Dry glue is a method of adhesion based upon the naturally occurring adaptations of the feet of gecko

Gecko

Geckos are lizards belonging to the infraorder Gekkota, found in warm climates throughout the world. They range from 1.6 cm to 60 cm....

s, which allow them to climb sheer surfaces, and even glass walls.

Background

A gecko can hang on a glass surface using only one toe. This ability of geckos has been attributed to van der Waals force

Van der Waals force

In physical chemistry, the van der Waals force , named after Dutch scientist Johannes Diderik van der Waals, is the sum of the attractive or repulsive forces between molecules other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral...

, although a more recent study suggests that water molecules of roughly monolayer thickness (present on virtually all natural surfaces) also play a role.

University of Akron and the Rensselaer Polytechnic Institute

Researchers announced in a paper published in the June 18–22, 2007 issue of the Proceedings of the National Academy of Sciences that using this technique they have created a synthetic “gecko tape” with four times the sticking power of a natural gecko foot. Particularly effective has been a checkerboard carpet of this material, which can be peeled and re-adhered repeatedly without weakening. The material is made of columns of carbon nanotubes rooted in pieces of flexible polymer. The nanotubes were grown on a silicon base and then transferred to the polymer to provide a flexible base, similar to a gecko's foot. When dried, the polymer holds the silicon base, which in turn, holds the nanotubes.

Stanford University and Carnegie Mellon University

In 2006, researchers at Stanford University

Stanford University

The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...

 and Carnegie Mellon University

Carnegie Mellon University

Carnegie Mellon University is a private research university in Pittsburgh, Pennsylvania, United States....

 developed a gecko-like robot

Robot

A robot is a mechanical or virtual intelligent agent that can perform tasks automatically or with guidance, typically by remote control. In practice a robot is usually an electro-mechanical machine that is guided by computer and electronic programming. Robots can be autonomous, semi-autonomous or...

 which uses synthetic setae

Synthetic setae

Synthetic setae emulate the setae found on the toes of a gecko and scientific research in this area is driven towards the development of dry adhesives. Geckos have no difficulty mastering vertical walls and are apparently capable of adhering themselves to just about any surface...

 to mount walls.

Georgia Institute of Technology in Atlanta

On October 9, 2008, the discovery of a new type of dry glue designed to mimic gecko feet was announced. The glue is 10 times stickier than that of the gravity-defying lizards, and three times stickier than other gecko-inspired glues. Liming Dai of the University of Dayton

University of Dayton

The University of Dayton is a private Roman Catholic university operated by the Society of Mary located in Dayton, Ohio...

said "It's the stickiest dry glue yet".

Defense Advanced Research Projects Agency

DARPA (Defense Advanced Research Projects Agency) is also currently working on this technology to enable a soldier to scale a wall at .5 m/s. This project is named Z-Man. Experiments are currently under way to develop nano-adhesives using the van der Waals effect.