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Gravity-Defying Geckos Teach Scientists a Lesson

By DENISE GRADY

Published: August 30, 2005 THE NEW YORK TIMES

 

The scientific quest to make artificial gecko feet has taken a leap forward.

 

Geckos, lizards that are notorious for their sticky feet, can run up walls and across ceilings, and hang tauntingly by one toe. They have no suction cups, hooks or glue on their feet, so how do they do it?

 

The soles of geckos' feet are covered by 500,000 minute hairs, and the tip of each hair splits into hundreds more. Top, a lizard's hairs are magnified 595 times.

Five years ago, researchers at the University of California, Berkeley; Stanford; and Lewis and Clark College found the secret: 500,000 minute hairs cover the sole of each foot, and the tip of each hair splits into hundreds more. The hairs are so elastic that they can bend or squish to conform to microscopic nooks and crannies under the creature's feet, even on the glass walls of an aquarium.

 

As a result, the tiny hairs touch so much surface area so closely that weak forces of attraction between molecules in the hairs and in whatever surface the animal is walking on add up and become sufficient to let the gecko hang on. The connection breaks when the gecko shifts its foot enough to change the angle between the hairs and the surface.

 

The discovery intrigued scientists, who immediately realized that if synthetic gecko-foot hairs could be made, they might be a great adhesive - strong, glue-free, dry, reusable and, unlike suction cups, capable of working in a vacuum like outer space. Engineers envisioned robotic instruments that could climb walls or grab objects without dropping them, and rovers that could maneuver rugged terrain on distant planets. Such adhesives could also be used to stick components together in electronic devices.

 

The National Science Foundation takes these ideas so seriously that it gave a $400,000 grant to scientists at the University of Akron and Rensselaer Polytechnic Institute to try making imitation gecko feet.

 

In a recent issue of the journal Chemical Communications, the team reported that it had indeed produced synthetic hairs, with 200 times the sticking power of the ones made by nature.

 

Although the scientists have tested only minute amounts of the material, they estimate that if its properties hold up on a larger scale, a dime-size patch of it could support 2 to 22 pounds, depending on how densely the hairs were packed.

 

"Think of it almost like nano-Velcro," said Ali Dhinojwala, an associate professor of polymer science at the University of Akron.

 

The synthetic hairs - one ten-thousandth the width of a human hair - are made of highly flexible carbon cylinders, or nanotubes, embedded in a plastic base like bristles in a hairbrush.

 

The tubes are strong and practically unbreakable, Professor Dhinojwala said, adding that other groups had tried making the tubes of plastic, but it turned out to be too weak.

 

He said people had asked him whether the new material could be fashioned into gloves and shoes for rock climbers.

 

"I'm a little hesitant on going too fast," Professor Dhinojwala said. "Nature has had more time than we have had. I would hesitate to extrapolate. But the imagination is there."

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Posted

The question must be asked how to deal with the issue of contamination. Surely anything that adheres to surfaces would also attract particles and quicky lose its sticky qualities. One should ask how does the gecko manage this? Are the hairs shed regularly so as to renew the surface?

Posted

I suspected that a topic as rich and sprayastic as gecko nano hairs would have been played out in spray before...I did a search on "gecko" before I posted that but it yielded no results...WTF? Come to think of it, I've never been able to find anything using the Search function. wazzup.gif

Posted
...WTF? Come to think of it, I've never been able to find anything using the Search function. wazzup.gif

 

Have you tried asking Googlebot to help you?

Posted
WTF? Come to think of it, I've never been able to find anything using the Search function. wazzup.gif

 

I think the default search only looks for messages newer than 1 week - you need to change that to look for older posts.

Posted
put a cork in it you self-righteous prick

 

yelrotflmao.gif

 

Someone forget to lube your joints this morning?

 

 

ps. in the future, you may address me as "Your Holiness, the Squid". Complaints can be directed to the appropriate department.

Posted
The question must be asked how to deal with the issue of contamination. Surely anything that adheres to surfaces would also attract particles and quicky lose its sticky qualities.

 

One word. Teflon!

Posted
The question must be asked how to deal with the issue of contamination. Surely anything that adheres to surfaces would also attract particles and quicky lose its sticky qualities.

 

One word. Teflon!

How does Teflon to stick to the pan?

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