| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 95 === In this study, particle tracking method and current monitoring method are used to evaluate the zeta potentials of microchannel walls with different surface charges. For the particle tracking method, an electrolyte solution containing fluorescent particles was added into a microchannel with electrodes at two ends. A potential difference was then applied to introduce an electric field in the microchannel, resulting in electroosmotic flow and particle electrophoretic motion. From the measurement of fluorescent particle velocity distribution and the best-fit analysis with theoretical models, the zeta potentials of the microchannel walls can be evaluated. For the current monitoring method, two ends of a microchannel were connected to two reservoirs containing electrolyte solutions with different concentrations, respectively. By applying an electric field, the electrolyte solution displacement phenomenon was resulted by the induced electroosmotic flow, causing the variations in the measured current. The experimental results indicated that the particle tracking method was unable to obtain the expected zeta potential data. However, by using the current monitoring method, the theoretical models proposed in the study could be used to improve the accuracy in evaluating the zeta potentials of microchannel walls with a uniform surface charge. Moreover, the approach could be also applied to evaluate the zeta potentials for microchannel walls with different surface charges.
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