Imaging the liquid film layer of slug flow within a microreactor

Segmented gas-liquid microreactors have gained attraction for high throughput material synthesis and sample processing in chemistry and biotechnology. The performance of the segmented gas-liquid microfluidic reactor derives from the uniformity of the gas-liquid segment lengths and the mixing that occurs within the liquid segment confined between gas slugs. The mixing process is a consequence of the recirculating flow that is set up within the liquid slugs. An important aspect of this flow geometry is that the liquid segments are not completely isolated but interconnected through a thin liquid film. Therefore, the behavior of the film layer and the flow field within the slugs are of great importance in hydrodynamics of the microreactor flow and improving the efficiency of such reactors. We present preliminary results of imaging, with quantum dots, the thin film layer surrounding the gas bubbles. The results are presented for stable slug flow of Ethanol/Nitrogen within a PDMS microreactor with channel size of 300$\times $250 micron.