Started by Lauren Hartle, Fall 2011.
A water droplet on a superhydrophobic surface has a contact angle of greater than 150 degrees and a very low roll-off angle. In nature and in man-made materials, this has been achieved with Structured Surfaces. Advantages of such surfaces include the ability to repel water and self-clean. Industrial applications include "self-cleaning window glasses, paints, and textiles to low-friction surfaces for fluid flow and energy conservation." To understand why water droplets wet these surfaces so poorly, one m
It is argued that surface structure can produce superhydrophobic effects, even on a hydrophilic surface. For example, lotus leaves have been shown to be superhydrophobic, despite the waxy, weakly hydrophilic coating on the surface. It has been demonstrated that the surface of a lotus leaf is superhydrophobic in part due to the presence of hierarchical surface structures structures consisting of micro- and nano-scale features.  Butterfly wings and parts of pitcher plants have observed superhydrophobic properties.
"Design parameters for superhydrophobicity and superoleophobicity". Anish Tuteja, Wonjae Choi, Gareth H. McKinley, Robert E. Cohen, and Michael F. Rubner. MRS Bulletin 33 (8), 752-758 (August 2008) "Fabrication of artificial Lotus leaves and significance of hierarchical structure for superhydrophobicity and low adhesion". Kerstin Koch, Bharat Bhushan, Yong Chae Jung and Wilhelm Barthlott. Soft Matter, 2009, 5, 1386–1393. "Self-cleaning materials: Lotus leaf inspired nanotechnology" Peter Forbes, Scientific American 30 July 2008.