Abstract
An active hydrophobic skin of deformable PDMS diaphragm with micro-pillar-array structure was fabricated for an application of droplet handling devices. The diaphragm was deformed to a displacement of 10 μm by vacuum of cavity underneath the diaphragm. Effect of dynamic structure change on surface hydrophobicity was evaluated. Contact angle of water droplet on the PDMS diaphragm decreased from 131° to 115° when the diaphragm was flattened after a droplet was placed on the rough surface. By repeatedly switching of flat and rough surface, contact angle decreased gradually. Moreover,the PDMS diaphragm surface was coated by high hydrophobic material. The contact angle on the high hydrophobic surface was not changed by switching of flat and rough surface due to the high initial hydrophobicity.
