Inspired by gecko feet, scientists invent super-adhesive material

Feb 16, 2012
A palm-sized pad of Geckskin can firmly attach very heavy objects such as this 42-inch television weighing about 40 lbs. (18 kg) to a smooth vertical surface. Credit: Courtesy of UMass Amherst

For years, biologists have been amazed by the power of gecko feet, which let these 5-ounce lizards produce an adhesive force roughly equivalent to carrying nine pounds up a wall without slipping. Now, a team of polymer scientists and a biologist at the University of Massachusetts Amherst have discovered exactly how the gecko does it, leading them to invent "Geckskin," a device that can hold 700 pounds on a smooth wall.

Doctoral candidate Michael Bartlett in Alfred Crosby's polymer science and engineering lab at UMass Amherst is the lead author of their article describing the discovery in the current online issue of . The group includes biologist Duncan Irschick, a functional morphologist who has studied the gecko's climbing and clinging abilities for over 20 years. are equally at home on vertical, slanted, even backward-tilting surfaces.

"Amazingly, gecko feet can be applied and disengaged with ease, and with no sticky residue remaining on the surface," Irschick says. These properties, high-capacity, and dry adhesion offer a tantalizing possibility for that can easily attach and detach heavy everyday objects such as televisions or computers to walls, as well as medical and industrial applications, among others, he and Crosby say.

This combination of properties at these scales has never been achieved before, the authors point out. Crosby says, "Our Geckskin device is about 16 inches square, about the size of an index card, and can hold a maximum force of about 700 pounds while adhering to a smooth surface such as glass."

Beyond its impressive sticking ability, the device can be released with negligible effort and reused many times with no loss of effectiveness. For example, it can be used to stick a 42-inch television to a wall, released with a gentle tug and restuck to another surface as many times as needed, leaving no residue.

Previous efforts to synthesize the tremendous adhesive power of gecko feet and pads were based on the qualities of microscopic hairs on their toes called setae, but efforts to translate them to larger scales were unsuccessful, in part because the complexity of the entire gecko foot was not taken into account. As Irschick explains, a gecko's foot has several interacting elements, including tendons, bones and skin, that work together to produce easily reversible adhesion.

Now he, Bartlett, Crosby and the rest of the UMass Amherst team have unlocked the simple yet elegant secret of how it's done, to create a device that can handle excessively large weights. Geckskin and its supporting theory demonstrate that setae are not required for gecko-like performance, Crosby points out. "It's a concept that has not been considered in other design strategies and one that may open up new research avenues in gecko-like adhesion in the future."

The key innovation by Bartlett and colleagues was to create an integrated adhesive with a soft pad woven into a stiff fabric, which allows the pad to "drape" over a surface to maximize contact. Further, as in natural gecko feet, the skin is woven into a synthetic "tendon," yielding a design that plays a key role in maintaining stiffness and rotational freedom, the researchers explain.

Importantly, the Geckskin's adhesive pad uses simple everyday materials such as polydimethylsiloxane (PDMS), which holds promise for developing an inexpensive, strong and durable dry adhesive.

The UMass Amherst researchers are continuing to improve their Geckskin design by drawing on lessons from the evolution of gecko feet, which show remarkable variation in anatomy. "Our design for Geckskin shows the true integrative power of evolution for inspiring synthetic design that can ultimately aid humans in many ways," says Irschick.

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Provided by University of Massachusetts at Amherst

4.6 /5 (17 votes)

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User comments : 15

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MrVibrating
1 / 5 (3) Feb 16, 2012
Fantastic development. The range of applications really gets the imagination going... can't wait to see products!
kaasinees
1.4 / 5 (9) Feb 16, 2012
Another years old article, thanks.
Sinister1811
1.6 / 5 (13) Feb 16, 2012
Yeah, that would be useful. Imagine being able to walk up the walls of a building. Now that would be awesome.
kevinrtrs
Feb 17, 2012
This comment has been removed by a moderator.
antialias_physorg
5 / 5 (2) Feb 17, 2012
it can be used to stick a 42-inch television to a wall, released with a gentle tug and restuck to another surface as many times as needed, leaving no residue.

Pretty awesome. though for more or less permanently installed objects I'd prefer another solution (imagine what happens in the case of a small earthquake - everything'd fall off the walls).
Another thing that would be interesting to know: Does it remain sticky forever. Or does it suddenly become unstuck after a year or so?

Yeah, that would be useful. Imagine being able to walk up the walls of a building.

You mean like this?
http://www.physor...549.html

antialias_physorg
5 / 5 (3) Feb 17, 2012
If you take one part away the rest fails

a) Nature has a variety of surfaces. From rough to smooth.
b) Conquering ever smoother surfaces is a survival advantage (new food sources avilable, new hiding places available)
c) The density of hairs determines how good the gecko can climb ever smoother surfaces - so a slow, evolutionary increase in hair density and size through mutation is perfectly adequate. No need to go from bark to glass in one generation (note: glass does not exist in nature as an environment).

How many times will it need to develop in a different direction before it gets it right? In fact probably can't walk properly and so cannot get food

Those mutations that couldn't get food died immediately or were outbred by those that had a better mutation (this is called: selection). Remember: evolution never needs to be perfect - it just needs to be good enough to survive/breed.

Mutation and selection. Try thinking about it before spouting nonsense.
Anda
5 / 5 (1) Feb 17, 2012
shows the true integrative power of evolution for inspiring synthetic design

So just how did the gecko feet "evolve" such an integrated design???
If you take one part away the rest fails, that's what the researcher means by "integrated design".

And if it fails, of what use is it to the animal?

How many times will it need to develop in a different direction before it gets it right? In the meantime it can't climb up walls and in fact probably can't walk properly and so cannot get food.

It's very easy to glibly say "it evolved". It's a lot more challenging to substantiate that statement with viable, demonstrable ways that it could have happened.

Such unsubstantiated statements amount to nothing more than pseudo science - as defined on Wikipedia (and referenced by Physorg).


God had to be drunk when it creates you
Sinister1811
1 / 5 (5) Feb 17, 2012
Yeah, that would be useful. Imagine being able to walk up the walls of a building.

You mean like this?
http://www.physor...549.html


Sweet. They should invent shoes that allow you to do that.
alfie_null
not rated yet Feb 17, 2012
I wonder how well it handles contamination? Can it be cleaned easily?
Green_Dragon
not rated yet Feb 17, 2012
i agree @ alfie null, plus id rather a locking mechanism of some sort if possible. Id hate for someone to bump into my tv somehow and ive it the right angle of force to jus fall and break...that would make me devolve n go ape shit
Royale
5 / 5 (1) Feb 17, 2012
Sweet. They should invent shoes that allow you to do that.


I wonder. If they did invent shoes like that would a human be able to walk up a wall, or would our anatomy not be able to handle a 90 degree change it forces like that? It seems to me that without using arms or being able to angle your ankles much it would be rather difficult.
Sinister1811
1.4 / 5 (11) Feb 17, 2012
Sweet. They should invent shoes that allow you to do that.


I wonder. If they did invent shoes like that would a human be able to walk up a wall, or would our anatomy not be able to handle a 90 degree change it forces like that? It seems to me that without using arms or being able to angle your ankles much it would be rather difficult.


You could be right. Our anatomy would probably fail miserably. I didn't really take that into consideration.
Xbw
2 / 5 (8) Feb 17, 2012
Sweet. They should invent shoes that allow you to do that.


I wonder. If they did invent shoes like that would a human be able to walk up a wall, or would our anatomy not be able to handle a 90 degree change it forces like that? It seems to me that without using arms or being able to angle your ankles much it would be rather difficult.

It is possible assuming you had shoes that could somehow engage and disengage with every step however, you would have to be pretty physically fit and would need to use the majority of your back and abdomen muscles if you wanted to stay tilted at 90 degrees. Gravity is a beast :)

It would be easier to use hands and feet.
dschlink
not rated yet Feb 17, 2012
I suspect kneepads and gloves would be the best approach for climbing. Although many other people have made something like this, large, simply-manufactured pads is the real break-through.
antialias_physorg
5 / 5 (1) Feb 17, 2012
It is possible assuming you had shoes that could somehow engage and disengage with every step

I guss the leverage would be way too much for adhesive pads on your shoes while walking 'upright' (unless they were enormously big)

Best bet would be hand, knee and foot pads for shimmying up the wall. Keeps best with the spiderman-style, too
Au-Pu
1 / 5 (3) Feb 19, 2012
Special forces and the like would love something like this.

Who knows they might monopolise it.

Please stop marking my correct use of "s" instead of the incorrect use of "z" as being incorrect? Learn to spell.

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