Stickier than gecko feet

Researchers have created a nanotube-based dry adhesive that surpasses the stickiness of gecko feet —no easy feat, since the animals can cling to nearly any type of surface, researchers report in the Oct. 9 issue of Science. Geckos rely on aligned microscopic hairs for their gravity-defying climbs, and the design by Liangi Qu and colleagues mimics this arrangement, with a vertically aligned array of straight carbon nanotubes topped by a layer of curly, entangled nanotubes. Just as in the gecko foot, the combination produces an adhesive with superior strength in the shear direction—clinging against the pull of gravity—and regular strength in the normal, perpendicular direction, which allows the adhesive to be easily pulled away from a surface. The shear adhesive force of the nanotube array is almost ten times that of the gecko foot.

ARTICLE #7: "Carbon Nanotube Arrays with Strong Shear Binding-On and Easy Normal Lifting-Off," by L.Qu; L. Dai at University of Dayton in Dayton, OH; M. Stone at Air Force Research Laboratory in Wright-Patterson Air Force Base, OH; Z. Xia at University of Akron in Akron, OH; Z.L. Wang at Georgia Institute of Technology in Atlanta, GA.