The octopus has amazing abilities to change skin color which it uses for camouflage and perhaps even communication. This trick is accomplished by squeezing small bags of pigment on the skin called chromatophores containing various colors, to which muscle fibres are attached. When the muscles contract, the sacs become large, and the area they cover appears colored. Relaxing the muscle fibres squeezes the sacs into a small volume, making the color appear to vanish. (Sorta like goosebumps in people, only in color). Now a material created by researchers at Fuji Xerox Company led by Ryojiro Akashi can do pretty much the same thing. As reported in the journal Advanced Materials they constructed tiny, contractible pigment bags just 20-200 thousandths of a millimetre across from a polymer known as NIPAM and filled them with India ink. Gel particles dispersed in a solvent at room temperature are swollen, and the liquid appears dark. When warmed to 40 C, the gel collapses to 10% or less of its original volume, the particles shrink and the liquid turns almost clear. Since the bags can be loaded with pigments of any color, effects far exceeding the natural abilities of octopi are possible. Already Akashi has produced a display panel based on this technology that operates on heat, not electricity as does a visually similar LCD panel, and he is searching for other polymer materials whos shrinking properties may be triggered by other stimuli such as ambient light level or pH. Can invisible cars be far behind?
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I wonder how much it costs to create a significant ammount of this material. And how rare or expensive are the components? I doubt we will see this in retail use in the near future. But, maybe in 2050, this will create cheaper, higher precision displays. I shall be waiting :)