Electrokinetic transport, as a non-mechanical tool in driving the fluid is widely used in microfluidics. This mode of transport is highly desirable due to simple integration, precise flow control by an external electric field and applicability over a wide range of sample conductivities. Fluid transport by electrokinetic techniques is dominated by surface and interfacial interactions through electrostatic attractions around charged particles(electrophoresis) or adjacent to the channel surface(electroosmosis). Miniaturization at microscale provides a high surface to volume ratio where the surface forces and interfacial effects are significantly enhanced compare to macroscale geometries. For a successful design of an optimum microfluidic device, these interactions need to be precisely quantified and controlled. This thesis focuses on studying the interfacial and electrokinetic interactions in micro-geometries, with the goal of designing an optimal platform for separation and detection of biomolecules. First, the interaction of proteins with surfactant molecules was studied to address some of the fundamental issues in microchip electrophoresis such as simultaneous quantification and detection. This work was followed by developing a rapid method for detection and quantification of proteins by electrophoresis and immunodepletion techniques. In order to quantify the effect of surfactant adsorption on electrokinetic flow, electroosmotic mobility measurements were performed at the solid-liquid interface of plastic microcapillaries(poly methylmethacrylate, PMMA). In addition, the electrokinetic effects with respect to electroporation of the cell wall were applied to develop an effective technique for inhibition of gram-negative bacteria(E.Coli). Finally, the dispersion of a semi-infinite suspension of particles was investigated in a capillary, in order to study the effects of hydrodynamic interactions and capillary confinement on the diffusive behavior of the particles.
Azadi, Glareh,
"Microscale Transport Mechanisms: Effect of Electrokinetic and Interfacial Interactions"
(2013).
Biomedical Engineering Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0TM78FH
