Colloidal photolithography applied to functional microstructure on cylinder based on photopatternable TiO2 sol-gel

The authors demonstrate a low cost direct process to print directly TiO2 grating on both planar and non-conventional substrate such as cylinders. A well collimated i-line source emitting at 365 nm wavelength illuminates a mono layer of 1 pm diameter silica microspheres deposited on a photosensitive TiO2-based sol-gel layer. No etching process is required since this layer is directly UV photo pattemable 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 TiO2 sol-gel layer process, the modeling of the electric field distribution below the spheres during the illumination process and preliminary results of TiO2 nanopillars of 200 nm diameter on the wall of a 5 cm diameter cylinder. (C) 2017 Elsevier B.V. All rights reserved.