A three-dimensional model for analyzing the anisotropic wetting behavior of striped surfaces

Anisotropic wetting shows potential application in advanced microfluidics and biosensors. This study proposes a three-dimensional (3-D) methodology using a finite element method to investigate the anisotropic wettability of striped surfaces. The variations of free energy (FE), free energy barrier (FEB), contact angle (CA), contact angle hysteresis (CAH), droplet shape and the three-phase contact line shape of an anisotropic droplet during the spreading process are explored. It is found that the droplet length and three-phase contact line length fluctuate by the increase of the droplet width and three-phase contact line width during the spreading process of droplet. In addition, a relatively small stripe width with higher free energy is necessary to achieve a large equilibrium CA and a small CAH or easily reach the equilibrium CA. The present methodology can be potentially used for designing architected surfaces with anisotropic wetting properties in microfluidic devices, lab-on-a-chip systems, and self-cleaning surfaces.