Fabrication of random microspikes on mold metal by ultrashort laser ablation for hydrophilic surface

Microsized spikes, which are smaller than laser focused spots, were fabricated by laser ablation in this study. The hydrophilic property of the surface with the microsize spikes was tested. Microspikes of 20 μm size were formed using a 50 μm laser focused spot size by optimizing the laser process parameters. Water drops were placed on the microspikes to measure the contact angle, which was 10° while that of the surface without microspikes was 80°. This shows that a surface can be processed to be hydrophilic with laser ablation, without applying hydrophilic chemical coating. Because the base material in this study was a mold metal, injection molding products with functional surfaces were produced economically by forming micropatterns on their surfaces. The economically micropatterns produced in this study will be applicable for controlling the friction of fluids on surfaces, as well as for producing hydrophilic surfaces.