Featured Research

from universities, journals, and other organizations

Mushrooms, Water-repellents More Similar Than You Might Think

Date:
October 27, 2009
Source:
Duke University
Summary:
The same phenomenon that occurs when it's time for certain mushrooms to eject spores also occurs when dew droplets skitter across a surface that is highly water repellent.

Jumping water droplet. What do spore-launching mushrooms have in common with highly water-repellent surfaces? According to Duke University engineers, the answer is "jumping" water droplets.
Credit: Image courtesy of Duke University

What do spore-launching mushrooms have in common with highly water-repellent surfaces?

Related Articles


According to Duke University engineers, the answer is "jumping" water droplets. As it turns out, the same phenomenon that occurs when it's time for certain mushrooms to eject spores also occurs when dew droplets skitter across a surface that is highly water repellent, or superhydrophobic.

Using a specially designed high-speed camera and microscope set-up, the engineers for the first time captured the actions of tiny water droplets on a man-made superhydrophobic surface, and to their surprise found that the droplets literally jumped straight up and off the surface.

Simply put, when two tiny water droplets -- whether on a mushroom's spore or on a water-repellent surface -- meet to form a larger drop, enough energy is released in the formation of the new droplet to cause it to "jump" off the surface.

"This spontaneous jumping is powered by the surface energy released when droplets coalesce," said 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. "Because this process involves very tiny droplets at high speeds, no one had captured this phenomenon before."

The results of the team's experiments were published early online in the journal Physics Review Letters.

"A similar phenomenon occurs with the ejection of spores, known as ballistospores, from certain kinds of mushrooms," Boreyko said. "When a drop of water condensate at the base of the spore comes into contact with the wetted spore, it triggers the propulsion of the spore into the air."

Chen and Boreyko's research is the first known engineering reproduction of the ballistospore ejection process.

The work also has immediate applications in energy harvesting and thermal management, Chen said. For example, the spontaneous jumping motion offers an internal mechanism, independent of gravity, to remove condensate from the condensers in power plants.

The superhydrophobic surface used by the researchers is characterized by rows and rows of tiny bumps, covered 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. This creates pockets of air underneath the droplet that keeps it from touching the surface. This cushion of air keeping the droplet aloft is much like a puck in an air-hockey game. The same principle allows water striders to skim along the surface of ponds without falling into the water, Chen said.

"When two of these condensate drops coalesce into one, they jump at very high speeds," Boreyko said. "They move as fast as one meter per second. By taking a side view of the phenomenon, we can plainly see the droplets jump. You wouldn't see it looking down on the surface."

Interestingly, the researchers found that the mechanism used to eject ballistospores is almost identical. The critical size of the droplet on the spore for the jumping to occur is the same as that on the man-made superhydrophobic surface, and spores "jump" off the mushroom at about the same speed.

Chen said knowing how superhydrophobic surfaces are able to repel condensate drops could lead to improvements in many types of systems where heat needs to be removed through condensation.

"Smaller water droplets are much more efficient at transferring heat," Chen explained. "With the jumping mechanism, the average droplet size is about one hundred times smaller.

"In conventional cooling systems, as in big industrial plants, condensate must be removed using external forces for continuous operation," Chen said. "One of the main benefits of this superhydrophobic surface is that it needs no external energy -- the coalescing of the droplets provides all the energy needed to remove the condensate."

Chen's research is supported by the National Science Foundation. Jonathan Boreyko is supported by the Pratt-Gardner Fellowship.


Story Source:

The above story is based on materials provided by Duke University. Note: Materials may be edited for content and length.


Cite This Page:

Duke University. "Mushrooms, Water-repellents More Similar Than You Might Think." ScienceDaily. ScienceDaily, 27 October 2009. <www.sciencedaily.com/releases/2009/10/091026103844.htm>.
Duke University. (2009, October 27). Mushrooms, Water-repellents More Similar Than You Might Think. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2009/10/091026103844.htm
Duke University. "Mushrooms, Water-repellents More Similar Than You Might Think." ScienceDaily. www.sciencedaily.com/releases/2009/10/091026103844.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Friday, December 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Lava on Track to Hit Hawaii Market

Raw: Lava on Track to Hit Hawaii Market

AP (Dec. 19, 2014) Lava from an active volcano on Hawaii's Big Island slowed slightly but stayed on track to hit a shopping center in the small town of Pahoa. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Arctic Warming Twice As Fast As Rest Of Planet

Arctic Warming Twice As Fast As Rest Of Planet

Newsy (Dec. 18, 2014) The Arctic is warming twice as fast as the rest of the planet, thanks in part to something called feedback. Video provided by Newsy
Powered by NewsLook.com
Prenatal Exposure To Pollution Might Increase Autism Risk

Prenatal Exposure To Pollution Might Increase Autism Risk

Newsy (Dec. 18, 2014) Harvard researchers found children whose mothers were exposed to high pollution levels in the third trimester were twice as likely to develop autism. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins