Glass, based on the chemical compound silica, was among the earliest materials humans learnt to use. Naturally occurring glasses like obsidian were utilised by Stone Age societies, and glass as we know it began to be manufactured in Ancient Egypt, Syria, or Mesopotamia.
Thanks to its properties – transparency, thermal stability and resistance to acids – it is used extensively today in manufacturing, technology and medicine.
A multidisciplinary team led by Dr Bastian Rapp at the Karlsruhe Institute of Technology set about making it possible to 3D print glass, which would allow the production of highly specialised and detailed structures. To achieve this, they developed a new technique; mixing nanoparticles of high purity quartz glass with a small quantity of liquid polymer. Using a laser beam, the mixture is treated at certain points, washed in a solvent bath, and then polymer is removed by heating.
“The shape initially resembles that of a pound cake; it is still unstable,” said Dr Rapp. “Therefore the glass is sintered in a final step, i.e. heated so that the glass particles are fused.”
The mixture is built into a structure layer by layer, and hardened using an automated laser beam. These structures can be up to a few centimetres in size.
The process is described in a Nature paper: ‘Three-dimensional Printing of Transparent Fused Silica Glass’.
3D printing is well established in using polymers, metals and some novel materials such as chocolate, or space dust. However, this is the first time glass has been used to 3D print useful structures.
Previous attempts to process glass into structures, such as by melting it and applying it through a nozzle, have resulted in useless structures with rough, porous surfaces. This new method manufactures high purity glass, which shows resolutions in the range of a few micrometres.
Fine glass microstructures could have applications in optics, such as in specialist glasses, and 3D-printed glass tubes could be useful components in medical technologies or tiny analytical systems.
“The next plus one generation of computers will use light, which requires complicated processor structures,” said Dr Rapp. “3D technology could be used, for instance, to make small, complex structures out of a large number of very small optical components of different orientations.”
This week, clinicians successfully used 3D printing to help treat a woman with a degenerative condition of the spinal column, by using a model of her lower spine to find a method to safely insert a catheter. Meanwhile, Johnson & Johnson have acquired 3D printing technology from Tissue Regeneration Systems, Inc, which could allow them to create implantable bone-like structures.