Photoinduced wettability transition and electrowetting in hierarchical ZnO and TiO2 structures

This study deals with self cleaning surfaces, where the wetting properties are controlled by the different external stimuli. ZnO and TiO₂ structures are fabricated by femtosecond laser irradiation of Si wafers and their subsequent coating with ZnO or TiO₂ by pulsed laser deposition (PLD). In the present experiment, the ZnO surface is coated by a thin layer of hydrophobic and dielectric Teflon. The electrowetting properties of this surface are studied, as well as the wettability of the final surface, which can be controlled by an electric voltage application between a droplet situated on top of the dielectric conductive ZnO substrate.