Iridescent green beetles could provide a blueprint for light reflecting materials. That's the conclusion of scientists at the Georgia Institute of Technology in Atlanta who recently discovered jewel beetles change color because of the light reflecting properties of the cells that make up their external skeletons. They say the finding could be important for industries such as car manufacturers that look to reflective light paints for automobiles. When light hits a surface that's difficult to see through, the surface either scatters, absorbs or reflects the light to produce colors. In the case of the jewel beetle's external skeleton, its five, six and seven sided cells spontaneously arrange themselves to reflect light at certain wavelengths that produce green, yellow and red colors.
Research suggests the cells come from spontaneous arrangement of glucose-like particles called chitin molecules that form as cones like those in a cholesteric liquid crystal. When these cones solidify, they preserve their structures and produce colors as light hits them from different angles.
The beetle's structure also forms helices similar to a cholesteric liquid crystal in that its straight cells sit on or are used to form the curved structure of its external skeleton. Research shows that when the pitch of the helix of cholesteric liquid crystals is close to the wavelength of visible light, they reflect light with specific wavelengths, leading to brilliant metallic colors.
Miniature optical devices and photonics such as those envisioned for microlasers and implantable medical sensors could benefit from the finding. Scientists already are studying ways to commercialize and apply materials that have properties similar to jewel beetles.
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