For the indecisive or expressive among us, MIT researchers have created a colour-changing ink that adds yet another layer of customisation to 3D printing.
3D printing is already being touted as the ultimate tool for manufacturing bespoke items, but a new ink is taking its reputation for customisation to another level.
In the past, once something was printed that was it – too bad if the colour didn’t turn out like you wanted. Now, an ink developed by researchers at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) lets you toggle between a few different options post production.
ColorMod (also called ColorFab), developed by MIT assistant professor of electrical engineering, mechanical engineering and computer science Stefanie Mueller, can change colour when exposed to ultraviolet light and can completely recolour an object in about 20 minutes.
Recipe for success
Colour-changing systems aren’t new, but previous iterations were restricted to single colours or 2D designs, for example. There were also issues with getting the colour to stay – previous versions had to constantly be subjected to UV light to stick, otherwise you’d lose the colour.
The ColorMod system uses a dual hardware/software workflow to get the multi-coloured, mutable effect. First, users upload their 3D design into a specially created ColorMod interface, pick their desired colour pattern and print their fully coloured object.
Next comes the actual colour-changing bit. The ink requires ultraviolet light to change the design’s pixels from transparent to coloured, and visible light to do the reverse. Mueller’s ink is also able to retain the change even after the light source is gone.
Several components within the ink combine to make this possible. The custom ink is made with a base dye, a photoinitiator and light-adaptable dyes. The light-adaptable, or photochromic, dyes bring out the colour in the base dye while the photoinitiator lets the base dye harden during 3D printing.
The developers are currently focusing on plastics and other common 3D printing materials, but expect the new ink to be suitable for use on clothing and other consumer goods before too long.
Besides its novelty and ‘cool’ factor, the ink has some practical uses. Mueller imagines this ink has potential to reduce waste in the retail sector and stop throw-away culture.
“Largely speaking, people are consuming a lot more than 20 years ago, and they’re creating a lot of waste,” said Mueller.
“By changing an object’s colour, you don’t have to create a whole new object every time … you can repurpose the stuff you already have.”
Others in the business have taken notice of this innovation’s potential applications as well. Co-director of Columbia University’s Computer Graphics Group called this work “a true breakthrough in being able to change the colour of objects without repainting them”.
Postdoc Parinya Punpongsanon, who collaborated with Mueller on the project, said it’s a big step for 3D printing to be able to change aspects of an object after fabrication. The user-friendly nature of the workflow is also a plus, and could lead to greater uptake by everyone from hobbyists to industry and entrepreneurs.
The team plans to look at ways to bring the transition time between colours down with tweaks to the formula, such as using a more powerful light or adding more light-adaptable dye to the ink. They also plan to develop smaller pixels to create higher resolution images and patterns.
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