• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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• pp.197-201
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• 2002

This paper presents optimized design, fabrication and thermal characteristics of micro-heaters for thermal MEMS (micro electro mechanical system) applications using SOI and trench structures. The micro-heaters are based on a thermal measurement principle and contains thermal isolation regions of 10 ${\mu}m$-thick Si membranes consisting of oxide-filled trenches in the SOI membrane rim. The micro-heaters were fabricated with Pt-RTD on the same substrate via MgO buff layer between Pt thin-film and $SiO_2$ layer. The thermal characteristics of micro-heater with trench-free SOI membrane structure was $280^{\circ}C$ at input power 0.9 W; in the presence of 10 trenches, it was $580^{\circ}C$ due to reduction of the external thermal loss. Therefore, a micro-heater with trenches in SOI membrane rim structure provides a powerful and versatile alternative technology for enhancing the performance of micro-thermal sensors and actuators.

• 대한기계학회논문집B
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• 제26권12호
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• pp.1639-1645
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• 2002

Micro engine that includes Micro scale combustor is fabricated. Design target was focused on the observation of combustion driven actuation in MEMS scale. Combustor design parameters are somewhat less than the size recommended by feasibility test. The engine structure is fabricated by isotropic etching of the photosensitive glass wafers. Electrode formed by electroplating of the Nickel. Photosensitive glass can be etched isotropically with almost vertical angle. Bonding and assembly of structured photosensitive glass wafer form the engine. Combustor size was determined to be 1 mm scale. Movable piston is engraved inside the wafer. Ignition was done by nickel spark plug which was electroplated with thickness of 40 ${\mu}{\textrm}{m}$. The wafers were bonded by epoxy that resists high temperature. In firing test due to the bonding method and design tolerance pressure buildup by reaction was not confirmed. But ignition, flame propagation and actuation of micro structure from the reaction was observed. From the result basement of design and fabrication technology was obtained.

• 대한기계학회논문집A
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• 제26권9호
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• pp.1931-1942
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• 2002

In this paper a formulation of robust optimization is presented and illustrated by a design example of vibratory micro gyroscopes in order to reduce the effect of variations due to uncertainties in MEMS fabrication processes. For the vibratory micro gyroscope considered it is important to match the resonance frequencies of the vertical (sensing) and lateral (driving) modes as close as possible to attain a high sensing sensitivity. A deterministic optimization in which the difference of both the sensing and driving natural frequencies is minimized as an objective function results in highly enhanced performance but apt to be very sensitive to fabrication errors. The formulation proposed is to attain robustness of the performance by including the sensitivity of the response with respect to uncertain variables as a term of objective function to be minimized. This formulation is simple and practically applicable since no detail statistical information on fabrication errors is required. The geometric variables, beam width, length and thickness of vibratory micro gyroscopes are adopted as design variables and at the same time considered as uncertain variables because here occur the fabrication errors. A robustness test in terms of a percentage yield by using the Monte Carlo simulation has shown that the robust optimum produces twice more acceptable designs than the deterministic optimum. Improvement of robustness becomes bigger as the amount of fabrication errors is assumed larger. Considering that the magnitude of fabrication errors and uncertainties in a MEMS structure are comparatively large, the present method is illustrated to be a viable approach for a robust MEMS design.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1897-1901
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• 2003

Recently, with the development of semiconductor technology the miniaturization of products as well as parts and the products with high precision are being required. In addition as a national competitive power is increasingly effected by micro part development through micro machining and the secure of micro machining technology, the study of micro machining technology is being conducted in many countries. The goal of this study is to fabricate micro tool under the size of 30$\mu\textrm{m}$ and machine micro holes through micro tool fabrication by grinding, the application of ELID to grinding wheel and the measurement of surface roughness for micro tool.

• Design & Manufacturing
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• 제16권3호
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• pp.58-65
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• 2022

Micro-fluidic chip has been fabricated by lithography process on silicon or glass wafer, casting using PDMS, injection molding of thermoplastics or 3D printing, etc. Among these processes, 3D printing can fabricate micro-fluidic chip directly from the design without master or template for fluidic channel fabricated previously. Due to this direct printing, 3D printing provides very fast and economical method for prototyping micro-fluidic chip comparing to conventional fabrication process such as lithography, PDMS casting or injection molding. Although 3D printing is now used more extensively due to this fast and cheap process done automatically by single printing machine, there are some issues on accuracy or surface characteristics, etc. The accuracy of the shape and size of the micro-channel is limited by the resolution of the printing and printing direction or layering direction in case of SLM type of 3D printing using UV curable resin. In this study, the printing direction and thickness of each printing layer are investigated to see the effect on the size, shape and surface of the micro-channel. A set of micro-channels with different size was designed and arrayed orthogonal. Micro-fluidic chips are 3D printed in different directions to the micro-channel, orthogonal, parallel, or skewed. The shape of the cross-section of the micro-channel and the surface of the micro-channel are photographed using optical microscopy. From a series of experiments, an optimal printing direction and process conditions are investigated for 3D printing of micro-fluidic chip.

• 한국공작기계학회논문집
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• 제14권5호
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• pp.13-20
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• 2005

Micro EDM process is generally used for machining microholes, cavities, and three dimensional shapes. For machining micro structures, first of all, micro tool electrode is indispensable and WEDG system is proposed for tool fabrication method. When using WEDG, its machining characteristics are highly affected by many EDM parameters such as applied voltage, current, rotation speed, capacitance, and pulse duration. Therefore, the design of experiment is introduced to fully understand the effect of the EDM parameters on machining tool electrode. And an attempt has been made to develop the mathematical model for predicting the size of the tool electrode by calculating spark distance. The suggested model was verified with experiment and predicted working gap distance is in good accord with the measured value.

• 한국공작기계학회논문집
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• 제16권6호
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• pp.168-174
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• 2007

A ceramic glass mold was developed for micro hot-embossing and replicated polymer parts are fabricated. The glass-ceramic micro mold could be fabricated with a laser process and a wet etching process and the fabrication time could be saved a lot. Various polymer micro structures can be obtained by hot-embossing. The process parameters such as ho-embossing temperatures or pressures were investigated and optimized. This process can be applied for fabrication of micro structures for flip-chips or micro fluidic channels for bio-engineering. The advantages and disadvantages of this process are discussed, too.

• 한국기계가공학회지
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• 제21권4호
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• pp.77-83
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• 2022

Amorphous alloys exhibit excellent mechanical properties; therefore, application technology development is being attempted in various fields. However, industrial use of application technology is limited owing to the limitations in fabrication. In this study, micropattern fabrication of an amorphous alloy was conducted using laser beam machining. Although microhole fabrication is possible without the deformation of the amorphous phase through nanosecond pulsed laser beam machining, there are limitations in the generation of recast layers and spatters. In cover plate laser beam machining (c-LBM), a cover plate is used to reduce the thermal deformation and processing area. Therefore, it is possible to fabricate holes at the level of several micrometers. In this study, it was confirmed that recast layers are hardly generated in c-LBM. Furthermore, square-shaped micropatterns were successfully fabricated using c-LBM.

• 대한기계학회논문집A
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• 제38권8호
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• pp.875-880
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• 2014

최근에, 3 차원 인공지지체와 나노섬유는 골 조직 재생을 위해 개발되고 있다. 본 연구에서는, 나노-마이크로 정밀 분사 시스템을 이용하여 하이브리드 인공지지체를 제작하였다. 하이브리드 인공지지체는 마이크로 인공지지체와 나노섬유가 결합하여 제작되었으며, 마이크로 인공지지체와 나노섬유를 얻기 위해 자유 형상 제작 기술과 전기방사 기법이 사용되었다. 마이크로 인공지지체는 정밀한 공극을 고려하여 CAD/CAM 데이터 따라 자유 형상 제작 기술에 의해 제작되었으며, 제작 공정은 $100^{\circ}C$의 온도, 평균 650 kPa의 압력, 그리고 250 mm/sec의 Z 축 이송속도가 적용되었다. 그리고 전기방사법을 통하여 나노섬유를 제작함에 있어서 본 시스템에 적용한 공정 조건은, 5 kV의 전압, 0.1 ml/min의 유량, 그리고 1 mm의 노즐 팁과 콜렉터와의 거리로 설정하였다. 제작된 하이브리드 인공지지체는 MG-63 세포를 이용하여 세포 증식 실험을 진행하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1415-1418
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• 2008

Scaffold fabrication for regenerating functional human tissues has an important role in tissue engineering, and there has been much progress in research on scaffold fabrication. However, current methods are limited by the mechanical properties of existing biodegradable materials and the irregular structures that they produce. Recently, Solid freeform fabrication (SFF) technology was remarked by fabricating 3D free-form micro-structures. Among SFF technologies, we tried to fabricate scaffolds using micro-stereolithography which contain the highest resolution of all SFF technologies and precision deposition system which can use various biomaterials. And we developed the CAD/CAM system to automate the process of scaffold fabrication and fabricate the patient customized scaffolds. These results showed the unlimited possibilities of our SFF technologies in tissue engineering.