AsianScientist (May 23, 2017) – A Nagoya University-led research team has mimicked the rich color of bird plumage used it to control how light interacts with materials. Their findings have been published in Advanced Materials.
Bright colors in the natural world often result from tiny structures that change the way light behaves when it’s reflected. Such structural color is responsible for the vivid hues of certain birds and butterflies. Artificially harnessing this effect could allow us to engineer new materials for applications such as solar cells and chameleon-like adaptive camouflage.
In the present study, researchers have reproduced the deep blue coloration of Stellar’s jay (Cyanocitta stelleri), giving rise to a new type of artificial pigment.
“The Stellar’s jay’s feathers provide an excellent example of angle-independent structural color,” said corresponding author Associate Professor Yukikazu Takeoka. “This color is enhanced by dark materials, which in this case can be attributed to black melanin particles in the feathers.”
In most cases, structural colors appear to change when viewed from different perspectives. For example, imagine the way that the colors on the underside of a CD appear to shift when the disc is viewed from a different angle. The difference in Stellar’s jay’s blue is that the structures, which interfere with light, sit on top of black particles that can absorb a part of this light. This means that the color of the Stellar’s Jay does not change, whichever angle you look at it.
The team used a layer-by-layer approach to build up films of fine particles that recreated the microscopic sponge-like texture and black backing particles of the bird’s feathers.
To mimic the feathers, the researchers covered microscopic black core particles with layers of even smaller transparent particles, to make raspberry-like particles. The size of the core and the thickness of the layers controlled the color and saturation of the resulting pigments. Importantly, the color of these particles did not change with viewing angle.
“Our work represents a much more efficient way to design artificially produced angle-independent structural colors,” Takeoka added. “We still have much to learn from biological systems, but if we can understand and successfully apply these phenomena, a whole range of new metamaterials will be accessible for all kinds of advanced applications where interactions with light are important.”
Source: Nagoya University.
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