Electric Field-Induced Droplet Detachment and Transport on Biomimetic Superhydrophobic Surfaces with Beetle Elytra–Seta Composite Structures

The regulation of droplet dynamics based on external electric fields and bioinspired functional surfaces has widespread applications in various fields. However, research on the coupling of these two factors to enhance oil-water separation efficiency is urgently needed. In this study, laser-induced and solvent treatment techniques were coupled to assemble a micronano setal and bioinspired beetle elytra textured substrate with the lotus effect, A "top conductive, bottom insulating" Desert beetle elytra micronano tuft composite texture (DBE) biomimetic superhydrophobic surface was fabricated. The droplet detachment and migration processes were analyzed to evaluate the surface performance. Additionally, a bioinspired surface correction coefficient (χ) was introduced, and a droplet detachment force model (ΔF) was established. Further comparative analysis of the droplet height ratio (Hw/Hw0), velocity (Vt), and contact line ratio (Lc) on three types of surfaces was conducted. The study found that compared with the previous artificial honeycomb microvilli texture (PLE) bionic hydrophobic surface, the DBE surface exhibited a 6.6% reduction in the electric field threshold (Ec = 77.9 kV/m), a 17.9% increase in the static contact angle, a 69.1% reduction in the critical rolling angle to 1.7°, and a shortening of the minimum jump time (tct) by 7.99%, 7.87%, and 17.27% under electric excitations of 86.9, 119.5, and 217.2 kV/m, respectively. This demonstrates that the DBE surface possesses "high contact angle and low adhesion force" properties, providing a new application approach for electrically induced high-efficiency oil-water separation.