October 10, 2008

New Glue Is 10 Times Stickier Than Gecko Feet

U.S. scientists on Thursday reported the development a new type of glue that was inspired by gecko feet.

The dry glue is designed to be 10 times stickier than gecko feet, and three times stickier than other previously developed glues based on the lizards' sticky feet.

"It's the stickiest dry glue yet," said Liming Dai of the University of Dayton, who reported on the glue in the journal Science.

A 1-inch (2.5-cm) square of the adhesive can support the weight of a 220-pound (100-kg) man climbing up a vertical surface, but it can be easily lifted and reapplied.

Researchers Wang and Dai said the new glue could also be used in electrical components without the need for soldering. It could also be used in space or other areas of low temperatures where others lose their effectiveness.

The new glue uses a carpet of carbon nanotubes, thin filaments of carbon molecules. Attached to the ends of these filaments are curly strands of carbon that expand the surface area of the glue's gripping action.

"Our sticky glue has a force 10 times that of gecko feet and three times more than previous sticky glues trying to mimic the gecko feet," said Dai, who also worked with teams from the U.S. Air Force Research Laboratory near Dayton and the University of Akron to develop the glue.

Dai said the design is meant to maximize the effect of atomic-scale attractive forces known as van der Waals forces. He said the curly parts of the tubes are designed to be pressed onto a surface, forming a strong bond. But, when lifted at an angle, this bond is broken.

Wang uses the analogy of having a foot stuck in mud. If you pull straight up, the foot stays stuck, but if you slowly peel the foot away, the bond is broken.


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