Color Changing Skin

Nature does not require dyes and pigments to create colours.
Here is another brilliant example of a new material development for camouflage colours, inspired by nature: Scientists at the University of California, Berkeley/US have created a thin, flexible material that changes colour when stretched or bent. It has potential for the future of camouflage The artificial skin was inspired by chameleons, and doesn’t involve any synthetic dyes or pigments. Physical effects can do the job.
The new material, a high-contrast metastructure (HCM), is made from silicon metastructures. It can be made to change color — on demand — by simply applying a minute amount of force. The Berkeley scientists call it “Flexible photonic metastructures for tunable coloration”.
The new material’s application is in creating adaptable camouflages that can change to adapt to various backgrounds. This new material offers exiting possibilities for an entirely new class of display technologies, color-shifting camouflage on textiles and other surface materials, and sensors that can detect otherwise imperceptible defects in buildings, bridges, and aircraft.
The material works by creating “structural colour” which is controlled by tiny scales or features on the surface of an object, which interact to reflect particular wavelights depending on their spacing. Structural colours is how butterflies create colours, how human eyes are coloured, and how chameleons control their skin tone.
Even the chameleon´s ability to create colours to their colors rapidly, has only been recently understood. Chameleons, unlike the squid and the octopus, do not modify their scaly hues by altering the pigments in their skin cells. The mysterious color-change abilities are actually attributed to a layer of special skin cells which contain light-reflecting nanocrystals.
Once again, we learn that nature does not require synthetic dyes and pigments to create colour effects, and that technology can get inspired from nature´s abilities to invent new concepts and develop innovative materials. Perhaps the future of colouration effects will be without dyes and pigments.

Source: blog.stepchange-innovations.com