How to Be Spider-Man, Walk on Walls
Were you the kind of kid that encouraged spiders to bite you in hopes that they were radioactive runaways whose venom would give you mysterious powers? Did you idolize Spider-Man, wishing in vain that one day you would be able to sling webs at your enemies, walk easily across walls and ceilings and swing from building to building? Or were you like me and watched The Fly first, then became too grossed out to think about it anymore?
Either way, the days where we are able to walk along walls may not be too far away. Researchers have devised a high-tech suction device that mimics the ability of beetles to hold onto an object with a force 100 times its weight (Beetleman, anyone?). The device is called a "Switchable Electronically-controlled Capillary Adhesion Device" (SECAD). The name pretty much explains how it works. The SECAD consists of two plates: The top plate has hundreds of tiny holes, and the bottom plate houses a thin layer of water. In between both of these is a porous middle layer. A 9-volt battery is used to create an electric field that causes the water to squeeze through the pores of the top layer. The droplets exposed on the top layer can be used to adhere to another surface. When you want to come down from your new perch on the wall, just flick the off switch, and get ready to catch your fall. The creative team behind SECAD supplied a video of the device at work, holding up a tasty Hershey's bar.
The device uses the well known property of water called adhesion. Adhesion is the tendency for water molecules to stick to other surfaces - the same property responsible for the incredible soaking properties of a towel. Even with one tip of a towel immersed in water, very soon the entire towel can become damp because water molecules pull on each other and other surfaces so strongly that they can defy gravity and move "up" a surface.
According to professor Paul Steen of Cornell University, "In our everyday experience, these forces are relatively weak. But if you make a lot of them and can control them, like the beetle does, you can get strong adhesion forces."
The device is just a prototype, but can already hold a man up against a vertical Plexiglass surface. Well, a Lego man, at least. More work would be required to make a version of the SECAD that could support human weight.
Source: Live Science