Surface characterization of butterfly wings

Surface roughness due to micro and nanostructures of butterfly wings create hydrophobic surfaces. In this study, two different experimental techniques were used to characterize the effect of structural features on hydrophobicity of wings. The static and dynamic (advancing and receding) contact angle studies, and Atomic force microscopy (AFM) and optical profilometry characterization were conducted on wings of different butterfly/moth species. Both types of contact angles were shown to be the highest on the butterfly wings that had a combination of both scales and hair like microtrichia. The microtrichia without scales showed almost similar hydrophobicity as on a surface with scales. The role of surface roughness was evaluated by correlating the roughness factor for different scan sizes. It was identified that roughness factor fluctuates rapidly for smaller scan sizes and takes slightly decreasing stable profile for larger scan areas.