Analysis and Application of Electroosmotic Flow in Microfluidics
| Autor: | Jeng-Yann Lin, 林政彥 |
|---|---|
| Rok vydání: | 2002 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 90 A theoretical study of electroosmotic microchannel flows is investigated in this thesis. The focus is to find the optimum design and operation conditions in microchannels. Our research consists of three parts as expressed in the following. First, in order to investigate the effect of the entry region on the flow characteristics and without assuming Boltzmann equation for the charge density distribution, we performed calculations using the full Navier-Stokes equation and Nernst-Planck equation. A nonlinear, two-dimensional Poisson equation governing the applied electrical potential and the zeta potential of solid-liquid boundary and the Nernst-Planck equation governing the ionic concentration distribution are numerically solved using a finite-difference method. The applied electrical potential and zeta potential are unified in the Poisson equation without using linear superposition. A body force caused by the interaction between the charge density and the applied electrical potential field is included in the full Navier-Stokes equations. Second, the term electroosmotic flow (EOF) refers to the bulk flow of an aqueous solution induced by the application of the electric field to the zeta potential. The characteristics of EOF in a microchannel depend upon the nature of the zeta potential, i.e. whether it is uniform or nonuniform. We performed the calculation using the full Navier-Stokes equation and Nerst-Planck equation to model the change in EOF characteristics that occur when a step change in zeta potential is applied. We present a comparison of the results predicted by the classical Poisson-Boltzmann model with those given by the proposed model. This paper uses the Nernst-Planck model to explore the effect on the EOF in the case where the EDL overlaps within the channel. Finally, we design a novel 1×3 pre-focused injection system with electrokinetic focusing effect and bring up a voltage control model. Sample can be easily led into the desired outlet ports precisely. We can control the quantity of sample by controlling the focusing voltage easily. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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