eliminating the need for 2D overlay — ScienceDaily


Don’t be fooled by the name. While 3D printers print tangible objects (and quite well), the way they get the job done doesn’t actually happen in 3D, but rather in classic 2D.

Working to change that is a group of former and current researchers from the Rowland Institute at Harvard.

First, here’s how 3D printing works: Printers lay down flat layers of resin, which will harden into plastic after being exposed to laser light, on top of each other over and over again from the bottom up. Eventually, the object, like a skull, takes shape. But if any part of the print sticks out, like a bridge or an airplane wing, it requires some type of flat support structure to actually print, otherwise the resin will collapse.

Researchers present a method to help printers live up to their name and deliver a “true” form of 3D printing. In a new article from Nature, they describe a volumetric 3D printing technique that goes beyond the bottom-up layered approach. The process eliminates the need for support structures because the resin it creates is self-supporting.

“What we were wondering was if we could actually print entire volumes without having to go through all those complicated steps?” said Daniel N. Congreve, an assistant professor at Stanford and a former fellow at the Rowland Institute, where most of the research took place. “Our goal was to just use a moving laser to create a true three-dimensional pattern and not be limited by that kind of layer-by-layer nature of things.”

The key element of their new design is to turn red light into blue light by adding what’s called an upconversion process to resin, the light-reactive liquid used in 3D printers that hardens into plastic.

In 3D printing, the resin cures in a flat, straight line along the light path. Here, researchers use nano capsules to add chemicals so that they only react to a certain type of light – blue light at the focal point of the laser that is created by the upconversion process. This beam is scanned in three dimensions, so it prints that way without needing to be overlaid on anything. The resulting resin has a higher viscosity than in the traditional method, so it can remain unsupported when printed.

“We designed the resin, we designed the system so that the red light wouldn’t do anything,” Congreve said. “But that little dot of blue light starts a chemical reaction that causes the resin to harden and turn it into plastic. Basically what that means is you have this laser going through the whole system and that’s just ‘to that little bruise you get polymerization. [only there] do you get the impression that is happening. We just scan that blue dot in three dimensions and wherever that blue dot touches it, it polymerizes and you have your 3D print.”

The researchers used their printer to produce a 3D Harvard logo, a Stanford logo and a small boat, a standard but difficult test for 3D printers due to the boat’s small size and fine details like overhanging portholes and gaps open cabins.

The researchers, which included Christopher Stokes of the Rowland Institute, plan to continue developing the system for speed and refining it to print even finer detail. The potential of volumetric 3D printing is considered a game changer, as it will eliminate the need for complex support structures and dramatically speed up the process when it reaches its full potential. Think of the “replicator” from “Star Trek” which materializes objects at once.

But for now, researchers know they still have a long way to go.

“We’re really just beginning to scratch the surface of what this new technique could do,” Congreve said.

Source of the story:

Material provided by Harvard University. Original written by Juan Siliezar. Note: Content may be edited for style and length.


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