The Longitudinal Dispersion and Separation of Species in an Oscillating Electroosmotic Flow in Micropipettes
Date Issued
2004
Date
2004
Author(s)
Fang, Yi-Chin
DOI
en-US
Abstract
ABSTRACT
Over the last decade, the potential of micro-miniaturization of analytical procedures has been explored with the maturity of MEMS technology. Several sequential experiments steps are integrated into a single automated process. These microfluid chips can be applied to perform chemical reactions, mixing and separations, biological detections, medical testing, and environmental monitoring, etc. The present study is aimed at investigatory theoretically the mass transfer and separation driven by an electroosmotic flow (EOF) in a micropipette.
Many researches about electrical double layer (EDL), EOF and Taylor dispersion have been published over the past five decades. However, the combination of a time periodic EOF and the phenomenon of Taylor dispersion is first investigated systematically in the present study.
A complex variable approach is used to solve analytically the solutions of the velocity profile, the concentration distribution, and the mass flow rate. The results show that the enhancement of mass transport rate, , arises first and then decendes with the increase of the frequency of the electrical field applied. Parametric studies uncovered that three time constants, , , and together with the three eiganvalues in the governing equations , , and play significant roles in the process of mass transfer. The effects of Schmidt number, , the thickness of EDL, , Reynolds number, , the electrical potential on the surface of the micropipette, , and the intensity of the applied electrical field, on are systematically analyzed and discussed. It is also shown that at low frequency the oscillating EOF is conducive to the separation of species.
Subjects
電雙層
振盪式電滲透流
質傳
泰勒傳遞
溶質分離
oscillating
electrical double layer(EDL)
Taylor dispersion
separation
time periodic
electroosmotic flow(EOF)
mass transfer
Type
thesis