• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.2004-2006
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• 1996

A thermally driven polysilicon micro actuator has been fabricated using surface micromachining techniques. It consists of P-doped polysilicon as a structural layer and TEOS (tetracthylorthosilicate) 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 the newly developed HF VPE (vapor phase etching) process was also used as an effective release method for the elimination of sacrificial TEOS layer. The thickneas of polysilicon is $2{\mu}m$ and the lengths of active and passive polysilicon cantilevers are $500{\mu}m$ and $260{\mu}m$, respectively. The actuation is incurred by die thermal expansion due to the current flow in the active polysilicon cantilever, which motion is amplified by lever mechanism. The moving distance of polysilicon micro actuator was experimentally conformed as large as $21{\mu}m$ at the input voltage level of 10V and 50Hz square wave. The actuating characteristics are investigated by simulating the phenomena of heat transfer and thermal expansion in the polysilicon layer. The displacement of actuator is analyzed to be proportional to the square of input voltage. These micro actuator technology can be utilized for the fabrication of MEMS (microelectromechanical system) such as micro relay, which requires large displacement or contact force but relatively slow response.

• 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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.56-64
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• 2006

This paper presents the development and application of a conducting shape memory polyurethane (CSMPU) actuator. While conventional shape memory polyurethanes were activated by external heat source, conducting shape memory polyurethanes introduced in 2004 are activated by electric power. Conducting shape memory polyurethane actuators were manufactured by adding carbon nano tube to conventional shape memory polyurethane. The main problem of the CSMPU developed in 2004 was bad dispersion of carbon nano tubes. In this paper, we tried to find how to solve the dispersion problem, and with a lot of elaborative works, conducting shape memory polyurethane actuators which had better electrical characteristics were developed. Then the actuation performance of the conducting shape memory polyurethane actuators was also measured and assessed. Finally, the possibility of applications were examined through the installation to Micro Air Vehicle.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.7
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• pp.717-722
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• 2012

This paper presents the design and dynamic model of the finger exoskeleton actuated by Ionic Polymer Metal Composites (IPMC) to assist a tip pinch task. Although this exoskeleton will be developed to assist 3 degree-of-freedom motion of each finger, it has been currently made to perform the tip pinch task using 1 degree-of-freedom mechanism as the first step. The six layers of IPMC were stacked in parallel to increase the low actuation force of IPMC. In addition, the finger dummy was manufactured to evaluate the performance of the finger exoskeleton. The pinch task experiments, which were performed on the finger dummy with the developed exoskeleton, showed that the pinch force close to the desired level was obtained. Moreover, the dynamic model of the exoskeleton and finger dummy was developed in order to perform the various analyses for the improvement of the exoskeleton.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.7
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• pp.586-593
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• 2014

The CNUSAIL-1 project aims to develop and operate a 3U-sized cube satellite with solar sail mechanism. The primary mission is to successfully deploy the solar sail in a low earth orbit, and the secondary mission is to collect the scientific data for the effect of the solar sail deployment and operation on orbit maneuver and attitude change of the cube satellite. For this, the bus system will collect and transmit the dynamic data of the satellite and the visual images of the solar sail operation. This paper describes solar sail mission and conceptual design of CNUSAIL-1. The actuation/operation of the solar sail and the bus system are preliminarily designed in terms of attitude control system, communication system, electrical power system, command and data handling system, structure and thermal control system is designed.

• Journal of Navigation and Port Research
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• v.28 no.5
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• pp.429-434
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• 2004

In this paper, we designed a reconfigurable slot antenna using sequentially voltage-applied RF MEMS switches. In order to obtain pull-in voltage and maximum stress of the MEMS switches, the switch structures in accordance with airgap height was analyzed by ANSYS simulation A actuation voltage of MEMS switches can be determined by switch geometry and airgap height between a movable plate and a bottom plate. The designed lengths of MEMS switches were 240 $\mu\textrm{m}$, 320 $\mu\textrm{m}$, 400 $\mu\textrm{m}$, respectively and the airgap was 6$\mu\textrm{m}$. The total size of the designed slot antenna was 10 mm x 10 mm and the slot length and width were 500 $\mu\textrm{m}$ and 200 $\mu\textrm{m}$, respectively. The length and size of the CPW feedline were 5 mm and 30-80-30 $\mu\textrm{m}$, respectively. and then the size of the CPW in the slot was 50-300-150 $\mu\textrm{m}$. The tuning of the resonant frequency of the proposed device is realized by varying the electrical length of the antenna, which is controlled by applying the DC bias voltages to the RF MEMS switches. The designed slot antenna has been simulated, fabricated and measured.