Volumetric 3D printing can make small glass parts in seconds

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Glass is increasingly used in fiber optics, consumer electronics, and microfluidics for “lab-on-chip” devices. Unfortunately, traditional glassmaking can be expensive and slow, and small 3D-printed glass objects have rough surfaces, making them unsuitable for lenses.

To solve these problems, a research team from Lawrence Livermore National Laboratory (LLNL) and the University of California, Berkeley has developed a new method of 3D printing known as volumetric additive manufacturing (VAM). The team used VAM to print microscopic, delicate, layerless silica glass objects in silica glass parts in just seconds or minutes.

VAM is based on computed axial lithography (CAL), a technology based on computed tomography, a medical imaging tool. CAL calculates projections from many angles on a model of the part being manufactured. It then uses the best set of projections to guide the LED light into a rotating vat of photoresist. Over time, the light beams establish a 3D light pattern in the resin, hardening it as the vat rotates. The fully formed object materializes in seconds, much faster than traditional layer-by-layer 3D printing. The tank is emptied to obtain the part.

The team’s new microscale VAM technique uses a laser instead of an LED and a nanocomposite glass resin developed in Germany by Glassomer and the University of Freiburg. The team took advantage of the higher light output of the laser and the new resin to rapidly fabricate robust, complex microstructured glass objects with a surface roughness of just 6 nm and features as small as 50 µm.

“Glass objects tend to break more easily when they contain more flaws or cracks or have a rough surface,” says Berkeley professor Hayden Taylor. “VAM’s ability to manufacture objects with smoother surfaces than other 3D printing processes is therefore a major potential advantage.”

The team compared the breaking strength of glass built with VAM to objects of the same size made by more conventional layer-based 3D printing. It turns out that the failure loads of VAM-printed structures are more tightly clustered, which means researchers could have more confidence in the failure load of VAM-printed components compared to those fabricated using conventional techniques. VAM also produces extremely smooth surfaces without layering artifacts, resulting in faster printing without additional post-processing.

“You can imagine trying to create these small, complex micro-optics and microarchitectures using off-the-shelf manufacturing techniques; it’s really not possible,” Cook said. “And being able to print ready-to-use parts without having to polish them saves a lot of time and money.”

Researchers predict that VAM patterned glass should help fabricate solid glass devices with microscopic features, fabricate optical components with more geometric freedom and at higher speeds, and potentially add new functions or reduce costs.

Real-world applications could include micro-optics in high-grade cameras, consumer electronics, biomedical imaging, chemical sensors, virtual reality headsets, advanced microscopes, and microfluidics with challenging 3D geometries such as “labs on a chip”. Additionally, the benign properties of glass lend themselves well to biomedical applications as well as those that must withstand high temperatures or chemical exposure.

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