. Researchers created a film which changes colors chameleon style when it is twisted or pulled. UC Berkeley engineers claim that they were inspired by nature. Connie ChangHasnain (professor of electrical engineering, computer sciences) is the study leader. She and her colleagues think that their thin skin could be used to create active camouflage for vehicle exteriors or another type of display technology. They also suggest that it could be applied to bridges and wings on aircrafts or in buildings as an early warning system of structural fatigue. The new chameleon-like “skin” changes its color when it is pulled or twist. Image courtesy Connie Chang Hasnain at UC Berkeley. The material is a thousand times thinner that human hair. Instead of using chemical dyes or pigments to absorb or reflect light, scientists altered the structure of this ultra-thin silicon film to create the colors. It’s about one thousandth of a human hair. There are rows of tiny ridges in the film that can reflect different wavelengths of light. Each ridge measures less than one wavelength of light. The spacing between the different ridges determines which wavelengths are reflected. Scientists were able select the colors that would reflect back by tuning the spacing between the ridges. Different wavelengths of light reflect back as the distance between the ridges changes when the material is stretched or twisted. The material’s color can be changed by twisting or stretching it. This is a sample of the super-thin and color-shifting film that scientists created. Image courtesy Connie Chang Hasnain. Chameleons arrange nanocrystals inside skin cells. Swiss researchers published a report earlier this week that showed that the chameleons can rearrange specific crystals within skin cells in order to achieve complex, rapid color changes. This is possible during camouflage or social interaction. Dirk van der Marel and Michel Milinkovitch explained that vivid colors result from the active tuning of a network of nanocrystals in the reptile’s iridophores, which are type of pigment cells. Professor Chang-Hasnain stated: “We were amazed by the chameleons’ ability to change color, and it was exciting to mimic their skin.” It’s amazing that the sample film can be held and stretched to show the color effect. Citation: Li Zhu. Jonas Kapraun. James Ferrara. Connie J. Chang.-Hasnain. Optica, Vol. Optica, Vol. 255-258 (2015). http://dx.doi.org/10.1364/OPTICA.2. 000255.
