Technique to Control Crystals Could Lead to Color-Changing Camouflage

Michigan University engineering researchers have discovered a template-free method for growing shaped crystals that allows for changeable structures that could appear as different colors and patterns. The ability to control crystals with light and chemistry could lead to color-changing camouflage for vehicle bodies and other surfaces. The researchers have found a way to control a crystal on the fly as it forms in a solution of latex paint microparticles, around 0.001 millimeters in diameter, in a kerosene-like fluid. By shining shaped ultraviolet light into the fluid, they were able to make the microparticles arrange into the Michigan Block M. Ordinarily, to get a shape like a Block M, the crystal would have to be built on top of a template. A template can make crystals of one shape only, but the new method can produce crystals in any shape that light can assume. The team found that the key to this flexible crystal formation is a light-induced chemical reaction. It occurs between the layer of indium tin oxide at the bottom of the tiny pool of solution and the kerosene-like fluid.