How many times have you purchased the same item, but in different colors? Those new Adidas are definitely rad with red stripes, but sometimes a nice blue would suit your outfit better. That flower print phone case your mom bought you protects your phone well, but maybe you’d prefer something a bit more modern. To avoid having to buy multiple colors of a single item — or throw away outdated designs — researchers from MIT’s CSAIL (Computer Science and Artificial Intelligence Laboratory) have developed a new reprogrammable color-changing dye.
This dye, called PhotoChromeleon, builds on a previous project that allowed 3D-printed objects to change color. During the 3D-printing process, the plastic was filled with special photochromic dyes. Those react to UV light to change from transparent to a specific color. The problem with that technique was that each “pixel” had to be dyed separately for each color, resulting in a grainy pattern. It also only worked with 3D-printed objects. PhotoChromeleon address both issues, as it can be applied to any object and the doesn’t needed to be separated by color.
To achieve that, PhotoChromeleon mixes three photochromic dyes that change color when exposed to a specific wavelength of light. Those colors are cyan, magenta, and yellow, and each one responds to a different wavelength. The PhotoChromeleon mixture can be sprayed onto anything from a pair of shoes to a car, and exposed to UV light to fully saturate all three colors. Then a projector is used to “turn off” each dye color in specific patterns. The entire object’s color can be changed, or detailed designs can be projected. That process can be repeated over and over whenever a change is desired. The research team even developed a software interface that makes it easy to control the projector and create a design. Now they want to collaborate with material scientists to create new dyes with a better range of colors.