Integrating materials science with new 3D printing technology


The glass has excellent transparency as well as stability when it comes into contact with chemicals or heat and is therefore considered suitable for several high-tech applications.

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But traditional glass shaping processes are known to be tedious, energy-intensive and quickly reach their limits for compact and complex components.

Freiburg materials scientists Dr. Frederik Kotz-Helmer and Prof. Dr. Bastian E. Rapp, in collaboration with the University of California, Berkeley in the United States, have developed a new process that could be used to generate very small transparent glass components quickly and accurately using 3D micro-printing.

Feasible applications integrate components not only for sensors and microscopes, but also for lab systems on a chip. The scientists reported their findings in the current issue of the renowned journal Science.

Glass powder in a plastic binder

The new technology is based on so-called Glassomer materials, which were jointly developed by Kotz-Helmer and Rapp at the Department of Microsystems Engineering (IMTEK) at the University of Fribourg.

Glassomer materials consist of glass powder in a special plastic binder to treat glass like plastic. In the end, the components are made of 100% highly transparent fused silica glass.

Dr Frederik Kotz-Helmer, Process Technology Laboratory, Department of Microsystems Engineering, University of Friborg

In addition, the resulting components are placed in a furnace, which causes the plastic to burn and the glass to sinter, i.e. to densify.

The component is created in one step

Currently, Freiburg scientists have integrated Glassomer materials using a new 3D printing process developed by a research group led by Professor Dr. Hayden Taylor of the University of California, Berkeley.

Traditional 3D printers will print their objects using a layer-by-layer method. But in the new process, called Computed Axial Lithography (CAL), the component is fabricated in a single step.

A container made of a liquid and a photosensitive material was exposed to two-dimensional light images of the object to be printed from several different angles. Here, there is an overlap of the images and the amount of light absorbed therefore locally exceeds a few thresholds.

The material hardens suddenly, in just a few minutes, and the component is formed. The excess material that is still liquid could then be washed away.

Structures with the thickness of a single hair

In principle, this process also works with the Glasomer materialsaid Kotz-Helmer. For this reason, the Freiburg researchers imagined a material made of glass powder and plastic that is both highly transparent and quickly hardens to an appropriate threshold value.

The devil was in the chemical details here“says the materials specialist. Previously, the CAL process was only suitable for relatively coarse structures.

Currently, it is possible to combine and improve these technologies by integrating the materials science expertise of the University of Freiburg and project partner Glassomer GmbH, a Freiburg spin-off, as well as the further development of the system technology at the University of California. .

For the first time, we were able to print glass with structures on the order of 50 micrometers in just a few minutes, which is about the thickness of a human hair.. In addition, component surfaces are smoother than with conventional 3D printing processes.

Dr Frederik Kotz-Helmer, Process Technology Laboratory, Department of Microsystems Engineering, University of Friborg

Glass as a substitute for vulnerable plastic

Kotz-Helmer believes this inventive manufacturing process has many feasible applications, for example, in virtual reality headsets and in the micro-optical components of modern sensors and microscopes.

The ability to manufacture such components at high speed and with great geometric freedom will enable new functions and more cost-effective products in the future..

Dr Frederik Kotz-Helmer, Process Technology Laboratory, Department of Microsystems Engineering, University of Friborg

In addition, microfluidic channels are required for so-called lab-on-a-chip systems in the field of research and medical diagnostics. Until now, these were mostly plastic, but they cannot withstand harsh chemicals and high temperatures.

Thanks to new process technology, complex channel systems can currently be made of glass

Kotz-Helmer said:Thanks to the thermal and chemical stability of glass, many new fields of application are opening up, particularly in the field of on-chip chemical synthesis..”

Journal reference:

Graves, JT, et al. (2022) Volumetric additive manufacturing of silica glass with computed axial lithography at the microscale. Science.



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