Electrically-Induced Droplet Detachment and Transport on Bionic Honeycomb-Fiber Composite Surfaces

The complex regulation of droplet dynamics, based on the application of external electric fields and micro/nano functional surfaces, has garnered widespread attention in fields such as enhanced oil-water separation, self-cleaning systems, and novel imaging technologies. In this study, a PLE surface (composite biomimetic hydrophobic surface with micron-level honeycomb texture and nanoscale villi) was fabricated. Using a high-speed microscopy system, the detachment and movement of droplets on the biomimetic surface under a direct current electric field were experimentally investigated. By introducing a biomimetic surface correction factor, (ξ), a polarization and force model for droplets on the PLE surface was established. The results indicate that the amount of polarized charge (<i>Q</i>) is positively correlated with the radius (<i>R</i>²), while the deformation degree (λ) is proportional to the electric field intensity (<i>E</i>_c). Key parameters for droplet detachment were determined, including the electric field threshold (<i>E</i>_c = 83.4 kV/m) and the correction factor (ξ = 0.1066). The relationship among surface electric field intensity <i>E</i>_c, droplet detachment time (<i>T</i>_L), the ratio of droplet height change (<i>H</i>_s) to initial height (<i>H</i>_s0), droplet velocity (<i>V</i>_t), and contact line ratio (<i>L</i>*) was analyzed. It was found that there exists a power-law relationship between <i>E</i>_c and <i>T</i>_L. Moreover, the PLE surface exhibits a more sensitive response to the applied electric field compared to the PI (polyimide) surface.