• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.47-48
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• 2006

Electrowetting phenomenon is applied in the various field of technology. One of that is electrowetting display as a paper like electronic paper. Fast response and easy to express a color is goodness. In spite of that, the oil movement of the electrowetting display is irregular. So it doesn't look like uniform. Because of the above reason, electrowetting display using patterned electrode is made and the characteristic of oil movement is observed. Electrode and polymer wall is patterned by photo-lithography. We analyze the oil movement according to the variation of size and the position of etched electrode area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.495-496
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• 2006

Electrowetting phenomenon is applied in the various field of technology. One of that is electrowetting display as a paper like electronic paper. Fast response and easy to express a color is goodness. In spite of that, the oil movement of the electrowetting display is irregular. So it doesn't look like uniform. Because of above reason, electrowetting display using patterned electrode is made and the characteristic of oil movement is observed. Electrode and polymer wall is patterned by photo-lithography. We analyze the oil movement according to the variation of size and the position of etched electrode area.

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.84-87
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• 2009

Electrowetting is a versatile tool to handle tiny droplets and forms a backbone of digital microfluidics. Numerical analysis is necessary to fully understand the dynamics of electrowetting, especially in designing electrowetting-based devices, such as liquid lenses and reflective displays. We developed a numerical method to analyze the general contact-line problems, incorporating dynamic contact angle models. The method is based on the conservative level set method to capture the interface of two fluids without loss of mass. We applied the method to the analysis of spreading process of a sessile droplet for step input voltages and oscillation of the droplet for alternating input voltages in electrowetting. The result was compared with experimental data. It is shown that contact line friction significantly affects the contact line motion and the oscillation amplitude. The pinning process of contact line was well represented by including the hysteresis effect in the contact angle models.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.557-560
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• 2006

The contact angle of a meniscus and a droplet can be controlled by using electrowetting phenomena. We investigated the dynamic aspect of electrowetting for an oil-electrolyte interface formed inside a closed glass tube. A step input voltage is applied and the subsequent motion of the interface is recorded by a high-speed camera. A kind of capillary instability is observed near the three-phase contact line, which could degrade the reliability of device utilizing electrowetting such as electrowetting liquid lens. The dynamics of interface motion for different input voltages and the fluid viscosities are analyzed and discussed based on the experimental results.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.175-176
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• 2006

Electrowetting is prevailing for its various applicability on lap-on-a-chip, and MEMS devices, such as a pump, lens, micro-actuator in the micro-TAS technology. In the usual electrowetting, an AC power is preferred to DC practically. The AC electric field delays the contact angle-saturation, decreases the hysterisis, and is more stable in the view point of dielectric strength. But researches for AC electric field on electrowetting have not been reported very much yet. The different effect of AC on the electrowetting system, especially the effect of a frequency needs to be understood more concretely. In this work, the usual system for electrowetting, water droplet on the dielectric coated electrode (EWOD) is analyzed. Experimental study on the response of contact angles on input frequencies is performed. The simple circuit-model for EWOD system is considered to explain the experimental results. For more concrete understanding, the system is analyzed numerically, where simple AC-conduction model is used. Wetting tensions are analyzed under various input frequency to excavate the experimental results for the responses of the system on input frequencies.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2995-2996
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• 2007

We found that there exists a flow inside a droplet in AC electrowetting, which is distinct from DC electrowetting. In order to investigate the origin of the flow inside the droplet, we performed an experiment and numerical simulation. It is conjecture, based on the results of the experiment and numerical simulation, the flow is caused by the so called induced-charge electroosmosis at high frequencies, and by droplet oscillation at low frequencies.

• Journal of the Korea Society of Computer and Information
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• v.17 no.9
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• pp.149-156
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• 2012

The Fabric Electrode was proposed for the effective production of the display based on electrowetting in this paper and designed the source driver of flexible display which could be driven by the electrowetting cell. The electrowetting cell matrix was implemented on the substrate(PET) by imprinting. The driver fabric, wetting electrode fabric and conductive fabric was placed horizontally and vertically in the groove between cell matrix and the electrowetting cell matrix can be driven by the cross-point as electric connection. The integration density of driver module is decreased because using the R/2R DAC module per channel in the conventional method. The proposed method could utilize the effective production process and reduce the production price of a display panel. The source driver which consume lower power and can increase the integration density because of reducing the number of driver device per channel was designed and evaluate the driver operation by the simulation using the VHDL programming in this paper.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.7
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• pp.956-962
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• 2003

The Lippmann-Young equation has been widely used in electrowetting to predict the contact-angle change of a droplet on a insulating substrate with respect to the externally-applied electrical voltage. The Lippmann-Young equation is derived by assuming a droplet as a perfect conductor, so that the effect of the electrical double layer and the line tension are not taken into account. The validity of the assumption has never been checked before, systematically. In the present investigation, a modified Lippmann-Young equation is derived taking into account of the effect of the electrical double layer and the line tension. To assess their influence on contact-angle change in electrowetting, the electrostatic field around the three-phase contact line is analyzed by solving the Poisson-Boltzmann equation numerically. The validity of the numerical methods is verified by using the past theoretical results on the electrostatic field around a wedge-shaped geometry, which shows fairly good agreement. The results of the present investigation clearly indicate that the effect of the electrical double layer and the line tension is negligible for a millimeter-sized droplet. On the other hand, for a micron-sized droplet, the effect of the line tension can become a dominating factor which controls the contact-angle change in electrowetting.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.155-158
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• 2009

We developed a numerical method to analyze the contact-line problems, incorporating a dynamic contact angle model. We used level set method to capture free surface. The method is applied to the analysis of dynamic behavior of a droplet in DC electrowetting. The result is compared with an experimental data and result of perturbation method.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1757-1760
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• 2007

Moving a droplet by electrowetting is the basis of our novel displays. This enables mechanical bistable and high reflective monochrome as well as color systems. Since no high temperature process is required, plastic substrates can be used. Our prototypes show promising performance in terms of a wide temperature range, contrast ratio and color.