• 전기화학회지
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• 제2권1호
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• pp.17-22
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• 1999

다공질 실리콘을 이용한 마이크로센서와 마이크로액츄에이터의 연구는 현재 초기단계에 있기 때문에, 지금까지 발광 다이오드나 화학 센서 등과 같은 몇몇 응용 소자가 발표된 수준에 머물러 있다. 본 논문에서는 화학 센서와 광소자를 중심으로 다공질 실리콘 센서 및 액추에이터 연구현황을 고찰 보고하고자 한다. 정전용량형 다공질 실리콘 습도센서의 감습 특성은 비선형이였으며, 저습보다는 $40\%RH$ 이상의 고습영역에서 더 높은 감도를 나타내었다. 다공질 실리콘 $n^+-p-n^+$ 소자는 에탄올에 노출되었을 때 소자 전류가 급격히 증가하였다. 다공질 실리콘 다이어프램에 제작된 $p^+-PSi-n^+$ 다이오드는 광 스위칭 현상을 나타내어 광센서 또는 광스위치로써의 응용 가능성을 보여주었다. 다공질 실리콘에 365nm를 조사해서 얻어진 광루미네센스(PL)는 넓은 스펙트럼을 보였으며, 피크 파장은 610 nm이었다. ITO/PSi/In LED의 전계발광(EL)스펙트럼은 PL에 비해 약간 더 넓은 영역에 걸쳐 나타났으며, 피크 에너지가 단파장(535nm)으로 이동하였다.

• 대한기계학회논문집A
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• 제28권12호
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• pp.1990-1996
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• 2004

This paper presents a nonlinearly modulated digital actuator (NMDA) for producing nano-precision digital stroke. The NMDA, composed of a digital microactuator and a nonlinear micromechanical modulator, purifies the stroke of the digital actuator in order to generate the high-precision displacement output required for nano-positioning devices. The function and concept of the nonlinear micromechanical modulator are equivalent to those of the nonlinear electrical limiters. The linear and nonlinear modulators, having an identical input and output strokes of 15.2${\mu}{\textrm}{m}$ and 5.4${\mu}{\textrm}{m}$, are designed, fabricated and tested, respectively. The linear and nonlinear modulators are linked to identical digital actuators in order to compare the characteristics of the linearly modulated microactuator (LMDA) and NMDA. In addition, an identical linear modulator is attached to the output ports of LMDA and NMDA. The NMDA shows the repeatability of 12.3$\pm$2.9nm, superior to that of 27.8$\pm$2.9nm achieved by LMDA. When the identical linear modulator is connected to LMDA and NMDA, the final modulated output from NMDA shows the repeatability of 10.3$\pm$7.2nm, superior to that of 15.7$\pm$7.7nm from LMDA. We experimentally verify the displacement purifying capability of the nonlinear mechanical modulator, applicable to nano-precision positioning devices and systems.

• 대한기계학회논문집A
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• 제25권1호
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• pp.16-24
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• 2001

This paper presents an electromagnetic microactuator using the copper coil electroplated on the p+silicon diaphragm. The microactuator generates a vertical motion of the diaphragm using the radial direction, we propose a new actuator structure with twin magnets. The microactuator field in the radial direction, we propose a new actuator structure with twin magnets. The microactator shows a values of resonant frequency and quality factor in the ranges of 10.51${\pm}$0.22kHz and 46.6${\pm}$3.3, respectively. The twin magnet microactuator generates the maximum peak-to-peak amplitude of 4.4$\mu\textrm{m}$ for the AC rms current of 26.8mA, showing 2.4 times larger amplitude than the single magnet microactuator.

• 한국정밀공학회지
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• 제14권12호
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• pp.153-159
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• 1997

A thermally-driven polysilicon microactuator has been fabricated using surface micromachining techniques. It consists of P-doped polysilicon as a structural layer and TEOS(tetraethylorthosilicate) oxide as a sacrificial layer. The polysilicon was annealed for the relaxation of residual stress which is the main cause to its deformation such as bending and buckling. And newly developed HF GPE(gas-phase etching) process was also employed to eliminate the troublesome stiction problem using anhydrous HF gas and CH$_{3}$OH vapor, and successfully fabricated the microactuators. The actuation is incurred by the thermal expansion due to the current flow in the active polysilicon cantilever, which motion is amplified by lever mechanism. The moving distance of polysilicon microactuator was experimentally conformed as large as 21 .mu. m at the input voltage level of 10V and 50Hz square wave. The actuating characteris- tics are also compared with the simulalted results considering heat transfer and thermal expansion in the polysilicon layer. This microactuator technology can be utilized for the fabrication of MEMS (microelectromechanical system) such as microrelay, which requires large displacement or contact force but relatively slow response.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.732-734
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• 1998

Metal thin films such as aluminum have been used as interconnects in semiconductor device. Recently, these materials are applied to structural materials in microsensors and microactuators. In this study, we evaluate deformation and strength behavior of aluminum alloy film. Three layer model for thermal deformation of multilayered thin film material is introduced and applied to Si/Al(1%Si)/$SiO_2$ system. Based on beam bending theory and concept of bending strain. elastic and elastic/plastic thermal deformation behaviors of multilayered materials can be estimated. In the case of plastic deformation of ductile layer, strain rate equations based on deformation mechanism map are employed for describe the stress relaxation effect. To experimentally examine deformation of multilayered thin film materials, in-situ laser scanning method is used to measure curvature of specimens during heating and cooling. The thickness of $SiO_2$ layer is varied to estimate third-layer effect of thermal deformation of metal films, and its effect on deformation behavior are discussed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.1010-1013
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• 1998

In micromechanical system (MEMS) such as microactuators. thin film has been widely used as structural material. MEMS materials have difference with bulk in terms of mechanical properties. So, we design the advanced test structure for micromechanical properties of MEMS. The designed structure includes the newly developed pre-crack and it is driven by electrostatic force. To measure the fracture toughness, the pre-crack formation in the test structure is developed with conventional etching process. The advanced test structure is fabricated by application of semiconductor technology. After this, we propose analytical methodology to evaluate the fracture toughness and fatigue properties through a prediction of crack behavior from the variations of stiffness and frequency. Additionally, life time of a mirror plane used in DVD(Digital Video Disk) is measured as a function of capacitance and applied voltage under the accelerated conditions. Ultimately, we propose the method to evaluate the micromechanical reliabilities of the MEMS materials using the advanced test structure.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.865-868
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• 2001

We designed and fabricated a planner-type thermoelastic microactuator with a latch-up operation for optical switching. Latch-up actuation is prerequisite to implement an optical switch with low power consumption and high reliability. The proposed microactuator consists of four cantilever-shaped thermal actuators, four displacement linkages, two shallow arch-shaped leaf springs, a mobile shuttle mass with a micromirror, and four elastic boundaries. The structural layer of the planar microactuator is phosphorous-doped 12$\mu\textrm{m}$-thick polysilicon, and the sacrificial layer is LTO(Low Temperature Oxide) of 3$\mu\textrm{m}$thickness. The displacement of actuator is as large as 3$\mu\textrm{m}$when the length of actuation bar is 100$\mu\textrm{m}$in length at 5V input voltage. The proposed microactuators have advantages of easy assembly with other optical component by way of fiber alignment in the substrate plane, and its fabrication process features simplicity while retaining batch-fabrication economy.

• 한국기계가공학회지
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• 제7권2호
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• pp.72-77
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• 2008

In this study, we propose and develop PDMS-based modular actuators. The microactuator which looks like a small insect uses thermal expansion power of the PDMS (polydimethylsiloxane; $sylgar^{(R)}$ 184 silicone elastomer). The PDMS-based microactuator provides a large displacement due to a high thermal expansion coefficient (approximately 310ppm). The microacruator with 1mm length $350{\mu}m$ width is optimized by using a numerical analysis. The shape of the PDMS actuatoris variously designed. They are placed at several positions to find the optimal position that provides a high transformation ratio. The PDMS-based microactuators are fabricated using a conventional micromaching technique. The fabricated microactuator is heated using a hot-plate. The actuator displacement is measured as a function of temperature from $27^{\circ}C$ to $300^{\circ}C$. The experimental results are compared to the simulation result. When heating temperature up to $300^{\circ}C$ is applied to the PDMS actuator, each V-groove-shaped joint is actuated $30{\mu}$ mat $300^{\circ}C$. Anotherdesign of the microactuator has a maximum displacement of about 656mm.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권11호
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• pp.581-588
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• 2001

This paper presents theoretical and experimental study on the quality-factor of the laterally oscillated electrostatic microactuator, driven by a lateral repulsive-force generated by the asymmetry of planar electric field. The quality-factor of the repulsive-force microactuator using a creeping flow model of the ambient air is evaluated. By filling the simulation results of damping force, we evaluate the dimensionless damping force, $\alpha$, thereby obtaining an analytical damping force, F, in the form of $F=\mu\; \alphaUL,\; where\; \mu,$ U and L denote the air viscosity, the velocity and the characteristic length of the movable electrodes. The measured quality-factor increases from 12 to 13 for the DC bias voltage increased from 60V to 140v. The theoretical quality-factor estimated from the creeping flow model increases from 14.9 to 18.7. Characteristics of quality-factor of the repulsive-force microactuator have been discussed and compared with those of the conventional attractive-force microactuator.

• 센서학회지
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• 제12권4호
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• pp.156-163
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• 2003

일반적인 표면 마이크로머시닝 공정과 고분자의 중합공정을 결합하여 전도성 고분자인 폴리피롤 액추에이터를 제작하였다. 폴리피롤 액추에이터의 제작 공정을 검증하기 위한 가장 기본적인 구조물은 폴리피롤 캔틸레버이며 이를 이용하여 세포 조작에 응용 가능한 폴리피롤 그리퍼 및 밸브의 기본 구조물들을 제작하였다. 그리퍼는 손가락과 유사한 형태로 뼈에 해당하는 단단한 고분자와 근육에 해당하는 폴리피롤 등으로 구성된다. 밸브는 폴리피롤 캔틸레버에 유로가 결합된 형태로 제작되었다. 제안한 폴리피롤 액추에이터의 제작 공정 및 기본 구조물들은 세포 조작기구와 같은 바이오 관련 응용에 이용될 수 있을 것이다.