Towards high-throughput polymer replication of transparent fused silica glass

Abstract

Microstructured fused silica glass is of high demand for many applications in microsystems engineering, microfluidics and microoptics. However, structuring of fused silica glass is extremely difficult needing either very high temperatures for melt processing, hazardous chemicals for wet etching or time-consuming mechanical post-processing steps. The lack of feasible high-throughput manufacturing techniques prevent the usage of fused silica for many applications so far. Recently, soft replication and 3D printing of fused silica were introduced using silica nanocomposites that are converted into fused silica glass in a subsequent heat treatment. While these processes allow facile structuring of silica glasses on the laboratory scale, it is not suited for high-throughput manufacturing. In this work, we present a process towards rapid manufacturing of microstructured fused silica glass by hot embossing a thermoplastic silica nanocomposite. The structured nanocomposite is converted to high quality fused silica glass by subsequent debinding and sintering at 1320°C. We show hot embossing of microoptical structures as well as microfluidic channels with an aspect ratio of up to 6. Further, we have developed facile solvent and thermal bonding procedures allowing the fabrication of embedded and fully functional microfluidic chips in fused silica.