Dept. Mechanical Engineering & Materials Science
Many plants exhibit remarkable water repellency owing to their rough surface. The textured surface traps air underneath water drops and the air cushioning gives rise to the superhydrophobicity. However, biomimetic superhydrophobic surfaces generally do not retain water repellency when exposed to a condensing environment. Water condensate proceeding from nanoscale nuclei tends to penetrate into the surface texture and displace the trapped air, forfeiting the superhydrophobicity.
In this talk, we will show that lotus leaves use two complementary strategies to achieve antidew superhydrophobicity. For condensate drops that are order of 100 um or smaller, drop coalescence triggers a self-propelled jumping motion which removes the sticky condensate along the pathway. [Boreyko and Chen (2009), Phys. Rev. Lett., 103, 174502.] For drops that are order of 1 mm or larger, lotus leaves harvest energy from ambient vibrations to overcome the adhesion between the sticky condensate and the rough surface. [Boreyko and Chen (2009), Phys. Rev. Lett., 103, 184501.]
Time permitting, we will briefly introduce the graduate program in the Department of Mechanical Engineering and Materials Science at Duke University.
Dr. Chuan-Hua Chen is Assistant Professor of Mechanical Engineering and Materials Science at Duke University, where he directs research in interfacial flows and microfluidics at the Microscale Physicochemical Hydrodynamics Laboratory. Dr. Chen received his B.S. degree in Applied Mechanics from Peking University (1998), M.S. and Ph.D. degrees in Mechanical Engineering from Stanford University (2004). Prior to joining Duke in 2007, he held positions as a postdoctoral associate at Princeton University and a research scientist at Rockwell Scientific Company. In 2009, Dr. Chen received the Powe Award from Oak Ridge Associated Universities and the CAREER Award from the National Science Foundation. His research work has appeared on the cover of Physical Review Letters, and has been featured by The New York Times, Discovery Channel, and Science Magazine.