For years, scientists have been amazed by gecko feet, which let these lizards produce an extremely powerful adhesive force. Now, Duncan Irschick, Biology, and Alfred Crosby, Polymer Science and Engineering, have discovered exactly how the gecko does it, leading them to invent "Geckskin," a device that can hold 700 pounds on a smooth wall.
Crosby, Irschick, doctoral candidate Michael Bartlett, and colleagues received international scientific and media attention over the past several weeks for their discovery reported in the journal Advanced Materials, of how gecko feet and skin produce an adhesive force roughly equivalent to the 5-ounce animal carrying nine pounds up a wall without slipping. This led them to invent "Geckskin," a device that can hold 700 pounds on a smooth wall. Irschick, a functional morphologist who has studied the gecko's climbing and clinging abilities for over 20 years, says the lizards are equally at home on vertical, slanted and even backward-tilting surfaces.
Geckos easily disengage their grip without leaving any residue on a surface, a highly sought-after quality that the polymer scientists on the team were able to retain in Geckskin. Guided by new understanding of interacting elements including tendons, bones and skin in the gecko foot, they made an integrated adhesive with a soft pad woven into a stiff fabric, Crosby explains, which allows the pad to "drape" over a surface, maximizing contact. Geckskin uses inexpensive materials such as polydimethylsiloxane woven into a synthetic tendon that maintains stiffness and rotational freedom.
Geckskin's combination of bearing heavy loads and being reusable/reversible in dry (not sticky) adhesion offers rich possibilities for new applications such in everyday life as well as in medicine and industry.
The key innovation 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.