A Droplet-Based Electricity Nanogenerator with Press-Release Structure for Revealing the Coupling of Displacement and Conducting Currents

Contact electrification (CE) and electrostatic induction (EI) are believed to be the core processes in classic liquid–solid triboelectric nanogenerators (L-S TENGs), including the classical transistor-like droplet-based electricity generator (DEG) and other forms of DEGs. Recently reported total current DEGs made full use of CE, EI, and charge transfer (CT) effects and realized the coupling of displacement and conducting currents. However, this method has only been revealed in special structures, which have limitations depending on the falling location of droplets. Here, we construct a press-release total current DEG (PRTC-DEG) using a single droplet of water to visually verify the universality of CT and the contribution of conducting current in the total current DEG. By simply squeezing and then releasing this PRTC-DEG, charges are squirted out to realize the separation of charges in space and time. The working mechanism of PRTC-DEG and the coupling between displacement current and conducting current are also demonstrated. In addition, the structural design proposed in this study alleviates the dependence of output on the falling location of droplets in DEG and provides a new working mode for DEG, which makes DEG expand to more scenarios.