It's been a big week for chameleons. On Tuesday, scientists announced they'd worked out the secret to the cross-eyed lizard's colour changing skin. A day later came the announcement that we'd replicated the skin artificially.
Chameleons are among the select few organisms that are able to change their colour at will. There are many different reasons colour-changing has evolved in nature, from camouflage to predation to attracting a mate. But most rely on a similar principle: Tuning nanoscale structures to bend and reflect light in different ways.
The chameleon's colour-changing trick is actually quite simple. A layer of skin cells contains nanocrystals which reflect light at wavelengths related to their spacing. When the chameleon's skin is relaxed, it takes on one colour. When it stretches, the nanocrystals spread out — andthe colour changes. That discovery was reported earlier this week in Nature Communications.
Now a synthetic colour changing material — described this week the journal Optica — takes a page from the chameleon's book, using nanoscale structural features to reflect select colours of light. Basically, tiny rows of ridges are etched onto a silicon film a thousand times thinner than a human hair. Each of these ridges reflects a very specific wavelength of light. By altering the spacing between the ridges, it's possible to finely tune the wavelength of light reflected. That means, like chameleon skin, this material's colour changes when stretched.
Image: The Optical Society
The researchers behind the new skin hope their colour-changing material will soon find its way onto everything from displays to automobiles. But this is not the only synthetic skin promising to make our world more colourful.
Image: Tambako The Jaguar
Earlier this week I wrote about yet another new material that changes colour when stretched — this one inspired by the octopus, nature's incontestable master of camouflage. The scientists behind synthetic octopus skin say their material could be used on windows and building facades, allowing structures to alter their transparency and heat intake based on the ambient temperature and sunlight.
Whichever camouflaging critter provides the inspiration, one thing is clear: Our world is about to get a lot more colourful. [The Optical Society]
Top image via The Optical Society.