Lotus technology and science

     Paula Biles, the worlds best friend of the Lotus and award winning co-author of the book “The Lotus: Know it and Grow it” pointed out a New York Times article last week about further discovery on how the lotus leaves stay dry. For readers of her book you will know that the lotus is one of the most scientifically studied plants in the world. Paula also noted there was a new Lotus book on the market “The Lotus Quest”, by Mark Griffiths. As soon as I get a copy I will post a review.

If you have never seen a drop of water on a lotus, the plant totally repels the drops. Often during a gentle rain it is fun to watch drops swirl around and collect on the lotus until the plant gently lowers the big drops off the leaf. Bigger drops rest on the leafs for hours or days depending upon conditions for evaporation. Scientists have been studying the plants properties to find out if they can recreate the effect and now some from Duke University may have solved the age old question.  

Confucian philosopher once said, “I love the lotus because while growing from mud, it is unstained.”
Skip forward one thousand years and we may now know why.

Jonathan Boreyko, a third-year graduate student at Duke’s Pratt School of Engineering, who works in the laboratory of assistant professor Chuan-Hua Chen. The results of the team’s experiments were published early on-line in the journal Physics Review Letters.

“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. Scientists and engineers have long wondered how these sticky drops are eventually repelled from the leaf after their impalement into the tiny projections,” Boreyko said. “After bringing lotus leaves into the lab and watching the condensation as it formed, we were able to see how the sticky drops became unsticky.”

The key was videotaping the process while the lotus leaf rested on top of the woofer portion of a stereo speaker at low frequency. Condensation was created by cooling the leaf. It turned out that after being gently vibrated for a fraction of a second, the sticky droplets gradually unstuck themselves and jumped off the leaf.

Voila, a dry leaf.

“This solves a long-standing puzzle in the field,” Chen said. “People have observed that condensation forms every night on the lotus leaf. When they come back in the morning the water is gone and the leaf is dry. The speaker reproduced in the lab what happens every day in nature, which is full of subtle vibrations, especially for the lotus, which has large leaves atop long and slender stems.”