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PORTLAND, Ore., Dec. 29 (AScribe Newswire) -- Duct tape that never loses its stick. Bandages that come off without sticky residue or an "ouch."
Gecko feet may hold the key to the development of synthetic self -cleaning adhesives, according to a biologist from Lewis & Clark College. The research is published in the online early edition of the Proceedings from the National Academy of Sciences of the United States, or PNAS (www.pnas.org) during the week of Jan. 3, 2005 (Article #08304:"Evidence for self-cleaning in gecko setae") .
"How geckos manage to keep their feet clean while walking about with sticky feet has remained a puzzle until now," said Kellar Autumn, associate professor of biology at Lewis & Clark College." Geckos don't groom their feet, and the adhesive on their toes is much too sticky for dirt to be shaken off. Conventional adhesives like tape just get dirtier and dirtier, but we discovered that gecko feet actually become cleaner with repeated use."
Autumn's new research, published in PNAS, found that the microscopic adhesive hairs--or setae--that create the gecko's adhesive qualities are also the first known self-cleaning adhesive. According to Autumn, gecko setae isolated from the gecko become cleaner by themselves.
"Our mathematical models suggest that self-cleaning in gecko setae is a result of geometry not chemistry," said Autumn." This means that synthetic self-cleaning adhesives could be fabricated from a wide variety of materials. The possibilities for future applications of a dry, self-cleaning adhesive are enormous. We envision uses for our discovery ranging from nanosurgery to aerospace applications. Who knows--maybe a gecko-inspired robot with sticky, self-cleaning feet will walk on the dusty surface of Mars someday."
An interdisciplinary team of researchers, led by Autumn, earlier confirmed speculation that the gecko's amazing climbing ability depends on weak molecular attractive forces called van der Waals forces, named after a Dutch physicist of the late 1800s. Van der Waals forces are weak electrodynamic forces that operate over very small distances but bond to nearly any material. Autumn's research team rejected a 30-year-old model based on the adhesion chemistry of water molecules. Instead, the research team demonstrated that a gecko's ability to stick to surfaces depends on geometry--not chemistry--to synthesize the world's first gecko -based adhesive microstructure.
The setae (microscopic hairs) on the bottom of gecko's feet are only as long as two diameters of a human hair. That's 100- millionths of a meter long. Each seta ends with 1,000 even tinier pads at the tip. These tips, called spatulae, are only 200- billionths of a meter wide--below the wavelength of visible light. In 2002, Ronald Fearing, a researcher at the University of California at Berkeley, was able to produce two artificial hair tips, while Autumn and colleagues concluded that"both artificial setal tips stuck as predicted and provide a path to manufacturing the first dry, adhesive microstructures." Fearing's group later made the first array of synthetic gecko hairs with long stalks (6 micron stalk) and relatively large diameters (6 micron diameter) .
The team's research is supported by the National Science Foundation and the Defense Advanced Research Projects Agency (DARPA). More information about Autumn's research is available online at www.lclark.edu/faculty/autumn/pnas05.html.
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ADVANCE, EMBARGOED COPIES OF THE ARTICLE: Available through the PNAS News Office at 202-334-1310 or PNASnews@nas.edu
MEDIA CONTACTS: Kellar Autumn, Associate Professor of Biology, Lewis & Clark College, 503-768-7205 or (cell) 503-869-3641 or autumn@lclark.edu or Tania Thompson, Senior Communications Officer, Lewis & Clark College, 503-768-7961 or (cell) 503-701-3211 or taniat@lclark.edu
BROADCAST OUTLETS: Gecko b-roll, video news releases, and interview segments with Kellar Autumn are available. Contact Tania Thompson, senior communications officer, for further details at 503-768-7961 or taniat@lclark.edu.
DIGITAL IMAGES: High-resolution digital images are available online at www.lclark.edu/faculty/autumn/pnas05.html.
NOTE: On Wednesday, Jan. 5, at 9:40 a.m., Kellar Autumn will give a presentation about the design of synthetic gecko setae during a Terrestrial Locomotion Mechanics session at the Society for Integrative and Comparative Biology meeting in San Diego, Calif. Information about the conference is available online at www.sicb.org/meetings/2005/index.php3.
THIS INFORMATION IS EMBARGOED FOR RELEASE UNTIL: 5 p.m. Eastern Time, Monday, January 3, 2005
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This news release was originally issued by Lewis & Clark College and is distributed by AScribe, The Public Interest Newswire. Questions or comments regarding the information contained in this release should be addressed solely to the originating organization.
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