New nanomaterial gives robots chameleon skin

Breakthrough could allow machines to communicate quickly and from distance by altering patterns

A new nanomaterial which can change colour in response to movement could be used to give robots chameleon-style abilities, scientists say.

The film – created by researchers in the US – could be coated onto machines which would then be able to communicate with humans quickly and from distance by simply altering shade.

The breakthrough, revealed in the Nature Communications journal this week, could allow robots to be sent into dangerous spaces with them then relaying information back to observers.

Its creators gave an example of a machine being dropped into an ocean crevice in camouflaged colours to avoid disturbing animals living there. By shifting its hue in response to the environment, the device would be able to tell biologists about life in the area.

But the scientists said the nanomaterial could be used in culture too.

“Artists could use this technology to create fascinating paintings that are wildly different depending on the angle from which they are viewed,” wrote Zhiwei Li, lead author and chemist at the University of California Riverside. “It would be wonderful to see how the science in our work could be combined with the beauty of art.”

The nature of the material is such that it could display a range of complex patterns by simply being bent or twisted, its creators say. It could be applied easily as a spray paint.

Nanomaterials are materials which have been reduced to the size of a virus. When this is done to gold or silver, their colours will change depending on their size, shape and the direction they face.

“In our case, we reduced gold to nano-sized rods,” said Yadong Yin, who also worked on the project. “We knew that if we could make the rods point in a particular direction, we could control their colour. Facing one way, they might appear red. Move them 45 degrees, and they change to green.”

The problem facing the research team, he explained, was how to take millions of gold nanorods floating in a liquid solution and get them all to point in the same direction to display a uniform colour.

Their solution was to fuse even smaller magnetic nanorods onto the larger gold ones and encase them both in a polymer shield, so their orientation was fixed uniformly in place.

And, although futuristic robots are one possible application of this material, it can be used in many other ways, such as incorporated into money as an authentication feature: under normal lighting, a note might look one colour but through another lens, elaborate patterns could be seen.