Biochemical Reactions on a Microfluidic Chip Based on a Precise Fluidic Handling Method at the Nanoliter Scale

Lee, Chang-Soo,Lee, Sang-Ho,Kim, Yun-Gon,Choi, Chang-Hyoung,Kim, Yong-Kweon,Kim, Byung-Gee The Korean Society for Biotechnology and Bioengine 2006 Biotechnology and Bioprocess Engineering Vol.11 No.2

A passive microfluidic delivery system using hydrophobic valving and pneumatic control was devised for microfluidic handling on a chip. The microfluidic metering, cutting, transport, and merging of two liquids on the chip were correctly performed. The error range of the accuracy of microfluid metering was below 4% on a 20 nL scale, which showed that microfluid was easily manipulated with the desired volume on a chip. For a study of the feasibility of biochemical reactions on the chip, a single enzymatic reaction, such as ${\beta}-galactosidase$ reaction, was performed. The detection limit of the substrate, i.e. fluorescein $di-{\beta}-galactopyranoside$ (FDG) of the ${\beta}-galactosidase$ (6.7 fM), was about 76 pM. Additionally, multiple biochemical reactions such as in vitro protein synthesis of enhanced green fluorescence protein (EGFP) were successfully demonstrated at the nanoliter scale, which suggests that our microfluidic chip can be applied not only to miniaturization of various biochemical reactions, but also to development of the microfluidic biochemical reaction system requiring a precise nano-scale control.

Microfluidic Skin-On-A-Chip with Vasculature for Modeling Inflammatory Dermal Diseases

( Seung Ri Kim ),( Jong Hwan Sung ) 한국피부장벽학회 2019 한국피부장벽학회지 Vol.21 No.1

Animal models have been primarily used for testing skin toxicity and sensitivity. However, animal models have many problems such as ethical issues, costs, time and safety evaluation and prediction are not accurate because there are differences between animals and humans. Therefore, the need for in vitro skin models is increasing. Current in vitro skin model has only a partial function of the skin. In particular, on-chip construction of an in vitro model comprising the epidermis and dermis layer with vascular structure for mass transport has not been reported yet. In this study, we aim to develop a skin on a chip using a three-dimensional skin chip that has fluidic channels and can mimic the human environment more closely. Skin on a chip is a model to reproduce skin reaction similar to human body and physiology by culturing cells constituting skin on chip. In this study, we established cell culture conditions to simulate dermis and epidermis and culture blood vessels, and observed immune response in skin chip. We expect that microfluidic skin on a chip with vasculature can reproduce skin reaction to cosmetic products and drugs and complement animal models.

Hard Mask의 종류 및 높이가 Glass Microfluidic Chip 제작에 미치는 영향

박병선(Byongson Park),송시몬(Simon Song) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

This paper compares the effects of a poly silicon mask and a chrome mask on the fabrication of a glass microfluidic chip. Although a poly-dimethylsiloxane (PDMS) is frequently used for a microfluidic chip due to an easy fabrication method and the replication of a chip by molding, there are many restrictions for wide applications because of the hydrophobic surface properties of PDMS. In contrast, a glass chip has a superior surface properties for a variety of biochemical analyses despite a complicated fabrication processes. Generally, a glass chip is fabricated by using wet etching process which uses buffered oxide etchant (BOE) to etch a glass substrate after making a pattern onto a glass wafer. We fabricate a glass microfluidic chip and examine the channel surface quality using different materials and height of hard masks. Poly silicon and chrome with different heights are deposited onto glass wafers. After making a microchannel pattern, we wet-etch the glass wafers, and examine channel surface quality using microscope. The results indicate that a poly-silicon hard mask leads to a smooth channel surfaces compared to a chrome mask despite a little complicated fabrication method.

Microfluidic platform for cell analysis using through-polydimethylsiloxane micro-tip electrode array

Shin, Young-min,Ha, Joon-Geun,Kim, Yong-Kweon,Lee, Seung-Ki,Park, Jae-Hyoung Elsevier 2019 MICROELECTRONIC ENGINEERING Vol.215 No.-

<P><B>Abstract</B></P> <P>In this study, we present the fabrication and measurement of a microfluidic system combined with a through-polydimethylsiloxane (PDMS) microtip electrode that can be used to measure the photosynthetic reaction of green algae cells in the microfluidic channel. The conventional single-cell based method has a disadvantage of low efficiency. To solve this problem, we propose a method of electrical feed-through interconnection of a microfluidic channel platform using a microtip electrode array. Silicon microtip arrays were fabricated using a combination of processes using deep reactive ion etching (DRIE) and reactive ion etching (RIE) steps. In the RIE process, the shape of the cylindrical silicon pillar changed from a cylinder to a probe shape according to the local change of the side-wall etching rate of the silicon pillar. The local ultra-micro electrode (UME) structure was fabricated using a self-alignment fabrication method without additional photolithography steps, and its electrochemical properties were confirmed using a cyclic voltammetry (CV) experiment. The photosynthetic algae cells were stacked in the PDMS microfluidic chip and then combined with the microtip electrode array using an acrylic jig. After assembling the microtip electrode array, the microtip was confirmed to penetrate the PDMS thin film through the CV experiment. When irradiated with light, the current induced by the oxygen produced by a photosynthetic reaction in the algae cells (stacked in the PDMS microfluidic chip) was measured using the microtip electrode array. Further, experiments were conducted to measure the force applied by the acrylic jig when combining the microtip electrode array with the PDMS microfluidic chip.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The silicon microtip arrays were fabricated using a deep reactive ion etching (DRIE) and reactive ion etching (RIE) steps. </LI> <LI> The local ultra-micro electrode (UME) structure was fabricated using a self-alignment fabrication method. </LI> <LI> The UME electrochemical properties were confirmed using a cyclic voltammetry experiment. </LI> <LI> The photosynthetic algae cells were stacked in the PDMS chip and then combined with the microtip electrode array using a jig. </LI> <LI> The photosynthetic reaction current in algae cells (stacked in the PDMS chip) was measured using the microtip electrode. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Polymers for Microfluidic Chips

송시몬,이근용 한국고분자학회 2006 Macromolecular Research Vol.14 No.2

Microfluidic systems have attracted much research attention recently in the areas of genomics, proteomics, pharmaceutics, clinical diagnostics, and analytical biochemistry, as they provide miniaturized platforms for conven tional analysis techniques. The microfluidic systems allow faster and cheaper analysis using much smaller amounts of sample and reagent than conventional methods. Polymers have recently found useful applications in microfluidic systems due to the wide range of available polymeric materials and the relative ease of chemical modification. This paper discusses the fundamentals of microfluidic systems and the roles, essential properties and various forms of polymers used as solid supports in microfluidic systems, based on the recent advances in the use of polymers for microfluidic chips.

미세유체칩내 electrode의 opening window형태에 따른 유전전기영동력 특성 규명

이재우,곽태준,윤대성,이상우,Lee, Jaewoo,Kwak, Tae Joon,Yoon, Dae Sung,Lee, Sang Woo 대한의용생체공학회 2013 의공학회지 Vol.34 No.4

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.

Neural Stem Cell Differentiation Using Microfluidic Device-Generated Growth Factor Gradient

( Ji Hyeon Kim ),( Jiyeon Sim ),( Hyun-jung Kim ) 한국응용약물학회 2018 Biomolecules & Therapeutics(구 응용약물학회지) Vol.26 No.4

Neural stem cells (NSCs) have the ability to self-renew and differentiate into multiple nervous system cell types. During embryonic development, the concentrations of soluble biological molecules have a critical role in controlling cell proliferation, migration, differentiation and apoptosis. In an effort to find optimal culture conditions for the generation of desired cell types in vitro, we used a microfluidic chip-generated growth factor gradient system. In the current study, NSCs in the microfluidic device remained healthy during the entire period of cell culture, and proliferated and differentiated in response to the concentration gradient of growth factors (epithermal growth factor and basic fibroblast growth factor). We also showed that overexpression of ASCL1 in NSCs increased neuronal differentiation depending on the concentration gradient of growth factors generated in the microfluidic gradient chip. The microfluidic system allowed us to study concentration-dependent effects of growth factors within a single device, while a traditional system requires multiple independent cultures using fixed growth factor concentrations. Our study suggests that the microfluidic gradient-generating chip is a powerful tool for determining the optimal culture conditions.

Water-assisted femtosecond laser ablation for fabricating three-dimensional microfluidic chips

Yan Li,Shiliang Qu 한국물리학회 2013 Current Applied Physics Vol.13 No.7

When the femtosecond laser focused in the water, the breakdown will be induced. The generated highspeed jet and shock wave can be used to etch silica glass for fabricating three-dimensional (3D)microfluidic chips. We present a simple and practical method to produce 3D multilayer microfluidic chips in silica glass. This method offers high design flexibility and fabricating feasibility. We also introduce a convenient cleaning method for diluting and ejecting the ablated debris from microchannel. Therefore, the femtosecond laser induced high-speed jet and shock wave can be used to fabricate complex microfluidic chips in silica glass. Experimental results show that the diameter of microchannel is uniform and the complexity of the microfluidic chip is under control. As a proof of principle, we demonstrate the feasibility of the fabricating process by using the water-assisted femtosecond laser ablation.

Easy module chip platform for microfluidics

이태재 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

Microfluidic technology is widely interested in many industrial fields. However, the complex and unique designs of microfluidic device is obstacle to expend its applications. Some scientists have tried to divide the complex function of microfluidic devices as several unit functional devices. However, the connectivity and the usage of the previous devices are still uncomfortable. Here we introduce an easy module chip platform for microfluidics. Each of modules are represent an unit function of microfluidic device such as Plasma separator, Valve, Mixer, DNA extractor, PCR, Sensor and etc. The module chip is consisted with a case frame, a core and silicon connectors. Module chips are easily connected and disconnected with each other using magnet force. The silicon connector is good for the liquid transportation without leakage. I believe that this module chip platform will be useful for not only researcher but also young students.

Recent advances in surface-enhanced Raman scattering detection technology for microfluidic chips

Chen, Lingxin,Choo, Jaebum WILEY-VCH Verlag 2008 Electrophoresis Vol.29 No.9

<P>Microfluidic chip devices and their application to sensitive chemical and biological analyses have attracted significant attention over the past decade. The miniaturization of reaction systems offers practical advantages over conventional benchtop systems. In this case, however, a highly sensitive on-chip detection method is important for the monitoring of chemical reactions as well as for the detection of analytes inside the channel because the detection volume in a micrometer-size channel is extremely small. Recently, a surface-enhanced Raman scattering (SERS) technique is being regarded as a potential candidate for the highly sensitive detection of analytes in a microfluidic chip. This review provides a general survey and an in-depth look at recent developments in SERS techniques for the biological/environmental analysis of minute analytes in a microfluidic chip.</P>