Cost-effective and large-area process for the functionalization and surface microstructuring using photo-patternable TiO2 sol-gel process and colloidal photolithography

The authors demonstrate a low cost direct process to directly print TiO 2 grating on both planar and non-conventional substrate such as cylinder components. A well collimated i-line source emitting at a 365nm wavelength illuminates a mono layer of 1μm diameter silica microspheres deposited on a photosensitive TiO 2 -based sol-gel layer. No etching process is required since this layer is directly UV photo patternable like a negative photo-resist. Furthermore this thin layer offers interesting optical properties (high refractive index) and good mechanical and chemical stability. The paper describes the photochemistry of the TiO 2 sol-gel layer process, the modeling of the electric field distribution below the spheres during the illumination process and preliminary results of TiO 2 nanopillars of 200 nm diameter.