Fabrication, characterization and applications development of a microfluidic device for the array deposition of biomolecules

In this work the motivation, fabrication and characterization of a microfluidic device for the flow deposition of biomolecules in an array format has been presented. The continuous flow microspotter (CFM) is a device that utilizes flow through microchannels for flowing biomolecule laden solution over specific areas of a substrate. The biomolecules are deposited on these specific areas to form microarrays. Novel applications have been demonstrated for the CFM. The microfabrication steps for prototyping the CFM have been described and an innovative process for the fabrication of high aspect ratio microfludic devices has been developed. A CFM device made using this process has been successfully tested. The effect of deposition parameters such as concentration, flow rate and time on the deposited arrays has been investigated and optimal conditions for flow deposition have been deduced. A higher flow rate for a shorter time gives better results for nonspecific adsorption and a lower flow rate for a longer time works better for specific adsorption on the substrate. The activity of antibodies (in binding to the corresponding antigens) deposited by the CFM has been verified in comparison with the same antibodies immobilized in-line using a commercially available instrument. The deposition of protein and antibody arrays on a variety of surfaces has been demonstrated using the CFM and compared to conventional array deposition methods. The results show the advantages of using flow deposition over conventional methods in producing high quality arrays from both dilute and concentrated solutions. Other applications for the CFM such as sequential chemistry on a spot, antibody capture from complex mixtures and antibody affinity determination have been proven. The flow deposition has been modeled using a computational fluid dynamics program and the model verified against experimental data. The model accounts for convective, diffusive transport and adsorption reaction at the surface. The relative rates of these processes affect the quantity of the biomolecules deposited on the array substrate.;The feasibility of the CFM as a device for flow deposition has been confirmed for a variety of biomolecules with different surface capture mechanisms. Optimal operating conditions for the CFM have been evaluated. The CFM can be used as a device to increase quality and throughput of biomolecular arrays for a variety of applications.