Innovation

Not otter nonsense: Wetsuit tech mimics hairy sea mammal

otter

 (Felice Frankel)

Surfers may be a little warmer while catching waves thanks to an unlikely source: the totally gnarly sea otter. Researchers at MIT are currently working on new wetsuits made from synthetic otter hair. The new technology mimics the way otter and beaver fur traps warm air, which enables the little critters to stay toasty in icy water.

The project began back in the summer of 2015, when professor Annette Hosoi, who leads the Sports Education and Technology at MIT, brought a group of students to Taiwan to meet with different sporting good companies. One of the companies, a wetsuit manufacturer named Sheico, expressed interest in a bio-inspired wetsuit for surfers.

Hosoi assigned grad student Alice Nasto with the task of finding marine animals that could be used as design models. Creatures that use blubber to stay warm, such as whales and walruses, were quickly eliminated.

“When the animal is out of the water, blubber can be heavy and cumbersome,” Hosoi told Foxnews.com. “Since we are primarily interested in surfing applications in which the athlete needs to stay nimble both in water and in air, we opted to pursue the fur strategy which preserves agility.”  

Sea otters and beavers fit the bill. Biologists have long known semiaquatic mammal fur trapped warm air—their longer, thinner hairs “guard” the shorter, denser underfur, keeping water from penetrating to the skin—but a thorough understanding of how to mimic this effect was lacking. Nasto and her team set out to fill in the blanks, which proved no easy task.

“In my view, one of the toughest challenges to overcome was fabricating controlled hairy surfaces,” Hosoi said. “One of our postdoctoral associates, Jose Alvarado, figured out how to manufacture these test surfaces; he devised a way to cast the hairs in acrylic molds using a teflon-like coating to facilitate the release of the final structures.”

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Using laser–cutting technology, the team cut thousands of tiny holes in acrylic blocks. After altering the size and spacing of the holes, the molds were filled with polydimethylsiloxane (PDMS), a soft casting rubber. Once dried, the hairy surface was pulled out of the blocks.

The synthetic pelts were then plunged into silicone oil, where it’s easier to observe the air bubbles. It became apparent that the amount of air trapped by the surface depended on the spacing of individual hairs and how fast the pelt was submerged. After testing, the researchers developed an equation to determine how much air can be trapped by different rubber hair arrangements.

Nasto believes that the new bio-inspired wet suits will offer a warmer, more flexible alternative to current foam surfing wetsuit.

“Neoprene foam is quite heavy and a thick layer is required for especially cold water,” she said. “If you can use a textile to instead trap air for insulation, then it could still insulate effectively but still be lightweight. Air is in fact an even better insulator than neoprene rubber– it is 10 times more insulating.”

No word yet on when the new wetsuits “otter” be available. In the meantime, the research could prove useful in other industries as well.

“This is also relevant to the industrial process of dip coating, where a thin film of material is applied by dipping an object the coating liquid,” Nasto said. “Many materials are textured, and our theory can tell you how slowly you need to plunge your textured materials in order to avoid trapping air, which can cause uneven coating.”