Traditionally, researchers have sought to create camouflaged materials by applying electric or magnetic fields to particles. But these methods are cumbersome and expensive, Solomon said.
By contrast, Kim and her team found a way to achieve shape- and color-changing effects using latex paint microparticles -- tiny particles about 0.001 millimeters (4/100,000th inch) in diameter -- in a kerosene-like fluid, by shining a laser on them. By manipulating these "camouflage crystals," the researchers were able to construct a letter "M," for the University of Michigan. They have also experimented with making optical lenses.
"We can shine the light in a certain region, and the particles create a crystalline region where they all come together and create this crystal structure," Kim said in a statement.
The researchers found that shining light on the microparticles made them react chemically with a layer of indium tin oxide on the bottom of the pool of fluid. The reaction produces an electric current in the fluid, which causes the particles to rearrange themselves.