The manufacturing method allows sooner manufacturing, larger optical high quality, and design flexibility.
Researchers on the University of California, Berkeley have developed a new way to 3D-print glass microstructures that is faster and produces objects with higher optical quality, design flexibility, and strength, according to a new study published in the journal Science.
Working with scientists from the Albert Ludwig University of Freiburg in Germany, the researchers extended the capabilities of a 3D-printing process they developed three years ago — computed axial lithography (CAL) — to print much finer features and to print in glass. They dubbed this new system “micro-CAL.”
Glass is often the preferred material for creating complicated microscopic objects, including lenses in compact, high-quality cameras used in smartphones and endoscopes, as well as microfluidic devices used to analyze or process minute amounts of liquid. However, present manufacturing methods can be slow, expensive, and limited in their ability to meet the industry’s increasing demands.
The CAL process is fundamentally different from today’s industrial 3D-printing manufacturing processes, which build up objects from thin layers of material. This technique can be time-intensive and result in rough surface texture. CAL, however, 3D-prints the entire object simultaneously. Researchers use a laser to project patterns of light into a rotating volume of light-sensitive material, building up a 3D light dose that then solidifies in the desired shape. The layer-less nature of the CAL process enables smooth surfaces and complex geometries.
This study pushes the boundaries of CAL to demonstrate its ability to print microscale features in glass structures. “When we first published this method in 2019, CAL could print objects into polymers with features down to about a third of a millimeter in size,” said Hayden Taylor, principal investigator and professor of mechanical engineering at UC Berkeley.
“Now, with micro-CAL, we can print objects in polymers with features down to about 20 millionths of a meter, or about a quarter of a human hair’s breadth. And for the first time, we have shown how this method can print not only into polymers but also into glass, with features down to about 50 millionths of a meter.”
To print the glass, Taylor and his research team collaborated with scientists from the Albert Ludwig University of Freiburg, who have developed a special resin material containing nanoparticles of glass surrounded by a light-sensitive binder liquid. Digital light projections from the printer solidify the binder, then the researchers heat the printed object to remove the binder and fuse the particles together into a solid object of pure glass.
“The key enabler here is that the binder has a refractive index that is virtually identical to that of the glass, so that light passes through the material with virtually no scattering,” said Taylor. “The CAL printing process and this Glassomer [GmbH]-developed materials are an ideal match for one another.”
The analysis group, which included lead writer Joseph Toombs, a Ph.D. pupil in Taylor’s lab, additionally ran checks and found that the CAL-printed glass objects had extra constant power than these made utilizing a traditional layer-based printing course of. “Glass objects have a tendency to interrupt extra simply once they comprise extra flaws or cracks, or have a tough floor,” stated Taylor. “CAL’s means to make objects with smoother surfaces than different, layer-based 3D-printing processes is due to this fact a giant potential benefit.”
The CAL 3D-printing methodology affords producers of microscopic glass objects a brand new and extra environment friendly method to meet clients’ demanding necessities for geometry, dimension and optical and mechanical properties. Particularly, this consists of producers of microscopic optical elements, that are a key a part of compact cameras, digital actuality headsets, superior microscopes and different scientific devices. “With the ability to make these elements sooner and with extra geometric freedom may doubtlessly result in new gadget features or lower-cost merchandise,” stated Taylor.
Reference: “Volumetric additive manufacturing of silica glass with microscale computed axial lithography” by Joseph T. Toombs, Manuel Luitz, Caitlyn C. Cook dinner, Sophie Jenne, Chi Chung Li, Bastian E. Rapp, Frederik Kotz-Helmer and Hayden Okay. Taylor, 14 April 2022, Science.
This research was funded by the Nationwide Science Basis, the European Analysis Council, the Carl Zeiss Basis, the German Analysis Basis and the U.S. Division of Power.