Featured Research

from universities, journals, and other organizations

World's First Synthetic Tree: May Lead To Technologies For Heat Transfer, Soil Remediation

Date:
September 11, 2008
Source:
Cornell University
Summary:
In Abraham Stroock's lab at Cornell, the world's first synthetic tree sits in a palm-sized piece of clear, flexible hydrogel -- the type found in soft contact lenses. Stroock and graduate student Tobias Wheeler have created a "tree" that simulates the process of transpiration, the cohesive capillary action that allows trees to wick moisture upward to their highest branches.

A transparent sheet of pHEMA, 1 millimeter thick, is etched with 80 parallel channels of varying lengths arranged to form a circle and connected by a single channel. The inset shows an optical micrograph of the cross-section of one microchannel.
Credit: Abraham Stroock and Tobias Wheeler

In Abraham Stroock's lab at Cornell, the world's first synthetic tree sits in a palm-sized piece of clear, flexible hydrogel -- the type found in soft contact lenses.

Stroock and graduate student Tobias Wheeler have created a "tree" that simulates the process of transpiration, the cohesive capillary action that allows trees to wick moisture upward to their highest branches.

The researchers' work, reported in the Sept. 11 issue of the journal Nature, bolsters the long-standing theory that transpiration in trees and plants is a purely physical process, requiring no biological energy. It also may lead to new passive heat transfer technologies for cars or buildings, better methods for remediating soil and more effective ways to draw water out of partially dry ground.

Of course, the synthetic tree doesn't look much like a tree at all. It consists of two circles side by side in the gel, patterned with evenly spaced microfluidic channels to mimic a tree's vascular system.

In nature, trees use water in tubular tissues, called xylem, like ropes that pull more water out of the ground, delivering it to leaves. They manipulate the water in the xylem under negative pressure -- what's called a metastable liquid state -- right on the verge of becoming a vapor.

Xylem-like capillaries are relatively easy to create by microfabrication, but the researchers' choice of a material to act as membranes in the leaf and root to separate the liquid from the atmosphere and the soil was much trickier.

Stroock, assistant professor of chemical and biomolecular engineering, and Wheeler, a graduate student in his lab, used pHEMA hydrogel, or polyhydroxyethyl methacrylate, to form the plant membranes. The hydrogel is a solid embedded with water and has nanometer-scale pores. The material acts as a wick by holding liquid in the pores, through which capillary action creates tension in the water.

By building mimics of xylem capillaries within the gels, the scientists were able to create negative-pressures of the magnitude observed in trees, and to pump water against large resistances and out of subsaturated, or partially dry, sources.

Besides supporting the theory of transpiration as a physical, not biological, process, the synthetic tree also introduces a new way to study water under tension -- a subject interesting to physicists and chemists. Many questions about the metastable state of water could be answered using this new "tree."

"Water is the most studied substance on Earth, and yet there is a big metastable region in its phase diagram waiting to be characterized," Stroock said. His lab is pursuing these studies with support from the National Science Foundation.

The capillary action used in trees might be applicable to developing new passive heat-transfer methods, Stroock said. The heat-transfer technology commonly used for cooling laptops, which uses vaporization to carry the heat to the fan on the edge of the computer, could be scaled up using the technology developed for the synthetic tree.

"It would be nice if you could, in a building, put these passive elements that carry heat around very effectively, for example, from a solar collector on the roof, to deliver heat all the way down through the building, then recycle that fluid back up to the roof the same way trees do it -- pulling it back up," Stroock said.

He also envisions the synthetic tree helping to build better soil remediation systems. Instead of having to soak contaminated soil to pump contaminants out, transpiration could help pull the contaminated fluid out of the soil without the use of more liquid. Similarly, the technology could also be used to draw water out of relatively dry soil without having to dig a well down to the water table.


Story Source:

The above story is based on materials provided by Cornell University. The original article was written by Anne Ju. Note: Materials may be edited for content and length.


Cite This Page:

Cornell University. "World's First Synthetic Tree: May Lead To Technologies For Heat Transfer, Soil Remediation." ScienceDaily. ScienceDaily, 11 September 2008. <www.sciencedaily.com/releases/2008/09/080910161900.htm>.
Cornell University. (2008, September 11). World's First Synthetic Tree: May Lead To Technologies For Heat Transfer, Soil Remediation. ScienceDaily. Retrieved August 23, 2014 from www.sciencedaily.com/releases/2008/09/080910161900.htm
Cornell University. "World's First Synthetic Tree: May Lead To Technologies For Heat Transfer, Soil Remediation." ScienceDaily. www.sciencedaily.com/releases/2008/09/080910161900.htm (accessed August 23, 2014).

Share This




More Matter & Energy News

Saturday, August 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Is It a Plane? No, It's a Hoverbike

Is It a Plane? No, It's a Hoverbike

Reuters - Business Video Online (Aug. 22, 2014) UK-based Malloy Aeronautics is preparing to test a manned quadcopter capable of out-manouvering a helicopter and presenting a new paradigm for aerial vehicles. A 1/3-sized scale model is already gaining popularity with drone enthusiasts around the world, with the full-sized manned model expected to take flight in the near future. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Coal Gas Boom in China Holds Climate Risks

Coal Gas Boom in China Holds Climate Risks

AP (Aug. 22, 2014) China's energy revolution could do more harm than good for the environment, despite the country's commitment to reducing pollution and curbing its carbon emissions. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Former TSA X-Ray Scanners Easily Tricked To Miss Weapons

Former TSA X-Ray Scanners Easily Tricked To Miss Weapons

Newsy (Aug. 21, 2014) Researchers found the scanners could be duped simply by placing a weapon off to the side of the body or encasing it under a plastic shield. Video provided by Newsy
Powered by NewsLook.com
Flower Power! Dandelions Make Car Tires?

Flower Power! Dandelions Make Car Tires?

Reuters - Business Video Online (Aug. 20, 2014) Forget rolling on rubber, could car drivers soon be traveling on tires made from dandelions? Teams of scientists are racing to breed a type of the yellow flower whose taproot has a milky fluid with tire-grade rubber particles in it. As Joanna Partridge reports, global tire makers are investing millions in research into a new tire source. Video provided by Reuters
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:
from the past week

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