A material inspired by chameleon skin can reveal the freshness of seafood and one day it can be used as a disguise by color-changing robots.

Panther chameleons can change their color quickly through a wide variety of different hues, but researchers have sought to restore these properties to man-made soft materials. Now, materials scientists, inspired by the unique structure of the chameleon’s skin, have developed a supramolecular hydrogel system that changes color in response to external chemical stimuli.

Photos on a graph showing a chameleon shape that changes color with temperature

While previous attempts to make soft, color-changing materials have incorporated multiple dyes into a single homogeneous matrix, chameleon’s skin separates different pigment-containing cells into different layers. Scientists led by Tao Chen from the Ningbo Institute of Materials Technology and Engineering in China concluded that by copying this layered structure, they could incorporate multiple fluorescent compounds into a single material. You wouldn’t have to worry about the chemical compatibility of the dyes or the complex photophysical interactions between them.

Chen’s team designed a hydrogel with a red fluorescent core surrounded by layers containing blue and green dyes that are temperature and pH sensitive, respectively. This means that the material can be programmed to change color under different environmental conditions over almost the entire visible spectrum.

The researchers showed how the system can be used to measure the freshness of seafood. During their demonstration, small strips of the material were packed next to fresh prawns. When shrimp stored at 30 ° C begin to release amine vapors as they spoil, the stripes change color from red to green.

In addition to this simple chemosensor application, Chen’s team suggests that such materials could be used for bioimaging, information encryption, and even for “dynamic cloaking robots”.


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