MIT creates “reprogrammable ink” so objects can change colour “like a chameleon”

A team at the Massachusetts Institute of Technology’s (MIT) Computer Science and Artificial Intelligence Laboratory (CSAIL) has created "PhotoChromeleon", a "reprogrammable" ink that can change colour when exposed to ultraviolet and visible light sources.

PhotoChromeleon uses a mix of photochromic dyes that can be sprayed or painted onto the surface of any object to change its colour repeatedly, as it is fully reversible.

The ink is created by spraying a mix of cyan, magenta, and yellow photochromic dyes in a single solution.

The team worked out how each dye interacted with varying wavelengths to control the three colour channels through activation and deactivation of the corresponding light sources.

An example of this is given by CSAIL, saying if a blue light were used, it would be mainly absorbed by yellow dye which would be deactivated, and blue would be made visible by the remaining magenta and cyan dye. If a green light were used, magenta would be deactivated and the yellow and cyan dyes would be visible, creating green.

A colouring pattern can be removed using ultraviolet light.

PhotoChromeleon has been tested on a car model, a phone case, a shoe, and a toy chameleon, taking between 15 and 40 minutes for the dye effect to be sprayed on. Previously, the MIT team had to 3D print individual pixels to change their colour with its "ColorMod" system.

Yuhua Jin, lead author on a paper on the project, said: "This special type of dye could enable a whole myriad of customisation options that could improve manufacturing efficiency and reduce overall waste.

"Users could personalise their belongings and appearance on a daily basis, without the need to buy the same object multiple times in different colours and styles."

More information is available via CSAIL here.

Image courtesy of MIT/CSAIL

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