Gecko-inspired adhesive enables people to scale buildings

Researchers at Stanford have invented a gecko-inspired climbing system that may enable the average Joe to scale walls like Spider-Man. The device, developed by engineer Mark Cutkosky and his team, consists of two hand-sized sticky-pads and foot platforms that are attached by cables. Researcher Elliot Hawkes demonstrated the device’s effectiveness by climbing a vertical glass wall. The team’s findings were published Nov. 19 in the Journal of the Royal Society Interface.

“It’s kind of a magical feeling, because it feels like somehow you’ve hooked onto glass,” Hawkes, a graduate student in mechanical engineering, told “That’s not really possible, so it feels really crazy.”

Known for their sticky feet, geckos are able to scale walls and ceilings using setae, which are microscopic bristles that generate an electronic force between a surface and the lizard’s toes. This lets a gecko to stick and unstick its feet as it shifts its weight on a surface. Scientists have been working with gecko-based adhesives for over a decade, but it wasn’t until now that they have been able to develop the synthetic material needed to support a human’s weight.

Cutkosky and his team solved this problem by first creating thousands of microscopic wedges made of silicone. These wedges, which act as synthetic setae, are then placed onto panels roughly the size of postage stamps that are then positioned on hand-sized plates and connected to springs, ensuring even weight distribution. Finally, the hand plates are attached by cables to platforms for a person’s feet, which in turn shift most of the weight to the legs.

Having the legs do the heavy lifting was the team’s aim for the device, though it didn’t start out that way.

“Our initial design was based upon how the gecko climbs, [which is] with its upper body, mostly. It pulls itself up a wall with its front legs, which are kind of like our arms,” Hawkes said. “I know one rock climber that can do that- climb up a wall without [using] his legs, but it’s not very easy.”

The system was designed with this difficulty in mind.

“I didn’t want something that could only be used by a professional rock climber,” he added. “We designed it so that you could use your legs to do the climbing.”

The hand-pads themselves aren’t sticky to the touch and, unlike suction cups, require minimal muscle power to use.

“That’s the cool thing about this adhesive,” Hawkes said. “It works how the gecko’s [feet] work- it can basically turn on and off. When I put my weight on the adhesive, it turns on, and when I take the weight off, it turns off. It makes it really nice to climb with it - there’s no struggling to get it off the wall or anything.”

The researchers also believe the new “controllable adhesive” may serve another purpose ­ ridding the galaxy of space-junk. Right now, there is a multitude of “dead” satellites that have been shut down orbiting the earth, taking up space where new satellites could go. These satellites are difficult to grab - they’re mostly comprised of non-magnetic material and so far glue and other materials haven’t been able to do the trick. However, this may change with the new kid in town.

“This gecko adhesive actually works in a space environment,” Hawkes asserted. “NASA’s tested it at their facility in Pasadena. It works in all of those conditions, [such as in] a vacuum and cold temperature. We’ve tested it in radiation… Hopefully a few years out it could actually happen.”

The Stanford team hopes that the adhesive can be used to latch onto dead satellites before flinging them into a higher “graveyard” orbit, or towards Earth where they’ll burn up in the atmosphere.

Still, when will the everyman be able to climb walls with some cool gecko gloves like the ones used by Tom Cruise in Mission Impossible: Ghost Protocol? According to Hawkes, it may be soon.

“We’ve been contacted by a rock climbing entrepreneur who wants to build climbing gloves with the technology,” Hawkes said. “It wouldn’t be so much for climbing up a sheer face, but [for] climbing up something you could almost climb as a rock climber, but can’t quite do it. Then you get these gloves with the extra adhesion, and now you can climb things you’ve never climbed before. That would definitely be available to the public.”