Innovative 3D-Printing Technology Creates Glass Microstructures With Rays of Light

Faster production, better optical quality, and design flexibility are all advantages of this manufacturing technology.

According to a new study published in the journal Science, researchers at the University of California, Berkeley have created a novel approach to 3D-print glass microstructures that is faster and generates things with improved optical quality, design freedom, and robustness.

The researchers collaborated with experts from the Albert Ludwig University of Freiburg in Germany to expand the capabilities of a three-year-old 3D-printing technology called computed axial lithography (CAL) to print more finer features and in glass. This new system is known as "micro-CAL."

Glass is frequently used to make sophisticated microscopic objects, such as lenses in smartphones and endoscopes, as well as microfluidic devices that analyze or process minute volumes of liquid. Current production methods, on the other hand, can be slow, costly, and limited in their capacity to satisfy the industry's growing demands.

The CAL technique differs significantly from today's industrial 3D-printing manufacturing processes, which construct items from thin layers of material. This method is time consuming and produces a harsh surface texture. CAL, on the other hand, 3D prints the whole thing at once. The researchers utilize a laser to beam light patterns into a spinning volume of light-sensitive material, forming a 3D light dosage that solidifies into the desired shape. Smooth surfaces and intricate shapes are possible thanks to the CAL process's lack of layers.

This research pushes the limits of CAL to show that it can print microscale details 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, principle 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.”

Taylor and his study team worked with scientists from the Albert Ludwig University of Freiburg, who produced a specific resin substance comprising glass nanoparticles encased in a light-sensitive binder liquid to print the glass. The researchers solidify the binder using digital light projections from the printer, then heat the printed object to remove the binder and fuse the particles together creating a solid form 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,” Taylor explained. “The CAL printing process and this Glassomer [GmbH]-developed material are a perfect match for each other.” 

The research team, which included lead author Joseph Toombs, a Ph.D. student in Taylor's lab, conducted tests and discovered that CAL-printed glass items had more consistent strength than those created using a traditional layer-based printing approach.   “Glass objects tend to break more easily when they contain more flaws or cracks, or have a rough surface,” said Taylor. “CAL’s ability to make objects with smoother surfaces than other, layer-based 3D-printing processes is therefore a big potential advantage.”

Manufacturers of microscopic glass items now have a new and more efficient approach to meet clients' stringent requirements for geometry, size, and optical and mechanical qualities thanks to the CAL 3D-printing process. Manufacturers of microscopic optical components, which are used in compact cameras, virtual reality headsets, advanced microscopes, and other scientific instruments, are included in this category. “Being able to make these components faster and with more geometric freedom could potentially lead to new device functions or lower-cost products,” Taylor said.

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