• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1912-1913
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• 2003

This paper presents a variable optical attenuator (VOA) that is fabricated using bosch deep silicon etching process [1] with silicon-on- insulator (SOI) wafer. The VOA consists of driving electrode, ground electrode, actuating mirror, and mechanical slower. In this VOA, actuating mirror is driven by electrostatic force [2] and the pull-in voltage is close to 13V, 28 V, 46V come along with the spring width of $3{\mu}m,\;5{\mu}m,\;7{\mu}m$ respectively.

• Advances in robotics research
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• 제1권1호
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• pp.1-19
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• 2014

Microgripper is an essential device in the micro-operation system. It can convert other types of energy into mechanical energy and produce clamp movement with required chucking force, which enables it a broad application prospect in the domain of tiny components' processing and assembly, biomedicine and optics, etc. The performance of a microgripper is dependent on its power supply, type of drive, mechanism structure, sensing components, and controller. This paper presents a state-of-the-art survey of recent development on flexure-based microgrippers. According to the drive type, the existing microgrippers can be mainly classified as electrostatic microgripper, electrothermal microgripper, electromagnetic microgripper, piezoelectric microgripper, and shape memory alloy microgripper. Additionally, some different mechanisms, sensors, and control methods that are used in microgripper system are reviewed. The key issue of how to choose those components in microgripper system design is also addressed.

• Transactions on Electrical and Electronic Materials
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• 제17권2호
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• pp.92-97
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• 2016

This paper presents design and simulation of wide band RF microswitch that uses electrostatic actuation for its operation. RF MEMS devices exhibit superior high frequency performance in comparison to conventional devices. Similar techniques that are used in Very Large Scale Integration (VLSI) can be employed to design and fabricate MEMS devices and traditional batch-processing methods can be used for its manufacturing. The proposed switch presents a novel design approach to handle reliability concerns in MEMS switches like dielectric charging effect, micro welding and stiction. The shape has been optimized at actuation voltage of 14-16 V. The switch has an improved restoring force of 20.8 μN. The design of the proposed switch is very elemental and primarily composed of electrostatic actuator, a bridge membrane and coplanar waveguide which are suspended over the substrate. The simple design of the switch makes it easy for fabrication. Typical insertion and isolation of the switch at 1 GHz is -0.03 dB and -71 dB and at 85 GHz it is -0.24 dB and -29.8 dB respectively. The isolation remains more than - 20 db even after 120 GHz. To our knowledge this is the first demonstration of a metal contact switch that shows such a high and sustained isolation and performance at W-band frequencies with an excellent figure-of merit (fc=1/2.pi.Ron.Cu =1,900 GHz). This figure of merit is significantly greater than electronic switching devices. The switch would find extensive application in wideband operations and areas where reliability is a major concern.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.246-250
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• 2003

In this study, two new types of micro-grippers in which micro-fingers are actuated by piezoelectric multi-layer benders and stacks are introduced for the manipulation of micrometer-sized objects. First, we constructed a 3-chopstick-mechanism tungsten gripper, which is composed of three chopsticks: two are designed to grip micro-objects, and tile third is used to help grasp and release the objects through overcoming especially electrostatic force among some surface effects including electrostatic, van der Waals forces and surface tension. Second, a 2-chopstick-mechanism silicon micro-gripper that uses an integrated force sensor to control the gripping force was developed. The micro-gripper is composed of a piezoelectric multilayer bender for actuating the gripper fingers, silicon fingertips fabricated by use of silicon-based micromachining, and supplementary supports. The micro-gripper is referred to as a hybrid-type micro-gripper because it is composed of two main components; micro-fingertips fabricated using micromachining technology to integrate a very sensitive force sensor for measuring the gripping force, and piezoelectric gripper finger actuators that are capable of large gripping forces and moving strokes. The gripping force signal was found to have a sensitivity of 667 N/V. To the design of each of components of both of the grippers. a systematic design approach was applied, which made it possible to establish the functional requirements and design parameters of the micro-grippers. The micro-grippers were installed on a manual manipulator to assess its performance in tasks such as moving micro-objects from one position to a desired position. The experiment showed that the micro-grippers function effectively.

• 폴리머
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• 제25권5호
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• pp.736-743
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• 2001

N,N-Methylenebisacrylamide (MBAA)로 가교 결합된 electro-active 고분자(EAP) (poly(2-acrylamido-2-methylpropane sulfonic acid), PAMPS) 겔을 수용액 상에서 potassium persulfate를 개시제로 하여 라디칼 중합시켜 제조하였다. PAMPS 겔의 구동성을 부여하기 위하여 계면활성제로 팽윤하며 치환하였다. 계면활성제가 치환된 PAMPS 겔은 용액내의 인가된 전압하에서, 그 전기장 변화에 의해 큰 변위를 나타내는 구동특성을 보였다. PAMPS 겔은 빠른 응답속도와 가역적인 bending을 나타내었다. 겔의 구동원리는 양극과 PAMPS 겔 음이온간의 정전기 인력, 겔의 swelling-deswelling 효과 그리고 계면활성제의 소수성 반응의 협동적 과정으로 나타난다. PAMPS 겔의 응답속도는 인가된 전압 및 가교도가 증가할수록 증가하였으며, 구동이 반복적으로 진행됨에 따라 응답속도는 증가하였다. 겔의 두께가 증가하면 응답속도는 감소하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.148-149
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• 2007

We present the design and fabrication prcoess of a two-axis tilting micromirror device driven by the electrostatic vertical comb actuator. A high aspect-ratio comb actuator is fabricated by multiple DRIE process in order to achieve large scan angle. The proposed fabrication process enables a mirror to be fabricated on the wafer-scale. By bonding a double-side polished (DSP) wafer and a silicon-on-insulator (SOI) wafer together, all actuators on the wafer are completely hidden under the reflectors. Nickel lines are embedded on a Pyrex wafer for the electrical access to numerous electrodes of mirrors. An anodic bonding step is implemented to contact electrical lines with ail electrodes on the wafer at a time. The mechanical angle of a fabricated mirror has been measured to be 1.9 degree and 1.6 degree, respectively, in the two orthogonal axes under driving voltages of 100 V. Also, a $8{\times}8$ array of micromirrors with high fill-factor of 70 % is fabricated by the same fabrication process.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.147-150
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• 2005

Low actuation voltage and no contact stiction are the important factors to apply MEMS RF switches to mobile devices. Conventional electrostatic MEMS RF switches require several tens of voltages for actuation. In this paper we propose PAS MEMS RF switch which adopt PZT actuators and seesaw cantilevers to meet the above requirements. The fundamental structures of PAS MEMS switch were designed, optimized, and fabricated. Through the developed processes PAS SPDT MEMS RF switches were successfully fabricated on 4" wafers and they showed good electrical properties. The driving voltage was less than 5 volts. And the insertion loss was -0.5dB and the isolation was 35dB at 5GHz. The switching speed was about 5kHz. So these MEMS RF switches can be applicable to mobile communication devices or wireless multi-media devices at lower than 6GHz.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1923-1925
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• 2003

본 논문은 유리 기판과 실리콘 기판의 양극접합과 CMP공정을 통하여 정전기력으로 구동되는 마이크로 비틀림 액추에이터를 제작하고 이 제작된 액추에이터의 성능을 개선하는 방법과 실험에 관한 것이다. 이 비틀림 액추에이터는 미소 거울로 사용하기 위해 제작하였다. 미소 거울은 영상을 정확히 반사하거나 회절 시키는 것이 목적이지만 MEMS 공정의 특성 문제로 인해 일관적인 성능을 나타내는 것이 비교적 힘들다. 따라서 이를 개선하기 위해선 구조적인 접근 보다 실제 구동될 때의 현상을 보상하는 것이 필요하다. 일정한 입력전압에 비례하는 미소 거울의 변위를 알고 이를 기준으로 하여 시스템을 구동하여야 한다. 여기서 인가되는 전압에 비례하는 변위가 정확한지 측정을 해야 하고 만약 오차가 있다면 이를 개선하여야 한다. 또한 구동 시 발생하는 overshoot 현상과 작은 떨림 현상을 줄이고 빠른 시간 내에 응답하도록 시스템을 보상하여야 한다. 본 논문에선 PID 제어기법을 사용하여 $0.5^{\circ}$의 각도로 구동할 때를 기준으로 이 때의 구동전압 200V를 인가하고 오차를 측정하여 시스템을 보상하였다.

• Transactions on Electrical and Electronic Materials
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• 제17권4호
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• pp.183-188
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• 2016

This paper presents the design and characterization of wide band ohmic microswitch with an actuation voltage as low as 20~25 V, and a restoring force of 14.1 μN. The design of the proposed switch is primarily composed of an electrostatic actuator, bridge membrane, cantilever (beam) and coplanar waveguide, suspended over the substrate. The analysis shows an insertion loss of −0.002 dB at 1GHz and remains as low as −0.35 dB, even at 100 GHz. The isolation loss of the switch is sustained at −21.09 dB at 100GHz, with a peak value of −99.58 dB at 1 GHz and up-state capacitance of 4 fF. To our knowledge, this is the first demonstration of a series contact switch, which works over a wide bandwidth (DC-100 GHz) and with such a high and sustained isolation, even at high frequencies and with an excellent figure of merit (f_c=1/2.pi.Ron.Cu= 39.7 THz).

• Smart Structures and Systems
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• 제29권5호
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• pp.705-714
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• 2022

In this paper, the effect of magnetic field on the vibration behavior of a Magnetorheological elastomer (MRE) sandwich MEMS actuated by electrostatic actuation with conductive skins are examined within the multiple scales (MMS) perturbation method. Magnetorheological smart materials have been widely used in vibration control of various systems due to their mechanical properties change under the influence of different magnetic fields. To investigate the vibrational behavior of the movable electrode, the Euler-Bernoulli beam theory, as well as Hamilton's principle is used to derive the equations and the related boundary conditions governing the dynamic behavior of the system are applied. The results of this study show that by placing the Magnetorheological elastomer core in the movable electrode and applying different magnetic fields on it, its natural vibrational frequency can be affected so that by increasing the applied magnetic field, the system's natural frequency increases. Also, the effect of various factors such as the electric potential difference between two electrodes, changes in the thickness of the core and the skins, electrode length, the distance between two electrodes and also change in vibration modes of the system on natural frequencies have been investigated.