• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.63-65
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• 2007

The paper reports on a new type of combinatorial chaotic and serpentine micromixer. Such a new and novel micromixer is simple to fabricate and easy to use. The micromixer is characterized and visualized with the help of the Micro-LIF technique. The new micromixer will e further applied to lab-on-chip device. The mixing capabilities of this mixer is about 30-33%.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.101-106
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• 2003

In this work, mixing phenomena in the mixing chamber of a ultrasonic micromixer are analyzed through an analytical approach. A simplified 2-dimensional model for the ultrasonic micromixer is presented. Analytical solutions for fluid flow induced by ultrasonic waves are obtained through successive approximations method. From simulation results on thermal diffusion in the mixing chamber, effects of relative location, size, and vibration frequency of a piezoelectric material and aspect ratio of the mixing chamber on mixing performance of the ultrasonic micromixer are investigated. Finally, design guidelines for the ultrasonic micromixer are suggested based on the parametric study.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.2 s.257
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• pp.159-166
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• 2007

Mixing between two or more reagents is one of important processes in biochemical microfluidics. In efficient micromixer design, it is essential to analyze flow pattern and evaluate mixing efficiency with good precision. In this work, mixing efficiency for Y-channel micromixer is measured by fluorescence intensity using LIF(Laser Induced Fluorescence) Confocal Microscope. The Y-channel micromixers are fabricated with polydimethylsiloxane(PDMS) and those are bonded to glass plate through Plasma bonding. Nile Blue A is injected into the micromixer as a fluorescence dye for measuring of fluorescence intensity by He/Ne laser. For visualization of the flow pattern, dynamic image capturing is carried out using CAM scope. For the comparison with computer simulation, modified SIMPLE algorithm for incompressible flow equation is solved for the same geometry as in the experiment. Throughout the experiments and computer simulation, accurate mixing efficiency evaluation process for a PDMS Y-channel micromixer is established.

• 한국가시화정보학회:학술대회논문집
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• 2006.12a
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• pp.96-101
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• 2006

3-D visualization using confocal laser scanning microscopy (CLSM) in a chaotic micromixer was performed as a reproduction experiment and the feasibility of 3-0 imaging technique in the microscale was confirmed. For diagonal micromixer (DM) and two types of staggered herringbone micromixers (SHM) designed by Whitesides et al., to verify the evolution of mixing, cross sectional images are reconstructed at the end of every cycle. In a DM, clockwise rotational flow motion generated by diagonal ridges placed on the floor of micromixer is observed and this motion makes the fluid commingle. On the contrary, there are two rotational flow structures in the SHM and the centers of rotation exchange their position each other every half cycle because of the V shape of ridges varying their orientation every half cycle. Local rotational flow and local extensional flow generated by the complicate ridge pattern make the flow be chaotic and accelerate the mixing of fluid. The dominant parameter that influences on the mixing characteristic of SHM is not the length of micromixer but the number of ridges under the same flow configurations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.10 s.241
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• pp.1289-1297
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• 2005

The flow in a microchannel is usually characterized as a low Reynolds number (Re) so that good mixing is quite difficult to be achieved. In this regard, we developed a novel chaotic micromixer, named Serpentine Laminating Micromixer (SLM) in the present study, Part 1. In the SLM, the higher level of chaotic mixing can be achieved by combining two general chaotic mixing mechanisms: splitting/recombination and chaotic advection. The splitting and recombination (in other term, lamination) mechanism is obtained by the successive arrangement of 'F'-shape mixing units in two layers. The chaotic advection is induced by the overall three-dimensional serpentine path of the microchannel. Chaotic mixing performance of the SLM was fully characterized numerically. To compare the mixing performance, a T-type micromixer which has the same width, height and length of the SLM was also designed. The three-dimensional numerical mixing simulations show the superiority of the SLM over the T-type micromixer. From the cross-sectional simulation results of mixing patterns, the chaotic advection effect from the serpentine channel path design acts favorably to realize the ideal lamination of fluid flow as Re increases. Chaotic mixing mechanism, proposed in this study, could be easily integrated in Micro-Total-Analysis-System, Lab-on-a-Chip and so on.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.1
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• pp.53-59
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• 2010

In this paper, we propose a novel chaotic micromixer of which mixing mechanism is based upon magnetohydrodynamic (MHD) multi-vortical flow generation in a simple straight microchannel. In the microchannel of the micromixer has electrodes patterned on two side walls and bottom wall. Lorentz forces are variously induced by changing applied voltages at the patterned electrodes in order to pump and mix conductive fluids in the microchannel. Three-dimensional computational fluid dynamics simulations were conduced to characterize mixing behaviors inside the MHD micromixer. The mixing efficiencies were also evaluated for the various flow conditions.

• Journal of the Korea Convergence Society
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• v.9 no.10
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• pp.237-242
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• 2018

A micromixer is a component of a lab-on-a-chip or microfluidic device that mixes two or more chemicals together(convergence). The purpose of this study is to assess the performance of passive micromixer of various shapes. Six shapes of micromixers were compared and three dimensional modeling was carried out to have the same hydraulic diameter. The commercial code, ANSYS Fluent, was used to simulate the internal mixing flow. A numerical analysis method is described in detail in this paper. The performance of the micromixer was compared with the mixing index and pressure drop. Consequently, the CDM-8T shape showed reasonable mixing performance and relatively low pressure drop.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.6 s.237
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• pp.904-912
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• 2005

The flow in a microchannel is usually characterized as a low Reynolds number (Re) so that good mixing is quite difficult to be achieved. In this regard, we developed a novel chaotic micromixer, named Barrier Embedded Kenics Micromixer (BEKM). In the BEKM, the higher level of chaotic mixing can be achieved by combining two general chaotic mixing mechanisms: (i) splitting/reorientation by helical elements inside the microchannel and (ii) stretching/folding via periodically located barriers on the channel wall. The fully three-dimensional geometry of BEKM was realized by a micro-stereolithography technology, in this study, along with a Kenics micromixer and a circular T-pipe. Mixing performances of three micromixers were experimentally characterized in terms of an average mixing color intensity of phenolphthalein. Experimental results show that BEKM has better mixing performance than other two micromixers. Chaotic mixing mechanism, proposed in this study, could be integrated as a mixing component with Micro-Total-Analysis-System, Lab-on-a-chip and so on.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.8
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• pp.624-632
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• 2008

In this research, we developed new PDMS-glass based microbiochip consisted of the micromixer and microreactor for DNA ligation. The micromixer was composed of a straight channel integrated with nozzles and pillars, and the microreactor was composed of a serpentine channel. We coated the PDMS chip surface with the 0.25wt.% PVP solution to prevent the bubble generation which was caused by the hydrophobicity of the PDMS. The new micomixer was passive type and the mixing was enhanced by a convective diffusion using the nozzle and pillar. The 10.33mm long micromixer showed the good mixing efficiency of 87.7% at 500 l/min flow rate. We could perform the DNA ligation successfully in the microbiochip, and the ligation time was shortened from 4 hours in conventional laboratory method to 5 min in the microbiochip.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.12 s.243
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• pp.1369-1376
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• 2005

Effective mixing gives strong advantageous impact on microfluidic applications since mixing is in general very slow process motivated by molecular diffusion transport only on the micro-scale. In this work, the mixing characteristics are analyzed in a Y-channel micromixer with obstacles. For the through analysis, our laboratory in-house unstructured grid CFD code is validated through solving a concentration transport in a uniform microchannel. The solutions well correspond to both exact solutions and those from MemCFD. Mixing in a Y-channel micromixer with obstacles is numerically investigated by the in-house code to search the optimal radius and layout of obstacles. From the simulations, the mixing efficiency appears to be proportional to the magnitude of the formation of lateral velocity component. It is also shown that the asymmetric layout and radius enlargement of obstacles greatly improves mixing efficiency.