Hydrophobic templates with rough patterns fabricated by laser micromachining for liquid droplets generation

This paper presents an approach to utilize high precision pulsed Nd:YAG laser to fabricate a rough array-pattern on a soda-lime glass plate by a laser-induced backside writing (LIBW) process, and a laser-induced plasma assisted ablation (LIPAA) technique. The current study investigates the effect of process parameters such as single-shot laser exposure time and number of passes on the material removal rate. After depositing 695 nm thick Teflon thin film on the glass plate, the surface of the laser micro-machined template becomes hydrophobic. The surface roughness, annular groove profile and surface micrograph were measured by an atomic force microscope, a profilometer, and a scanning electron microscope, respectively. A uniform liquid droplet by the sessile drop method is generated on the hydrophobic template. Droplet characteristics, such as contacted angle, size, and shape, are measured with a surface tension analyzer and microscope. This work also discusses the relationship between the formed droplets and the process recipe of the micro-machined template. The proposed approach can apply to future for uniform lens array formation.