• 설비공학논문집
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• 제23권1호
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• pp.23-31
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• 2011

An analysis has been conducted of the flow characteristics and pumping performance of a thermopneumatic micropump with electrically conducting fluid. In the present study, considered is a thermopneumatic micropump for electrically conducting fluids with electromagnetic resistance alternately exerted at the inlet and outlet by alternately applied magnetic fields. A model of Prescribed Deformation is used for the motion of the membrane. Here, the pumping performance of the micropump and flow characteristics of the electrically conducting fluid are investigated in the range of Hartmann number less than 30. The current numerical study shows that the net flow rate through the micropump is almost proportional to the strength of the applied magnetic field.

• 대한기계학회논문집B
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• 제33권10호
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• pp.778-782
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• 2009

Recently, we developed a simple thermopneumatic micropump having neither a membrane nor a valve. This micropump discharges liquid by a thermopneumatic pressure and refill by a capillary attraction. In case of the micropump driven by the capillary attraction, the flow characteristic depends mainly on the geometry of the micropump. In this paper, we investigated the influence of the geometry of the micropump on the performance of the micropump to illustrate the properness of the micropump shape. We analyzed the micropump characteristics of six types having different geometries by FVM simulation with a commercial CFD tool. Also we fabricated the micropumps with PDMS and glass by micromachining, and tested the performances. The simulation and the test results illustrate that the discharge volume and the discharge time depend on the chamber volume. The expansion angle of the inlet channel location has influence on the refill time, while the front air channel direction has influence on the backward flow loss.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권6호
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• pp.342-346
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• 2004

A thermopneumatic-actuated polydimethylsiloxane (PDMS) micropump has been fabricated and their properties are characterized. The diffusers are used as a flow-rectifying element instead of passive check valves. The advantages of the proposed microvalve are of the low cost fabrication process and the transparent optical property using PDMS and indium tin oxide (ITO) glass. We presented the PDMS micropump that is easily integrated with the in-channel PDMS microvalves on the same substrate. The flowrate of the micropump increases linearly as the applied pulse voltage to the ITO heater increases. The fabricated ITO heater resistance is 6.54k$\Omega$. The peak of the flow rate is observed at the duty ratio of 10% for the applied pulse voltage of 55V at 6Hz and the maximum flow rate of 78nl/min is measured.

• 설비공학논문집
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• 제17권7호
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• pp.642-648
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• 2005

This study has been conducted to investigate the thermopneumatic and flow characteristics of diffuser/nozzle based thermopneumatic micropumps. In this study, a transient three-dimensional numerical analysis using FSI (Fluid-Structure Interaction) model has been employed to analyze the effects of the interaction between the membrane and two fluids (air and water) in the thermopneumtic micropump. The transient temperature and pressure in the cavity, the transient displacements of the membrane and the net flow rate of the micropump have been closely calculated for the frequency of 1 Hz. It has been found that the difference of the flow rates at the inlet and outlet is larger in the cooling period than in the heating period and that the duty ratio is very important in association with pump performance because the temperature in the cavity ascends drastically in the heating period and descends slowly in the cooling period. This study can be regarded as fundamental understandings for the design and analysis of thermopneumatic micropumps.

• 설비공학논문집
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• 제19권9호
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• pp.654-661
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• 2007

This study has been conducted to investigate the pumping characteristics of diffuser-nozzle based thermopneumatic micropumps with different input voltages and frequencies. In this study, the displacements of the membrane have been obtained changing the input voltage and frequency in load-free state because it is very difficult to measure the displacement of the membrane in an actual load state. It has been found that the amplitude of the membrane displacement increases as the input voltage increases. The pressure head of the thermopneumatic micropump increases almost linearly over some range of the input voltage and decreases almost linearly as the frequency increases. Also, the results show that the thermopneumatic micropump can pump the fluid over a certain input voltage. This study can be utilized as basic data for design and evaluation of thermopneumatic micropumps.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.369-370
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• 2009

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권4호
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• pp.137-141
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• 2004

In this paper, a thermopneumatic PMDS (polydimethlysiloxane) micropump with nozzle/diffuser elements is presented. The micropump is composed of nozzle/diffuser elements as dynamic valves, an actuator consisting of a circular PDMS diaphragm and a Cr/Au heater on a glass substrate. Four PDMS layers are used for fabrication of an actuator chamber, actuator diaphragm by a spin coating process, spacer layer, and nozzle/diffuser by the SU-8 molding process. The radius and thickness of the actuator diaphragm is 2 mm and 30 ${\mu}{\textrm}{m}$, respectively. The length and the conical angle of the nozzle/diffuser elements are 3.5 mm and 20$^{\circ}$, respectively. The actuator diaphragm is driven by the air cavity pressure variation caused by ohmic heating and natural cooling. The flow rate of the micropump in the frequency domain is measured for various duty cycles of the square wave input voltage. When the square wave input voltage of 5 V DC is applied to the heater, the maximum flow rate of the micropump is 44.6 ${mu}ell$/min at 100 Hz with a duty ratio of 80% under the zero pressure difference.

• Journal of Mechanical Science and Technology
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• 제19권2호
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• pp.649-654
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• 2005

This paper presents fabrication and drive test of a peristaltic PDMS micropump actuated by the thermopneumatic force. The micropump consists of the three peristaltic-type actuator chambers with microheaters on the glass substrate and a microchannel connecting the chambers and the inlet/outlet port. The micropump is fabricated by the spin-coating process, the two-step curing process, the JSR (negative PR) molding process, and etc. The diameter and the thickness of the actuator diaphragm are 2.5 mm and $30{\mu}m$, respectively. The meniscus motion in the capillary tube is observed with a video camera and the flow rate of the micro pump is calculated through the frame analysis of the recorded video data. The maximum flow rate of the micropump is about $0.36\;{\mu}L/sec$ at 2 Hz for the zero hydraulic pressure difference when the 3-phase input voltage is 20 V.

• 대한기계학회논문집A
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• 제32권9호
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• pp.720-727
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• 2008

Microfluidic single chip integrating thermopneumatic micropump and micro check valve are developed. The micropump and micorvalve are made of biocompatible materials, glass and PDMS, so as to be applicable to the biochip. By using the passive-type check valve, backward flow and fluid leakage are blocked and flow control is stable and precise. The chip is composed of three PDMS layers and a glass substrate. In the chip, flow channel and pump chamber were made on the PDMS layers by the replica molding technique and pump heater was made on the glass substrate by Cr/Au deposition. Diameter of the pump chamber is 7 mm and the width and depth of the channel are 200 and $180{\mu}m$, respectively. The PDMS layers chip and the heater deposited glass chip are combined by a jig and a clamp for pumping operation, and they are separable so that PDMS chip is used as a disposable but the heater chip is able to be used repeatedly. Pumping performance was simulated by CFD software and investigated experimentally. The performance was the best when the duty ratio of the applied voltage to the heater was 33%.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권2호
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• pp.88-92
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• 2006

We present a microfluidic system with microvalves and a micropump that are easily integrated on the same substrate using the same fabrication process. The fabricated microfluidic system is suitable for use as a disposable device and its characteristics are optimized for use as a micro chemical analysis system (micro-TAS) and lab-on-a-chip. The system is realized by means of a polydimethylsiloxane (PDMS)-glass chip and an indium tin oxide (ITO) heater. We demonstrate the integration of the micropump and microvalves using a new thermopneumatic-actuated PDMS-based microfluidic system. A maximum pumping rate of about 730 nl/min is observed at. a duty ratio of 1 $\%$ and a frequency of 2 Hz with a fixed power of 500 mW. The measured power at flow cut-off is 500 mW for the microvalve whose channel width, depth and membrane thickness were 400 $\mu$m, 110 $\mu$m, and 320 $\mu$m, respectively.