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Physics and Astronomy

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NanoSEC Seminar

Biological micro-fluidics: lessons from insects  
Guest Speaker
Prof. David Hu  
Guest Affiliation
Department of Mechanical Engineering and Biology, Georgia Institute of Technology  
Friday, December 3, 2010 4:00 pm - 5:00 pm  
Riverbend Research South Laboratory Auditorium  

The future of engineering is in the small. The past decade has shown numerous advances in manufacturing science that bring lab-on-a-chip applications closer to reality. How can we control the motion of droplets cheaply, easily and robustly? As a biologist and an engineer, the speaker presents experiments demonstrating how insects manipulate fluid surfaces to their advantage. Social insects (fireants) link their bodies to together to weave hydrophobic surfaces in order to keep their colonies dry in rainstorms and floods. On dry surfaces, they excrete oily drops from their feet to scale smooth surfaces. Other insects, such as water striders, have evolved such mastery of surface tension that they can live atop water surfaces indefinitely. We use basic principles (energetics, Cassie and Wenzel laws) to provide a
unified view of capillarity in the insect world. Particular attention is paid to rationalizing insect waterrepellency in terms of passive surface properties and active behaviors. Applications of our work towards building small-scale machines are also discussed.