Additive Manufacturing Glass from the 3D Printer

Researchers at Kiel University (CAU), Germany have used the "Laser-Assisted Melt Printing" (LAMP) process to fuse glass directly into solid structures for the first time. The process opens up prospects for sustainable ceramic bone or dental implants and photonic applications.

In the laboratory, invisible laser beams hit wafer-thin layers of glass powder. Layer by layer, the laser melts the particles and immediately solidifies them into smooth, dense and transparent 3D structures—without the need for conventional firing in an oven. The materials scientists at Kiel University (Germany) have developed a special silica-based particle ink, the main component of glass, using the "Laser-Assisted Melt Printing" (LAMP) process and applied it in thin layers. High-energy laser pulses fused the particles precisely and automatically.

During printing, the researchers can specifically control the properties of the material: By adjusting the laser power and writing speed, smooth, dense structures are created without air inclusions, and even the color of the glass can be adjusted. Electron microscopic and spectroscopic measurements showed that the material was fully compacted—a significant advance over previous glass 3D printing processes.

LAMP allows the physical properties such as density, smoothness, color and transparency to be controlled during printing.

Dr. Leonard Siebert

In many conventional 3D printing processes for glass or ceramics, the material is first printed and then hardened in a kiln. This step consumes a lot of energy and takes several hours. In addition, the material structure can no longer be influenced locally during this process. "LAMP makes it possible to control physical properties such as density, smoothness, color and transparency during the printing process," says Dr. Leonard Siebert, who led the study. According to the materials scientist, this opens up new possibilities for customized medical implants and optical components.

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Nanoparticles for Targeted Light Control

The adaptation of the optical properties is particularly innovative: The researchers mixed gold and silver ions into the printing ink, which developed into tiny metal nanoparticles during laser melting. Their size determines which light colors are absorbed or scattered—small particles shift the color to blue, larger ones to red. "These nanoparticles act like tiny filters: they only allow certain wavelengths to pass through and block others," explains Kolja Krohne, who was also involved in the study.

In this way, glass filters can be produced that only allow certain colors to pass through. Such filters could be used in optical sensors, laser components or microlenses. Waveguides, tiny light channels that guide light from one point to another, are also likely to benefit: Color gradients or patterns in the glass direct or attenuate the light so that its guidance can be controlled in the smallest of spaces.

Great Potential for Ceramic Implants

Even though the current study examines glass, the researchers see great potential for other materials, particularly ceramics, which are frequently used in medical technology. "In conventional processes, ceramics usually have to be fired in ovens at well over 1830 °F. This consumes a lot of energy, takes a long time, exposes the components to high stresses and makes it difficult to manufacture delicate or patient-specific implants," explains Siebert. LAMP avoids this problem. In future, it will also be possible to directly print complex-shaped or customized unique ceramic parts—for dental or bone implants, for example, which are optimally adapted to patients.

A joint study by Siebert and the University Medical Center Schleswig-Holstein in Kiel was able to 3D print dental ceramic materials with high strength as early as 2023, albeit using the conventional furnace process. The team is already working on transferring LAMP to these new material systems. In the long term, the process could become an energy-efficient platform technology for the production of personalized implants.

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