EUROPE: Engineers have created an incredibly thin, chameleon-like material that can change colour – on demand – by simply applying a minute amount of force.
The material paves the way for an entirely new class of display technologies, colour-shifting camouflage, and sensors that can detect otherwise imperceptible defects in buildings, bridges, and aircraft.
“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 from the University of California at Berkeley.
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.
Researchers etched rows of ridges onto a single, thin layer of silicon. Rather than spreading the light into a complete rainbow, however, these ridges – or bars – reflect a very specific wavelength of light.
By “tuning” the spaces between the bars, it’s possible to select the specific colour to be reflected. Unlike the slits in a diffraction grating, however, the silicon bars were extremely efficient and readily reflected the frequency of light they were tuned to.
