Smart skin developed to change colors like chameleon
Certain light waves pass through the spaces between photonic crystals to produce visible colours.
ATLANTA (Web Desk) - Researchers have developed a flexible smart skin which changes colour with exposure to heat and light like a chameleon.
According to iNews, A team from Emory University in Atlanta were inspired by the colour-changing reptile to develop a skin from colourless photonic crystals, which are also present in butterfly wings and peacock feathers.
The study, published in journal ACS Nano, explored researchers’ previous difficulty in making a colour-changing smart skin which didn’t shrink in response to its environment, causing senior author Khalid Salaita to remark: “No one wants a camouflage cloak that shrinks to change colour.”
Watching a video of a chameleon, which changes colour when it tenses or relaxes its skin, provided lead study author Yixiao Dong with the breakthrough he needed.
Certain light waves pass through the spaces between photonic crystals to produce visible colours which change depending on factors including lighting conditions or shifts in the spacing.
Colour-shifting crystals
Embedding the crystals into hydrogels – a form of watery gel often used to treat wounds – shifts the spacing between them, resulting in a colour change. The team used magnets to arrange patterns of the crystals containing iron oxide within a hydrogel, which echoed the way the crystals are distributed on a chameleon’s skin.
However, these large fluctuations in size often strains the material and causes them to buckle. The team found once the arrays were embedded into a second hydrogel, it changed colour but maintained a near-constant size.
The second colourless hydrogel acted as a supportive layer, and supported the strain necessary to change colour without forcing the skin to dramatically change shape or snap.
Such skins could prove useful in camouflage, signalling and anti-counterfeiting measures, the team claimed.
“We’ve provided a general framework to guide the future design of artificial smart skins,” Dong said.
“There is still a long way to go for real-life applications, but it’s exciting to push the field another step further.”
Chameleons are not the only animals capable of changing colour. Neon tetra fish turn from deep indigo to a bluey-green when they swim into sunlight, and squids, octopuses and cuttlefish change colour thanks to colour-shifting cells called chromatophores.
