PHYSICISTS have discovered how subtle differences in the crystals of butterfly wings create their vivid patterns.
Replicating this process could create materials that would be "tuned" to change colour on demand, said Dr Kok Wai Cheah of Hong Kong Baptist University.
Three tropical butterflies the researchers studied all displayed iridescence, a property of materials that change colour depending on the viewing angle. The scientists examined a cross-section of each species' wing under an electron microscope.
They found that the wings contained solid, flat layers known as cuticles, alternating with "air" layers known as laminae. The laminae also contain pillars of the cuticle material that gives the wing a crystal-like structure, which is similar to a multi-layered mirror that reflects only certain wavelengths, or colours, of light. It was from minute differences in the crystals that variations in colours arose.
"It all comes from the fact that the wing structure has subtle differences in each butterfly," said Cheah. He added that the study's findings could lead to materials that could change colour. For example, a single item of clothing could reflect a subdued colour during the day and a more showy one at night.
"You would just tune your structure to produce the colour you want," he said.
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