Chameleons can change their color thanks to photonic crystals in their skin. As they tense or relax their muscles, the light reflects in a different pattern, causing a change in color. The problem with synthetic color-changing skin lies in the hydrogel in which the photonic crystals are packed: After expanding and contracting, the large amount of crystals would cause the medium to settle. Khalid Salaita and his colleagues have solved this problem by concluding that less is more.
The team looked at time-lapse videos of the phase-shifting skin of chameleons and found that the reptiles have fewer skin cells with photonic crystals than previously thought. If you pack less photonic crystals in a thin layer of hydrogel and then place this layer on a larger layer of colorless hydrogel, the smart skin can expand and contract easily. When the temperature or sunlight hits the surface, the color of the material changes.
ACS Nano a journal for nanotechnology in which this study was published suggests that smart skin may have camouflage applications, signaling and counterfeit security. MIT's color changing ink allows users to change patterns and colors of their shoes, cars, and more. Choosing a color for an expensive device, such as a smartphone, can be stressful. you will have to live with this choice for years. But with smart skin, we may be able to change the colors of our gadgets as often as we change our wallpaper backgrounds.