This dissertation describes development of techniques and materials for microfluidic devices. Specifically, two major projects were done. The first project related to development of Laser Induced Fluorescence (LIF) detection for portable bead-based immunoassay and was done using two different approaches. In the first approach the reaction product was detected at the reaction end-point. The detection was evaluated using the dye fluorescein as a model fluorophore in polydimethylsiloxane (PDMS) and Kapton® test microfluidic platforms. The second approach was to detect the fluorescence with capture beads present in the microfluidic channel. It was found that PDMS was prone to adsorbing beads when unmodified. In order to reduce the nonspecific adsorption of beads, we combined surface modifications with different rinsing solutions. While rinsing was not successful at removing high percentages of adsorbed beads, surface modification treatments suggested a possible solution to this problem.
The second part of this dissertation was to develop high-throughput plastic microchip analytical technology based on capillary electrophoresis for pharmaceutical and medical applications. The development has gone through several phases including, assay development on single lane glass chips, performance characterization of single lane plastic chips, and separations on multi-lane chips. A fluorescently-labeled photoaptamer probe using microchip affinity capillary electrophoresis with direct LIF detection was used to detect the vascular endothelial growth factor 165 on a single lane glass chip. Injection molded poly(methylmethacrylate) (IM-PMMA) chips were modified by plasma oxidation and dynamic coating with the running buffer containing polyethylene oxide to get reproducible separations. We have characterized modified and unmodified chips by their physical characteristics and by their analytical performance in sets of uniformly fabricated chips. IM-PMMA chips exhibited great potential for mass fabrication, since chip-to-chip reproducibility measurements showed that chips could be fabricated reliably. A glass multi-lane CE microchip with multi-lane LIF detection was used to demonstrate system feasibility by determining the pKa of fluorescent dyes as model analytes. Calculated pKa values agreed well with literature values obtained by traditional methods. Based on these results we showed that the multi-lane CE microchip method offers increased daily throughput over a single-lane CE method.