Geckos Have us Climbing the Walls

Posted on July 15, 2013


Since the advent of comics we’ve been daydreaming of having the wall-climbing prowess of spiders, which begs the question: How do they do that? We’ve imagined they have suction cups on their legs like an octopus and tried to duplicate that, but those attempts have been clunky at best. Try as we may we still can’t navigate vertical surfaces as adeptly as lizards, who can suspend their entire body weight by just one toe. They scurry up walls and across ceilings out of harm’s way with the quickness of ground walking.

Scientists look to the ability of gecko lizards for answers. Their wall-walking ability is due to nanosized, elastic, hair-like branches in their toes called seta. Many researchers have tried to recreate those gripping hairs using polymers and nanotubes. Kellar Autumn from Lewis and Clark College in Oregon made the discovery that the hairs use van der Waals forces to attract and adhere to surfaces, and has worked on recreating a gecko-inspired adhesive.

Van der Waals forces operate on the principle that certain elements have a vaguely present attraction to each other due to fluctuating polarization. It’s not a more concrete covalent or ionic bond, but temporary and fragile. A good example of van der Waals forces at work are gases. They are made up of all one element like helium. Helium needs to be contained in a tank because the van der Waals force that holds the atoms together is weak, and the bond breaks and reforms constantly. The gas molecules prefer to be apart from each other, so containing them is required or they dissipate into the atmosphere.

Even though the van der Waals bond is supposedly fragile, scientists were stumped about how to remove the bond they created with the gecko adhesive. The US Air Force and the University of Akron managed to fine-tune a prototype that removes easily without any residue – just like a real gecko. They even created a carbon nanotube material that actually outperforms geckos on vertical surfaces. This would give anyone wearing the material the ability to scale sheer surfaces at will. Like geckos, the adhesive fabric slides onto a surface to create its bond, and lifts off with ease when the fabric angle is increased, much like common tape.

Besides using the adhesive as a substitute for tape, the Air Force fabric could have many applications. It is currently being tested for its use in suture substitutions, and in the dry vacuum of space. “Geckel,” another adhesive which combines gecko-inspired technology with the wet-hold ability of your friendly local shellfish, the mussel, picks up where the Air Force adhesive leaves off: under water. Here the strong, yet reversible hold can be used in engineering feats such as patching underwater tanks and building bridges.

Of all the future uses of gecko adhesive, none of them include DIY cat burglar wall-scaling, Mission Impossible style. Yet. So if that’s your bag, you’re better off going to a good rock gym with a rubbery pair of climbing shoes and honing your skills, or flinging yourself at a Velcro wall at an amusement park.

If you’re really inventive, like 13-year-old Hibiki Kono, you can strap two hardware store vacuums to your back, add some suction pads, and suck your way up the side of your apartment building. So there are plenty of climbing options available while geckos don’t quite have us climbing the walls. If nothing else, we can always put on Velcro suits and throw ourselves at them.

Kiped from the archives of the SyFy channel’s IdeaLab Blog for the TV show Eureka. Well kinda kiped, since I wrote it to begin with. Edited by Tiffany Lee Brown, without whom I’d be stuck in the land of curly quotes.

Posted in: science, writing