Bio-inspired blueprint for new material
11 Oct 2016 by Evoluted New Media
MIT engineers have designed a beaver-inspired wetsuit material to insulate surfers.
MIT engineers have designed a beaver-inspired wetsuit material to insulate surfers.
This was achieved after they identified how beavers and sea otters — which do not have blubber like walruses and whales — were able to trap air to stay warm and dry while diving.
Associate head of mechanical engineering at MIT and co-author Anette (Peko) Hosoi, said: “We are particularly interested in wetsuits for surfing, where the athlete moves frequently between air and water environments.“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.”
Lead author Alice Nasto, after meeting with a wet suit manufacturer who had asked MIT students if there was a bioinspired solution for wetsuits, looked for examples in nature. Scientists had known beavers were able to trap air in their fur, but it was not very well understood how.
Beavers are covered in both long, thin guard hairs and shorter, more dense hairs called underfur. Guard hairs are able to keep water from penetrating the underfur. To replicate this, Nasto and her team used lasers to cut thousands of tiny holes in small acrylic blocks. A software program altered the size and spacing of individual hairs in the acrylic blocks, before rubber was poured into them — creating a number of different ‘hairy’ moulds.
These moulds were next submerged in silicone oil — to easily observe air pockets forming — and researchers observed air forming a thicker layer in hairs closer to the surface. Surfaces covered with denser fur plunged at higher speeds in the oil retained a thicker layer of air.
Mathematical models were then created that enabled researchers to predict the thickness of an air layer on a hairy surface. Hosoi said: “We have now quantified the design space and can say, if you have this kind of hair density and length and are diving at these speeds, these designs will trap air, and these will not.”The study was published in Physical Review Fluids.
