• New process enables 3D printing of small

    From ScienceDaily@1:317/3 to All on Tue Apr 19 22:30:44 2022
    New process enables 3D printing of small and complex components made of
    glass in just a few minutes
    Scientists combine materials science invention with newly developed 3D printing technology

    Date:
    April 19, 2022
    Source:
    University of Freiburg
    Summary:
    Scientists combine materials science invention with newly developed
    3D printing technology. Components made of highly transparent
    glass can be manufactured in just a few minutes and with great
    geometric freedom.

    Possible applications of the new process technology are
    micro-optical components of sensors, microscopes or lab-on-a-chip
    systems


    FULL STORY ========================================================================== Because of its outstanding transparency as well as its stability in
    contact with heat or chemicals, glass is relevant for many high-tech applications.

    However, conventional processes for shaping glass are often tedious,
    energy- intensive and quickly reach their limits for small and complicated components.

    The Freiburg materials scientists Dr. Frederik Kotz-Helmer and Prof. Dr.

    Bastian E. Rapp, in cooperation with the University of California
    at Berkeley in the US, have developed a novel process that can be
    used to produce very small components from transparent glass quickly
    and precisely using micro 3D printing. Possible applications include
    components for sensors and microscopes, but also for lab-on-a-chip
    systems. The researchers were able to publish their results in the
    current issue of the journal Science.


    ========================================================================== Glass powder in plastic binder The new technology is based on so-called Glassomer materials, which Kotz-Helmer and Rapp developed at the
    Department of Microsystems Engineering (IMTEK) at the University of
    Freiburg. "Glassomer materials consist of glass powder in a special
    plastic binder," says Kotz-Helmer, "allowing to process glass like
    a plastic." The resulting components are then placed in a furnace,
    which causes the plastic to burn and the glass to be sintered,
    i.e. densified. "In the end, the components consist of one hundred
    percent highly transparent fused silica glass," says Kotz-Helmer.

    Component is created in a single step The Freiburg scientists have now
    combined Glassomer materials with a new 3D printing process developed
    by a research team led by Prof. Dr. Hayden Taylor from the University of California, Berkeley. Conventional 3D printers print their objects layer
    by layer. However, in the new process, called Computed Axial Lithography
    (CAL), the component is created in a single step. A vessel containing
    liquid, light-sensitive material is exposed to two-dimensional light
    images of the object to be printed from many different angles. Where the
    images overlap and the amount of light absorbed thus locally exceeds
    a certain threshold, the material hardens abruptly -- within a few
    minutes, the component is formed. The excess, still liquid material can
    be washed off.

    Structures with the thickness of a single hair "In principle, this
    process also works with Glassomer material," says Kotz- Helmer. For
    this purpose, the Freiburg scientists developed a material made of glass
    powder and plastic that is both highly transparent and hardens quickly at
    a suitable threshold value. "The devil was in the chemical details here,"
    says the materials scientist. Previously, moreover, the CAL process had
    only been suitable for relatively coarse structures. By combining the
    materials science expertise at the University of Freiburg and the project partner Glassomer GmbH, a Freiburg spin-off, as well as the further
    development of the system technology at the University of California,
    it has now been possible to combine and improve these technologies. "For
    the first time, we were able to print glass with structures in the range
    of 50 micrometers in just a few minutes, which corresponds roughly to the thickness of a hair," says Kotz-Helmer. "In addition, the surfaces of the components are smoother than with conventional 3D printing processes."
    Glass as a substitute for vulnerable plastic Kotz-Helmer sees possible applications for the innovative manufacturing process, for example,
    in micro-optical components of sensors, virtual reality headsets and
    modern 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." Microfluidic channels are
    also needed for so-called lab-on-a-chip systems for research and medical diagnostics. Until now, these have mostly been made of plastics, but they
    often cannot withstand high temperatures and aggressive chemicals. Thanks
    to the new process technology, complex channel systems can now be
    manufactured in glass, says Kotz-Helmer: "Thanks to the thermal and
    chemical stability of glass, many new fields of application are opening
    up, especially in the area of chemistry on-a-chip synthesis."

    ========================================================================== Story Source: Materials provided by University_of_Freiburg. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Joseph T. Toombs, Manuel Luitz, Caitlyn C. Cook, Sophie Jenne,
    Chi Chung
    Li, Bastian E. Rapp, Frederik Kotz-Helmer, Hayden
    K. Taylor. Volumetric additive manufacturing of silica glass with
    microscale computed axial lithography. Science, 2022; 376 (6590):
    308 DOI: 10.1126/science.abm6459 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220419112422.htm

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