• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.727-730
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• 2005

Cellulose based Electro-Active Papers (EAPap) is very promising material due to its merits in terms of large bending deformation, low actuation voltage, ultra-lightweight, and biodegradability. These advantages make it possible to utilize applications, such as artificial muscles and achieving flapping wings, micro-insect robots and smart wall papers. This paper investigates the in-plane strains of EAPap under electric fields, which are useful for a contractile actuator application The preparation of EAPap samples and the in-plane strain measurement system are explained, and the test results are shown in terms of electric field, frequency and the oriental ions of the samples. The power consumption and the strain energy of EAPap samples are discussed. Although there are still unknown facts in EAPap material, this in-plane strain may be useful for artificial muscle applications.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.337-341
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• 2010

In this paper, an extremely low voltage operated micro corner cube retroreflector (CCR) was fabricated for free-space optical communication applications by using bulk silicon micromachining technologies. The CCR was comprised of an orthogonal vertical mirror and a horizontal actuated mirror. For low voltage operation, the horizontal actuated mirror was designed with two PZT cantilever actuators, torsional bars, hinges, and a mirror plate with a size of $400{\mu}m{\times}400{\mu}m$. In particular, the torsional bars and hinges were carefully simulated and designed to secure the flatness of the mirror plate by using a finite element method (FEM) simulator. The measured tilting angle was approximately $2^{\circ}$ at the applied voltage of 5 V. An orthogonal vertical mirror with an extremely smooth surface texture was fabricated using KOH wet etching and a double-SOI (silicon-on-insulator) wafer with a (110) silicon wafer. The fabricated orthogonal vertical mirror was comprised of four pairs of two mutually orthogonal flat mirrors with $400{\mu}m4 (length) $\times400{\mu}m$ (height) $\times30{\mu}m$ (thickness). The cross angles and surface roughness of the orthogonal vertical mirror were orthogonal, almost $90^{\circ}$ and 3.523 nm rms, respectively. The proposed CCR was completed by combining the orthogonal vertical and horizontal actuated mirrors. Data transmission and modulation at a frequency of 10 Hz was successfully demonstrated using the fabricated CCR at a distance of approximately 50 cm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.735-738
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• 2005

Electro-Active Paper (EAPap) is attractive as an EAP actuator material due to its merits in terms of lightweight, dry condition, large displacement output, low actuation voltage and low power consumption. This paper presents the performance of EAPap actuators with thickness variation. The EAPap is made with cellulose paper, and is shown to bend in response to an external electric field. Up to the present, we have tested displacement, current and force of EAPap with 20 $\mu$m thickness. The thickness of EAPap is important factor that affects the performance of the actuator. Therefere, three different thickness of EAPap, 20, 30, and 40 $\mu$m are investigated that inference the tip displacement, blocked force, the resonance and the actuator efficiency. There is an optimum thickness of EAPap, which is resulted from the stiffness and the mass. The performance of EAPap with thickness is discussed.

• Transactions on Electrical and Electronic Materials
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• v.17 no.2
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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.

• Polymer(Korea)
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• v.26 no.1
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• pp.113-120
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• 2002

Electrostriction is the phenomenon that a material is strained due to Maxwell stress developed by the applied voltage. In many electrostrictive materials, especially polymeric elastomers can produce large deformation and force due to their low elastic modulus. In this study, polyurethanes and acrylic rubber with compliant electrodes were used as electrostrictive polymer(EP) actuator. Actuation characteristics of the EP actuators with different physical properties of dynamic modulus and dynamic dielectiric constant were analyzed under AC field. The classical laminate theory was also used to simulate the actuation process in relation to the geometry and the physical properties of the actuators.

• Polymer(Korea)
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• v.26 no.1
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• pp.105-112
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• 2002

The low actuation voltage and quick bending response of IPMC(ion-exchange polymer metal composite) are considered attractive for the construction of various types of actuators. In this study, in order to develop a new type actuators by using the IPMC platinum electrode of IPMC are fabricated by using electroless impregnation-reduction method plating. As the platinum-plating times are increased, IPMC performance was improved in terms of bending displacement and force due to the enhanced surface conductivity. In addition, we investigated the basic actuation characteristics of resonance frequency and actuator length as well as the effect of water uptake and ion mobility. Using the classical laminate theory(CLT), a modeling methodology was developed to predict the deformation, bending moment, and residual stress distribution of anisotropic IPMC thin plates. In this modeling methodology, the internal stress evolved by the unsymmetric distribution of water inside IPMC was quantitatively calculated and subsequently the bending moment and the curvature were estimated for various geometry of IPMC actuator.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.594-599
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• 2008

This paper presents a micro air pump based on the synthetic jet to supply reactant at the cathode side for micro fuel cells. The synthetic jet is a zero mass flux device that converts electrical energy into the momentum. The synthetic jet actuation is usually generated by a traditional PZT-driven actuator, which consists of a small cylindrical cavity, orifices and PZT diaphragms. Therefore, it is very important that the design parameters are optimized because of the simple configuration. To design the synthetic jet micro air pump, a numerical analysis has been conducted for flow characteristics with respect to various geometries. From results of numerical analysis, the micro air pump has been fabricated by the PDMS replication process. The most important design factors of the micro air pump in micro fuel cells are the small size and low power consumption. To satisfy the design targets, we used SP4423 micro chip that is high voltage output DC-AC converter to control the PZT. The SP4423 micro chips can operate from $2.2{\sim}6V$ power supply(or battery) and is capable of supplying up to 200V signals. So it is possible to make small size controller and low power consumption under 0.1W. The size of micro air pump was $16{\times}13{\times}3mm^3$ and the performance test was conducted. With a voltage of 3V at 800Hz, the air pump's flow rate was 2.4cc/min and its power consumption was only 0.15W.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.527-532
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• 2005

Ionic polymer metal composites (IPMC) are soft polymeric smart materials having large displacement at low voltage in air and water. The polymeric electrolyte actuator consists of a thin and porous membrane and metal electrodes plated on both faces, in impregnation electro-plating method. The response and actuation of actuator are governed. Among many factors governing the activation and response of IPMC actuator, the surface electrode plays an important role. In this study, the well-designed modification of electrode surface was carried out in order to improve the chemical stability well as electromechanical characteristics of the IPMC actuator. We employed Ion Beam Assisted Deposition (IBAD) method to prepare the topologically homogeneous thin surface electrode. After roughing the surface of Nafion membrane in order to get a larger surface area, the IPMC was prepared by impregnation for electro-plating and re- coating on the surface through traditional chemical deposition, followed by an additional surface treatment with high conductive metals with IBAD. It was observed that our IPMC specimen shows the enhanced surface electrical properties as well as the improved actuation and response characteristics under applied electric field.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.9
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• pp.869-874
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• 2010

Recently, a piezo actuator based linear motor has been actively studied because of its higher power density, compactness and quick response. However, the characteristic of small displacement makes the application of a piezo actuator limitative. In order to overcome this limitation, some actuation mechanisms using a piezo actuator are designed by bi-metal composite or more than two piezo actuators. Therefore, it enables to generate large displacement and have high resolution. In the proposed piezo motor, we have designed a bi-directional linear motor that can be operated by only one piezo actuator. In addition, it is activated with low frequency of the applied voltage, since, we utilize first mode shape of structure of motion generator to vibrate. Finally, moving direction can be simply controlled by changing the ratio of input frequency to natural frequency of structure of motion generator.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.9
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• pp.455-463
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• 2002

Ionic Polymer metal composite(IPMC), one of new actuation materials of EAPs is fabricated by electroless plating of platinum on both sides of the perfluorosulfonic acid film or Nafion film and its electromechanical characteristics are investigated. The IPMC strip bends towards anode under electrical field. As the number of plating cycle increases, the distance between plated platinum electrodes on both sides of Nafion membrane decreases and also the displacement is almost inversely proportional to the number of plating. The displacement of IPMC strip depends on voltage magnitude and applied signal frequency and its maximum deformation is observed at a critical frequency, resonant frequency. Low pressure sandblasting is used for surface treatment of Nafion membrane and at 8 times of plating cycle produced actuator with high displacement performance. For more efficiency of fabricated IPMC, it is useful to add one or two surface developing step which is the second reduction process using hydrazine.