Model for gas film damping in a silicon accelerometer

Veijola, Timo; Kuisma, Heikki; Lahdenpera, J.

doi:10.1109/sensor.1997.635391

Cited by 36 publications

(14 citation statements)

References 9 publications

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“…We adapted this expression from the damping coefficients for transverse motion as derived by Ref. 8,9 . Taking the relatively small width of these gaps and the relatively high distance from the rotation axis into account, the rotation of this particular part of driving plate can be neglected in comparison to its transverse motion.…”

Section: Electrode Gapmentioning

confidence: 99%

A novel 24-kHz resonant scanner for high-resolution laser display

et al. 2005

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This contribution deals with design, fabrication and test of a micromachined resonant scanner usable for horizontal deflection of the laser beam in a projection display. The electrostatically driven plate is separated from the mirror in order to reduce air damping and electrostatic non linearity. The device consists of a circularly shaped mirror which is suspended by torsion beams in the center of an elastically suspended driving plate. A resonator with two rotational degrees of freedom is arranged in this way. The rotation axes of mirror and driving plate are the same. A suitable design of the properties of the two degrees of freedom resonator leads to a significant amplification of the oscillation of the mirror compared to the oscillation of the driving plate. The first resonant mode is a rotation of both plates with nearly the same magnitude at a frequency of approx. 5 kHz. The second mode with paraphase deflection at 24 kHz shows a deflection amplification by a ratio of 53 and is used for scanning operation. A supporting part made of glass carries two electrodes in the region of the driving plate and has a micro sandblasted hole beneath the mirror. Bulk micromachining, KOH wet etching of the electrode gap size on the back side of the driving plate, reactive ion etching for contour shaping of the mirror, of the driving plate and of the torsion beams and anodic bonding have been used for fabrication of the mechanical structure. The mirror is evaporated by an aluminum layer. Applying a voltage of 380V results in a mechanical deflection of ± 5.5 degrees at 24 kHz at atmosphere pressure. The device shows very small dynamic warp (<100nm) of the mirror plate even though the relatively large size of 2.2 mm diameter because of the thickness of 280 µm. The measured mechanical Q-factor is 5100.

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Section: Electrode Gapmentioning

confidence: 99%

A novel 24-kHz resonant scanner for high-resolution laser display

et al. 2005

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“…Again, the differences are striking: reducing the pressure decreases the closing as well as the opening times, but also increases the degradation rate. Note that although no open transients are shown here, other measurements we conducted clearly show a reduction of the opening time with decreasing pressure, which is a logical result of the reduced squeeze film damping due to rarefaction effects [15].…”

Section: Measurement Resultsmentioning

confidence: 52%

“…The latter can be a function of u, since for low pressure and small gaps the mean free path can be on the order of the gap height, reducing the effective viscosity [15]. As can be seen, because of the damping force the differential equation is highly non-linear, so solving this problem analytically is problematic.…”

Section: Dynamic and Higher Order Modelingmentioning

confidence: 99%

Degradation of RF MEMS capacitive switches

Herfst¹

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“…An approximate equation for the effective viscosity is presented in [4]. The approximation is based on the exact solution given in [5].…”

Section: N Gas Filmsmentioning

confidence: 99%

“…Frequency respons eFigure 5shows the measured and simulated frequence responses with different symmetrical (UA = u g ) bias voltages ( 2 V ) 5 V and 9 V ) . The measurement setup is presented in[4]. The change in the effective spring constant due t o Fel vs. symmetrical bias voltage causes the different frequency responses inFig.…”

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confidence: 99%

Model of capacitive micromechanical accelerometer including effect of squeezed gas film

Veijola¹,

Ryhänen²

Proceedings of ISCAS'95 - International Symposium on Circuits and Systems

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An electrical component model for a micromechanical accelerometer is presented. In addition to the varying capacitances, the motion of the seismic mass and the damping gas films are described by means of an electrical equivalent circuit. The resulting model can be analyzed together with the interfacing electronics utilizing all analysis modes available in a circuit simulator.The model has been implemented in the general purpose circuit simulation tool APLAC. The model simulations show an excellent match with the measured frequency responses.

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Model for gas film damping in a silicon accelerometer

Cited by 36 publications

References 9 publications

A novel 24-kHz resonant scanner for high-resolution laser display

A novel 24-kHz resonant scanner for high-resolution laser display

Degradation of RF MEMS capacitive switches

Model of capacitive micromechanical accelerometer including effect of squeezed gas film

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