Engineers at China’s Wuhan University have built a lizard-shaped robot that can change color to match its surroundings.
As New Scientist explains, the effect is achieved by covering the 3D robot model with plasmonic displays. The displays are made by drilling 50 nanometer holes into glass sheets, and then putting gold on the glass so it creates tiny domes within each hole. The glass is finally encased in an electrolyte gel full of silver ions.
When light hits these displays, it creates plasmons, described by New Scientist as “ripples of electrons” that determine the display’s light-reflection and light-absorption properties. When an electric field is applied, interaction between the silver ions and gold nanostructures changes the color of the display.
Outfitted with a light sensor, the robot can determine its background color and tweak the electric field accordingly. So far it can only produce red, green, and blue, but hopefully in the future it will be able to display a wider range of color.
Scientists are still figuring out exactly how real-life chameleons change color, and recent research points to tiny guanine crystals in cells underneath the skin. It seems that by altering the spacing between these crystals, chameleons can alter the wavelength of reflected light. The robot’s concept is similar—its color depends on tuning the electric field in a similar fashion to how the chameleon’s body adjusts its guanine crystals.Lead engineer Guoping Wang and his colleagues envision their innovation being used by the military, for camouflage-capable body armor or vehicles. The displays will need some more work before that becomes possible, but it seems the technology is well on its way.