• Proceedings of the KSME Conference
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• 2005.11a
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• pp.55.2-55.2
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• 2005

• Journal of Biosystems Engineering
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• v.41 no.1
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• pp.60-65
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• 2016

Purpose: The necessity for precise manipulation of bioparticles has greatly increased in the fields of bioscience, biomedical, and environmental monitoring. Dielectrophoresis (DEP) is considered to be an ideal technique to manipulate bioparticles. The objective of this study is to develop a DEP microfluidic device that can trap fluorescent beads, which mimic bioparticles, at the low voltage and frequency of the sinusoidal signal supplied to the microfluidic device. Methods: A DEP microfluidic device, which is composed of polydimethylsiloxane (PDMS) channels and interdigitated electrode networks, is fabricated to trap fluorescent beads. The geometry of the interdigitated electrodes is determined through computational simulation. To determine the optimum voltage and frequency of the sinusoidal signal supplied to the device, the experiments of trapping beads are conducted at various combinations of voltage and frequency. The performance of the DEP microfluidic device is evaluated by investigating the correlation between fluorescent intensities and bead concentrations. Results: The optimum ratio of the widths between the negative and positive electrodes was 1:4 ($20:80{\mu}m$) at a gap of $20{\mu}m$ between the two electrodes. The DEP electrode networks were fabricated based on this geometry and used for the bead trapping experiments. The optimum voltage and frequency of the supplied signal for trapping fluorescent beads were 15 V and 5 kHz, respectively. The fluorescent intensity of the trapped beads increased linearly as the bead concentration increased. The coefficient of determination ($R^2$) between the fluorescent intensity and the bead concentration was 0.989. Conclusions: It is concluded that the microfluidic device developed in this study is promising for trapping bioparticles, such as a cell or virus, if they are conjugated to beads, and their concentration is quantified.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.10
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• pp.845-851
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• 2014

Dielectrophoresis (DEP) is defined as the motion of suspended particles in solvent resulting from polarization forces induced by an inhomogeneous electric field. DEP has been utilized for various biological applications such as trapping, sorting, separation of cells, viruses, nanoparticles. However, the analysis of DEP trapping has mostly employed the period-averaged ponderomotive forces while the dynamic features of DEP trapping have not been attracted because the target object is relatively large. Such approach is not appropriate for the nanoscale analysis in which the size of object is considerably small. In this study, we thoroughly investigate the dynamic response of trapping to various system parameters and its influence on the trapping stability. The effects of particle conductivity on its motion are also focused.

• Journal of Sensor Science and Technology
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• v.18 no.2
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• pp.154-159
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• 2009

This paper describes two methods - stamp-to-stick bonding and microtransfer molding - to integrate microfluidic channel into an optoelectrofluidic device for in-channel microparticle manipulation. We have demonstrated the optoelectronic microparticle manipulation in the channel-integrated optoelectrofluidic device using a liquid crystal display. As injecting a liquid sample containing $15{\mu}m$-diameter polystyrene particles into the fabricated channel, trapping and transport of individual microparticles have been successfully demonstrated. This channel-integrated optoelectrofluidic device may be useful for several in-channel applications based on the optoelectrofluidics such as optoelectronic flow control, droplet-based protein assay and bead-based immunoassay.

• 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.