Interfacial droplet-based triboelectric nanogenerator with optimized architecture for highly efficient vibrational energy conversion

Droplet-based nanogenerators, harnessing the dynamic interaction between droplets and tribo-layer surfaces for electricity generation, demonstrate substantial promise in nano-micro energy harvesting. However, conventional devices face limitations in charge and voltage outputs due to the constrained liquid-solid interface and intrinsic parasitic capacitance, resulting in comparatively low power density. Herein, regulated by heterogeneous wetting surfaces, the periodic squeezing of a 3D droplet to a 2D plate maximizes the effective interface for triboelectrification and electrostatic induction, leading to a remarkable charge density of ∼2.0 C m⁻³. Additionally, optimizing electrode configuration reduces parasitic capacitance and elevates output voltage by 80 folds. A recorded peak power density of 5,865 W m⁻³ is obtained, which is 48 times higher than previous works. Furthermore, the droplet’s non-Hookean elastic behavior extends the frequency response band by 89.3%, enabling small electronics to operate under micro-vibration conditions. This study offers valuable insights for efficient electric energy extraction from interfacial droplets.