Chameleon-Inspired Material Could Be A New Frontier In Camouflage

With recent advances in understanding the science behind chameleons' color changes, researchers have been able to develop an artificial chameleon-like skin that shifts color when deformed. The new material will have a number of exciting applications ranging from camouflage to color-changing sensors to next-generation color displays.

Panther chameleons change their color by altering the salt balance in a special type of skin cell: Image reproduced with permission from Nature Communications 6, Article number: 6368.Panther chameleons change their color by altering the salt balance in a special type of skin cell: Image reproduced with permission from Nature Communications 6, Article number: 6368.

Just this month, in Nature Communications, researchers reported the mechanism by which chameleons control their external colouring. Without going into too much detail, the basic premise is that chameleon skin consists of two layers. A top layer is composed of cells called iridiphores, each containing a lattice of nanoparticles. By quickly changing the salt balance in these cells causing them to swell, the chameleons alter the spacing between the nanoparticles and thus the color of the reflected light. A lower layer acts as an efficient light reflector.

Very soon after, another group of researchers were able to exploit this knowledge in the development of an artificial alternative. They too used the notion of a lattice in which changes in spacing between nodes changes the perceived color of the reflected light. Instead of cells containing nanocrystals, the artificial lattice was made up of an etched silicon film that was embedded into a flexible plastic sheet. When the sheet was stretched, the spacing within the silicon lattice changed yielding a color change analogous to that of the chameleons. 

These materials could one day be used as effective camouflage that can be varied with changes in surroundings much the way chameleons use their skin. There are other less intuitive possibilities as well. This method of controlling coloring could be employed in low-power-consumption flexible color displays as this strategy for color switching is less energy intensive than current technology. Another possibility is using larger area films as structural sensors; for example, using it to coat stressed regions of bridges or buildings and monitoring changes in color as an indicator of cracks or compression. Indeed, the technological applications for this research are manifold and demonstrate the value that comes from understanding the scientific basis of natural occurrences.