• 한국가시화정보학회지
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• 제17권2호
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• pp.90-95
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• 2019

In the present work, the effect of flow parameters such as volume flow rate on focal point of fluidic micro lens is investigated numerically. ANSYS Fluent is used for simulations, and the flow parameters and number of simulations are determined using the space filling method of design of experiment (DOE). Having determined the location of interfaces between fluids inside the micro lens which acts as the lens curvature, a ray tracking simulation on each case is performed using COMSOL Multiphysics to determine the focal point for each lens. These data are then used to provide a relation between flow parameters and the focal point of the lens.

• 한국생산제조학회지
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• 제21권3호
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• pp.355-361
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• 2012

Though a micro pump is a crucial element in miniaturized bio-fluidic systems or drug delivery systems, it has some intrinsic disadvantages such as backward flow, pulsation of flow, low repeatability and producibility, and high cost. To overcome these limitation, a PZT disc actuated micro pump including a novel ring-shaped multi-flap check valve is introduced. To enhance the performance of the micro pump, the static behaviour of flap valve module and the micro fluidic behavior of fluids are numerically modelled and analyzed. As results of the numerical analysis, the optimal dimension and configuration of the ring-shaped multi flap valve are $1{\times}0.05$ mm and 2 (inlet side)${\times}1$ (outlet side) type. The obtained maximum flow rates and flow resolution are about 90 ml/min and 30 ${\mu}l$/stroke respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1924-1926
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• 2001

A novel wet release process ($\mu$ CARP - Micro Channel Assisted Release Process) for releasing an extreme large-area plate structure without etching hole is proposed and experimented. Etching holes in conventional process reduce a effective area and degrade an optical characteristics by a diffraction. In addition, as the area of a released structure increases, the stietion becomes more serious. The proposed process resolves these problems by the introduction of a micro fluidic channel beneath the structure which will be released. In this paper, a 5 mm${\times}$5mm-single crystal silicon plate structure was released by the proposed $\mu$CARP without etch holes on the structure. The variation in etching time with respect to the of the introduced micro channel is also examined. This process is expected to be beneficial for the actuator of a nano-scale data storage and the scanning mirror.

• 대한기계학회논문집A
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• 제29권7호
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• pp.998-1004
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• 2005

A nano-stereolithography (NSL) process has been developed for fabrication of 3D shell structures which can be applied to various nano/micro-fluidic devices. By the process, a complicated 3D shell structure on a scale of several microns can be fabricated using lamination of layers with a resolution of 150 nm in size, so it does not require the use of my sacrificial layer or any supporting structure. A layer was fabricated by means of solidifying liquid-state monomers using two-photon absorption (TPA) induced using a femtosecond laser processing. When the polymerization process is finished, unsolidified liquid state resins can be removed easily by dropping several droplets of ethanol fur developing the fabricated structure. Through this work, some 3D shell structures, which can be applied to various applications such as nano/micro-fluidic devices and MEMS system, were fabricated using the developed process.

• 설비공학논문집
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• 제27권10호
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• pp.552-557
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• 2015

The nanostereolithography process using a femtosecond laser has been shown to have strong merits for the direct fabrication of 2D/3D micro structures. In addition, a femtosecond laser provides efficient tools for precise micromachining owing to the advantages of a small and feeble heat effect zone. In this paper, we report an effective fabrication process of 3D micro optical and fluidic devices using nanostereolithography process composed of a dual stage system. Process conditions for additive and subtractive fabrication are examined. The Piezo stage scanning system is used for 3D micro-fabrication in unit area of sub-mm scale, and the motor stage is employed in fabrication on the scale of several mm. The misalignment between the pizeo- and motor- stages is revised through rotational transformation of CAD data in the unit domain. Here, the effectiveness of the proposed process is demonstrated through examples using 3D optical and microfluidic structures.

• Journal of Mechanical Science and Technology
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• 제20권4호
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• pp.554-560
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• 2006

This paper describes the demonstration of successful fabrication and initial characterization of micromachined pressure sensors and micromachined jets (microjets) fabricated for use in macro flow control and other applications. In this work, the microfabrication technology was investigated to create a micromachined fluidic control system with a goal of application in practical fluids problems, such as UAV (Unmanned Aerial Vehicle)-scale aerodynamic control. Approaches of this work include: (1) the development of suitable micromachined synthetic jets (microjets) as actuators, which obviate the need to physically extend micromachined structures into an external flow; and (2) a non-silicon alternative micromachining fabrication technology based on metallic substrates and lamination (in addition to traditional MEMS technologies) which will allow the realization of larger scale, more robust structures and larger array active areas for fluidic systems. As an initial study, an array of MEMS pressure sensors and an array of MEMS modulators for orifice-based control of microjets have been fabricated, and characterized. Both pressure sensors and modulators have been built using stainless steel as a substrate and a combination of lamination and traditional micromachining processes as fabrication technologies.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.572-575
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• 2005

A microlens connected to microfluidic channel is fabricated. The microlens is sealed with an elastomeric membrane which deforms by pressure of fluid driven by a syringe pump resulting in the shape change of the microlens. The optical properties of the microlens could be controlled by changing the microlens shape. The microlens system were made of an elastomer, PDMS, using molding from a photoplastic master patterned by UV photolithography. The test results show the optical property of the lens could be made into convex and concave type by applying the fluidic pressure positive and negative.

• JSTS:Journal of Semiconductor Technology and Science
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• 제2권4호
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• pp.253-258
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• 2002

This paper reports the design, modeling, fabrication and measurement of passive microvalves, which are applicable to glaucoma implants. The proposed microvalves were designed using fluidic theory. The microvalves consisted of microchannels and chambers. The microchannels had a constant fluidic resistance generating a pressure difference. Six kinds of microvalves were designed using fluidic equations for laminar flow and fabricated to examine the influences of chamber size, channel length and the shape of channel cross section. The pressure difference between the designed microvalve and the fabricated microvalve was measured to be less than 4%.

• 대한의용생체공학회:의공학회지
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• 제34권4호
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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.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.482-485
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• 2002

Development projects in KAIST rotted to the micro thermal device is introduced. Multi disciplinary research team is composed by combustion group and semiconductor group in KAIST and catalyst research center in KRICT to develop micro thermal/fluidic device and various items are on development. Among the projects, various kind of componenst that is required by the micro thermal devicesystem is introduced. Technology related to development of micro combustor, Micro igniter, micro fabrication of 3D structure, micro reactor and micro catalyst preparation is introduced.