Effect of 3D microstructure geometry on wetting properties of PDMS surfaces by micro 3-dimensional (3D) grayscale fabrication technique

We develop a 3D microstructures on polydimethylsiloxane (PDMS) surface by grayscale fabrication technique with a single mask layer. The effect of the microstructures on wetting properties of the surface was studied. Contact angles of pure water droplet were measured on circular pillar, square pillar and hierarchical pillar to investigate the wetting properties. Results shown that the contact angles on the PDMS surface with microstructures increased. The Wenzel wetting mode occurred in all types of microstuctured PDMS surfaces. The contact angle was improved from 105° to 131.89°.