MMaterialsgateNEWS vom 26.10.2009

The lotus's clever way of staying dry

An ancient Confucian philosopher once said, "I love the lotus because while growing from mud, it is unstained."
Now, almost one thousand years since Zhou Dunyi wrote these lines in China, scientists finally understand how the plant keeps itself clean and dry. It took an ultra high speed camera, a powerful microscope and an audio speaker to unlock a secret that has puzzled scientists for ages. The process of solving this biological problem inspired Duke University engineers to make use of man-made surfaces resembling the lotus to improve the efficiency of modern engineering systems, such as power plants or electronic equipment, which must be cooled by removing heat through water evaporation and condensation. For the first time, scientists were able to observe water as it condensed on the leaf's surface, and more importantly, how the water condensate left the leaf. The trick lies in the surface of the plant's large leaves, and the subtle vibrations of nature. The leaves are covered with tiny irregular bumps spiked with even tinier hairs projecting upward. When a water droplet lands on this type of surface, it only touches the ends of the tiny hairs. The droplet is buoyed by air pockets below and ultimately is repelled off the leaf. "We faced a tricky problem – water droplets that fall on the leaf easily roll off, while condensate that grows from within the leaf's nooks and crannies is sticky and remains trapped," said Jonathan Boreyko, a third-year graduate student at Duke's Pratt School of Engineering, who works in the laboratory of assistant professor

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Recherchiert und dokumentiert von:

Dr.-Ing. Christoph Konetschny, Inhaber und Gründer von Materialsgate
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