Superhydrophobic surface obtained using pyramidal PTFE film fabricated on RIE etched silicon

We have developed a surface texturing process using a polytetrafluoroethylene coating with a pyramidal structure for obtaining superhydrophobic surfaces. In order to investigate the hydrophobic properties of the surface, we measured the contact angle and roughness values. The calculated roughness factor and root mean square roughness ranged from 2.47 to 2.6 and from 0.25 μm to 0.4 μm, respectively. The contact angle of a water droplet on the surface was greater than 150°; moreover, this angle was maintained for over 7 weeks. This observation implies that extremely low wettability is achievable on superhydrophobic surfaces.