On the utilisation of Taylor flows for automated cell to signal

Microfluidics has enormous potential as a tool for developing new technology and reducing cost. In this thesis, Taylor flows are utilized to develop an automated system capable of loading, transporting, processing and recovering of low volume microreactors. Analysis of low volumes is particularly important in cellular biology where the heterogeneity of biological samples is well documented. The ability to process low volumes not only reduces cost and increases accuracy, it also provides the potential for the analysis of rare targets such as circulating tumor cells (CTCs) shed into the bloodstream from primary and metastatic tumor deposits. This thesis investigates the application of gene expression automatically from whole cells, envisioning that future revisions of this instrument could be used to analyse CTCs. The developed instrument conducts cell lysing followed by RT-qPCR on a continuous system. This requires the interaction of several di erent subsystems. Microreactors are transported from one subsystem to the next in the form of a Taylor flowing slug, where di erent microfluidic junctions allow the addition of reagents. The microfluidic propulsion is provided by a gravity driven siphon. This enables aspiration and dispensing of microreactors non-intrusively. This method of propulsion produces flows within the Stokes flow regime, a previously unstudied area within Taylor flows. Therefore, a comprehensive study was undertaken to understand pressure drop associated with slug flow in this regime. Of particular note, it was found that interfacial tension was a dominating factor on the pressure drop, while the spacing between slugs proved negligible. To the best of the author’s knowledge, this is the first fully automated gene expression system developed. The system was validated by examining the gene regulation of a number of genes after stimulation with Lapatinib, a targeted therapy cancer drug for HER2 positive breast cancer.