Anisotropic wetting on microstrips surface fabricated by femtosecond laser

In this paper, we present a new method to realize anisotropy by restricting a droplet on an unstructured Si hydrophobic domain between two superhydrophobic strips fabricated by femtosecond laser. The water contact angles and corresponding water baseline length were investigated. The results showed that anisotropy would vary with the volume-induced pinning-depinning-repinning behavior of the droplet. Furthermore, through the observation of water response on small Si domain, the adhesive force of the structure is proven to be the key factor giving rise to the anisotropy wetting. This phenomenon could potentially be used as a model for fundamental research, and such structures could be utilized to control large volume in microfluidic devices, lab-on-chip system, microreactors, and self-cleaning surfaces.