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15th International Conference on Miniaturized systems for Chemistry and Life Sciences 2011, MicroTAS 2011

作者： Lee, Donghee Hyun, Ji-Chul Hong, Sung A. Yang, Sung Graduate-program of Medical System Engineering Korea Republic of School of Mechatronics Korea Republic of Department of Nanobio Materials and Electronics GIST Korea Republic of

ISBN: (纸本)9781618395955

In this study, a method to modify hydrophobic PDMS (Polydimethylsiloxane) surface to be long-lasting hydrophilic surface by applying atmospheric-pressure plasma polymerization is proposed. To enhance the sustainability of the modified hydrophilic PDMS, two kinds of plasma polymerized layers were implemented on the surface of the PDMS block sequentially. The highly cross-linked hydrocarbon layer deposited by atmospheric-pressure plasma polymerization from CH 4 plays a role as a physical barrier layer (PBL) to prevent hydrophobic recovery of the hydrophilic layer deposited from TEOS (Tetraethylorthosilicate) and O2. The modified PDMS surface shows long-lasting superhydrophilic wetting property over 28 days of aging time. Copyright © (2011) by the Chemical and Biological Microsystems Society.

关键词： Surface treatment

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Silica nanochannel device for pH sensing based on surface charge density changes

Silica nanochannel device for pH sensing based on surface ch...

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2010 10th IEEE Conference on Nanotechnology, NANO 2010

作者： Lee, Sang Young Yoon, Sang Youl Lee, Kyeong-Hwan Yang, Sung Department of Nanobio Material and Electronics School of Information and Mechatronics GIST Korea Republic of Graduate- Program of Medical System Engineering Biomedical Micro/Nano Device Laboratory GIST Korea Republic of

ISBN: (纸本)9781424470334

This paper demonstrates a novel micro/nano fluidic device for continuous pH sensing of small fluid volumes. The working principle of the device is based on the change of the surface charge density within the silica nano channels with respect to the pH levels of the electrolyte. In order to measure pH levels of various solutions, AC potential is applied along the silica nanochannels which have 50 nm depth, 2 μm width, and 30 μm length. The running current along the nanofluidic channels is directly measured with respect to pH levels. It was found that the running current is inversely proportional to pH levels regardless of ion concentrations. ©2010 IEEE.

关键词： Electrolytes

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A novel peristaltic micropump using three wings with different widths for fluid circulation

A novel peristaltic micropump using three wings with differe...

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14th International Conference on Miniaturized systems for Chemistry and Life Sciences 2010, MicroTAS 2010

作者： Mun, Byung Phil Park, Chang Ju Yoo, Sung Keun Lee, Jong Hyun School of Information and Mechatronics GIST Gwangju Korea Republic of Graduate Program of Medical System Engineering GIST Gwangju Korea Republic of Dept. of Nanobio Materials and Electronics GIST Gwangju Korea Republic of

ISBN: (纸本)9781618390622

This paper reports a novel micropump to effectively rotate fluid in a circular channel. The proposed micropump having different wing widths, which squeezes the flexible part of the fluidic channel at a different time interval, provides a peristaltic effect with a single pneumatic pressure source. This allows simple operation and easy integration with a micro total analysis system (μ-TAS).

关键词： Flexible structures

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Contamination-free cell lysis microfluidic device using cell cross over

Contamination-free cell lysis microfluidic device using cell...

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13th International Conference on Miniaturized systems for Chemistry and Life Sciences, MicroTAS 2009

作者： Mun, Byung Phil Jung, Seung Mo Yoon, Sang Youl Lee, Jong Hyun Yang, Sung School of Information and Mechatronics Gwangju Institute of Science and Technology Korea Republic of Graduate Program of Medical System Engineering Gwangju Institute of Science and Technology Korea Republic of Department of Nanobio Materials and Electronics Gwangju Institute of Science and Technology Korea Republic of

ISBN: (纸本)9780979806421

Complicated and time-consuming cell purification processes prevent a micro cell lysis device from integrating with LOC (Lab-on-a-chip) or μ-TAS (μ-Total Analysis system) devices for cell analysis. In this paper, we present a microfluidic cell lysis device using a contamination-free cell cross over method in order to minimize the cell pretreatment procedure. © 2009 CBMS.

关键词： Microfluidics

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Largely deformable surface electrode based on PDMS for cortical recording and stimulation

Largely deformable surface electrode based on PDMS for corti...

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International IEEE/EMBS Conference on Neural engineering, CNE

作者： Namsun Chou Soonki Yoo Sohee Kim School of Mechatronics Gwangju Institute of Science and Technology Gwangju South Korea Faculty of the school of Mechatronics and Graduate Program of Medical System Engineering Gwangju Institute of Science and Technology Gwangju South Korea

This paper describes a largely deformable surface electrode based on poly-dimethylsiloxane (PDMS) substrate, including its fabrication, electrochemical characterization, adhesion test, and bending test results. The fabricated electrode is made of both PDMS and parylene C layers, which are completely attached to each other. Between the two parylene layers gold patterns are located in the mechanical neutral plane. In the fabrication process, PDMS is supported by parylene layer when the metal layer is sputter deposited, resulting in no cracks. The electrode provides highly deformable neural electrode structure with mechanical integrity and electrical stability. With these advantages, it is expected to be suitable in stable neural recording and stimulation.

关键词： Electrodes Adhesives Substrates Metals Impedance Impedance measurement

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Selectively bonded polymeric check valve for the reliable regulation of intraocular pressure

Selectively bonded polymeric check valve for the reliable re...

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作者： Im, Seongmin Mun, Byungphil An, Jaeyong Choi, Jongchan Yang, Sung Lee, Jonghyun School of Mechatronics Gwangju Institute of Science and Technology Gwangju Korea Republic of Graduate Program of Medical System Engineering Gwangju Institute of Science and Technology Gwangju Korea Republic of Department of Nanobio Materials and Electronics Gwangju Institute of Science and Technology Gwangju Korea Republic of

ISBN: (纸本)9789898425379

A glaucoma drainage device for the regulation of intraocular pressure is presented. The device consists of three biocompatible polymer layers: the cover (top layer), the diaphragm (intermediate layer), and the baseplate with a cannular (bottom layer). Finite element analyses (FEA) were performed to find optimal design parameters for the targeted cracking pressure: the diameter of orifice, the thickness of intermediate layer, the width of the channel, and the overlapped length of the orifice over valve seat. Top and bottom layers were made by polydimethylsiloxane (PDMS) replica molding process, and an intermediate thin layer with through-holes was fabricated by PDMS fill-in molding method and hydrophobic treatment. The overlapped area of the bottom layer was coated with Cr and Au by using PDMS as a shadow mask. Metal layers are not to be bonded between the bottom and the intermediate layers so that the device showed the enhanced reliability in operation and the higher yield in production. Oxygen plasma treatment was performed for irreversible bonds between separate three PDMS layers. The experimental cracking pressure of the fabricated valve was 2.50 kPa, which is very close to the target value (2.67 kPa). The experiments showed that the proposed polymer check valve can regulate the pressure of the aqueous humour, fluid in an anterior chamber, within the normal intraocular pressure range (15-20mmHg) with a high repeatability.

关键词： Polydimethylsiloxane

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Microfluidic device for refractive index measurement of fluid sample

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Procedia engineering 2010年 5卷 1340-1343页

作者： Sang Youl Yoon Sung Yang Graduate-program of Medical System Engineering GIST Gwangju Republic of Korea School of Information & Mechatronics GIST Gwangju Republic of Korea Department of Nanobio Materials and Electronics GIST Gwangju Republic of Korea

This paper represents a novel microfluidic device for simple refractive index (RI) measurement of fluid sample with sub microliter volume. The defocusing imaging technique using a three pinhole aperture plate is implemented for the refractive index measurement. For the self-calibration, the microfluidic device has a measurement region and a self-calibration region, and both regions are designed to be captured on single image frame. Thus, the refractive index of a sample fluid is automatically calculated with the self-calibration. For the demonstration of the proposed device, standard refractive index liquids with the refractive indices of 1.300, 1.400, 1.500, 1.600 and 1.700 are used. The measured refractive index has the maximum deviation of 0.0036 (0.24%) from the standard refractive index values.

关键词： Refractometer Microfluidic device Defocusing imaging Three pinhole Self-calibration Refractive index measurement

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A microassembly process to realize angular vertical comb electrodes for a gimbal-less two-axis electrostatic scanner

A microassembly process to realize angular vertical comb ele...

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IEEE International Conference on Micro Electro Mechanical systems

作者： Min-Ho Jun Seunghwan Moon Jong-Hyun Lee Graduate School of Information and Mechatronics Gwangju Institute of Science and Technology Gwangju South Korea Graduate-program of Medical System Engineering Gwangju Institute of Science and Technology Gwangju South Korea

This paper proposes a microassembly process that easily realizes a gimbal-less two-axis electrostatic MEMS scanner with fixed angular vertical comb electrodes (FAVCs). The fabrication steps can be remarkably reduced by employing a microassembly, as there is no need to add an insulation layer and conduct a multi-step etching process for SVCs. The reduction in the number of fabrication steps also improves the device yield and reduces fabrication errors. The proposed scanner can be readily applied to various optical applications, as the slow axis is driven by quasi-static operation, allowing the amplitude of the scanning angle to remain constant within a specific frequency range.

关键词： Microassembly Springs Electrostatics Silicon Optical device fabrication Mirrors

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Micromachined ultrasonic transducer using piezoelectric PVDF film to measure the mechanical properties of bio cells

Micromachined ultrasonic transducer using piezoelectric PVDF...

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IEEE SENSORS

作者： Minhyun Jung Man Geun Kim Jong-Hyun Lee School of Information and Mechatronics Gwangju Institute of Science and Technology Gwangju South Korea Graduate-program of Medical System Engineering Gwangju Institute of Science and Technology Gwangju South Korea

We proposed a new method to measure the frequency-dependent attenuation of bio cells using piezoelectric ultrasonic transducer. The polyvinylidene fluoride (PVDF) polymer was employed as piezoelectric material to take an advantage of its low acoustic impedance (2.7 Mrayl) so that the transmission of acoustic power will be improved by impedance matching with that of liquid medium. The thickness of PVDF film is 110 ¿m and the resonance frequency of the 1 st thickness mode is 8.7 MHz. In order to characterize the fabricated ultrasonic transducer, a transducer and an acoustic wave reflector were positioned face to face. The output voltage for reflected transmitted ultrasonic wave was measured with impulse method and was transformed into the Round Trip Insertion Loss (RTIL) where the dominant frequency ranges from 5 MHz to 9 MHz.

关键词： Ultrasonic transducers Piezoelectric films Mechanical variables measurement Ultrasonic variables measurement Mechanical factors Acoustic measurements Frequency measurement Attenuation measurement Polymers Piezoelectric materials

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PDMS through-hole fabrication by soft lithography using CH4/He atmospheric RF plasma surface treatment

PDMS through-hole fabrication by soft lithography using CH4/...

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IEEE International Conference on Micro Electro Mechanical systems

作者： Jongchan Choi Kyeong-Hwan Lee Ji A Choi Sun Hwa Lee Sung Yang School of Information and Mechatronics Gwangju Institute of Science and Technology Gwangju South Korea Department of Rural and Biosystems Engineering Chonnam National University Gwangju South Korea Institute of Medical System Engineering Gwangju Institute of Science and Technology Gwangju South Korea Department of Nanobio Materials and Electronics School of Information and Mechatronics Graduate Program of Medical System Engineering Gwangju Institute of Science and Technology Gwangju South Korea

This paper presents a PDMS micro through-hole molding method by simple soft lithography process in which the surface of a master mold and a substrate is treated by atmospheric CH 4 /He RF plasma to feature hydrophobic property on the surface. Rectangular and circular-shaped PDMS micro through-hole layers are made by the proposed fabrication method. As one of the applications of the PDMS micro through-hole layer for multi-layered systems, a radial concentration gradient generator including a micro through-hole layer is constructed and its performance is tested. The micro through-holes fabricated by the proposed method are well-defined. The concentration gradients measured in radial directions are in a similar level. Also, the tearing problem, which is often happened in spin-coating and lift-off molding methods, is not observed during the fabrication process of the PDMS micro through-holes. Therefore, we believe that the proposed fabrication method contributes to improve the technology for PDMS through-hole fabrication.

关键词： Surface treatment Fabrication Plasmas Substrates Helium Generators Radio frequency

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