Researchers at the University of Cambridge have developed an artificial ‘chameleon skin’. Once exposed to light the material changes colour. Researchers believe that this could hold a multitude of practical applications such as; active camouflage and large-scale dynamic displays.
The University of Cambridge’s new development is made of small particles of gold which is coated in a polymer shell. They are then squeezed into micro-droplets of water in oil. Once exposed to heat or light the particles are drawn together which subsequently changes the colour of the material.
In order to change colour, chameleons and cuttlefish are able to change colour due to their skill cells, which have contractile fibres that move the pigment in their skin. These pigments can be spread out, showing colour, or they can be contracted in order to make the cell clear.
Researchers at the University of Cambridge were inspired by the colour changing properties of the chameleon. However, instead of using contractile fibres, researchers used light-powered nano-mechanisms.
Once the artificial skin is heated over 32C, the nano-particles of the material bind together into clusters. Once cooled the polymers take on water and expand.
Dr Andrew Salmon from Cambridge’s Cavendish Laboratory was the study’s co-first author. Dr Salmon said: “Loading the nano-particles into the micro-droplets allows us to control the shape and size of the clusters, giving us dramatic colour changes.”
When the particles are warm, they become dark blue. Once cooled, the particles turn red.
Another co-author of this study is Sean Cormier from the NanoPhotonics Centre at the University of Cambridge. Cormier said: “This work is a big advance in using nano-scale technology to do bio-mimicry…We’re now working to replicate this on roll-to-roll films so that we can make metres of colour changing sheets. Using structured light, we also plan to use the light-triggered swimming to ‘herd’ droplets. It will be really exciting to see what collective behaviours are generated.”