• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.6
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• pp.494-502
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• 1999

This paper represents an electrostatic micro plate resonator which consists of a rigid plate suspended with four bridges and a counter electrode. The bridges of the resonator are designed corrugated so that the residual stress are released. The FEM simulation results confirmed that the deflection characteristic of the corrugated bridge is hardly affected by the initial residual tensile stress. One resonator with the corrugated bridges and the other with the flat bridges were fabricated by the boron diffusion process and the anisotropic etch process. The vertical deflection of the fabricated electrostatic resonator was measured with a laser vibrometer, and the data were compared with the calculation results. The deflection of the resonator with the flat bridges is smaller than the deflection of that with the corrugated ones because of the residual stress. The residual stress release effect was confirmed by the fact that the measured deflection of the resonator with the corrugated bridges in close to the calculated deflection of the resonator with the flat ones with the initial stress neglected.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.9
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• pp.813-819
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• 2011

This paper predicted nonlinear dynamic responses of a cantilevered carbon nanotube(CNT) resonator incorporating the electrostatic forces and van der Waals interactions between the CNT cantilever and ground plane. The structural model of CNT includes geometric and inertial nonlinearities to investigate various phenomena of nonlinear responses of the CNT due to the electrostatic excitation. In order to solve this problem, we used Galerkin's approximation and the numerical integration techniques. As a result, the CNT nano-resonator shows the softening effect through saddle-node bifurcation near primary resonance frequency with increasing the applied AC and DC voltages. Also we can predict nonlinear secondary resonances such as superharmonic and subharmonic resonances. The superharmonic resonance of the nano-resonator is influenced by applied AC voltage. The period-doubling bifurcation leads to the subharmonic resonance which occurs when the nano-resonator is actuated by electrostatic forces as parametric excitation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1084-1088
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• 1995

In this paper, an electrostatic plate resonator with four corrugated bridges and another with four flat ones have been fabricated and tested by the electrostatic actuation. The resonators consist of one rigid plate and four bridges. Boron diffusion process and anisotropic etch process with EPW are mainly used to fabricate the resonators. The dynamic characteristics of the fabricated resonators are obtained by measuring the velocity of the center of the rigid plate using a laser vibrometer. The results show that the deflection of the resonator with the corrugated bridges is larger than the resonator with the flat ones. It has been confirmed that the corrugated structure releases the residual tensile stress in the bridges resulted from the diffusion process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.447-452
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• 2011

This paper predicted the dynamic behaviors of a cantilevered carbon nanotube(CNT) incorporating the electrostatic force, van der Waals interactions between the CNT and ground plane. The structural model of the CNT includes geometric and inertial nonlinearities for predicting various phenomena of nonlinear responses of the CNT due to the electrostatic force. In order to solve the problem, we used Galerkin's approximation and the numerical integration techniques and as a result, we predicted characteristics of nonlinear response of nano resonator. The cantilevered CNT shows complex dynamic responses and instabilities due to the applied ac and ac voltages, and driving frequencies. The results investigated in this paper are helpful to the modeling of nanotube based electromechanical devices such as nano-resonators and nano-sensors.

• Journal of Mechanical Science and Technology
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• v.19 no.9
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• pp.1711-1719
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• 2005

In an electro statically actuated nanoelectromechanical system (NEMS) resonator, it is shown that both the resonance frequency and the resonance quality (Q) factor can be manipulated. How much the frequency and quality factor can be tuned by excitation voltage and resistance on a doubly-clamped beam resonator is addressed. A mathematical model for investigating the tuning effects is presented. All results are shown based on the feasible dimension of the nanoresonator and appropriate external driving voltage, yielding up to 20 MHz resonance frequency. Such parameter tuning could prove to be a very convenient scheme to actively control the response of NEMS for a variety of applications.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.625-626
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1089-1092
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• 1995

A planar vibratory gyroscope using electrostatic actuation and electromagnetic detection is proposed. The gyroscope has large sensitivity and can be fabricated by using surface micrimachining, bulk micromachining and conventional machining technology. In this paper, the gyroscope and the electromagnetic detecting system equations are derived to determine the output characteristics for the planar vibratory gyroscope using electrostatic acturation and electromagnetic detection. The maximum output is obtained when the driving frequencyequals to the detecting frequency. The resonant frequencies of the resonator are determined by the beam stiffness, i.e. the material constants and spring dimensions. The dimensions of the beams are determined using the analytic vibration modelling. The expected resonant frequencies are 200Hz both and the sensitivity is 62mV/deg/sec with 4000 electronic circuit amplifying coefficient for an AC drive voltage of 3V bias voltage of 15V and DC field current of 50 mA.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.3
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• pp.520-528
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• 2001

This paper investigates a resonant microaccelerometer that measures acceleration using a built-in micromechanical resonator, whose resonant frequency is changed by the acceleration-induced axial force. A set of design equations for the resonant microaccelerometer has been developed, including analytic formulae for resonant frequency, sensitivity, nonlinearity and maximum stress. On this basis, the sizes of the accelerometer are designed for the sensitivity of 10$^3$Hz/g in the detection range of 5g, while satisfying the conditions for the maximum nonlinearity of 5%, the minimum shock endurance of 100g and the size constraints placed by microfabrication process. A set of the resonant accelerometers has been fabricated by the combined use of bulk-micromachining and surface-micromachining techniques. From a static test of the cantilever beam resonant accelerometer, a frequency shift of 860Hz has been measured for the proof-mass deflection of 4.3${\pm}$0.5$\mu\textrm{m}$; thereby resulting in the detection sensitivity of 1.10${\times}$10$^3$Hz/g. Uncertainty analysis of the resonant frequency output has been performed to identify important issues involved in the design, fabrication and testing of the resonant accelerometer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.874-877
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• 2001

SOI(Silicon-On-Insulator) technology is proposed as an alternative to bulk silicon for MEMS(Micro Electro Mechanical System) manufacturing. In this paper, we fabricated the SOI wafer with uniform active layer thickness by silicon direct bonding and mechanical polishing processes. Specially-designed electrostatic bonding system is introduced which is available for vacuum packaging and silicon-glass wafer bonding for SOG(Silicon On Glass) wafer. We demonstrated thermopile sensor and RF resonator using the SOI wafer, which has the merits of simple process and uniform membrane fabrication.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2524-2526
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• 1998

In this paper, the residual stress and young's modulus of the p+ thin film have been estimated by using the electrostatic resonators. The electrostatic plate resonator with four corrugated bridges and another with four flat ones have been fabricated. The deflection of the plate has been calculated under the induced tension and the residual stress and compared with the dynamic test results. When the young's modulus of the p+ silicon is 125 GPa. The estimated residual stresses of the flat and the corrugated bridges are about 15 MPa and less than 5 MPa, respectively. It has been confirmed that the corrugated structure releases the residual tensile stress resulted from the heavy boron diffusion process.