Deflection of an Eccentric Tooth of a Comb Drive in an Electrostatic Field

Meijaard, J. P.; Krijnen, B.; Brouwer, Dannis Michel

doi:10.1115/detc2013-12956

Cited by 3 publications

(6 citation statements)

References 9 publications

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“…actuator is calculated as a function of the number of combfingers, the width of the comb-fingers and the width of the air gap between the comb-fingers. A safe maximum actuation voltage is chosen to be 80 V, to prevent pull-in of individual comb-drive fingers for displacements up to ±150 μm, as described in [23,24]. The value for the maximum actuation voltage is used to calculate the number of comb-fingers N using equation ( 5) and as such, influences the area of the actuator.…”

Section: Flexurementioning

confidence: 99%

Flexures for large stroke electrostatic actuation in MEMS

Krijnen

Brouwer

2013

J. Micromech. Microeng.

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The stroke of a microelectromechanical systems (MEMS) stage suspended by a flexure mechanism and actuated by electrostatic comb-drives is limited by pull-in. A method to analyze the electrostatic stability of a flexure mechanism and to optimize the stroke with respect to the footprint of flexure mechanisms is presented. Four flexure mechanisms for large stroke are investigated; the standard folded flexure, the slaved folded flexure, the tilted folded flexure and the Watt flexure. Given a certain stroke and load force, the flexures are optimized to have a minimum wafer footprint. From these optimizations it is concluded that the standard folded flexure mechanism is the best flexure mechanism for relatively small strokes (up to ±40 μm) and for larger strokes it is better to use the tilted folded flexure. Several optimized flexure mechanisms have been fabricated and experimentally tested to reach a stroke of ±100 μm. The displacement of the fabricated stages as a function of the actuation voltage could be predicted with 82% accuracy, limited by the fairly large tolerances of our fabrication process.

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Section: Flexurementioning

confidence: 99%

Flexures for large stroke electrostatic actuation in MEMS

Krijnen

Brouwer

2013

J. Micromech. Microeng.

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“…For instance, in a tilted folded flexure with a leaf-spring length of 1000 μm and a tilt angle of 5 • [8], the lateral displacement (translation) is about 200 nm and the angular displacement (rotation) about 1.0 mrad for a longitudinal displacement of 150 μm, but the precise values depend strongly on the specific guidance and the configuration used. As an extension to [9], where only a lateral base displacement was considered, rotation as well as displacement are considered here. The analysis is restricted to the pull-in behavior of an individual finger placed between two rigid matching fingers.…”

Section: Introductionmentioning

confidence: 99%

Deflection and Pull-In of a Misaligned Comb Drive Finger in an Electrostatic Field

Meijaard

Krijnen²,

Brouwer

2014

J. Microelectromech. Syst.

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The elastic deflection of a comb drive finger in an electrostatic field is considered. The finger can be symmetrically located between two rigid fingers of the matching comb, in which case the problem reduces to a pure bifurcation problem for which the critical voltage can be determined. Alternatively, due to the nonlinear motion of an approximate straight-line guidance mechanism, the base of the finger can have a lateral and angular displacement, which results in a smooth curve of equilibria with a limit point, after which pull-in occurs. An analytic model is derived, which is validated by 2-D and 3-D finite-element analyses and experiments. For the analytic model, an assumed deflection shape and a series expansion of the electrostatic capacity yield the deflection curves. This shows that the pull-in occurs at a voltage that is reduced by an amount that is about proportional to the two-third power of the relative base displacement. The theoretical results for the case of a lateral base displacement have been experimentally tested. The results show a qualitative agreement with the analytic model, but the experimental deflections are larger and the pull-in voltages are lower. The finiteelement analyses show that these differences can be explained from neglected fringe fields and deviations from the nominal shape.[2013-0270]

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“…However, the comb-drive fingers need to be twice as long and the actuation force needs to be twice as high. The comb-drive fingers, as well as the complete flexure mechanisms, suffer from electrostatic pull-in, as described in [35,88]. Rough calculations show that either increasing the number of comb-drive fingers or increasing the actuation voltage and the finger thickness both result in an increase of the actuator area of at least a factor of 1.33.…”

Section: Flexure Mechanismsmentioning

confidence: 99%

“…The area of the actuator is calculated as a function of the number of comb-fingers, the width of the comb-fingers and the width of the air gap between the comb-fingers. A safe maximum actuation voltage is chosen to be 80 V, to prevent pull-in of individual comb-drive fingers for displacements up to ±150 ñm, as described in [35,88]. The value for the maximum actuation voltage is used to calculate the number of comb-fingers N using equation (2.5) and as such influences the area of the actuator.…”

Section: Wafer Footprintmentioning

confidence: 99%

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A large-stroke planar MEMS-based stage with integrated feedback

Krijnen¹

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Deflection of an Eccentric Tooth of a Comb Drive in an Electrostatic Field

Abstract: The

Cited by 3 publications

References 9 publications

Flexures for large stroke electrostatic actuation in MEMS

Flexures for large stroke electrostatic actuation in MEMS

Deflection and Pull-In of a Misaligned Comb Drive Finger in an Electrostatic Field

A large-stroke planar MEMS-based stage with integrated feedback

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