Water transport control on a patterned superhydrophobic surface via laser direct writing

Abstract

A simple method for fabricating line patterns on a superhydrophobic surface is demonstrated using nanosecond laser direct writing. A laser-induced superhydrophobic surfaces exhibit the excellent superhydrophobicity with a contact angle of 158° and a sliding angle of less than 5°. By changing the superhydrophilic linewidth and line intervals, the authors investigated the anisotropic wetting and adhesive properties on the as-prepared line-patterned superhydrophobic surface. The experimental results showed that the linewidth and line intervals have an important influence in anisotropic wetting, including contact angles and sliding angles in both parallel and perpendicular directions. This data allow control of adhesion by having droplets slide off at designated tilting angles on the patterned superhydrophobic surface. The water droplet array can be easily separated into any configuration, such as an upper triangular array. The as-prepared patterned superhydrophobic surface can transfer different microliter-sized droplets from one superhydrophobic surface to another. This patterned superhydrophobic surface has some potential applications for the droplet manipulation, microfluidic devices, and cell culture.