ABSTRACT
Abstract-The atomic force microscopy provides a detailed characterization of surface roughness and has enabled researchers to relate surface roughness to the macroscopic contact angle; however, only a little work has been done at the microscale, to tie surface parameters to the properties of the meniscus at the contact line. Here we report on studies looking at octane on a structured surface formed by a plasma etching process and focus on the effects of the surface on a heated contact line. We note that the adsorbed film thickness ahead of the contact line is a strong function of surface roughness, and so are the tangent angle and peak curvature at the contact line. The curvature exhibits a large jump in the region of the contact line which is a function of the surface roughness. The variation in adsorbed film thickness leads to an apparent Hamaker constant that is now a function of the surface structure as well as the dielectric properties of the medium. Peak curvature, tangent angle, and meniscus recession all are strong functions of heat input and surface roughness. As the surface roughens, the adsorbed film ahead of the meniscus becomes unstable, leading to a dropwise evaporation/condensation process.
