• 한국정밀공학회지
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• 제33권1호
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• pp.63-67
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• 2016

We present a method of fabricating poly (lactic-co-glycolic acid) (PLGA) porous microfibers using a pore template. PLGA microfibers were synthesized using a glass capillary tube in a poly-(dimethylsiloxane) (PDMS) microfluidic chip. Gelatin solution was used as a porous template to prepare pores in microfibers. Two phases of PLGA solutions in different solvents-DMSO (dimethyl sulfoxide) and DCM (dichloromethane)-were used to control the porosity and strength of the porous microfibers. The porosity of the PLGA microfibers differed depending on the ratio of flow rates in the two phases. The porous structure was formed in a spiral shape on the microfiber. The porous structure of the microfiber is expected to improve transfer of oxygen and nutrients, which is important for cell viability in tissue engineering.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2349-2351
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• 2003

This paper reports a novel microfluidic system, by which microfluidic delivery, transport and control can be digitally realized in femtoliter scale. Microelectronic grade $N_2$ from a pressurized canister was passed through HPLC tubing into a micro injector. The micro injector was driven and controlled digitally by the control system that can apply various control parameters such as pulse frequencies. A front-end of micro nozzle was inserted the dyed oil to collect droplets injected. The diameter of a droplet was measured by a microscope and a CCD camera, and then its volume can be calculated on the assumption that the droplet is spherical. The micro nozzles were simply pulled in glass capillary tubes by the micro puller self-made, and the geometry parameters of the micro nozzles can be adjusted easily. Experiments have successfully been carried out, and the results demonstrated that the proposed digital micro injector possesses three significant advantages : precise ultra-small liquid volume in femtoliter scale, digital microfluidic control and micro devices fabricated by simple glass process, not based on IC process.

• 센서학회지
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• 제13권5호
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• pp.378-382
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• 2004

A micromachined fluidic structure for the introduction of liquid samples into a chip-based sensor array composed of individually addressable polymeric microbeads has been developed. The structure consists of a separately attached cover glass, a single silicon chip having micromachined channels and microbead storage cavities, and a glass carver. In our sensor array, transduction occurs via colorimetric and fluorescence changes to receptors and indicator molecules that are covalently attached to termination sites on the polymeric microbeads. Data streams are acquired for each of the individual microbeads using a CCD. One of the key parts of the structure is a passive fluid introduction system driven only by capillary force. The velocity of penetration of a horizontal capillary for the device having a rectangular cross section has been derived, and it is quite similar to the Washburn Equation calculated for a pipe with a circular cross section having uniform radius. The test results show that this system is useful in a ${\mu}$-TAS and biomedical applications.

• Korean Chemical Engineering Research
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• 제50권4호
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• pp.733-737
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• 2012

본 연구는 미세유체의 수력학적 조절을 통한 단분산성 다중 액적 형성방법을 기술한다. 다중 액적을 형성하기 위해 별도의 표면 개질이 필요 없는 co-flowing stream 시스템과 유리 모세관을 이용하여 미세유체 칩을 제작하였다. 유리모세관 미세유체 칩 내부로 0.5 wt% Tween 20이 함유된 증류수, n-hexadecane (5 wt% Span 80), 그리고 10 wt% poly(vinyl alcohol) (PVA) 수용액을 흘려줌으로써 단분산성 다중 액적(W/O/W)을 성공적으로 형성하였다. 더불어, 내부 액적의 개수를 제어하기 위해 수력학적 변수로 작용하는 중간 유체와 최외각 유체의 부피유속을 고정시키고 내부 유체의 부피유속을 조절하는 방법을 사용하여 다양한 내부 액적을 지니는 다중 유화 액적을 성공적으로 완성하였다. 이와 같은 미세유체 시스템을 통해 형성된 다중 액적은 내부물질의 종류에 따라 다양한 화학반응을 위한 하나의 독립된 마이크로 반응기로 사용될 수 있을 것으로 기대한다.

• Nuclear Engineering and Technology
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• 제47권6호
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• pp.738-745
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• 2015

The catalytic exchange of hydrogen isotopes between hydrogen and water has been known to be a very useful process for the separation of tritium from tritiated water. For the process, a highly active hydrophobic catalyst is needed. This study provides an effective fabrication method of size-controlled platinum/poly[styrene-divinylbenzene-tri(propylene glycol) diacrylate] [Pt/poly(SDB-TPGDA)] hydrophobic catalyst beads with a narrow size distribution. Platinum nanoparticles were prepared by ${\gamma}$-ray-induced reduction in the aqueous phase first, and then uniformly dispersed in SDB-TPGDA comonomer after the hydrophobization of platinum nanoparticles with alkylamine stabilizers. The porous Pt/poly(SDB-TPGDA) hydrophobic catalyst beads were synthesized by the UV-initiated polymerization of the mixture droplets prepared in a capillary-based microfluidic system. The size of as-prepared catalyst beads can be controlled in the range of $200-1,000{\mu}m$ by adjusting the flow rate of dispersed and continuous phases, as well as the viscosity of the continuous phase. Sorbitan monooleate and cyclohexanol were used as coporogens to control the porosities of the catalyst beads.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.2102-2104
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• 2004

In this study, sheathless electrospray from PDMS/glass microchips with conducting metal emitter tip is described. A chip-based capillary electrophoresis/mass spectrometry (CE/MS) system has advantages of the CE separation and on-line electrospray detection of peptide solution. We have fabricated a new electrospray ionization(ESI) device composed of the metal emitter tip and CE separation channel monolithically in a glass microchip. The separation channel and metal emitter tip are fabricated using a glass wet etching and gold electro plating process, respectively. The fabricated micro electrospray chip was tested by spraying peptide sample for mass spectrometric analysis. Singlely-charged peak and doublely-charged peak of peptide were detected and further MS/MS fragmentation was performed in each peak. Direct comparisons with conventional glass or fused silica emitters showed very similar performance with respect to signal strength and stability.