

Airdate: Jan 08, 2010
Scientist: Dr. Ron Fearing

Kids' Science Challenge: Biomimicry - Toothbrush Toes

Kids' Science Challenge: Biomimicry - Toothbrush Toes
If you want to understand gecko-inspired adhesion, just pick up a toothbrush and follow along.

music; sfx tooth brushing

RF: These are animals that can climb up any surface, whether it's vertical or inverted, as easily as running on the ground.

JM: If you want to understand how geckos can adhere to almost any surface, you'll need a gecko, a microscope and perhaps, a toothbrush. I'm Jim Metzner, and this is the Pulse of the Planet. Ron Fearing is an engineer at the University of California, and he's applying the principles of gecko adhesion to new manmade materials.

RF: On the toe of the gecko there are these millions and millions of very, very tiny hairs. And those nano-hairs are on top of micro-hairs, which are on top of mini-hairs. And all of these work together to give a very powerful way-very flexible way of adhering to a surface. If you play with a toothbrush on, say, a piece of plastic, what you can notice is if you just press into the surface-it's actually very stiff, and you don't get much contact area.

JM: If you press harder as you drag the brush over the plastic, the bristles bend, and the surface increases, and so does the grip.

RF: When the hairs bend over, the contact area increases, and that's the secret to the gecko adhesive. When it climbs and slides, the fibers engage and get a lot of contact area, and it adheres. When it wants to release, it just comes right off with very little work.
And so what we've been doing is designing arrays of nano-fibers that give us some of the same remarkable properties the gecko has. That is, when you press into the surface, it doesn't stick, but when you slide on the surface, it does adhere.

JM: Ron Fearing is one of the participants in this year's Kids' Science Challenge, our free nationwide competition for 3rd to 6th graders, made possible by the National Science Foundation. Can you dream up a bio-inspired invention? Well, check out I'm Jim Metzner.