3D Direct laser writing of glass based microstructures

• Applicant: Professor Dr.-Ing. Bastian Ernst Rapp
• Subject Area: Glass, Ceramics and Derived Composites ; Microsystems
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 529880944

Glass is one of the oldest materials of mankind with the oldest specimen dating back to 5000 BC. Interestingly, despite its age, the techniques for shaping glass have seen little progress within the last five centuries. Recent key achievements in three-dimensional printing has opened the door to the fabrication of complex glass based objects. Notably, high-resolution microstructures have been achieved by microstereolithography, but their resolution is not sufficient for many applications. This is mainly due to the inherent problems associated with one-photon absorption (1PP) based 3D Printing techniques such as the layer-to-layer structure. In this context, 3DGlass aims to explore the fabrication of glass based microstructures by 3D direct laser writing using two-photon polymerization (2PP). The latter offers unmatched degree of freedom coupled with resolutions no other manufacturing techniques can achieve. Being able to generate high-resolution 3D structures with a direct writing process would be a key enabling technology for several key technologies such as precision and microoptics. This project will explore nanocomposite glass precursors termed Glassomer which have been used for 1PP of glass and, very recently, have attracted interest for 2PP although neither resolution nor processing speeds expected from 2PP have been achieved. Furthermore, we will explore techniques which allow creating porous glass monoliths via 2PP, a technique which would open up the manufacturing of engineered-porous glass scaffolds for applications in separation science, catalysis and precision optics. The research hypothesis of this project is that, building on prior work of the two groups, it is possible to redesign Glassomer for high-resolution and high-speed structuring via 2PP. Furthermore, we will optimize these formulation such that a precise adjustment of the bulk porosity of the material can be achieved. The objectives of the project are thus to create a nanocomposite formulation for 2PP structuring of glass at a resolution of 1 μm and processing speeds of 100 cm/s. Furthermore, we intend to provide a material solution which allows generating porous glasses with porosities ranging from a new 10 to a few 100 nm via 2PP. Several technical barriers need to be overcome in order to facilitate this. Firstly, a suitably sensitive photoinitiator, co-initiator and crosslinking system needs to be found which allows 2PP structuring of the Glassomer nanocomposites without inducing gelation during processing or crystallization of the glass during post-processing. Secondly, a scalable formulation modification needs to be implemented which allows tuning of the glass component’s porosities over 2-3 length scales. Thirdly, process optimizations need to be implemented which ensure that the components generated by 2PP can be created directly inside of pre-existing Glassomer structures generated, e.g., using 3D Printing via 1PP.

• DFG Programme: Research Grants
• International Connection: France
• Cooperation Partner: Arnaud Spangenberg, Ph.D.