미세유동시스템 내에서의 입자의 위치제어 연구

허윤석(Yun Seok Heo) Korean Society for Precision Engineering 2014 한국정밀공학회지 Vol.31 No.6

Circulating tumor cells (CTCs) in the bloodstream of cancer patients provide an accessible source for detection, characterization, and monitoring of nonhematological cancers. The effectiveness of the CTC-Chip for the isolation of ovarian cancer cells was demonstrated by adapting the herringbone-chip (HB-Chip). The motions of the particles on the HB chip were simulated by a unique combination of buoyant, gravitational forces, and helical flows with a computational modeling. The motions of cells are demonstrated by applying polystylene bead and ovarian cancer cells into the microfabricated HB-Chip. The experimental results from beads and cells are well accordance with the simulated ones, as previously reported by Toner group. Thus, I expect that these modeling and experimental skills will play key roles in the clinical applications on CTC isolation as well as the basic research on characterization of CTCs under flow.

미세유동을 이용한 공액 고분자 센서 섬유 제작

유임성(Imsung Yoo),송시몬(Simon Song) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.10

본 연구는 미세유동칩을 이용하여 당의 일종인 cyclodextrine(CD)과 알루미늄 이온 검출이 가능한 polydiacetylene(PDA)이 집적된 미세섬유를 제작하는 방법을 제안한다. PDA는 공액 고분자의 일종으로 외부 자극에 대해 blue-to-red 색 전이 및 형광이 발현되며 원료가 되는 PCDA의 head group에 따라 자극에 대한 감도가 달라지는 매력적인 특성을 가지고 있다. 따라서, 이온간 교차결합으로 야기되는 하이드로젤 형성 메커니즘과 미세유동칩 내 3차원 유체집속효과를 활용하여 PCDA-EDEA 기반의 diacetylene(DA) 단량체가 집적된 센서 섬유를 제작하였다. 섬유 내 DA 단량체는 UV에 의해 파란색의 PDA로 상 전이가 일어나며 CD나 알루미늄 이온에 반응하여 붉은색으로의 색 전이 및 붉은 형광이 발현되는 특성을 보였다. 또한 형광세기는 CD와 금속 이온의 농도에 따라 변화하는 특성을 나타내었다. 이는 미세섬유가 건조된 경우에도 동일하게 관찰되었다. We propose a fabrication method for polydiacetylene (PDA)-embedded hydrogel microfibers on a microfluidic chip. These fibers can be applied to the detection of cyclodextrines (CDs), which are a family of sugar and aluminum ions. PDA, a family of conjugated polymers, has unique characteristics when used for a sensor, because it undergoes a blue-to-red color transition and nonfluorescence-to-fluorescence transition in response to environmental stimulation. PDAs have different sensing characteristics depending on the head group of PCDA. By taking advantage of ionic crosslinking-induced hydrogel formation and the 3D hydrodynamic focusing effect on a microfluidic chip, PCDA-EDEA-derived diacetylene (DA) monomer-embedded microfibers were successfully fabricated. UV irradiation of the fibers afforded blue-colored PDA, and the resulting blue PDA fibers underwent a phase transition to red and emitted red fluorescence upon exposure to CDs and aluminum ions. Their fluorescence intensity varied depending on the CDs and aluminum ion concentrations. This phase transition was also observed when the fibers were dried.

미세유체 칩의 초소형 사출성형 공정에 대한 수치적 연구

이봉기(Bong-Kee Lee),강석원(Seok Won Kang) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

In the present study, a numerical study was carried out to investigate a melt flow behavior and effects of processing parameters in an injection molding process of a novel microfluidic chip platform. The platform mainly consisted of upper and lower plates, which included several basic components such as T-shaped microchannels, through-holes, interconnecting ports, and guiding elements. In order to manufacture the platform plates efficiently, an injection mold core having two distinct cavities was designed and employed in the molding experiments. Based on the numerical simulations for the designed mold structures, the detailed melt flow behaviors inside the mold cavities, for instance flow balance, filling pattern, and relevant defects, were inspected. Also, the effects of important processing parameters were investigated, which could be used as a stepping-stone toward an optimized injection molding process for the microfluidic chip platform.

마이크로 필라 구조물을 이용한 마이크로채널 유동 특성

김형진(Hyung Jin Kim),서영호(Young Ho Seo),김병희(Byeong Hee Kim) 한국생산제조학회 2011 한국생산제조시스템학회 학술발표대회 논문집 Vol.2011 No.4

This paper presents control of fluid flow in microchannel using micro-pillar structures. The channel of polymer microfluidic chips were designed by simulation using computational fluid dynamics (CFD ACE+). In order to control advancing meniscus of fluid flow, cylindrical micropillar structures were designed on the microchannel by four different micropillar arrays. From the simulation results, diagonal arrangement of micropillars and microchannels wall with micropillars was most effective to control the advancing meniscus as flat shape. Advancing meniscus shape of fabricated PDMS microfluidic chips and simulation shows the same shape. Also, fluid speed of microchannels could be confirmed that micro-grooved channel flow is slower than normal channels flow.

모세관 힘으로 구동되는 단백질칩용 폴리머 미세유체제어소자

고종수,윤현철 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.12

This paper describes the design, fabrication, and test of a PDMS and PMMA -laminated microfluidic device for an immunosensing biochip. A PDMS top substrate molded by polymer casting and a PMMA bottom substrate fabricated by hot embossing are bonded with pressing force and hermetically sealed. Two inlet ports and an air vent are opened through the PDMS substrate, while Au electrodes for electrochemical detection are patterned onto the PMMA substrate. The analyte sample is loaded from the sample inlet port to the detection chamber by capillary force, without any intervening forces. For this and to control the time duration of sample fluid in each compartment of the device, including the inlet port, reaction barrier, reaction chamber, flow-delay neck, and the detection chamber, the fluid conduit has been designed using varying geometry. Especially, the fluid path has been designed so that the sample flow stops after filling the detection chamber to allow sufficient time for biochemical reaction and subsequent washing steps. The washing solution is supplied through the buffer solution inlet port by an external syringe pump. As a model system for a configurable microfluidic device, the functionalization of ferritin (antigen) to the sensing monolayer and their biospecific interaction with anti-ferritin antiserum has been investigated. An electrochemical detection method for immunosensing by biocatalyzed has been developed and applied for signal registration.

3-D 유체집속효과와 레이저 중합반응을 이용한 PDA 센서 미세섬유 제작

유임성(Im-Sung Yoo),송시몬(Simon Song) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

Polydiacetylene (PDA) is chemosensor materials that exhibit non-fluorescent-to-fluorescent transition as well as blueto-red visible color change upon chemical or thermal stress. They have been studied in forms of film or microarray chip, so far. In this paper, we provide a novel technique to fabricate continuous micro-fiber PDA sensor using in-situ laserpolymerization technique and 3-D hydrodynamic focusing on a microfluidic chip. The flow of a monomer solution with diacetylene (DA) monomer is focused by a sheath flow on a 3-D microfluidic chip. The focused flow is exposed to 365 nm UV laser beam for in-situ polymerization which generates a continuous fiber containing DA monomers. Then, the fiber is exposed to 254 nm UV light to polymerize DA monomers to PDA. Preliminary results indicate that the fiber size can be controlled by the flow rates of the monomer solution and sheath flows and that a PDA sensor fiber successively responds to chemical and thermal stress.

Engineering of vascularized 3D cancer on a chip modeling for drug delivery

김다솜,김홍남 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4

The tumor microenvironment (TME) is an environment around the tumor, including blood vessels, immune cells, fibroblasts, signaling molecules and the extracellular matrix (ECM). TME influences tumor growth and metastasis as a complex interacting system of tumor and surrounding environment. To mimic more accurate TME in vitro, several vascularized cancer models are being actively studied. However, the lack of experimental tools capable of analyzing complex interactions has made it difficult to study TME in detail. In this study, we present a tumor-on-a-chip that enables the evaluation of tumor growth rate with tumor vascular network and delivering anti-tumor drugs on a microfluidics chip. First, we fabricated microfluidics devices with polydimethylsiloxane (PDMS). To create a vascularized 3D cancer model, Human umbilical vein endothelial cells (HUVECs) and Human Lung Fibroblasts were co-cultured and angiogenic sprouts were induced towards tumor spheroid. The effects of the three angiogenic factors were screened and the most appropriate combination was identified. This vascular channel created by this combination can be perfused. The resulting of anti-tumor drug treatment, doxorubicin, was confirmed that the tumor growth rate decreased after treatment. A proper vascularization helped increasing efficient drug delivery.

튜머로이드-혈관신생 상호작용의 가시화를 위한 개방형 구조 미세유체 칩 개발

김승규(Seunggyu Kim),김지원(Jiwon Kim),박준하(Joonha Park),오상윤(Sangyoon Oh),신현정(Jennifer H. Shin),전성윤(Jessie S. Jeon) 한국가시화정보학회 2020 한국가시화정보학회지 Vol.18 No.3

Cancer cells secrete angiogenic factors, and nearby vasculatures make new blood vessels essential for cancer development and metastasis in response to these soluble factors. Many efforts have been made to elucidate cancer-endothelial cell interactions in vitro. However, not much is known due to the lack of a suitable co-culture platform. Here, we introduce a 3D printing-based microfluidic system that mimics the in vivo-like cancer-endothelial cell interactions. The tumoroids and endothelial cells are co-cultured, physically separated by porous fibrin gel, allowing communication between two cell types through soluble factors. Using this microfluidic system, we were able to visualize new vessel formation induced by tumoroids of different origins, including liver, breast, and ovary. We confirmed that the ovarian tumoroids most induced angiogenesis while the other two cancer types suppressed it. Utilization of the proposed co-culture platform will help the researchers unveil the underlying mechanisms of the dynamic interplay between tumor and angiogenesis.

Numerical Analysis of the Filling Stage in Insert Injection Molding of Microfluidic Chip with Metal Electrodes

이봉기(Bong-Kee Lee),나승식(Seung-Sik Na) Korean Society for Precision Engineering 2015 한국정밀공학회지 Vol.32 No.11

In the present study, a numerical investigation of an insert injection molding process was carried out for the development of thermoplastic microfluidic chip plates with metal electrodes. Insert injection molding technology enables efficient realization of a plastic-metal hybrid structure and various efforts have been undertaken to produce novel components in several application fields. The microfluidic chip with metal inserts was proposed as a representative example and its molding process was analyzed. The important characteristics of the filling stage, such as the effects of filling time and thickness of the part cavity, were characterized. Furthermore, the detailed distributions of pressure and temperature at the end of the filling stage were investigated, revealing the significance of metal insert temperature.

미세유체칩 제작을 위한 투명 열가소성 고분자 압출 적층제조 연구

박성제(Seong Je Park),이지은(Ji Eun Lee),손용(Yong Son),박석희(Suk?Hee Park) 한국기계가공학회 2022 한국기계가공학회지 Vol.21 No.10