Dynamic evolution of surface charge on dielectric materials

The regulation of surface charge states on materials is pivotal for electrostatic applications. However, the instability of surface charges hinders the progress. A critical aspect of addressing this challenge lies in elucidating the evolution of surface charges, which yet is poorly understood. In this work, the dynamic evolution of the surface charges on materials is investigated, which reveals the universal "charge reversion" phenomenon under high voltages. This phenomenon is caused by charge migration, as substantiated by visual analysis. Moreover, the visual information enables further research on charge stability, confirming the electron-driven contact electrification process between metal and dielectric. Besides, diverse methods to regulate the surface charge states on dielectric and a paradigm of microfluidic based on the observed charge evolution are achieved, which paves the way for advancements in various electrostatic applications.