Autumn Lab - PNAS Article 2005

All information is Embargoed until 5 pm EST Mon 3 Jan 2005.

PUBLICITY INFORMATION FOR: Hansen and Autumn (2005). Evidence for self-cleaning in gecko setae. Proceedings of the National Academy of Sciences, USA. Vol 102(2).

For use of images, contact Prof. Kellar Autumn (autumn@lclark.edu) or Tania Thompson (taniat@lclark.edu).

PRESS RELEASE: http://www.lclark. edu/faculty/autumn/ pnas05-pr.html

BROADCAST OUTLETS: Gecko b-roll, video news releases, and interview segments with Prof. Kellar Autumn are available. Contact Tania Thompson, senior communications officer, for further details at 503-768-7961 or taniat@lclark.edu.

Evidence for Self-Cleaning in Gecko Setae

Published in Proceedings of the National Academy of Sciences

Authors: Wendy Hansen and Kellar Autumn

AutumnLab Logo For inquiries, contact:

Prof. Kellar Autumn

Department of Biology, Lewis & Clark College, Portland, Oregon. Phone: 503-768-7502 (Office), 503-869-3641 (Mobile). autumn@lclark.edu

http://www.lclark. edu/~autumn/

View the Video News Release

Summary

How geckos manage to keep their feet clean while walking about with sticky feet has remained a puzzle until now. 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 geckos' feet actually become cleaner with repeated use!

In fact, we found that the microscopic adhesive hairs -or setae- that make up the gecko adhesive are the first known self-cleaning adhesive. 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. 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 feet will walk on the dusty surface of Mars someday.

Images

High Quality JPG Medium Size TIF High Resolution TIF	High Quality JPG Medium Size TIF	High Quality JPG Medium Size TIF High Resolution TIF
Self-cleaning adhesive: tokay gecko (Gekko gecko) climbing on vertical glass, with laser illuminated microsphere footprint left behind. Copyright (c) 2004 Kellar Autumn, Lewis & Clark College, Portland, Oregon.	Self-cleaning adhesive: tokay gecko (Gekko gecko) toe adhering to glass, with laser illuminated microsphere toeprint left behind. Copyright (c) 2004 Kellar Autumn, Lewis & Clark College, Portland, Oregon.	Tokay gecko (Gekko gecko) inverted on glass. Copyright (c) 2002 Kellar Autumn, Lewis & Clark College, Portland, Oregon.
High Quality JPG Medium Size TIF High Resolution TIF	High Quality JPG Medium Size TIF High Resolution TIF	High Quality JPG Medium Size TIF
Self-cleaning adhesive: scanning electron microscope image of tokay gecko spatulae during self-cleaning from 2.5 micron silica-alumina microspheres. Copyright (c) 2004 Wendy Hansen & Kellar Autumn, Lewis & Clark College, Portland, Oregon.	Self-cleaning adhesive: scanning electron microscope image of tokay gecko spatulae during self-cleaning from 2.5 micron silica-alumina microspheres. Copyright (c) 2004 Wendy Hansen & Kellar Autumn, Lewis & Clark College, Portland, Oregon.	Self-cleaning adhesive: scanning electron microscope image of tokay gecko spatulae during self-cleaning from 2.5 micron silica-alumina microspheres. Copyright (c) 2004 Wendy Hansen & Kellar Autumn, Lewis & Clark College, Portland, Oregon.
High Quality JPG	High Quality JPG	High Quality JPG
Tokay gecko (Gekko gecko) climbing on glass. Copyright (c) 2004 Kellar Autumn, Lewis & Clark College, Portland, Oregon.	Tokay gecko (Gekko gecko) climbing on glass. Copyright (c) 2004 Kellar Autumn, Lewis & Clark College, Portland, Oregon.	Tokay gecko (Gekko gecko) climbing on glass. Copyright (c) 2004 Kellar Autumn, Lewis & Clark College, Portland, Oregon.
High Quality JPG		High Quality JPG
Tokay gecko (Gekko gecko) climbing on glass. Copyright (c) 2004 Kellar Autumn, Lewis & Clark College, Portland, Oregon.		Tokay gecko (Gekko gecko) climbing on glass. Copyright (c) 2004 Kellar Autumn, Lewis & Clark College, Portland, Oregon.

Current News Coverage

Sticky Business, Portland Tribune
http://www.portlandtribune. com/archview.cgi?id=27965

Scientists Unravel How Geckos Keep Their Sticky Feet Clean, ScientificAmerican.com
http://www.sciam. com/article.cfm?chanID=sa003&articleID= 000B3BBB-C506-11D9- 850683414B7F0000

Grip Minus Grime: Consider the Gecko, NYTimes.com
http://www.nytimes. com/2005/01/04/science/ 04geck.html

Secret of Geckos feet unraveled, Earthtimes.org
http://www.earthtimes. org/articles/show/ 1097.html

Twinkle Toes: How geckos' sticky feet stay clea, Science News Online
http://www.sciencenews. org/articles/20050108/ fob6.asp

Duct tape that never loses its stick, PhysOrg.com
http://www.physorg. com/news2602.html

Previous Research from the Gecko Team

Autumn et al. Nature 2000:

Presented the first measurements of adhesion in a single isolated gecko seta.
Discovered the mechanical requirements for attachment of a seta.
Discovered the mechanical requirements for detachment of a seta.
Could not reject vdW forces on theoretical grounds.

Autumn et al. PNAS 2002:

Provides the first direct experimental verification for a van der Waals mechanism of gecko foot-hair adhesion;
Predicts foot-hair design based on adhesive theory. Adhesion is enhanced simply by splitting a surface into small protrusions to increase surface density - just what has evolved in nature independently numerous times.
Reports the gecko-inspired fabrication of synthetic foot-hair tips that stick. If van der Waals force is the mechanism, then adhesion should depend more on size and shape than on the nature of the surface. Our ability to fabricate artificial foot-hair tips that stick from two different materials strongly supports our experimental and theoretical results.

Ron Fearing at UC Berkeley was able to produce two artificial hair tips. Autumn and colleagues (2002) concluded, "Both artificial setal tips stuck as predicted and provide a path to manufacturing the first dry, adhesive microstructures."

Later in 2002, Ron Fearing's group made the first array of synthetic gecko hairs with long stalks (6 um stalk) and relatively large diameters (6 um diameter; Sitti and Fearing, 2002).

For more information:

http://www.lclark. edu/~autumn/dept/ index.html

http://www.pnas. org/content/vol99/ issue19/cover.shtml

Autumn, K., M. Sitti, A.M. Peattie, W. Hansen. S. Sponberg, Y.A. Liang, T. Kenny, R. Fearing, J.N. Israelachvili, R.J. Full. 2002. Evidence for van der Waals adhesion in gecko setae. PNAS 99(19): 12252-12256. http://www.pnas. org/content/vol99/ issue19/cover.shtml

Autumn, K. and A.M.Peattie. 2002. Mechanisms of adhesion in geckos. Integrative and Comparative Biology 42(6): 1081-1090.

Autumn, K., W.-P. Chang, R. Fearing, T. Hsieh, T. Kenny, L. Liang, W. Zesch, R.J. Full. 2000. Adhesive force of a single gecko foot-hair. Nature 405:681-685.

M. Sitti and R.S. Fearing, Nanomolding Based Fabrication of Synthetic Gecko Foot-Hairs. IEEE Nano, August 2002, Washington, DC.