Making 3D printing truly 3D: eliminating need for 2D layering

Date:
April 22, 2022
Source:
Harvard University
Summary:
Researchers describe a technique of volumetric 3D printing that
goes beyond the bottom-up, layered approach. The process eliminates
the need for support structures because the resin it creates is
self-supporting.



FULL STORY ========================================================================== Don't be fooled by the name. While 3D printers do print tangible objects
(and quite well), how they do the job doesn't actually happen in 3D,
but rather in regular old 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: The printers lay down flat layers
of resin, which will harden into plastic after being exposed to laser
light, on top of each other, again and again from the bottom to the
top. Eventually, the object, such as a skull, takes shape. But if a
piece of the print overhangs, like a bridge or a wing of a plane, it
requires some type of flat support structure to actually print, or the
resin will fall apart.

The researchers present a method to help the printers live up to their
names and deliver a "true" 3D form of printing. In a new paper in Nature,
they describe a technique of volumetric 3D printing 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 is, could we actually print entire volumes without needing to do all these complicated steps?" said Daniel N. Congreve,
an assistant professor at Stanford and former fellow at the Rowland
Institute, where the bulk of the research took place. "Our goal was to
use simply a laser moving around to truly pattern in three dimensions
and not be limited by this sort of layer-by-layer nature of things."
The key component in their novel design is turning red light into blue
light by adding what's known as an upconversion process to the resin,
the light reactive liquid used in 3D printers that hardens into plastic.

In 3D printing, resin hardens in a flat and straight line along the
path of the light. Here, the researchers use nano capsules to add
chemicals so that it only reacts to a certain kind of light -- a blue
light at the focal point of the laser that's created by the upconversion process. This beam is scanned in three dimensions, so it prints that
way without needing to be layered onto something.

The resulting resin has a greater viscosity than in the traditional
method, so it can stand support-free once it's printed.

"We designed the resin, we designed the system so that the red light
does nothing," Congreve said. "But that little dot of blue light
triggers a chemical reaction that makes the resin harden and turn into
plastic. Basically, what that means is you have this laser passing all
the way through the system and only at that little blue do you get the polymerization, [only there] do you get the printing happening. We just
scan that blue dot around in three dimensions and anywhere that blue
dot hits it polymerizes and you get your 3D printing." The researchers
used their printer to produce a 3D Harvard logo, Stanford logo, and a
small boat, a standard yet difficult test for 3D printers because of
the boat's small size and fine details like overhanging portholes and
open cabin spaces.

The researchers, who included Christopher Stokes from the Rowland
Institute, plan to continue developing the system for speed and to
refine it to print even finer details. The potential of volumetric 3D
printing is seen as a game changer, because 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"
that materializes objects all at once.

But right now, the researchers know they have quite a ways to go.

"We're really just starting to scratch the surface of what this new
technique could do," Congreve said.


========================================================================== Story Source: Materials provided by Harvard_University. Original written
by Juan Siliezar.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Samuel N. Sanders, Tracy H. Schloemer, Mahesh K. Gangishetty, Daniel
Anderson, Michael Seitz, Arynn O. Gallegos, R. Christopher Stokes,
Daniel N. Congreve. Triplet fusion upconversion nanocapsules
for volumetric 3D printing. Nature, 2022; 604 (7906): 474 DOI:
10.1038/s41586-022-04485-8 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220422161524.htm

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