Nature-inspired engineers from the University of California at Berkeley have created an incredibly thin chameleon-like material that can be made to change colour on demand.
For consumers, this chameleon material could be used in a new class of display technologies, adding brilliant colour presentations to outdoor entertainment venues.
It is also possible to create an active camouflage on the exterior of vehicles that would change colour to better match the surrounding environment.
More day-to-day applications could include sensors that would change colour to indicate that structural fatigue was stressing critical components on bridges, buildings or the wings of airplanes.
"This is the first time anybody has made a flexible chameleon-like skin that can change colour simply by flexing it," said Connie J Chang-Hasnain, member of the Berkeley team and co-author of the paper.
By precisely etching tiny features - smaller than a wavelength of light - onto a silicon film one thousand times thinner than a human hair, the researchers were able to select the range of colours the material would reflect, depending on how it was flexed and bent.
Changing the colour of a surface, such as the leaves on the trees in autumn, requires a change in chemical make-up.
Recently, rather than controlling the chemical composition of a material, engineers are trying to control the surface features on the tiniest of scales so they interact and reflect particular wavelengths of light.
This type of "structural colour" is much less common in nature but is used by some butterflies and beetles to create a particularly iridescent display of colour.
"If you have a surface with very precise structures, spaced so they can interact with a specific wavelength of light, you can change its properties and how it interacts with light by changing its dimensions," Chang-Hasnain explained.
The semiconductor material also allowed the team to create a "skin" that was incredibly thin, perfectly flat, and easy to manufacture with the desired surface properties.
This produces materials that reflect precise and very pure colours and that are highly efficient, reflecting up to 83 percent of the incoming light.
Their initial design created brilliant colours that could be shifted from green to yellow, orange and red - across a 39-nanometer range of wavelengths.
Future designs, the researchers believe, could cover a wider range of colours and reflect light with even greater efficiency.
The paper appeared in Optica, The Optical Society's (OSA) new journal.
