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Sticky business

• Secret behind geckos’ fancy footwork may yield amazing inventions

By Ben Jacklet

The Portland Tribune, Jan 18, 2005, Updated Oct 30, 2009

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Kellar Autumn was on vacation in Hawaii, lying on his back in a hotel room, when he saw a monstrous spider on the ceiling directly over his face.

While he was trying to determine what to do next, a gecko glided across and took care of the problem for him. The lizard easily outmaneuvered the hapless spider, picking it up and throwing it down from the ceiling to the floor.

The upside-down battle would have grabbed anyone’s attention, but for Autumn it was a moment of insight. He’d spent much of his adult life studying geckos. “It hadn’t even occurred to me that the most interesting thing about geckos is that they have sticky feet,” he says.

Seven years later, Autumn, a 40-year-old associate professor of biology at Lewis & Clark College, is arguably the world’s expert on gecko feet. He’s learned that gecko feet aren’t just incredibly weird. They also could prove extremely valuable, because their feet function as self-cleaning adhesives that one day may be replicated synthetically, leading to all sorts of potential inventions.

Imagine reusable duct tape, without the messy goo. Or a rock-climbing anchor that could stick to a solid granite face without budging.

Or climbing robots to help with search and rescue missions.

Or a nontoxic medical adhesive for internal use.

Or an improved version of the Mars rover, with gecko toes instead of wheels.

“If you had asked me 10 years ago if my gecko research would have been useful, I would have said, ‘I doubt it. I’m just curious,’ ” Autumn says. “But now, in this serendipitous sequence of events that’s been totally unpredictable, it’s turning out to be really, really useful.”

When Autumn returned to Portland from that vacation in 1998, he went straight to the library, assuming that somebody must have figured out how gecko feet work. It turned out no one had, though many had tried.

So how do gecko feet work? Do they contain tiny suction cups? Or tiny spikes like the crampons on climbing boots? Do they secrete some chemical that makes them sticky? Do they use static electricity?

None of the above. But clearly the key to the puzzle lay somewhere in the tiny hairs on a gecko’s toes. So in 2000 Autumn collaborated with scientists and engineers at the University of California, Berkeley (where he had earned his doctorate in integrative biology in 1995) to isolate a single hair on a gecko’s foot, an object one-tenth the diameter of a human hair, with hundreds of branches or split ends so small they can only be seen through an electron microscope.

They had what they needed, but they couldn’t figure out how it worked. Months went by, and everybody wanted to quit, Autumn recalls. And then came the breakthrough realization: Gecko feet don’t stick by chemical attraction but by very weak molecular attractions called van der Waals forces.

In other words, gecko feet are sticky by design. Ron Fearing, an engineer at UC-Berkeley, was able to nanofabricate synthetic gecko hair from two different materials.

Not only did this revelation free Autumn and his colleagues from having to spend years studying complex genetic sequences and chemical formulas, it also opened the door to a huge array of potential practical uses.

“What it meant was that to make a synthetic gecko, you don’t have to copy the gecko’s chemistry,” Autumn says. “You don’t have to sequence gecko genes. Instead you use geometric structural principles to take something that used to be slippery and make it sticky.”

Autumn and his colleagues immediately began filing patents, and all sorts of people started showing interest. Today their sponsors include the National Science Foundation, the U.S. military’s Biologically Inspired Multifunctional Dynamic Robotics Program, the M.J. Murdock Charitable Trust, the John S. Rogers Science Research Program and multiple corporate sponsors who are withholding their names.