A novel 3D printing technique produces objects out of resin in mere seconds

Engineers at EPFL’s Laboratory of Applied Photonic Devices (LAPD), within the School of Engineering, have developed a novel 3D printer capable of fabricating objects almost instantaneously in opaque resin, according to a press release by the institution published on Monday.

EPFL claims its new 3D printer is one of the fastest in the world. It achieves this speed by replacing additive manufacturing with a new volumetric method.

A Star Wars-inspired test

“We pour the resin into a container and spin it,” said in a statement Christophe Moser, a professor at LAPD. “Then we shine light on the container at different angles, causing the resin to solidify wherever the accumulated energy in the resin exceeds a given level. It’s a very precise method and can produce objects at the same resolution as existing 3D-printing techniques."

This new technique can be employed for objects of just about any shape. To prove this, the engineers produced a tiny Yoda in just 20 seconds. This is a task that would take ten minutes for a conventional additive-manufacturing process.

How does it work?

The plastic used in the new printer contains a photosensitive compound that interacts with the light to quickly solidify the resin. “Our method works only if the light passes through the resin in a straight line without being deviated,” added Antoine Boniface, a postdoc at LAPD. “Until now, we’ve always used transparent resin, but we wanted to see if we could print objects in the kind of opaque resin that’s used in the biomedical industry.”

Still, the experiment is not without its challenges. The light does not propagate smoothly in resin which makes it difficult to concentrate enough energy to solidify the substance. 

A new solution

“With opaque resin, we lost a lot of resolution in the printed object,” said Jorge Madrid-Wolff, a Ph.D. student at LAPD. “So we tried to come up with a solution that would let us fabricate objects in this resin but without losing the advantages of our 3D printer.”

The engineers, therefore, designed computer calculations to compensate for the light-ray distortion, programming their printer to automatically correct the light rays as it operates. This proved to be so effective that the engineers were able to print objects in opaque resin with almost the same precision and superior speed as for transparent resin.

The new 3D printing method can be used to produce biological materials, such as artificial arteries and other useful body parts. Now, the engineers are working to adjust their approach to be able to print several materials at once and increase their printer’s resolution from one-tenth of a millimeter to a micrometer. If they do achieve these two lofty goals, their 3D printer may forever revolutionize the industry, providing unparalleled printing speeds and quality.

The study has been published in the journal Advanced Science.

Abstract: 

3D printing has revolutionized the manufacturing of volumetric components and structures in many areas. Several fully volumetric light-based techniques have been recently developed thanks to the advent of photocurable resins, promising to reach unprecedented short print time (down to a few tens of seconds) while keeping a good resolution (around 100 μm). However, these new approaches only work with homogeneous and relatively transparent resins so that the light patterns used for photo-polymerization are not scrambled along their propagation. Herein, a method that takes into account light scattering in the resin prior to computing projection patterns is proposed. Using a tomographic volumetric printer, it is experimentally demonstrated that implementation of this correction is critical when printing objects whose size exceeds the scattering mean free path. To show the broad applicability of the technique, functional objects of high print fidelity are fabricated in hard organic scattering acrylates and soft cell-laden hydrogels (at 4 million cells mL⁻¹). This opens up promising perspectives in printing inside turbid materials with particular interesting applications for bioprinting cell-laden constructs.