Beavers and sea otters are known for having this amazing fur that traps air when they dive underwater, helping to keep their little blubber-less bodies warm. This is what inspired MIT engineers to create a fur-like rubbery pelt. They wanted to figure out how these mammals star warm and even dry while diving in and out of icy waters.
The Plan: Make precise, fur-like surfaces of various dimensions, dunk the surfaces in liquid at different speeds, and use video imaging to measure the air that is trapped in the fur during each each dive.
“We are particularly interested in wetsuits for surfing, where the athlete moves frequently between air and water environments,” says Anette (Peko) Hosoi, a professor of mechanical engineering and associate head of the department at MIT. “We can control the length, spacing, and arrangement of hairs, which allows us to design textures to match certain dive speeds and maximize the wetsuit’s dry region.”
The team at MIT made several molds by laser-cutting thousands of tiny holes in small acrylic blocks. Each mold was altered, varying in size and the spacing of individual hairs. The molds were then filled with a soft casting rubber.
Researchers mounted each hairy piece of rubber and submerged them in silicone oil. They chose oil so they could better observe any air pockets forming.
Results: The team learned that the spacing of individual hairs, and the speed at which they were plunged, played a large role in determining how much air a surface could trap. Surfaces with denser fur, plunged at higher speeds, generally retained more air within the hairs.
So, what does this mean? If you’ve ever worn a wetsuit you know they can be heavy and hard to move around in. Let’s pretend a wetsuit is made out of this fabricated hairy material, using air for insulation instead of soggy rubber. The bio-inspired wetsuit would be lightweight and behave better in water.
Can you imagine? Light, warm, furry wetsuits? I’m in! 🏄
The results were published in the journal Physical Review Fluids. You can view the study here -along with some pretty epic charts, diagrams, and photos.