Equivalent circuit model and simulation for dynamic sliding droplet-based triboelectric nanogenerators

Recently, there has been an increase of attention to employing liquid-solid contact to harvest or sense energy from water flow. Water's considerable deformability, however, makes it challenging to investigate how water moves dynamically in relation to a water-based triboelectric nanogenerator's (TENG) output characteristic. There are a few studies examining the fundamental mechanism of a droplet-based energy generator (DEG). In addition, such an electrical model has been established based on the consideration of instantaneous output at a specific period in a saturated state. Here, we first propose the circuit model and governing equations for simulating the double-electrode DEG's electrical output, comprehensively covering the L-S contact's dynamic process. Four essential stages of charge generation of the DEG are considered in unsaturated and saturated stages. The proposed model is verified systematically with the experimental data. The relationship between structural parameters and output performance of the DEG, such as internal capacitance, residual charge, dielectric constant, droplet spreading size, and dielectric thickness, has emerged. In summary, our model effectively establishes theoretical guidance, which paves the way for high-performance supply and sensor applications based on the L-S interface.