Artificial ColorChanging Chameleon Skin Reacts to Heat Light

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first_img Artificial ‘Tongue’ Can Taste Subtle Differences in Whiskey’NanoZymes’ Use Light to Kill Harmful Bacteria Taking cues from chameleons and cuttlefish, University of Cambridge researchers developed artificial skin that changes color when exposed to light.The technology, inspired by naturally occurring pigment-containing and light-reflecting cells, could be used for active camouflage or large-scale dynamic displays.Some animal species are known to change their skin coloration and pattern through chromatophores: skin cells with contractile fibers that move pigments around.The artificial version developed by Cambridge researchers is built on the same principles. But rather than contractile fibers, they rely on light-powered nano-mechanisms. And the “cells” are actually itty bitty drops of water.As described in a paper published by the journal Advanced Optical Materials, the substance is made of tiny particles of gold, coated in a polymer shell and squeezed into microdroplets of water in oil.When heated to temperatures above 32 °C (89 °F), the polymer coatings expel water and collapse, forcing the nanoparticles together, changing the color. Once cooled, the polymers absorb that water, expanding and pushing the nanoparticles apart like a spring.“Loading the nanoparticles into the microdroplets allows us to control the shape and size of the clusters, giving us dramatic color changes,” study co-author Andrew Salmon, from Cambridge’s Cavendish Laboratory, said in a statement.The geometry of the particles when bound into clusters determines their color: spread apart they are red, bundled together they are dark blue. (Watch them change in the video above.)In its current state, the material developed at Cambridge is in a single layer, allowing it to fluctuate between only two colors. Different nanoparticle materials and shapes—ideal for fully dynamic equipment—may be achieved with extra layers (just like real chameleon skin).Researchers also found that their artificial cells can “swim,” similar to the algae Volvox. Shining a light on one edge of the droplets causes the surface to peel toward the light, pushing it forward. Under stronger illumination, high-pressure bubbles form to push the droplets along a surface.“This work is a big advance in using nanoscale technology to do biomimicry,” study co-author Sean Cormier said. “We’re now working to replicate this on roll-to-roll films so that we can make meters of color-changing sheets.“Using structured light we also plan to use the light-triggered swimming to ‘herd’ droplets,” he explained. “It will be really exciting to see what collective behaviors are generated.”More on Hope Artificial Skin Can Help Burn Victims ‘Feel’Artificial ‘Tongue’ Can Taste Subtle Differences in WhiskeySpider Silk Could Be Used to Make Artificial Muscles Stay on targetlast_img

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