• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.5
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• pp.241-246
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• 2004

In this paper, we present a novel integrated cell processor to handle individual embryos. Its functions are composed of transporting, isolation, orientation, and immobilization of cells. These functions are essential for biomanipulation of single cells, and have been typically carried out by a proficient operator. The purpose of this study is the automation of these functions for safe and effective cell manipulation using a MEMS based cell processor. This device is realized with a relatively simple design and fabrication process. Experimental results indicate that it can act as an efficient substitute for essential but very tiresome and repetitive manual work while contributing significantly to the improvement of speed and success rate of operation by facilitating cell manipulation. The cell viability test for the device is studied through the distribution of mitochondria in mice embryos and cultivation of cells for 86h.

• Tribology and Lubricants
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• v.18 no.4
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• pp.267-272
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• 2002

Nano adhesion between SPM(scanning probe microscope) tips and DDPO$_4$(octadecylphosphoric acid ester.) and ODPO$_4$(octadecylphosphoric acid ester) SAM(self-assembled monolayer.) was experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM(atomic force microscope) and LFM(lateral force microscope) modes with the applied normal load. DDPO$_4$ and ODPO$_4$ SAM were formed on Ti and TiOx surfaces. Ti and TiOx were coated on the Si wafer by ion sputtering. Adhesion and friction of DDPO$_4$ and ODPO$_4$ SAM surfaces were compared with those of OTS(octadecyltrichlorosilane) SAM and DLC surfaces. DDPO$_4$ and ODPO$_4$ SAM converted the Ti and TiOx surfaces to be hydrophobic. When the surface was hydrophobic, the adhesion and friction forces were found lower than those of bare surfaces. Work of adhesion was also discussed to explain how the surface was converted into hydrophobic Results also showed that tribological characteristics of DDPO$_4$ and ODPO$_4$ SAM had good properties in the adhesion, friction, wetting angle and work of adhesion. DDPO$_4$ and ODPO$_4$ SAM could be one of the candidates for the bio-MEMS elements.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.130-130
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• 2009

This paper describes the temperature characteristics of polycrystalline 3C-SiC micro resonators. The 1.2 ${\mu}m$ and 0.4 ${\mu}m$ thick polycrystalline 3C-SiC cantilever and doubly clamped beam resonators with 60 ~ 100 ${\mu}m$ lengths were fabricated using a surface micromachining technique. Polycrystalline 3C-SiC micro resonators were actuated by piezoelectric element and their fundamental resonance was measured by a laser vibrometer in vacuum at temperature range of $25{\sim}200^{\circ}C$. The TCF(Temperature Coefficient of Frequency) of 60, 80 and 100 ${\mu}m$ long cantilever resonators were -9.79, -7.72 and -8.0 $ppm/^{\circ}C$. On the other hand, TCF of 60, 80 and 100 ${\mu}m$ long doubly clamped beam resonators were -15.74, -12.55 and -8.35 $ppm/^{\circ}C$. Therefore, polycrystalline 3C-SiC resonators are suitable with RF MEMS devices and bio/chemical sensor applications in harsh environments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.185-185
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• 2009

Micropump is very useful component in micro/nano fluidics and bioMEMS applications. Using the flexural vibration mode of PZT bar, a piezopump is successfully made. The PZT bar is polarized with thickness direction. The proposed structure for the piezo-pump consists of an input and an output port, piezoelectric ceramic actuator, actuator support, diaphragm. The traveling flexural wave along the bar is obtained by dividing two standing waves which are temporally and spatially phase shifted by 90 degrees from each other. Fluid is drawn into a forming chamber, eventually the forming chamber closes trapping the fluid therein. The finite elements analysis on the proposed pump model is carried out to verify its operation principle and design by the commercial FEM software. Components of piezopump were made, assembled, and tested to validate the concepts of the proposed pump and confirm the simulation results. The performance of the proposed piezopump the highest pressure level of 83.4kHz.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1194-1197
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• 2005

Micro nozzle is employed as a dynamic passive valve in micro fluidic devices. Micro nozzle array is used in micro droplet generation in bio-medical applications and propulsion device for actuating satellite and aerospace ship in vacuum environments. Aperture angle and the channel length of the micro nozzle affect its retification efficiency, and thus it is needed to produce micro nozzle precisely. MEMS process has a limit on making a micro nozzle with high-aspect ratio. Reactive ion etching process can make high-aspect ratio structure, but it is difficult to make the complex shape. Focused ion beam deposition has advantage in machining of three-dimensional complex structures of sub-micron size. Moreover, it is possible to monitor machining process and to correct defected part at simultaneously. In this study, focused ion beam deposition was applied to micro nozzle production.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1303_1304
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• 2009

With recent advanced in portable electric devices, wireless sensor, MEMS and bio-Mechanics device, the new typed power supply, not conventional battery but self-powered energy source is needed. Particularly, the system that harvests from their environments are interests for use in self powered devices. For very low powered devices, environmental energy may be enough to use power source. Therefore, in other to made piezoelectric energy harvesting device. The made 31type triple-morph cantilever was resulted from the conditions of $100k{\Omega}$, 0.25g, 154Hz respectively. The thick film was prepared at the condition of 6.57Vrms, and its power was $432.31{\mu}W$ and its thickness was $50{\mu}m$. And than, the fabricated piezoelectric cantilever was packaged for application.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.11
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• pp.2901-2919
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• 2012

Recent research in MEMS (Micro-Electro-Mechanical Systems) and wireless communication has enabled tracking of continuous objects, including fires, nuclear explosions and bio-chemical material diffusions. This paper proposes an energy-efficient scheme that detects and tracks different dynamic shapes of a continuous object (i.e., the inner and outer boundaries of a continuous object). EBCO (Efficient Boundary detection and tracking of Continuous Objects in WSNs) exploits the sensing capabilities of sensor nodes by automatically adjusting the sensing range to be either a boundary sensor node or not, instead of communicating to its neighboring sensor nodes because radio communication consumes more energy than adjusting the sensing range. The proposed scheme not only increases the tracking accuracy by choosing the bordering boundary sensor nodes on the phenomenon edge, but it also minimizes the power consumption by having little communication among sensor nodes. The simulation result shows that our proposed scheme minimizes the energy consumption and achieves more precise tracking results than existing approaches.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.4
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• pp.314-317
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• 2009

This paper describes the temperature characteristics of polycrystalline 3C-SiC micro resonators. The $1.2{\mu}m$ and $0.4{\mu}m$ thick polycrystalline 3C-SiC cantilever and doubly clamped beam resonators with $60{\sim}100{\mu}m$ lengths were fabricated using a surface micromachining technique. Polycrystalline 3C-SiC micro resonators were actuated by piezoelectric element and their fundamental resonance was measured by a laser vibrometer in vacuum at temperature range of $25{\sim}200^{\circ}C$. The TCF(Temperature Coefficient of Frequency) of 60, 80 and 100 On long cantilever resonators were -9.79, -7.72 and -8.0 ppm/$^{\circ}C$. On the other hand, TCF of 60, 80 and $100{\mu}m$ long doubly clamped beam resonators were -15.74, -12.55 and -8.35 ppm/$^{\circ}C$. Therefore, polycrystalline 3C-SiC resonators are suitable with RF MEMS devices and bio/chemical sensor applications in harsh environments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.220-221
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• 2008

With recent advanced in portable electric devices, wireless sensor, MEMS and bio-Mechanics device, the new typed power supply, not conventional battery but self-powered energy source is needed. Particularly, the system that harvests from their environments are interests for use in self powered devices. For very low powered devices, environmental energy may be enough to use power source. Therefore, in other to made piezoelectric energy harvesting device. The made 31 type triple-morph cantilever was resulted from the conditions of 100k$\Omega$, 0.25g, 154Hz respectively. The thick film was prepared at the condition of $6.57V_{rms}$, and its power was $432.31{\mu}W$ and its thickness was $50{\mu}m$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.5
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• pp.644-654
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• 2003

An analytical solution for a vertically stratified viscous flow in a microchannel with a rectangular cross-section is constructed, assuming fully developed laminar flow where the interfaces between the fluid layers are flat. Although the solution is for n-layer flow, restricted results to symmetrical three-layer flow are presented to investigate the effects of the viscosity and thickness ratios of the fluid layers and the aspect ratio of the microchannel on the flow field. Relations between the flow rate and thickness ratios of the fluid layers with varying viscosity distributions are found, considering the cross -sectional velocity profiles which vary noticeably with the three parameters and differ significantly from the velocity profiles of the flow between infinite parallel plates. Interfacial instability induced by the viscosity stratification in the microchannel is discussed referring to previous studies on the instability analysis for plane multilayer flow. Exact solution derived in the present study can be used for examining a diffusion process and three -dimensional stability analysis. More works are needed to formulate the equations including the effects of interfacial' tension between immiscible liquids and surface wettability which are important in microscale transport phenomena.