Scientists build a 3D printer that turns goo into solid objects

"The Replicator" uses light to transform liquids into 3D objects in a matter of minutes.

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UC Berkeley

The next generation of 3D printing has turned to Star Trek for a bit of inspiration.

Researchers at the University of California at Berkeley have built a 3D printer dubbed "the replicator" that uses light to build solid 3D objects from a gelatinous solution. It shares its name with a Star Trek device that conjures objects out of thin air.

This version of the replicator isn't quite that advanced, but it is a step forward for 3D printing. It uses a repurposed digital video projector as a light source to crafts object that are smoother, more flexible and more complex than a traditional 3D printer.

"Basically, you've got an off-the-shelf video projector, which I literally brought in from home, and then you plug it into a laptop and use it to project a series of computed images, while a motor turns a cylinder that has a 3D-printing resin in it," said Hayden Taylor, assistant professor of mechanical engineering at UC Berkeley.

The projector is loaded with a series of 3D-computed models that it beams out as a series of light patterns at a gelatinous resin contained within a jar. The resin is composed of light-sensitive molecules and dissolved oxygen, and is slowly spun in place as the light is beamed at it. As the light hits the liquid, the oxygen is depleted, which allows the molecules within the resin to form cross-links. 

Those links are the key to the transformation, turning the liquid into a solid.

The replicator shines a light through the gel to craft solid objects

UC Berkeley

Traditional 3D printers have typically used a layering process, where the structure is built from the ground up by constructing an object in thin horizontal slices  Because the replicator

So far, the team has created a number of different objects using the new printer, including a replica of Rodin's Thinker statue, a smooth and highly flexible doughnut and a model of the lower jaw. The printer is currently limited to producing objects within a diameter of 4 inches (10.16 centimeters) and doesn't produce any waste -- the goo can be reused in subsequent prints.

Importantly, it also allows the researchers to fabricate 3D objects around preexisting structures. For instance, the team placed a screwdriver shaft within the resin, then used their printer to fabricate a handle. 

"I think this is a route to being able to mass-customize objects even more, whether they are prosthetics or running shoes," Taylor said.

The research was published in Science on Jan. 31. You can watch the full process in action via UC Berkeley's video below. 

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