• Journal of Magnetics
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• 제22권2호
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• pp.214-219
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• 2017

Magnetic separators that clean the fluid stream from impurities, protect the installations in numerous industries. This paper introduces a graphical user interface (GUI) which proposes an optimized coil separating magnetic particles with a radius from 1 up to 500 µm. High gradient magnetic fields are employed in an arbitrary user defined fluidic channel which is made of a nonmetallic material. The effects of coil parameters are studied and adjusted to design an optimum coil with a minimum Ohmic loss. In addition, to design the coil scheme based on the particle movements, a mathematical particle-tracing model within the fluid channels has been utilized. In comparison to conventional magnetic separators, this model is reconfigurable by the user, produces a weaker magnetic field, allows for continuous purifying and is easy to install, with high separation efficiency. The presented GUI is simple to use, where the coil's manufacturing limitations can be specified.

• 대한의용생체공학회:의공학회지
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• 제40권5호
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• pp.151-157
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• 2019

An acoustofluidic device using conductive liquid-based electrodes was developed for malaria parasite separation from white blood cells. In this device, the electrode channels filled with a conductive liquid were used to generate standing surface acoustic waves (SSAWs) in a fluidic channel, which can overcome the limitation of conventional patterned metal electrodes. Separation performance of the device was evaluated using fluorescent polystyrene particles with two different sizes (2 and $10{\mu}m$ diameters), which were successfully separated. In addition, a mixture of malaria parasites and white blood cells were also efficiently separated with high purity of ~98% in the CL-SSAW device at the flow rate of $12{\mu}l/min$.

• 대한의용생체공학회:의공학회지
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• 제38권6호
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• pp.302-307
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• 2017

This paper presents a paper-based concentration gradient chip to analyze colorimetric glucose assay. The paper-based concentration gradient chip was fabricated through a wax patterning technique that can design the fluidic channel by selectively printing hydrophobic and hydrophilic areas. Afterwards, glucose and dilution solutions were loaded into the inlet of a concentration gradient chip and each solution was then mixed sequentially at mixing channel. Finally, concentration gradient was formed at each outlet of the chip. To measure the glucose concentration of the solution in outlets, we conducted colorimetric glucose assay with fixed concentration of glucose solution (0, 5, 10, 15 and 20 mM) and obtained normalized intensity. Subsequently, glucose concentrations of the outlets were calculated by substituting the normalized intensity to linear regression function based on the normalized intensity of fixed glucose concentration. Finally, the concentration gradient of glucose was formed on the chip with the result of colorimetric assay. The concentration gradient paper chip has the potential to accurately analyze unknown glucose concentration.

• 대한기계학회논문집B
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• 제36권5호
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• pp.545-551
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• 2012

마이크로 유체구조를 기반으로 하는 약물전달장치는 마이크로 유체 채널형상의 간단한 변형만으로 약물분출량을 쉽게 조절할 수 있는 장점이 있다. 그러나 디바이스 제작에 사용된 생분해성 고분자 85/15poly(lactic-co-glycolic acid) (85/15PLGA)의 소수성 기질 때문에 약물전달 장치내부로의 release medium의 유입이 원활하게 이루어지지 않으며 그 결과, 디바이스의 임플랜트 후 초기의 약물 분출에 영향을 줄 것으로 예상된다. 따라서 surfactant인 polyethylene-glycol600 (PEG600)과 Tween80을 이용하여 micro-channel의 표면처리를 한 디바이스와 surfactant를 사용하지 않은 디바이스를 각각 제작하여 약물 전달 실험을 하였으며, 이를 바탕으로 마이크로 유체 채널의 기하학적 형상에 따른 국소 마취제의 일종인 bupivacaine HCl(BHCl)의 분출속도제어를 입증하였다.

• Journal of Biosystems Engineering
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• 제42권1호
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• pp.1-11
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• 2017

Purpose: Methods: Three-dimensional CFD modeling was conducted to analyze the flow structure and discharge flow rate corresponding to the variation in the geometry of the flow channel in a microtube. Additionally, experiments were carried out, and the discharge flow rate was measured at various inlet pressures and inclination angles of the microtube. Results: The quantitative data of velocity distribution and discharge flow rate were obtained. As the width and length of the microtip increased, the discharge flow rate decreased significantly because of the increase in the loss of pressure along the microtube. As the depth of the microtip increased, the flow rate also increased because of the reduction in the flow resistance. However, in this analysis, the variation in the angle of the microtip did not influence the flow rate. From the experimental results, it was observed that the flow rate increased linearly with the increase in the inlet pressure, and the effects of the inclination angle were not clearly observed in those test cases. The values of the flow rate obtained from the experiments were significantly lower than that obtained from the CFD analysis. This is because of the distortion of the shape of the flow path inside the microtube during the fabrication process. The distortion of the flow path might decrease the flow cross-sectional area, and it would increase the flow resistance inside the microtube. The variation in the flow rate corresponding to the variation in the inlet pressure showed similar trends. Conclusions: Therefore, the results of the numerical analysis obtained from this study can be efficiently utilized for optimizing the shape of the microtip inside a microtube.

• 한국전자파학회논문지
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• 제26권1호
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• pp.47-53
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• 2015

본 논문은 미세유체채널에 채워진 유체를 이용하여 위상응답을 제어하는, 잉크젯 프린터로 인쇄된 미세유체채널 복합 좌 우향 전송선로(CRLH TL: Composite Right/Left Handed Transmission Line)를 제안한다. 제안된 CRLH TL은 종이 위에 은 나노입자 잉크를 이용하여 인쇄되었으며, Poly Methyl Methacrylate(PMMA)에 레이저 식각을 이용하여 제작된 미세유체채널은 잉크젯 프린터로 인쇄된 접착물질인 SU-8을 이용하여 CRLH TL 위에 부착되었다. 제안된 CRLH TL은 미세유체채널에 채워진 유체에 따라서 위상응답을 변화시킬 수 있으며, 미세유체채널에 각기 다른 유체가 흐를 때, 900 MHz에서 -10 dB 이하의 반사계수를 유지한 상태로 위상 지연, $0^{\circ}$ 위상, 위상 앞섬 특성을 모두 나타낼 수 있음을 확인하였다. 제안된 CRLH TL의 성능은 시뮬레이션 결과와 측정 결과를 통하여 성공적으로 증명되었다.

• 한국정밀공학회지
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• 제29권2호
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• pp.214-221
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• 2012

Recently, the biochip which is a prime representation of NT, IT, BT, as an example of convergence technology, has been frequently mentioned. With the recent rapid advance in biotechnology, these compact devices, such as lab-on-a-chip or u-TAS, have been developed, and more research is needed. These compact devices typically use the micro-channel in order to shed or detach and mix a variety of materials. Specially, in micro-fluidic systems, a mixer is necessary to produce a mixture because only laminar flow occurs at a low-Reynolds number. To solve this problem, HVM a micromixer that induces a horizontal and vertical multi-mixing flow motion, is proposed. The mixing performance was analyzed and verified by optimizing the shape through the CFD analysis and evaluating the structural analysis and the soundness with material properties that are obtained through the basic experiment.

• 대한기계학회논문집 C: 기술과 교육
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• 제3권3호
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• pp.217-223
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• 2015

유체채널 내에서의 미세입자의 패터닝은 생물 및 의료 응용분야에서 활용될 가치가 높은 응용 기술이다. 본 연구는 미세유체 채널 내에서 구조물 없이 외부 자석의 배열만을 이용한 미세입자 패터닝 방법을 제안한다. 자석의 같은 극과 서로 다른 극끼리의 배열을 이용한 일렬 배열, 적층 배열 등을 고안하여, 다양한 미세입자 패터닝에 실험적으로 적용하였다. 서로 같은 극끼리의 배열은 입자 포획에 쉽게 적용 가능하여, 독립적 배열이 가능하였다. 특히 적층 배열은 다양한 패터닝을 할 수 있음을 확인할 수 있었다. 자기력 1.08mT 수준에서까지 자석 배열에 의한 일정한 패턴을 관찰할 수 있었고, 패터닝된 입자들은 20 ml/hr 의 유체 속도에서도 안정하게 유지되었다. 본 연구는 간단하면서도 자성 입자의 다양한 패터닝을 가능케 하는 방법으로 면역자기성 입자를 이용한 의학/바이오 분야로의 폭넓은 응용을 기대케 한다.