Modest Mollusk May Sport World's Strongest Material

The limpet's hardy teeth may inspire new vehicular designs, experts say.

Nature's latest discovered supermaterial comes from a decidedly modest creature: A type of mollusk found on the rocky shores of western Europe.

The teeth of these marine animals, called limpets, might be the strongest natural material yet documented—even stronger than spider silk, the previous record holder, a new study says. (See "Artificial Spider Silk Could Be Used for Armor, More.")

The discovery may inspire performance engineers to create better and more robust vehicles—such as bicycles, boats, and race cars—in the not-so-distant future.

"It's about translating design principles found in limpets to form structures that are strong, yet light," says study leader Asa Barber, a professor of advanced materials engineering at the University of Portsmouth in the United Kingdom.

Mighty Mollusks

Limpet teeth grow from a radula, a ribbonlike structure used to scrape and cut food, such as algae, off rocky surfaces. The teeth are built of protein frames reinforced by closely packed nanofibers of a mineral called goethite.

When scientists attempted to pull this light structure apart in the lab, it displayed a very high tensile strength, with up to 6.5 gigapascals (GPa) of pressure needed to deform a strand of tooth material.

In comparison, spider silk has a tensile strength of up to 4.5 GPa, and Kevlar boasts only about 3 to 3.5 GPa, according to the study, published this week in the journal Interface.

What's interesting is that limpet teeth retain their strength regardless of size, noted Barber. In general, the larger structures get, the more flaws they contain—which makes them weaker than smaller, less flawed, structures. (Also see "Watery Gecko Grip Could Lead to Stickier Tape.")

Not so for limpets.

"Limpets are clever because they use mineral fibers below a particular size, where flaws [in the fibers] don't affect the strength of the composite structure," Barber says.

What's Next?

A design in which tiny flaws won't compromise strength is of great interest to vehicular engineers.

For instance, racing bikes and race cars use light, strong composite materials to cope with stress, and a limpet-tooth-inspired design could help engineers build a stronger chassis that doesn't sacrifice speed.

"For the next five or ten years, this is the challenge," Barber says of efforts to bring such natural designs into engineering. (See "Twisting Everyday Fibers Could Make 'Smart Clothes' a Reality.")

Performance engineers drawing inspiration from a limpet? That's quite an achievement for an animal that spends most of its day anchored to a rock.

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