Fundamental Studies of AC/DC Electrokinetic Phenomena for the Realization of Microchip Capillary Electrophoresis for Single-Cell Analysis

The goal of this research was to investigate AC and DC electrokinetic phenomena to better understand their individual and combined effects on particle and fluid motions in microchannels in order to realize microchip capillary electrophoresis for single cell analysis AC-DC electroosmotic flow interaction was studied by observing the motions of polystyrene microbeads suspended in deionized water in a microchannel as the main AC and DC electrokinetics parameters were varied. Particle-particle interactive dielectrophoretic (DEP) force under electrohydrodynamic flow conditions was studied by performing experiments on a microchannel - microelectrode system containing polystyrene beads and comparing the experimental results with numerical simulation results using the Maxwell stress tensor calculation. Efficient sample injection and separation is another key to successful microchip CE. Accurate numerical studies were performed for understanding 3-D characteristics of the dispersion of sample species that is injected and carried by electroosmotic flow in diverse microchannel geometries. The following three cases were investigated; (1) non-rectangular cross section of microchannels, (2) different zeta potential for the top and bottom microchannel substrates, and (3) development of internal pressure gradient by variation of electric or electrolcinetic properties along the channel direction. The results of the numerical study for the aforementioned 3 cases showed that 3-D modeling is crucial for accurate predictions of sample injection and migration in microchip electrophoresis system. Finally, continuous cell lysis in microchip CE devices was investigated experimentally by adopting a combination of electrical and osmotic cell lysis methods. The concept of continuous single cell lysis and CE was proven by analysis of single red blood cells labeled with FITC.