Facile integration of electronics in glass microfluidic devices for electrochemical synthesis and analysis

Poly(dimethylsiloxane) (PDMS) is one of the widely-used materials to fabricate microfluidic devices because of its facile handling, optical transparency and elastic mechanical properties. However, this polymer has its limitations if chemical, thermal and mechanical stability are needed for novel devices such as flow through “chemistry-on-chip” synthesis. Fused silica glass or borosilicate glass are indubitably the materials of choice for chemical synthesis due to its extraordinary chemical and thermal stability as well as its optical transparency. Microfluidic glass devices are however notoriously difficult to fabricate and usually require wet chemistry or dry etching using hazardous chemicals like hydrofluoric acid (HF). To overcome these fabrication issues, we have developed the Glassomer process that renders the structuration of fused silica glass like a polymer possible including technologies like softlithographic replication or stereolithography printing. In order to take the concept of “chemistry-on-chip” to the next level, electronics need to be integrated into the Glassomer process for the detection and localization of droplets inside microfluidic devices, for electrochemical analysis and electrochemical synthesis. In this work, we show that platinum electrodes can be integrated into the process using wires and sputtering of platinum in the polymeric state. The samples are subsequently converted into transparent fused silica glass via thermal debinding and sintering. We demonstrate that with our process the fabrication of glass microfluidic devices containing electronic conductors is feasible and facile to obtain and that they can be used to detect changes of conductivity