I’ve been intrigued by ‘gecko technology’ or ‘spiderman technology’ since I first started investigating nanotechnology about four years ago.  This is the first time I’ve seen theory put into practice. From the news item on Nanowerk,

Mark Cutkosky, the lead designer of the Stickybot, a professor of mechanical engineering and co-director of the Center for Design Research [Stanford University], has been collaborating with scientists around the nation for the last five years to build climbing robots.

After designing a robot that could conquer rough vertical surfaces such as brick walls and concrete, Cutkosky moved on to smooth surfaces such as glass and metal. He turned to the gecko for ideas.

“Unless you use suction cups, which are kind of slow and inefficient, the other solution out there is to use dry adhesion, which is the technique the gecko uses,” Cutkosky said.

Here’s a video of Stanford’s Stickybot in  action (from the Stanford University News website),

As Cutkosky goes on to explain in the news item,

The interaction between the molecules of gecko toe hair and the wall is a molecular attraction called van der Waals force. A gecko can hang and support its whole weight on one toe by placing it on the glass and then pulling it back. It only sticks when you pull in one direction – their toes are a kind of one-way adhesive, Cutkosky said.

…

“Other adhesives are sort of like walking around with chewing gum on your feet: You have to press it into the surface and then you have to work to pull it off. But with directional adhesion, it’s almost like you can sort of hook and unhook yourself from the surface,” Cutkosky said.

After the breakthrough insight that direction matters, Cutkosky and his team began asking how to build artificial materials for robots that create the same effect. They came up with a rubber-like material with tiny polymer hairs made from a micro-scale mold.

The designers attach a layer of adhesive cut to the shape of Stickybot’s four feet, which are about the size of a child’s hand. As it steadily moves up the wall, the robot peels and sticks its feet to the surface with ease, resembling a mechanical lizard.

The newest versions of the adhesive, developed in 2009, have a two-layer system, similar to the gecko’s lamellae and setae. The “hairs” are even smaller than the ones on the first version – about 20 micrometers wide, which is five times thinner than a human hair. These versions support higher loads and allow Stickybot to climb surfaces such as wood paneling, painted metal and glass.

The material is strong and reusable, and leaves behind no residue or damage. Robots that scale vertical walls could be useful for accessing dangerous or hard to reach places.

The research team’s paper, Effect of fibril shape on adhesive properties, was published online Aug. 2, 2010 in Applied Physics Letter.