Butterfly Wings Have a Hidden Structure That Rivals Vantablack in Its Darkness (Nature)
Butterflies have taken the colour black to an entirely new level. The scales that shingle this insect's dark wings are nearly on par with the blackest of black coatings made by humans - except they're only a fifth of the thickness. At just a few microns wide, these natural nanostructures absorb 99.94 percent of the light that hits them, allowing only a tiny amount to be reflected.
To put that in perspective, Vantablack, which used to be the blackest material known to science, absorbs 99.96 percent of light. And the material that surpassed its blackness has vertically aligned carbon nanotubes (CNTs) that can absorb more than 99.995 percent. Examining 10 species from around the world, which were either ultra-black, regular black or dark brown, researchers at Duke University found these creatures were between 10 to 100 times darker than charcoal, fresh asphalt and velvet.
"Given that these structural changes increase the surface area for absorption," the authors write, "we conclude that butterflies operate under the same design principles as synthetic ultra-black materials - high surface roughness and a large area for absorption."
But because these scales are several times thinner than stacked carbon nanotubes, engineers and biologists alike are interested in learning how they can trap so much light without weighing themselves down. The answer could possibly help us design better solar panels and telescopes. It could maybe even camouflage an aircraft so it can't be detected at night or by radar. The possibilities are huge for such a nanoscopic mechanism.