Researchers at Nagoya University in Japan have found a way to replicate the iridescent colour often found on birds’ and butterflies’ wings. The bright blue wings of the Steller's jay (a bird native to North America) were a particular source of inspiration for the scientists, who were able to reproduce the colour in a lab and synthesise a new kind of artificial pigment.
In the natural world, this “structural colour” phenomenon is created when microstructures change the way light is reflected from a surface. Currently in manmade materials, structural colour tends to change as you look at it from different angles, such as the surface of a CD. With the feathers of a Steller's jay, the light-reflecting properties sit on black melanin particles, which add to the richness and stability of the colour. This new pigment from Japan behaves in the same way, giving it the same electric colour from any angle.
The pigment was achieved by building up fine layers of transparent and black particles into “raspberry-like particles”. The colour and saturation can then be changed by altering the size of the dark core and the depth of the transparent layers.
As this structural colour doesn’t rely on the dyes, pigments, chemicals and water that are ordinarily used to colour materials, this will be an interesting technology to consider in terms of environmental responsibility. It could inspire a whole new range of metamaterials for numerous advanced applications. See Stretchy Structural Colour for more.