A team of researchers at Massachusetts Institute of Technology (MIT) is developing a special dye system that could allow consumers to change the colour and design of their apparel and footwear post-purchase.

MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) is working on a technology that uses reprogrammable ink so that objects change colours when exposed to ultraviolet (UV) and visible light sources.

Dubbed 'PhotoChromeleon,' the system uses a mix of photochromic dyes that can be sprayed or painted onto the surface of any object to change its colour – a fully reversible process that can be repeated infinitely.

PhotoChromeleon can be used to customise anything from shoes to a phone case or even car. The colour remains, even when used in natural environments, MIT says.

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

PhotoChromeleon builds off of the team's previous 'ColorMod' system, which uses a 3D printer to fabricate items that can change their colour. Frustrated by some of the limitations of this project, such as small colour scheme and low-resolution results, the researchers decided to investigate potential updates.

The ink was created by mixing cyan, magenta, and yellow (CMY) photochromic dyes into a single sprayable solution, eliminating the need to painstakingly 3D print individual pixels. By understanding how each dye interacts with different wavelengths, each colour channel was controlled by activating and deactivating with the corresponding light sources.

After coating an object using the solution, the user simply places the object inside a box with a projector and UV light. The UV light saturates the colours from transparent to full saturation, and the projector desaturates the colours as needed. Once the light has activated the colours, the new pattern appears. To change the design, the UV light can be used to erase it.

"By giving users the autonomy to individualise their items, countless resources could be preserved, and the opportunities to creatively change your favourite possessions are boundless," says MIT Professor Stefanie Mueller.