Chameleon-inspired robot mimics its surroundings

The robot could be a precursor to next-generation wearable camouflage which rapidly adapts to its environment.

Artificial camouflage – which has been continuously developed since the nineteenth century, largely for military purposes – is inspired by natural camouflage present in nature, such as in octopuses and chameleons. Natural camouflage normally relies on the mechanical action of muscle cells, while artificial camouflage can use a more diverse range of strategies to achieve colour changing.

Camouflage devices must be capable of conveying a range of colours which can be controlled on demand; this is a complex challenge when working with high-resolution camouflage patterns (necessary for larger devices) at the complete device level. This requires not only consideration of colour but also the selective expression of patterns to match backgrounds. The challenge is rendered greater by the need for the device to be flexible and robust, such that it can be incorporated into clothing.

“Since its resolution is determined by the number of pixelated units and their sizes, the conception of a high-resolution artificial camouflage device that incorporates densely packed arrays of individually addressable multiplexed units leads to an explosive increase in the system complexity,” the researchers wrote.

“While on the other hand, solely from the perspective of camouflage performance, the delivery of high spatial frequency information is important for more natural concealment by articulating the texture and patterns of the surface to mimic the microhabitats of the living environments.

“As a result, the development of autonomous and adaptive artificial camouflage at a complete device level with natural camouflage characteristics becomes an exceptionally challenging task.”

The Korean researchers applied a new strategy to develop their colour-changing soft robot. They used integrated thermochromic liquid crystal layers with vertically stacked, patterned silver nanowire networks. This more sophisticated design overcomes the limitations of conventional hardware (reducing overall system complexity), which tends to be laterally pixelated to mimic its background.

The hardware was integrated with colour sensors and feedback control systems to create the 'Artificial Chameleon Skin', which the researchers applied to a soft-bodied robot. The robot was subsequently capable of detecting its local background colour and transitioning its skin colour to match its surroundings as it moved.

“Combined with the active control system and sensing units, the complete device chameleon model successfully retrieves the local background colour and matches its surface colour instantaneously with natural transition characteristics to be a competent option for a next-generation artificial camouflage,” the researchers wrote in their Nature Communications paper.