Improvement of Mixing Performance of 2D and 3D Micromixer by Applying Electrothermal Effect
Date Issued
2012
Date
2012
Author(s)
Lu, Chiung-Tzu
Abstract
In recent years, with the rapid development of the micro electro mechanical systems, the "lab-on-a-chip" technique is widely used in the bio-examination. Among the microfluidic systems, a micromixer device is usually utilized for mixing medicines. Via some physical mechanisms, the efficiency of the bio-examination for the micromixer can be accelerated and improved.
In microfluidic systems, AC electrokinetics is commonly used as the major tool to manipulate the particles in the suspensions and control fluid motions. AC electrokinetics can be classified into three categories, dielectrophoresis (DEP), AC electroosmosis (ACEO), and electrothermal force (ET). Then, their operating characteristics vary with the permittivity and conductivity of particles and fluids, the magnitude of applied voltage, and the AC frequency.
In this study, micromixers are ameliorated in terms of theories and finite element method (FEM). These theories can be divided into three major topics：dielectrophoresis, electrothermal micromixers, and the micromixer driven by DC-biased AC electric field.
For dielectrophoresis (DEP), a crossover frequency, which is an AC operating frequency corresponding to positive and negative DEP will be estimated in different characteristics of the particles and surrounding fluids. Furthermore, Physical correlations among them will be investigated by a novel microchannel, which is made by silver mirror reaction. Besides, when the particle behaviors are examined and predicted in terms of simulatiuons, the Stokes drag force contributed by the fluid motion will be also considered except for DEP.
For the electrothermal micromixers, the geometrical design of the novel microchannel (2D simulations) will be ameliorated to enhance the mixing efficiency by observing the shape and position of the vortices induced by electrothermal force. On the other hand, a relation between the depth of 3D traditional microchannel and the mixing quality will be calculated and discussed in this part.
The last part is the electrothermal micromixer driven by DC-biased AC electric field. Compared with the traditional electrothermal micromixer, with introducing the disturbance of the electroosmotic flow on the microchannel walls, the mixing quality can be enhanced easily, such as few electrode pairs.
Subjects
micromixer
dielectrophoresis
particle operation
electrothermal force
finite element method
Type
thesis
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