• Journal of the Korean Ceramic Society
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• v.54 no.1
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• pp.66-69
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• 2017

In this study, the fabrication and electrical properties of aligned single-walled carbon nanotube (SWCNT) networks using a template-based fluidic assembly process are presented. This complementary metal-oxide-semiconductor (CMOS)-friendly process allows the formation of highly aligned lateral nanotube networks on $SiO_2/Si$ substrates, which can be easily integrated onto existing Si-based structures. To measure outstanding electrical properties of organized SWCNT devices, interfacial contact resistance between organized SWCNT devices and Ti/Au electrodes needs to be improved since conventional lithographic cleaning procedures are insufficient for the complete removal of lithographic residues in SWCNT network devices. Using optimized purification steps and controlled developing time, the interfacial contact resistance between SWCNTs and contact electrodes of Ti/Au is reached below 2% of the overall resistance in two-probe SWCNT platform. This structure can withstand current densities ${\sim}10^7A{\cdot}cm^{-2}$, equivalent to copper at similar dimensions. Also failure current density improves with decreasing network width.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.482-485
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• 2002

Development projects in KAIST rotted to the micro thermal device is introduced. Multi disciplinary research team is composed by combustion group and semiconductor group in KAIST and catalyst research center in KRICT to develop micro thermal/fluidic device and various items are on development. Among the projects, various kind of componenst that is required by the micro thermal devicesystem is introduced. Technology related to development of micro combustor, Micro igniter, micro fabrication of 3D structure, micro reactor and micro catalyst preparation is introduced.

• Journal of Energy Engineering
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• v.17 no.2
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• pp.67-76
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• 2008

A thermal-hydraulic integral effect test facility, ATLAS (Advanced Thermal-hydraulic Test Loop for Accident Simulation), has been constructed at KAERI (Korea Atomic Energy Research Institute). Recently several integral effect tests for the reflood period of a LBLOCA (Large Break LOss of Coolant Accident) of the APR1400 have been performed with the ATLAS. In the APR1400 a high flow condition is changed to a low flow condition due to an fluidic device during an operation of the SIT. As the self-controlled fluidic device was not installed in the ATLAS, a set of characterization tests was performed to simulate its injection capability from the SIT for the APR1400 simulation. In the ATLAS the required SIT flow rate in the high flow condition was acquired by installing orifices with an optimized flow area to throttle the SIT discharge line and the low flow condition was achieved by changing the opening of the flow control valve in the SIT injection line. The test results showed that the safety injection systems of the ATLAS could simulate the required high and low flow rates of the SIT for the APR1400 simulation efficiently.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2781-2784
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• 2007

Early detection of a disease is important to tackle treatment issues in a better manner. Several diagnostic techniques are in use, these days; for such purpose and tremendous research is going on to develop newer and newer methods. However, more work is required to be done to develop cheap and reliable early detection techniques. Micro-fluidic chips are also playing key role to deliver new devices for better health care. The present study focuses on a review of recent developments in the interrogation of different techniques and present state-of-the-art of microfluidic sensor for better, quick, easy, rapid, early, inexpensive and portable POCT (Point of Care testing device) device for a particular study, in this case, bone disease called osteoporosis. Some simulations of the microchip are also made to enable feasibility of the development of a blood-chip-based system. The proposed device will assist in early detection of diseases in an effective and successful manner.

• Journal of Sensor Science and Technology
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• v.13 no.5
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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.

• Journal of Biomedical Engineering Research
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• v.32 no.1
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• pp.32-36
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• 2011

The insufflators in endoscopic surgery supply carbon dioxide to make the air-filled cavity in the abdomen. It contains many kinds of pneumatic and electronic parts and they are connected with the air tubes and electrical wires. The printed circuit boards (PCB) perform wiring, holding and cooling tasks in electronic systems. In this study, the PCB is used as the air channel for insufflators to decrease the cost, volume, and the malfunction according to aging of the device. Three layers of PCB made of FR4 are combined with prepreg as adhesive which has the internal airway channel according to the design. By mounting the pressure sensors and valves, the PCB based fluidic system is implemented. After calibration of flow sensor, the flow rate of the gas also can be measured. The climate test, temperature test, and biocompatibility test showed this idea can be used in insufflators for laparoscopic surgery.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.6
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• pp.573-576
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• 2009

We present a passive flow-rate regulator, capable to compensate inlet pressure variation and to maintain a constant flow-rate for precise liquid control. Deflection of the parallel membrane valves in the passive flowrate regulator adjusts fluidic resistance according to inlet fluid pressure without any external energy. Compared to previous passive flow-rate regulators, the present device achieves precision flow regulation functions at the lower threshold compensation pressure of 20kPa with the simpler structure. In the experimental study, the fabricated device achieves the constant flow-rate of $6.09{\pm}0.32{\mu}l/s$ over the inlet pressure range of $20{\sim}50$ kPa. The present flow-rate regulator having simple structure and lower compensation pressure level demonstrates potentials for use in integrated micropump systems.

• Journal of Biomedical Engineering Research
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• v.40 no.5
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• pp.151-157
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• 2019

An acoustofluidic device using conductive liquid-based electrodes was developed for malaria parasite separation from white blood cells. In this device, the electrode channels filled with a conductive liquid were used to generate standing surface acoustic waves (SSAWs) in a fluidic channel, which can overcome the limitation of conventional patterned metal electrodes. Separation performance of the device was evaluated using fluorescent polystyrene particles with two different sizes (2 and $10{\mu}m$ diameters), which were successfully separated. In addition, a mixture of malaria parasites and white blood cells were also efficiently separated with high purity of ~98% in the CL-SSAW device at the flow rate of $12{\mu}l/min$.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.4
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• pp.40-46
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• 2006

The market of programmable implantable pumps has bound to a monopolistic situation, inducing high device costs, thus making them inaccessible to most patients. Micro-mechanical and medical innovations allow improved performances by reducing the dimensions. This affects the consumption and weight, and, by reducing the number of parts, the cost is also affected. This paper presents the procedure followed to design an innovative implantable drug delivery system. This drug delivery system consists of a low flow pump which shall be implanted in the human body to relieve pain. In comparison to classical known solutions, this pump presents many advantages of high interest in both medical and mechanical terms. The first section of the article describes the specifications which would characterize a perfect delivery system from every points of view. This concerns shape, medication, flow, autonomy, biocompatibility, security and sterilization ability. Afterwards, an overview of existing systems is proposed in a decisional tree. Positive displacement motorized pumps are classified into three main groups: the continuous movement group, the fractioned translation group and the alternative movement group. These systems are described and the different problems which are specific to these mechanisms are presented. Since none of them fully satisfy the specifications, an innovation is justified.. The decisional tree is therefore extended by adding new principles: fractioned refilling and fractioned injection within the fractioned translation movement group, spider guiding system within the alternative translation movement group, rotational bearing guided device and notch hinge guided device in the alternative rotation movement group.

• Journal of Biomedical Engineering Research
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• v.34 no.4
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• pp.189-196
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• 2013

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.