• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.99-100
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.571-572
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• 2013

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.05a
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• pp.27.1-27.1
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• 2007

• Journal of Information Display
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• v.11 no.2
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• pp.84-90
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• 2010

This paper presents the effects of a dielectric layer and an electrolyte on the driving performance of an electrowetting on dielectric (EWOD)-based liquid lens. The range of tunable focal length of the EWOD-based liquid lens was highly dependent on the conditions of the dielectric layer, which included an inorganic oxide layer and an organic hydrophobic layer. Moreover, experiments on the physical and optical durability of electrolyte by varying temperature conditions, were conducted and their results were discussed. Finally, the lens with a truncated-pyramid silicon cavity having a sidewall dielectrics and electrode was fabricated by anisotropic etching and other micro-electromechanical systems (MEMS) technologies in order to demonstrate its performance. The lens with $0.6-{\mu}m$-thick $SiO_2$ layer and 10 wt% LiCl-electrolyte exhibited brilliant focal-length tunability from infinity to 3.19 mm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.825-826
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• 2009

• Journal of the Optical Society of Korea
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• v.17 no.5
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• pp.447-453
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• 2013

A micro zoom system without moving elements by use of two liquid lenses is designed and optimized in this paper. The zoom equations of the system composed of two liquid lenses are deduced. The structure parameters including radius and thickness of a conical double-liquid electrowetting based lens are analyzed and calculated. Because the liquid thickness varies non-linearly with the radius of the interface, it's very difficult to optimize a real liquid lens using commercial optical design software directly. Through the Application Programming Interface (API) of the optical design software CODE V, a zoom system with two real electrowetting based liquid lenses is modeled and optimized. A two-liquid-lens zoom system without moving elements, with a zoom factor of 1.8 and a compact structure of 10 mm is designed for illustration. This can be useful for the camera design of mobile phones, tablets and so on. And this paper presents a convenient way of designing and optimizing a zoom system including liquid lenses by commercial optical design software.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.89-90
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• 2007

Electrowetting 현상을 contact angle의 변화가 아닌 전자기 체적력의 관점으로 고찰한다. 정수역학의 방정식과 Kelvin 식, 표면장력 공식을 도입하고, 체표면의 모든 곳에서의 압력이 일정하다는 원리를 이용하여 유체 표면의 형상을 고찰한다. 액적의 초기 형상은 반원, 반지름은 1mm이다. 절연 처리한 판형태의 도체위에 액적을 올려놓고 그 액적에 핀을 꽃은 형태로 전계를 인가한다.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.27-30
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• 2015

In this study, we attempted to harvest energy using water droplet based on Reverse Electro Wetting On Dielectric (REWOD) phenomenon between water droplet and dielectric surface without external bias. REWOD device can be fabricated via simple coating process, which is highly economic and easy. We believe that our system is well-suited for IoT(Internet of Things) embedded electronics that require low but consistent electricity. Moreover, our device can be integrated with window to generate electricity upon raindrops.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1537_1538
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• 2009

기존의 초소형 렌즈모듈들은 초점 거리 가변을 위한 구동장치가 필요하여 소형화 한계, 큰 전력소모, 부품의 기계적 결함 등 해결해야 할 부가적인 문제점들이 존재하였다. 액체렌즈는 이러한 문제를 해결할 수 있는 유력한 기술로 주목받고 있으며, 특히 부가적인 구동 장치가 필요없고 비교적 간단한 원리로 렌즈 곡률을 조절할 수 있는 일렉트로웨팅 기반의 액체렌즈는 초점 거리 조절 및 줌 조절이 필요한 휴대폰, 캡슐 내시경 등에 적용이 가능하다. 그러나 기존의 일렉트로웨팅 기반의 액체렌즈는 렌즈 캐비티의 크기에서 큰 단점이 있으며, 렌즈모듈구성 시에도 소형화하는데 한계가 존재하였다. 본 연구에서는 렌즈 캐비티를 MEMS 기술을 이용하여 실리콘 기판 상에 제작함으로써 구동회로의 집적이 가능한 액체렌즈를 제작하였다.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1098-1102
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• 2008

To increase the ink transfer rate in the micro-gravure-offset printing, the liquid transfer process between two separating plates is investigated. During the liquid transfer process, in which one plate is fixed and the other one moves vertically, a sessile droplet is separated into two droplets. The volume ratio of the two droplets depends on the contact angles of the two plates. In a numerical study of the ink transfer processes, liquid transfer between two parallel separating plates and between a trapezoidal cavity and an upward moving plate are simulated, as models of the printing of ink from the offset pad onto the substrate and the picking up of ink from the gravure plate by the offset pad, respectively. Also, in experimental study, to obtain various surface contact angles, chemical treatment, plasma treatment, and electrowetting- on-dielectric (EWOD) surface are considered. The transfer rate between two plates is calculated by analyzing the droplet images. From the results, the optimal surface contact angles of the units of the micro-gravure-offset printing can be characterized.