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MIT engineers have developed a technique for making intricate structures with supports that can be dissolved and reused instead of thrown away. Hearing aids, mouthguards, dental implants, and other highly tailored structures are typically made via vat photopolymerisation—a form of 3D printing that uses patterns of light to shape and solidify a resin, one layer at a time.
The process also involves printing structural supports from the same material to hold the product in place as it’s printed. Once a product is fully formed, the supports are removed manually and typically thrown out as unusable waste.
MIT engineers have found a way to bypass this last finishing step, in a way that could significantly speed up the 3D-printing process. They developed a resin that turns into two different kinds of solids, depending on the type of light that shines on it: ultraviolet light cures the resin into a highly resilient solid, while visible light turns the same resin into a solid that is easily dissolvable in certain solvents.
The researchers applied the new method to print complex structures, including functional gear trains and intricate lattices.
“You can now print, in a single print, multipart, functional assemblies with moving or interlocking parts, and you can basically wash away the supports,” graduate student Nicholas Diaco said. “Instead of throwing out this material, you can recycle it onsite and generate a lot less waste. That’s the ultimate hope.”
He and his colleagues report the details of the new method in Advanced Materials Technologies. The MIT study’s co-authors include Carl Thrasher, Max Hughes, Kevin Zhou, Michael Durso, Saechow Yap, Professor Robert Macfarlane, and Professor A. John Hart, head of MIT’s Department of Mechanical Engineering.
The team applied the new method to print a variety of intricate structures, including interlocking gears, intricate lattices, a ball within a square frame, and, for fun, a small dinosaur encased in an egg-shaped support that dissolved away when dipped in solution.
“With all these structures, you need a lattice of supports inside and out while printing,” Diaco said. “This shows we can print multipart assemblies with a lot of moving parts, and detailed, personalised products like hearing aids and dental implants, in a way that’s fast and sustainable.”
