Robotic chameleon can move and change colour to its surroundings

11 Aug 2021

A panther chameleon. Image: © Jan /Stock.adobe.com

Researchers used a chameleon prototype to show an innovative solution to problems in the multibillion-dollar field of artificial camouflage.

The ability of animals such as the octopus to change the colour of their skin is an idea we are familiar with in nature, but any scientist who has attempted to replicate the ability of camouflage artificially will realise how astounding and difficult of a task is actually at hand.

New research published in Nature Communications has managed to achieve just that, however. Creating a soft robot inspired by the chameleon, a research team at Seoul National University in South Korea has advanced the field of artificial camouflage with its working prototype.

The researchers combined thermochromic liquid crystal ink with silver nanowire heaters. This ink changes colour depending on the application of heat and so allows the pattern on the robot chameleon’s skin to change based on the output from the wire.

By combining this technology with colour sensors, the research team was able to create a prototype that shifted colours alongside its surroundings.

“While the active camouflage found in nature mostly relies on the mechanical action of the muscle cells, artificial camouflage is free from matching the actual anatomies of the colour-changing animals and therefore incorporates much more diverse strategies,” said the study, highlighting that its solution is just one of many possible answers.

The researchers encountered several problems in developing an effective artificial camouflage device, however. The material needed to be flexible as to allow movement and to cover the shape of the wearer.

Its colour range also needed to be broad to be able to shift depending on the where the user is standing. Few surroundings consist of a single colour and so being able to vary the colour across the material is equally important.

Other research has drawn on nature to solve camouflage problems, such as a fish-inspired material and a ‘chameleon skin’ of tiny particles of gold coating in a polymer shell. For all of their inspiration and ingenuity, most of these inventions come with constraints and limited applicability.

Solving the problems of artificial camouflage may seem like an unnecessary headache for a researcher but the potential market payoff could be massive. The estimated market value of camouflage military uniforms was $11.5bn in 2020 and is forecast to grow to $13.9bn by 2027.

Not only that, but as camouflage is used in art, architecture and fashion, the technology could have a place everywhere from secret bunkers to experimental clothing on runways.

The researchers acknowledged that while this innovative solution cuts down on the complexity of competing methods, it does have its drawbacks. Because the system relies on heat to function, the temperature in the environment can affect the camouflage.

The paper highlighted that this would become particularly problematic above 25.5 degrees Celsius and below minus 20 degrees Celsius, meaning arctic and desert camouflage may be a while away yet.

The researchers did argue that there are different forms of the crystal ink available and so there would be a range of temperature-colour settings available, depending on the user’s intended environment.

They also suggested substituting the wire heater with a thermoelectric device, which would allow for both heating and cooling. This would also solve the potential issue of achieving a cooler-state colour after the device has heated up, which could be problematic with current technology.

Unfortunately, most thermoelectric devices are currently rigid, making it unsuitable for use in this context.

Nevertheless, with a working artificial chameleon and plenty of opportunity for improvement, the research team clearly stand out in the camouflage field while the prototype is busy blending in.

Sam Cox is a journalist at Silicon Republic covering sci-tech news

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