Engineers have developed a new material that changes color with a slight movement, according to research published in the journal Optical. The new fabric is a super thin composite material, made up of strips that reflect different wavelengths of light. As the fabric bends or moves, different strips are revealed, reflecting different a different wavelength and effectively changing color.
The material has many possible applications, e.g. military camouflage, clothing that can skip the expensive dyeing process, or even as an indicator of metal fatigue. The material is being billed as “artificial chameleon skin,” but how does it stack up to a real chameleon?
Not too well, as it turns out. The color changing properties of lizards were of great interest to turn of the century scientists. Nobody really understood the mechanism, however, until the 1930s, according to Earl Perkins writing in The Scientific Monthly. By that time, a century of experiments, many of them gruesome, had finally revealed the chameleon’s secret: layers of pigmented cells in their skin.
Each cell, called a chromatophore, could be expanded from an invisible dot into a colorful disk, which grants color to a corresponding portion of the skin. The skin is layered, and each layer holds chromatophores of different colors. Brown chromatophores are nearest the surface, reds and yellows are below the brown, and then iridescent blues and greens are on the innermost layer.
To appear green, for example, the chameleon contracts the upper layers into invisible dots, allowing the green chromatophores, which have been expanded, to show through to the surface. This can be done in any combination, e.g. (hide the greens, show the yellow, etc.) resulting in an almost infinite color palette, far beyond the capability of the artificial material.
Having exposed the chameleon’s secrets, later researchers wanted to know what triggered the color changing ability. While it was noted that chameleons and other lizards did have excellent camouflage, a series of simple experiments in the 1950s by Dr. Raymond Ditmars quickly eliminated camouflage as the reason for the color change.
By systematically placing an anole lizard (also known for color changes) in a box with different patterns, Ditmars quickly realized that the lizard stayed the same color regardless of the background. After careful experimentation, he determined that the lizards actually changed color in response to temperature, levels of ambient light, and state of mind (i.e. the presence of another chameleon). Ditmars’ experiments, refined by later researchers, showed that contrary to popular belief, chameleons change colors primarily for thermoregulation and display. Camouflage is merely an incidental benefit.
In this respect, the new material and a real chameleon might have something in common after all. The artificial material would respond to temperature-related expansion/contraction and might make an excellent heat indicator. Whatever the final use of this material, it’s one of the many examples of an idea originally inspired by the natural world. Let’s be honest, though; the natural world often does it better.