Gecko's, typically 5 ounce lizards, amaze scientists (and non-scientists) with their ability to grip and scamper up the smoothest of surfaces. Their feet are covered in self-cleaning microscopic hairs, known as setae, with even smaller branches at the tips, called spatulae. These ensure that a gecko's foot has a large surface area in contact with any surface, maximizing the weak but ever-present attraction between adjacent molecules known as the van der Waals force -- Gecko feet produce an adhesive force nearly equivalent to 18 times their own body weight. Most previous efforts were based on creating materials (e.g., carbon nanotubes) attempting to act like the gecko's setae.
Researchers at the University of Massachusetts Amherst, however, have taken a somewhat different approach by evaluating how several interacting elements in gecko feet, including tendons, bones and skin, work together to produce easily reversible adhesion. In fact, their novel design approach has demonstrated that setae are not required for gecko-like adhesion.
They developed Geckskin, which integrates adhesive with a soft pad woven into a stiff fabric, allowing 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. An index-card-sized sheet can hold up to 700 pounds on a smooth wall, and using the same types of high-capacity reversibility and dry adhesion as gecko feet, can easily attach and detach heavy objects (like say a big screen TV) on flat or slanted surfaces — even glass. The Geckskin can be released with little effort and re-used, and leaves no residue. Best of all, 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 product.
And we thought velcro was cool ...
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