt battery theory to increase the current output. A peak short-circuit current output of 35 μA is achieved with NaCl solution droplet of 50 μL. Meanwhile, further increase in the short-circuit current and open-circuit voltage up to 110 μA and 1.8 V, respectively, can be achieved by a DC-WDEH array. Moreover, a motion sensor based on DC-WDEH is proposed to demonstrate its potential application in direction and frequency detection of droplet movement.