Laser parallel micro/nano patterning of hydrophobic surfaces in optical near fields

Laser surface micro/nanopatterning by using Contact Particles Lens Array (CPLA) has been extensively utilized but there is no suitable technique for deposition of CPLA on Hydrophobic surfaces. In this research a novel technique for patterning of hydrophobic surfaces has been proposed and demonstrated. For the deposition of CPLA, conventional techniques necessarily require the surface to be hydrophilic whereas the proposed technique could deposit CPLA on both hydrophilic and hydrophobic surfaces. In the proposed technique, a hexagonal closed pack monolayer of SiO₂ spheres is first formed by self assembly on a flat, smooth and hydrophilic glass surface. The formed monolayer of particles is picked up by a flexible sticky surface and placed on the hydrophobic surface to be patterned. Thus effectively covering the hydrophobic surface with a CPLA. A 532 nm wavelength Nd:YVO₄ laser was then used to irradiate the substrate with the laser passing through the flexible surface and the particles. Experimental investigations are made to determine the properties of the patterns. The optical near field around the particles is numerically simulated using Finite Integral Technique (FIT).