Until recently, spider’s silk reigned supreme. In fact, the material once hailed as the strongest substance on earth has now been dethroned—by snail teeth, or Limpet teeth, of all things. Despite being microscopic, limpet teeth are stronger than titanium and are so durable they could potentially reinforce boats, airplanes—even create Formula 1 race cars. They’re also being considered as an alternate material for dental fillings. This discovery was made by a research team from the University of Portsmouth in England. Limpets are sea snails that typically languish on rocks, scraping their vegetarian diet off surfaces with a tongue-like appendage covered in tiny teeth called a radula. Not exactly the picture of strength. Yet one engineering professor, Asa Barber, chose to give the critters a second-look. Upon investigating, Barber discovered that limpet teeth are comprised of densely-packed goethite mineral fibers. “I thought, ‘Wow, this is like the structures we use in aerospace structures, but on a much smaller scale.’” Thus, Barber went on to test their strength. The limpet teeth required 6.5 gigapascals (GPa) of pressure to be pulled apart. Spider silk scored a distant second at 4.5 GPa in tensile strength and Jevkar 3 to 3.5 GPa. Limpet teeth are also unique in that they hold no correlation between size and weakness. The rules typically state the larger the structure, the more opportunity for flaws. Yet limpet teeth dodge this weakness because their fibers are so small and dense. So what does this discovery mean for technology? Barber claims limpet teeth could have applications in engineering, particularly for vehicles. Cars that require extreme speed—such as race cars—must be durable. However, the stronger the material, typically the heavier, and therefore slower the vehicle becomes. Limpet teeth could be a solution to the strength/lightness dichotomy, as they sacrifice neither velocity nor durability. Though scientists have not yet discovered how to harness the limpet teeth technology for engineering purposes, they intend on discovering how to do so. They hope to duplicate their structure and thus create higher-performing materials. Peter Fratzl, of the Department of Biomaterials at the Max Planck Institute of Colloids and Interfaces, says the study "is extremely interesting in at least two ways." "First," he says, "it shows that an intricate microstructure makes limpet teeth incredibly strong for biogenic material, certainly stronger than silk or cellulose. Second, the experimental approach, using tiny tensile specimens just a few microns long, is really impressive." "It's about translating design principles found in limpets to form structures that are strong, yet light," said Barber, reported National Geographic. "For the next five or ten years, this is the challenge." As for dentistry? Stay tuned—you never know when a new (snail-inspired) filling material may hit the market.
Scanning electron microscope image of limpet teeth (University of Portsmouth: Asa Barber)
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