Sputter-coated rutile-TiO2 on topological micro-structure for providing high photoresponsivity in a wide range wettability switching

This paper describes excellent performance of wettability switching by selecting a combination of attractive material and structural design. We employ sputter-coated rutile-TiO₂ as a photoresponsive surface. In addition, the micro-pillar array with pent-roofs is designed to enhance the hydrophobicity. The pent-roof structure allows hydrophilic materials to exhibit Cassie-Baxter type superhydrophobic state by prevention of air-pockets at liquid/solid interface from liquid invasion. Rutile-TiO₂ thin films exhibit faster recovery rate from photo-induced hydrophilic state and wider wettability transition than anatase-TiO₂ [1]. Rutile-TiO₂ combined with the micropillar to provide faster photoresponsivity in a wide range wettability switching is reported.