• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 학술대회 및 기술세미나 논문집 디스플레이 광소자
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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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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• 한국전산유체공학회 2009년 추계학술대회논문집
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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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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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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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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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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.

• 한국컴퓨터정보학회논문지
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• 제17권9호
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• pp.149-156
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• 2012

본 논문에서는 전기습윤(Electrowetting) 디스플레이의 효율적인 생산을 위해 섬유형식의 전극들을 제안하고, 이러한 방법을 이용한 전기습윤 셀 구동형 플렉서블 디스플레이의 소스 드라이버 설계방법을 제안하였다. 전기습윤 셀 매트릭스는 임프린팅 방법에 의하여 PET 등의 Substrate 위에 구성하고 셀 매트릭스 사이의 간격에는 드라이버섬유, 습윤 전극섬유와 전도성 섬유를 가로와 세로로 배치하고, 교차점에는 전기적 접점을 구성하여 전기습윤 셀매트릭스가 구동되도록 하였다. 기존의 소스 드라이버에서는 각 채널당 R/2R방식의 DAC을 사용하므로 사용되는 소자의 수가 증가하여 집적도가 저하되는 단점이 있다. 따라서 본 논문에서는 채널당 소자의 수를 감소시켜 집적도를 높이고 비용을 절감할 수 있는 저 전력 소스 드라이버 설계방법을 제안하고 VHDL 프로그램을 이용한 시뮬레이션으로 타당성을 검증하였다.

• 대한기계학회논문집B
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• 제27권7호
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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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• 한국전산유체공학회 2009년 춘계학술대회논문집
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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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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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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.