Three-dimensional (3D) solids can be printed quickly and continuously from puddles of liquid resin, researchers report in the 20 March issue of the journal Science. Their approach applies a careful balance of oxygen and light to print solid objects from a liquid pool in minutes instead of hours — rates far faster than traditional printing can achieve.

"Our technology promises to advance the [3D printing] industry beyond basic prototyping to 3D manufacturing," explained senior author Joseph DeSimone, a professor of chemistry at University of North Carolina and North Carolina State.

Although 3D printing is now possible using relatively small and low-cost machines, it is still a fairly slow process that involves several steps for each printed layer, including the need to reposition the object before adding the next layer of material. "Essentially," DeSimone said, "it's two-dimensional printing over and over."

Using such methods, an object just several centimeters in height can take hours to construct, relegating 3D printing to the development of models that guide manufacturing, but do not produce the actual manufactured goods.

The technology developed by DeSimone and his team looks to advance 3D printing beyond basic prototyping in three important ways: It offers game-changing speeds up to 100 times faster than conventional 3D printers, it grows solid objects with consistent and predictable mechanical properties (like smoothness), and it enables creation of a broad range of materials.

The technology works by putting a bath of resin on top of a digital light projection system. A special window, rather like a contact lens, sits between the bath and projector. Ultraviolet light is projected in bursts through the window. Typically, ultraviolet light triggers resin to harden, but the key to DeSimone's process is the interaction of light with oxygen, which allows the resin to maintain its liquid state.

By carefully coordinating bursts of light and oxygen to firm up the resin where desired, the system makes complex, 3D shapes. And critically, instead of growing objects as a series of two-dimensional layers that are stacked together, this process grows objects continuously, allowing them to be made in one piece. This means they are smoother, a desirable trait in manufacturing.

"We are excited to see what designers and engineers will be able to do with this technology," DeSimone said. "We are able to throw the entire polymer chemistry textbook at it and make parts like hard prototyping resins and elastomers. This technology can also make materials with high elasticity for athletic shoes or high dampening for applications like engine motor mounts for vibrational control...The process lends itself to the entire range of properties that people want in their parts."

DeSimone is CEO and cofounder of Carbon3D, the company that developed this printing technology, which he and his colleagues call "continuous liquid interface production technology" or CLIP. He demonstrated the technology at a TED Talk this week that coincided with the publication of his report in Science.