• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.597-599
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• 1995

We have analyzed the dielectrophoretic(DEP) force on a cell in a micro planar electrode structure. We fabricate a micro planar electrode structure using micro machining technology and measure the motion of a cell that is accelerated by DEP force. DEP force on a cell is calculated by curve fitting the motion of a cell. Radish and yeast are used for the experiment. In case of radish, DEP force is increased as the voltage and the frequency is increased, and in case of yeast, DEP force is increased only as the voltage is increased DEP force on a yeast does not vary when the frequency varies from 1 MHz to 3 MHz. The result will be helpful to the manipulation of cells using DEP force.

• Journal of Electrical Engineering and information Science
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• v.2 no.4
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• pp.66-71
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• 1997

The dielectrophoretic(DEP) force acting on a cell in an electric field is experimentally determined. A cell is accelerated by the DEP force in an electric field generated between micro planar electrodes. the position of the cell is measured and the velocity and acceleration of the cell are calculated based on the measured position data. The DE force is determined from the motion equation of a moving cell in suspension. The electrode structure is fabricated by micromachining technology and the height of electrodes is 1 $\mu\textrm{m}$. Radish cell and yeast are used in th experiments. In the case of radish cell, the DEP force increases as voltage or frequency(1MHz∼3MHz) increases. The voltage dependence can be explained that the DEP force increases when ▽│E│$^2$increases. The frequency dependence means that Re[x\ulcorner] of radish cell is maximized in a certain frequency. In the case of yeast, the DEP force increases only as voltage increases. The reason for the voltage dependence is the same with the case of radish. The DEP force increases only as voltage increases. The reason for the voltage dependence is the same with the case of radish. The DEP force on a yeast does not vary when the frequency varies from 1MHz to 3MHz. This result coincides with the fact that the value of calculated Re[x\ulcorner] is constant in the test frequency range.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.3
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• pp.136-143
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• 2001

A micro particle manipulator, which is devised for trapping particles at fixed positions by negative dielectrophoretic force (DEP force), has been fabricated and experimented. It is composed of square type electrode arrays fabricated by nickel electroplating with the height of 28 ${\mu}m$. To improve the quality of electroplated nickel electrodes, plating conditions have been optimized. Micro particles used in this study are polystyrene spheres and their to the specific position and trapped. The DEP force along the moving path of the particles has been estimated by the motion equation of a single particle. The displacement of a particle with an elapsed time was measured using a high-speed camera (1000 frames/sec). The velocity and acceleration of the particle were calculated from the measured data. The DEP force acting on the particle was estimated.

• Journal of Biomedical Engineering Research
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• v.34 no.3
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• pp.123-128
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• 2013

The 'Dielectrophoretic Tweezers(DEP Tweezers)' can be used as a facile, economical toolkit for quantitative measurement of chemical and biological binding forces related to many biological interactions within a microfluidic device. Our experimental setup can probe the interaction between a single receptor molecule and its specific ligand. Immunoglobulin G(IgG) functionalized on polystyrene microspheres has been used to detect individual surface linked Staphylococcus protein A(SpA) molecules and to characterize the strength of the noncovalent IgG-SpA bond. It was measured and compared with the existing measurements. Measured single binding force of between Goat, Rabbit IgG and SpA were $17{\pm}7pN$, $74{\pm}16pN$. This work can be used to investigate several different ligand-receptor interactions and antigen-antibody interactions.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.183-185
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• 1994

A new method for determination of electric parameter of cell membranes is proposed. Two circular electrodes is designed to have repulsive force. From the potential energy analysis, stable points where a cell is levitated between electrodes exist and move as frequency or voltage change. The levitated cell in the stable point fall freely when DEP force is zero. The DEP force is dependent on the frequency and the force is zero at the critical frequency. The critical frequency is determined by measuring the difference between the time taken at zero-applied voltage and the time taken at the frequency and the voltage. For example, the critical frequency and stable points of N.crassa slime cell is numerically evaluated. In the exeriment, polystyrene in water is levitated at the stable point. We show that the stable point move as the applied voltage is changed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.1
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• pp.49-55
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• 2009

This paper presents the optimal shape of microelectrode that generates dielectrophoretic(DEP) force to separate particles in homogeneous medium. The principle of the particles sorting is based on the use of the relative strengths of negative DEP (nDEP) and drag forces, as in a general DEP-activated cell sorter (DACS). To numerically calculate the DEP force and drag force, the simulation is implemented in MATLAB 7.0. The properties of particles, which are used in simulation, are similarly selected as those of cells to apply cell separation. The most optimized shape of electrode is selected by numerical simulation according to a variety of electrode shape such as rectangle, trapezoidal, and right-triangle. Through, in addition, parameter study, we found that applied frequency is more significant factor on the separation than various parameters, such as applied voltage and permittivity of medium, that decide on the strength of DEP force.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1687-1689
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• 2008

In the detection of pathogenic microorganisms ATP-bioluminescence reaction is a fascinating method. ATP(adenosine triphosphate) is an energy source of all kinds of living organism and ATP-bioluminescence reaction uses this ATP. However, ATP exists not only in the cells but also outside the cells. Therefore ATP-bioluminescence reaction only with intracellular ATP is very important in pathogenic microorganism detection. Because of that reason we developed a microfluidic channel containing Dielectrophoretic zone which capture microorganisms and eliminating and washing extracellular ATP with ATP-degarading enzymes, adenosine phosphate deaminase and apyrase. Microorganisms are captured by pDEP force at the DEP electrode zone and only extracellular ATPs are washed and eliminated outside the zone.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.11
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• pp.824-831
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• 2008

We present a continuous size-dependent particle separator using a negative dielectrophoretic (DEP) virtual pillar array. Two major problems in the previous size-dependent particle separators include the particle clogging in the mechanical sieving structures and the fixed range of separable particle sizes. The present particle separator uses the virtual pillar array generated by negative DEP force instead of the mechanical pillar array, thus eliminating the clogging problems. It is also possible to adjust the size of separable particles since the size of virtual pillars is a function of a particle diameter and applied voltage. At an applied voltage of 500 kHz $10\;V_{rms}$ (root mean sqaure voltage) sinusidal wave and a flow rate of $0.40\;{\mu}l\;min^{-1}$, we separate $5.7\;{\mu}m$-, $8.0\;{\mu}m$-, $10.5\;{\mu}m$-, and $11.9\;{\mu}m$-diameter polystyrene (PS) beads with separation purity of 95%, 92%, 50%, and 63%, respectively. The $10.5\;{\mu}m$- and $11.9\;{\mu}m$-diameter PS beads have relatively low separation purity of 50% and 63%. However, at an applied voltage of $8\;V_{rms}$, we separate $11.9\;{\mu}m$-diameter PS beads with separation purity over 99%. Therefore, the present particle separator achieves clog-free size-dependent particle separation, which is capable of size tuning of separable particles.

• Journal of Biomedical Engineering Research
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• v.34 no.4
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• pp.189-196
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• 2013

Dielectrophoresis(DEP) is useful in manipulation and separation of micro-sized particles including biological samples such as bacteria, blood cells, and cancer cells in a micro-fluidic device. Especially, those separation and manipulation techniques using DEP in combination of micro fabrication technique have been researched more and more. Recently, it is revealed that a window structure of insulating layer in microfluidic DEP chip is key role in trap of micro-particles around the window structure. However, the trap phenomenon-driven by DEP force gradient did not fully understand and is still illusive. In this study, we characterize the trap mechanism and efficiency with different shapes of window in a microfluidic DEP chip. To do this characterization, we fabricated 4 different windows shapes such as rhombus, circle, squares, and hexagon inside a micro-fluidic chip, and performed micro-sized particles manipulation experiments as varying the frequency and voltage of AC signal. Moreover, the numerical simulation with the same parameters that were used in the experiment was also performed in order to compare the simulation results and the experimental results. Those comparison shows that both results are closely matched. This study may be helpful in design and development of microfluidic DEP chip for trapping micro-scaled biological particle.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.3
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• pp.139-143
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• 2017

In this paper, we propose a separation method of the dielectric particles in the liquid flow. Since particles are dielectric in most cases, they experience dielectrophoretic(DEP) force under non-uniform electric field. The field characteristics in the electromagnetic and fluid dynamic systems are solved by using the finite element method. The motional equation of the particles is calculated by the Runge-Kutta method. The field analysis shows the feasibility of the proposed method. The particle separation model with large DEP force exerting on particles is designed by analyzing field characteristics.