• 한국가시화정보학회지
• /
• 제15권3호
• /
• pp.41-46
• /
• 2017

The apoptosis of macrophages occurs throughout all stages of atherosclerosis. It is known to constitute atheromatous plaque, increase plaque instability, and thus contribute to the development of atherosclerosis. However, there still remains much to be elucidated on how the apoptotic macrophages affect the endothelial cells and also how they contribute to the development of atherosclerosis. Here we present a microfluidic system, which enables co-culture of apoptotic macrophages and endothelial cells in fibrin gel that mimics in vivo extracellular matrix. With the system, we can investigate the effect of macrophage apoptosis on vascular endothelial cells by quantitatively analyzing the level of reactive oxygen species of HUVECs, integrity of VE-cadherin and cell proliferation. We expect that this system could be utilized further for understanding different mechanisms of apoptotic macrophage on the development of atherosclerosis.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
• /
• pp.233-233
• /
• 2015

We report on a simple method for inducing physical and chemical property-gradient on nanoimprinted patterns by intensity-regulated plasma treatment under caved sample stage. As for the size gradient, a line pattern having a linewidth of 294.9 nm was etched to have gradually varying width from 277.4 nm to 147.9 nm. Modified pattern was proven to be adaptable to replica stamp for reversal patterning. To investigate the wettability gradient, imprinted nanopatterns were coated with fluoroalkylsilane to increase the hydrophobicity, and the surface was modified to have gradually varying wettability from hydrophobic to hydrophilic (contact angle was ${\sim}160^{\circ}$ to ${\sim}5^{\circ}$ on a single chip). This method is expected to be applicable to the selective adsorption of biological entities and hydrodynamic manipulation of liquid droplets for the pumpless microfluidics.

• 한국자기학회지
• /
• 제20권4호
• /
• pp.167-172
• /
• 2010

게놈 프로젝트 이후 급격하게 발전하고 있는 나노자성-바이오 의료 컨버젼스 기술은 신약 개발 프로세스, 임상 진단 등의 분야에 혁신적인 변화를 일으킬 것으로 주목을 받고 있다. 이 중에서 차세대 바이오 에세이 기술은 암, 임상 유전적 질병의 조기진단 및 현장진단(point-of-care)과 같은 유비쿼터스 진단(U-health care)시대에 부응하는 휴대화 자동화 고속화 저비용화 사용편의성뿐만 아니라 post-genome 시대의 요구에 맞는 대용량화 다중 감지화 요건을 충족하는 기술이다. 본 논고에서는 바이오 에세이용 자기센서 및 미세유체역학하에서 바이오 분자 이송용 온 칩 자석(on-chip magnet) 연구에 대해서 소개하고자 한다.

• 대한기계학회논문집B
• /
• 제34권1호
• /
• pp.53-59
• /
• 2010

본 논문에서는, 자기유체역학(MHD)을 기반으로 마이크로 채널 내부에 다중 와류 유동을 발생시키는 새로운 형태의 카오스 마이크로 믹서를 제안한다. 제안된 마이크로 믹서의 마이크로 채널 내부에는 양측면과 바닥면에 전극들이 배치되어 있다. 배치된 전극들에 인가되는 전압 조건에 따라 다양한 형태로 로렌츠 힘이 유도되며, 이렇게 유도된 로렌츠 힘은 마이크로 채널 내부 유체의 추진 및 혼합을 야기할 수 있다. 제안된 MHD 마이크로 믹서의 혼합 양상을 평가하기 위해 3 차원 전산유체역학 시뮬레이션을 수행하였다. 이를 통해 다양한 유동 조건에 대해 MHD 마이크로 믹서의 혼합 성능을 평가하였다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집C
• /
• pp.47-52
• /
• 2001

Micro-injection molding and microfluidic devices with the help of MEMS technologies including the LIGA process are expected to play important roles in. micro-system industries, in particular the bioapplication industry, in the near future. Understanding fluid flows in micro-channels is important since micro-channels are typical geometry in various microfluidic devices and mold inserts for micro-injection molding. In the present study, both experimental and numerical studies have been carried out to understand the detailed flow phenomena in micro-channel filling process. Three sets of micro-channels of different thickness were fabricated and a flow visualization system was also developed to observe the filling flow into the micro-channels. Experimental flow observations were extensively made to find the effects of channel width and thickness, and effects of surface tension and volume flow rate and so on. And a numerical analysis system has been developed to simulate the filling flow into micro-channels with the surface tension effect taken into account. Discussed are the flow visualization experimental observations along with the predictability of the numerical analysis system.

• 한국진공학회지
• /
• 제16권1호
• /
• pp.65-73
• /
• 2007

마이크로유체 채널 내에서 표면 성질과 기능성 분자들의 공간적인 위치를 제어하는 것은 진단소자, 마이크로 반응기, 또는 세포와 마이크로 유체역학의 기본적인 연구를 일해 매우 중요하다. 이 논문에서는 소프트 리소그라피 방법을 이용하여 채널 안에 패턴된 구조물을 포함하는 안정적인 마이크로 채널을 제작하는 방법을 소개하려 한다. 먼저 패턴된 영역을 폴리디메틸실록세인(PDMS) 몰드의 치수와 제작 과정을 적당히 조절함으로써 산소 플라즈마로부터 보호한다. 마이크로 구조물은 대표적인 생물오손(biofouling) 억제 물질인 폴리에틸렌 글리콜(PEG)계 공중합 고분자 혹은 다당류인 히알루산(HA)을 패턴하여 얻었으며 이러한 패턴을 이용하여 피브로넥틴(FN), 소의 혈장 알부민(BSA) 등의 단백질과 동물 세포의 어레이를 제작하였다.

• Interdisciplinary Bio Central
• /
• 제2권2호
• /
• pp.1.1-1.8
• /
• 2010

Microdevices have been used as effective experimental tools for the rapid and multiplexed analysis of individual cells in single-cell assays. Technological advances for miniaturizing such systems and the optimization of delicate controls in micron-sized space homing cells have motivated many researchers from diverse fields (e.g., cancer research, stem cell research, therapeutic agent development, etc.) to employ microtools in their scientific research. Microtools allow high-throughput, multiplexed analysis of single cells, and they are not limited by the lack of large samples. These characteristics may significantly benefit the study of immune cells, where the number of cells available for testing is usually limited. In this review, I present an overview of several microtools that are currently available for single-cell analyses in two popular formats: microarrays and microfluidic microdevices. Then, I discuss the potential to study human immunology on the single-cell level, and I highlight several recent examples of immunoassays performed with single-cell microdevice assays. Finally, I discuss the outlook for the development of optimized assay platforms to study human immune cells. The development and application of microdevices for studies on single immune cells presents novel opportunities for the qualitative and quantitative characterization of immune cells and may lead to a comprehensive understanding of fundamental aspects of human immunology.

• 대한기계학회논문집A
• /
• 제28권1호
• /
• pp.63-69
• /
• 2004

It is of great interest to enhance mixing performance in a microchannel in which the flow is usually characterized as a low Reynolds number (Re) so that good mixing is quite difficult to be achieved in this laminar flow regime. In this regard, we present a new chaotic passive micromixer, named Barrier Embedded Micromixer (BEM), of which the mixing mechanism is based on chaotic flows. In BEM, chaotic flow is induced by periodic perturbation of the velocity field due to periodically inserted barriers along the channel wall while a helical type of flow is obtained by slanted grooves on the bottom surface of the channel in the pressure driven flow. To experimentally compare the mixing performance, a T-microchannel and a microchannel with only slanted grooves were also fabricated. All microchannels were made of PDMS (Polydimethylsiloxane) from SU-8 masters that were fabricated by conventional photolithography. Mixing performance was experimentally characterized with respect to an average mixing intensity by means of color change of phenolphthalein as pH indicator. It was found that mixing efficiency decreases as Re increases for all three micromixers. Experimental results obviously indicate that BEM has better mixing performance than the other two. Chaotic mixing mechanism, suggested in this study, can be easily applied to integrated microfluidic systems , such as Micro-Total-Analysis-System, Lab-on-a-chip and so on.

• Korean Chemical Engineering Research
• /
• 제52권2호
• /
• pp.141-153
• /
• 2014

액적기반의 미세유체 시스템은 마이크로 시험관으로서 화학, 생물학 연구에 적용하기 위해 개발되었다. 미세유체 시스템에서 피코부피(picoliter)의 매우 작은 액적은 소형화된 시스템 내에서 잘 정형화 되고 구획화된 반응기로 제공되어 진다. 매우 작은 액적에서의 반응은 자동화된 초고속 대용량 스크리닝 시스템을 통하여 저가이면서 고효율적으로 수행될 수 있다. 본 총설에서는 액적 기반의 미세유체시스템의 기능들인 액적 형성, 정교한 액적 제어, 다양한 응용분야에 대해 소개하고자 한다. 또한 화학적, 생물학적 새로운 응용분야에 관해 알아보고, 기존의 방법과 비교하여 액적기반의 미세유체 시스템이 갖는 장점에 관해 논의하고자 한다.

• 대한기계학회논문집B
• /
• 제28권9호
• /
• pp.1015-1021
• /
• 2004

Micro-resolution Particle Image Velocimetry(Micro-PIV) was used to measure the flow in a micro-branch(Micro-Bypass). In this paper, effects of particle lump at the tip of a Micro-branch and difficulties of Micro-PIV measurements for microfluidics with branch passage were described. Micro-bypass was composed of a straight channel(200(100)${\mu}$m width ${\times}$ 80${\mu}$m height) and two branches which has 100(50)${\mu}$m width ${\times}$ 80${\mu}$m height. One of branches was straight and the other was curved. Experiments were performed at three regions along streamwise direction(entrance, middle and exit of branch) and five planes along vertical direction (0, ${\pm}$10, ${\pm}$20 ${\mu}$m) for the range of Re=0.24, 1.2, 2.4. Numerical simulation was done to compare with the measurements and understand the effects of particle lump at the tip of branch. And another fluid(3% poly vinyl Alcohol aqueous solution) were adapted for this study, so there were no particle sticking. In this case, we could get velocity difference between straight and curved branches.