Cambridge, Mass. September 21, 2011 After a rain, the cupped leaf of a pitcher plant becomes a virtually frictionless surface. Sweet-smelling and elegant, the carnivore attracts ants, spiders, and even little frogs. One by one, they slide to their doom.
Adopting the plant's slick strategy, a group of applied scientists at Harvard have created a material that repels just about any type of liquid, including blood and oil, and does so even under harsh conditions like high pressure and freezing temperatures.
The bio-inspired liquid repellence technology, described in the September 22 issue of Nature, should find applications in biomedical fluid handling, fuel transport, and anti-fouling and anti-icing technologies. It could even lead to self-cleaning windows and improved optical devices.
"Inspired by the pitcher plant, we developed a new coating that outperforms its natural and synthetic counterparts and provides a simple and versatile solution for liquid and solid repellency," says lead author Joanna Aizenberg, Amy Smith Berylson Professor of Materials Science at the Harvard School of Engineering and Applied Sciences (SEAS), Director of the Kavli Institute for Bionano Science and Technology at Harvard, and a Core Faculty member at the Wyss Institute for Biologically Inspired Engineering at Harvard.
By contrast, current state-of-the-art liquid repellent surfaces have taken cues from a different member of the plant world. The leaves of the lotus resist water due to the tiny microtextures on the surface; droplets balance on the cushion of air on the tips of the surface and bead up.
The so-called lotus effect, however, does not work well for organic or complex liquids. Moreover, if the surface is damaged (e.g., scratched) or subject to extreme conditions, liquid drops tend to stick to or sink into the textures rather than roll away. Finally, it has proven costly and difficult to manufacture surfaces based on the l
|Contact: Michael Patrick Rutter|