To make the tape, the researchers used an electron beam to pattern a mold for an array of tiny silicon pillars, each 400 nanometers wide and 600 nanometers tall. (A human hair is about 100,000 nanometers—or billionths of a meter—thick.)
Once the pillars were cast and peeled from the gecko-inspired mold, the team dipped them into a solution with the mussel-adhesive-inspired protein.
The tiny patch of geckel held together for more than a thousand contact-and-release cycles in both wet and dry environments, Messersmith said.
But for the technology to reach a mass market, researchers will need a faster and less expensive method, he added.
Few Years Away?
Ronald Fearing is the director of the Biomimetic Millisystem Lab at the University of California at Berkeley. His research team has developed a flexible array of gecko-like hairs.
He said that several of the gecko-adhesive teams have tested .15-square-inch (one-square-centimeter) pieces of tape and found they fall apart or get dirty after just a few contact-and-release cycles.
Similar wear-and-tear problems might also be encountered with a larger piece of geckel, he pointed out.
"It comes down to if you have a single stalk, it's hard for it not to stick," he said. "Getting millions of stalks all working together—so far, that's been a challenge for many groups."
However, Fearing and Messersmith both predict gecko- and mussel-inspired adhesives are just a few years shy of the market for applications like waterproof bandages or clingy clothing.
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