A substance that acts like a chameleon. Impressive solution straight from MIT

The MIT team has engineered a material capable of changing its color in response to mechanical stimuli. Scientists also have some ideas for its use.

In the nineteenth century, Gabriel Lippmann proposed an unusual method that was used, among other things, in photography. Create colorful images by placing the mirror behind a thin, transparent emulsion. This material consists of very fine grains with photosensitive properties: bromide and silver chloride. He then exposed the system to a beam of light that was reflected by the mirror so that it would pass through this emulsion again.

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The main role in what happened next was the interference of incoming and outgoing light waves. This changed the position of the grains and reflected the pattern and wavelength of light. As a result, Lippmann projected colorful images of flowers and other scenes on skeletal emulsions. Unfortunately, the whole process was extremely time consuming: the process required manual preparation of the emulsion and waiting days for the material to be sufficiently lit.

Materials designed by MIT representatives use Lippmann’s achievements

The technology of the nineteenth century was a source of inspiration for the engineers who decided to implement it in their design. Present their achievements so far on the pages nature materials. The ultimate goal of the research was to find out if the combination of the Lippmann method with modern stereoscopic materials could result in the production of large-scale colored structural materials. Importantly, current holographic materials are also composed of light-sensitive particles. When photons reach it, these particles can cross to form colored mirrors.

The team decided to stick a flexible, transparent 3D foil on the mirror surface in the form of an aluminum sheet. Then they put the projector in front of this paper and started projecting the pictures. The pace of this process was much higher – it only took a few minutes, not days as before. Later, the researchers removed the metallic foil from the mirror and glued it to a black flexible silicone coating.

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After the wafer was extended, the colors changed as a result of the structural color of the material. Due to the stretching, their nanostructures are reshaped to reflect other wavelengths, which can, for example, result in a color change from red to blue. Scientists were even able to display hidden images: it was enough to tilt the film at an angle with the incoming light when creating colored mirrors. Possible applications of such a method include, but are not limited to, information encryption.