Krystian Wlodarczyk : Picosecond laser manufacturing of glass microfluidic devices for the study of flow and reactive transport in porous media Wojciech Góra: Laser polishing - a way of improving surface quality of additively manufactured parts

Picosecond laser manufacturing of glass microfluidic devices for the study of flow and reactive transport in porous media
Krystian Wlodarczyk

Microfluidic devices can be manufactured from different materials, such as glass, plastic, photoresist or silicon. The high transparency, thermal stability, hardness and chemical resistance of glass often make this material a preferred substrate over silicon and polymers for the manufacturing of microfluidic devices. Unfortunately, conventional manufacturing of glass microfluidic devices is a complex, multistep process that involves the combination of photolithography, chemical etching, and thermal or anodic bonding. This means that the whole fabrication process of microfluidic devices is time consuming and expensive.
During my talk, I will present a different approach for the fabrication of microfluidic devices from glass substrates. The entire fabrication process involves only the use of a picosecond pulsed laser both for: (i) generating microfluidic patterns directly on glass (by ablating the material) and (ii) enclosing these patterns with another glass plate (by welding two glass plates together). The whole manufacturing process can take only a couple of hours which makes this process suitable for rapid prototyping of fully-functional microfluidic devices. Such enclosed microfluidics are planned to be used as customized micromodels of subsurface systems for the investigation of flow and reactive transport of various fluids and minerals in porous media.

Laser polishing - a way of improving surface quality of additively manufactured parts
Wojciech Góra

Powder-based additive manufacturing (AM) processes such as selective laser melting have been the subject of intense interest and engineering development in recent years. However the as-manufactured parts have rough surfaces that are generally not suitable for their intended use (e.g. medical implants) or as a part of bigger assembly (e.g. aerospace industry). As a result post-processing techniques (often semi-manual) are employed, adding significant cost to the AM process. Laser polishing provides the prospect of a fully-automated solution, that can controllably provide different surface textures on different areas of the AM part – a requirement e.g. for dental implants where a somewhat rough surface is required for the adhesive bonding surfaces, whilst a much smoother surface is required for the surfaces that will be in contact with soft tissue.
In laser polishing the focused beam is scanned over the surface in a specific pattern, locally melting a small volume of material. Due to surface tension effects the molten material flows and resolidifies providing a smooth surface. Compared to the currently-used electrochemical and mechanical polishing techniques, laser polishing offers easily-implementable automation, shorter processing times, zero waste (e.g. no abrasives/liquids involved), and more repeatable results. However, although the process is conceptually simple, there are the complicating factors of the variation of surface tension with temperature; the roughness of the initial surface; the interfaces between scanning lines; and the metallurgy of the re-solidified material.
In this presentation laser polishing of AM components formed of two different alloys, cobalt chrome CoCr and Titanium Ti6Al4V, will be presented. A surface roughness improvements of over 90% for both CoCr and Ti6Al4V for both flat and curved surfaces were achieved.