Shaping Crystals for Camouflage Surfaces

Mark Fowler | April 28, 2014
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A recent discovery indicates that certain particles can be drawn into crystalline structures through the controlled use of ultraviolet light and chemistry. This discovery can eventually lead to the possibility of creating color-changing surfaces and materials for reasons of dynamic camouflaging.

Shaping Crystals Using Just Light

According to an article posted on Phys.org, researchers at the University of Michigan College of Engineering have discovered a way to shape crystals with a photochemical reaction, enabling crystal structures to appear in various patterns and colors. Such a technique could lead to materials and surfaces with color-changing, camouflage-like properties (much like a chameleon!).

A chameleon on a twig

In their experiments, the research team shone ultraviolet light in the shape of the University of Michigan’s “M” logo onto a solution of latex paint microparticles in a kerosene-like fluid. As a result, the microparticles were successfully arranged in the desired “M” shape. When the light was pulled away, the crystal formation dissolved.

The Science Behind it

The Michigan Engineering researchers concluded that a photochemical reaction occurs between a layer of indium tin oxide at the bottom of the solution and is responsible for the crystal formation when illuminated. A current of ions is generated in the fluid due to the reaction. Microparticles are attracted to the area of indium tin oxide if they are negatively charged, while they create a void in the shape of the light if they are positively charged.

You may be wondering how the color changes, too. The color of a crystal can be altered by adjusting the spacing between the particles that compose the crystal structure. If you can manipulate the shape of the structure, you can change its color.

Other Potential Applications

The team has already imagined potential uses for their discovery other than color-changing coatings. One potential case includes alternative ways to dynamically update graphics on billboards and e-readers. Another is a more complex application: they envision sensors whose color will change in order to detect molecules crucial for environmental and medical surveillance.

Further Reading

Read the original article and watch the videos: “Chameleon crystals could enable active camouflage (w/ video)

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