▎ WuXi AppTec content team editor
In recent years, 3D printing technology has been applied to industrial manufacturing, scientific research, medicine and other fields, so that people from all walks of life can easily print out three-dimensional objects. However, although the products of 3D printing are three-dimensional, the current 3D printing itself is actually a two-dimensional planar process.
The basic working principle of 3D printing is: First, a flat layer of resin under the irradiation of the laser, hardening to form plastic. Subsequently, the process is repeated several times, the resin is stacked layer by layer, and finally the complete three-dimensional object is printed from the bottom up. However, if part of the target product is overhanging, such as printing a bridge or wing, then the printing process requires a horizontal external support structure to avoid resin collapse.
Now, in a recent study published in the journal Nature, a team of researchers from Harvard and MIT has developed 3D printing in the true sense of the word. This technology, known as "volumetric 3D printing," breaks the limits of bottom-up layer-by-layer printing, allowing the 3D printing process to be self-supporting without the need for external support structures.
"What we wanted to know was if we could put aside these complex steps and print the entire object directly," said Daniel N. Congreve, an assistant professor at Stanford University who led the study, "and our goal is to really print out three-dimensional patterns with the movement of the laser alone, rather than being limited by the nature of layer-by-layer printing." ”
The key to this new design is to convert red light into blue light through an inter-frequency conversion process.
During the 3D printing process, the resin hardens in a straight line along the path of the laser on a flat surface. In the latest study, the research team used nanocapsules to package molecules that enable frequency conversion, so that the resin reacts only to the blue light formed by the frequency increase at the laser focus. The beam scans from 3 different directions, so there is no need to print on top of the previous layer of material.
Compared with traditional means, the resin produced by the new method is more viscous, so during the printing process, it is possible to "stand" without the help of external forces.
Blue-light-induced chemical reactions harden the resin during the all-new 3D printing process (Video credit: Tracy H. Schloemer and Arynn O. Gallegos)
"Through our design of the resin, the printing system, the red light doesn't work here," Professor Congreve says, "but the chemical reaction induced by the small blue dots of light hardens the resin and forms plastic." Overall, this means that lasers from all directions pass through the system, but only blue light can polymerize the resin, enabling printing. ”
Using this new device, the research team printed three-dimensional objects, including The Emblems of Harvard and MIT. In addition, the device printed out a small boat— an object that is often used as a standard test object for 3D printers, because such a small boat is small enough and requires fine details such as portholes and open cabin space.
▲ Boat printed using new 3D printing technology (Image: Dan Congreve)
Of course, the researchers also admit that there is still a long way to go. "We've just touched the shallows of this new technology." Professor Congreve said. Next, they plan to continue to improve the system to make it more efficient and contain more detail. Professor Congreve expects that this new technology may create a new future of 3D printing: not only will printing equipment no longer need complex support structures, but also the potential will be realized, which is expected to greatly increase the printing speed.
Resources:
[2] Making 3D printing truly 3D. Retrieved Apr. 20, 2022 from https://www.eurekalert.org/news-releases/950588
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