New 3D printing technique prints glass for microstructures

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The researchers developed a new way to 3D print glass microstructures that could address a manufacturing need to create small glass objects with high optical quality, design flexibility and strength, they said. A team from UC Berkeley has partnered with researchers from Albert Ludwig University in Freiburg, Germany to develop a polymer-based 3D printing technique called computed axial lithography (CAL) that they developed three years ago. The new system, which the researchers call micro-CAL, can print finer features and use glass as the printing material.

Glass is used in many microscopic objects, such as the lenses of compact cameras found in smartphones. However, it has always been slow and expensive to manufacture in current manufacturing processes, which are also limited in terms of the scope of applications for which they can provide high quality objects.

Rather than constructing objects from thin layers of material, like typical manufacturing processes, the CAL method takes a different approach. It uses a laser to project patterns of light into a rotating volume of light-sensitive material to 3D print the entire object simultaneously. This saves time, smooths surface texture and also enables complex geometries in a way not possible in traditional manufacturing methods, the researchers said.

Evolution of the 3D printing process

Micro-CAL is evolving this process to print objects on a much smaller scale, with features down to about 20 millionths of a meter, or about a quarter of the width of a human hair, said lead researcher Hayden Taylor. and professor of mechanical engineering at UC Berkeley. . It also adds glass as a material that can be used in the process of printing these tiny objects when previously only polymers could be printed using the method, he said.

To print the glass, Taylor and his research team collaborated with scientists from Freiburg. Specifically, they used a special resin material containing glass nanoparticles surrounded by a light-sensitive binder liquid that German scientists developed.

In the micro-CAL process, digital light projections from the printer solidify the binder, then the printed object is heated to remove the binder and fuse the particles into a solid object of pure glass, the researchers said.

“The key factor here is that the binder has a nearly identical refractive index to glass, so light passes through the material with virtually no scattering,” Taylor said in a press release.

The researchers published an article about their work in the journal Science.

Gains in strength and complexity

Tests the researchers performed on glass objects printed with the technique demonstrated more consistent strength than those performed using a conventional layer-based printing process, the researchers reported. Taylor attributed this strength to micro-CAL’s ability to fabricate objects with smoother surfaces than those printed by layer-based 3D printing processes, which he cited as an advantage of the new technique.

“Glass objects tend to break more easily when they contain more flaws or cracks, or have a rough surface,” he explained in a press release.

Another advantage is that manufacturers can use the technique to print glass objects with more complex geometries, Taylor said. It’s a boon for makers of microscopic optical components, which are a key component of compact cameras, virtual reality headsets, advanced microscopes and other scientific instruments, he said.

“Being able to fabricate these components faster and with greater geometric freedom could potentially lead to new device functions or lower-cost products,” Taylor said.

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