BThe expanses of paradise have long been a source of inspiration. The popularity of their shiny, showy feathers for women's hats nearly led to the extinction of the entire family of birds (Paradisaeidae) in the 19th century. Thanks to modern legal protections and a decline in interest in fancy hats, birds of paradise are still hanging on. Now the feathers of one striking species, the magnificent gunbird, have inspired fashion once again, only this time in a more sustainable way.
A new research published in Natural communications describes the invention of an “ultra-black” fabric that took a page from the gunbird's feather book. While ultra-black is quite useful for things like telescopes and solar panels, it is difficult to create because it absorbs more than 99.5 percent of the light that hits it and reflects less than 0.5 percent. Producing synthetic ultrablack materials is expensive and requires the use of toxic substances such as carbon nanotubes. But the black feathers of the magnificent shooting bird (Ptiloris grandiose), native to the rainforests of New Guinea and northern Australia, naturally absorbs an astonishing 99.95 percent of light. No toxins needed.
In a feat of biomimicry, engineers at Cornell University's Department of Human-Centered Design have created ultra-black wool that absorbs 99.87 percent of incoming light. First, the researchers dyed regular merino wool with a chemical called polydopamine, a synthetic pigment that mimics the melanin in the feathers of cut birds. They then used plasma to eat away the material on the outside of the wool fibers, leaving behind spiky nanofibrils that match the surface structure of feathers—rows of microscopic, tightly clustered barbs. This structure also allowed the synthetic melanin to penetrate deep into the fur.
Read more: “Reinventing black»
“The light is basically bouncing back and forth between the fibrils rather than being reflected back—that's what creates the ultrablack effect,” explained the Cornell Ph.D. student and co-author Hansadi Jayamaha statement.
The resulting ultra-black wool is not only the darkest fabric ever created, but also more practical than any ultra-black fabric to date. The researchers washed it in a laundry room, exposed it to bright light, and stretched and compressed it between steel plates to see if it retained its ultra-black properties. The material passed with a complete lack of color.
Moreover, ultra-blackness even turned out to be resistant to modifications of material images. Inspired by the beauty of gunbirds, Cornell design student Zoe Alvarez used wool in her dress. When the researchers took pictures of the dress and then manipulated the contrast, brightness, hue, and lightness of the photos, all the colors changed…except ultra-black.
“From a design perspective, I think it's interesting because many of the existing ultra-black materials aren't really as wearable as ours,” said Cornell fiber scientist and co-author Larrisa Shepard.
From rainforests to Parisian runways, ultra black is the new black.
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