A method to extract the lateral and normal components of motion from the capacitance change of a moving MEMS comb drive

Spengen, W. Merlijn van; Heeres, Erwin C

doi:10.1088/0960-1317/17/3/005

Cited by 12 publications

(19 citation statements)

References 10 publications

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“…3 and ref. [34]) shows that at low voltages significant out-of plane motion occurs, saturating at an equilibrium height approximately 0.5 lm above the rest position. By not operating the device around a lateral actuation voltage of 0 V, but working in the offset window of 40-80 V, where the levitation has already reached its saturation height, the out-of-plane motion cannot influence the measurement anymore.…”

Section: Methods To Measure Friction Loopsmentioning

confidence: 98%

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The Leiden MEMS Tribometer: Real Time Dynamic Friction Loop Measurements With an On-Chip Tribometer

Spengen

Frenken

2007

Tribol Lett

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On-chip MEMS tribometer devices until now have been much less sophisticated for dynamically sensing frictional forces than their FFM (friction force microscope) counterparts. In this article, we present a MEMS-based tribometer that can be used to measure dynamically, onchip and in-situ, the frictional properties of MEMS-scale contact geometries. The device provides the first FFM-like friction loops with contacting MEMS sidewall surfaces. Depending on the normal load two regimes of operation are identified. At low and intermediate loads, the frictional behaviour reflects wear-less relative motion of the silicon oxide surfaces of the MEMS device and we observe repeatable, irregular stick-slip behaviour, related to the surface roughness. At very high loads, wear causes changes in the topography of the contacting surfaces.

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Section: Methods To Measure Friction Loopsmentioning

confidence: 98%

“…This out-of-plane motion influences the capacitance readings and also causes the device to move upward significantly as well as sideways, at low actuation voltages. We have developed an analytical model to extract from the motion-related capacitance change both the in-plane and out-of-plane component [34].…”

Section: Devicementioning

confidence: 99%

The Leiden MEMS Tribometer: Real Time Dynamic Friction Loop Measurements With an On-Chip Tribometer

Spengen

Frenken

2007

Tribol Lett

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“…While the frequency is varied to be away from the resonance frequency of the fingers, the error in the capacitance measurement due to the limitation of the impedance analyzer becomes higher. The other reason may be because of parasitic displacement in the unintended direction at the out-of-plane direction [6]. The C-V behaviors of the sensors require further research.…”

Section: Electromechanical Characterizationsmentioning

confidence: 99%

In-Plane MEMS Acoustic Emission Sensors Development and Experimental Characterization

Saboonchi

Ozevin

2013

MEMS and Nanotechnology, Volume 5

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Damage initiation and growth in materials releases elastic waves, which can be detected by surface mounted acoustic emission (AE) transducers. In this paper, new MEMS comb-drive AE transducers, responsive to in-plane motion, manufactured using electroplating technique for highly elevated microstructure geometries are presented. The transduction principle is capacitance change achieved by area/gap change in two separate designs. Mechanism of spring orientation, dimensions and mass have been selected in such a way that they satisfy three design criteria as the frequency range of 100-200 kHz, 2-30 pF capacitance and the functionality under atmospheric pressure. The challenge of coupling the microstructure vibration in out-of-plane and in-plane directions is addressed with differential mode approach and frequency domain responses. The squeeze film damping is reduced with 8 μm gap between moving electrodes so that the transducers are operational under atmospheric pressure. The directional independence of the transducers to two orthogonal directions is demonstrated using laser source as the excitation signal. The Nd: Yag Q switch laser has 3 mm beam diameter and is focused on the top and the edge of the transducer package. The results show a distinct output signal for in-plane and out-of-plane motions due to the directional sensitivity of the MEMS transducers. IntroductionAcoustic emission (AE) method relies on propagating stress waves due to newly formed damage surfaces. Conventional piezoelectric sensors have bulky geometry and are sensitive to the wave motion in thickness mode and tangential mode due to lateral deformation of the sensor geometry. Understanding the propagating wave direction through differentiating orthogonal wave motions can improve the source localization and characterization. The comb drive sensors have interdigitized fingers formed by the stationary part known as stator and the moving part known as rotor [1]. Comb drive sensors created using Micro-Electro-Mechanical Systems (MEMS) can be designed to be sensitive to tangential wave motion with respect to the structure that the sensor is attached. Harris et al.[2] designed comb drive sensor using the surface micromachining method for detecting the in-plane motion. However, the sensor has coupled response for in-plane and out-of-plane motions. The unwanted out-of-plane motion dominated the sensor response. The surface micromachining method has the limited thickness as 2 μm, which limits the sufficient separation of the resonant frequency modes of in-plane and out-of-plane motions. The lateral instability of the comb drive is a known problem [3].The metalMUMPs incorporates LIGA-like, thick metal electroplating and bulk/surface micromachining processes to develop thick metal layer. The process is available by Memscap Inc since 2003. The process has been implemented by several researchers in the literature. For instance, Tsai et al.[4] designed out-of-plane rotational platform using in-plane electrostatic comb drive actuators. Almeida [5] dev...

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“…structure deforms and therefore change the electrostatic force distribution, resulting in a complex electromechanical coupling of the devices and inducing non-linearity in electrostatic forces ultimately leading to a pull in stage. Many researchers often estimate the capacitance and electric forces by some analytical models for simple geometries (Engelen et al 2010;van Spengen and Heeres 2007;van Spengen and Oosterkamp 2007). In these models, the geometric simplicity is used to justify the assumption that some parts of the electric field can be neglected and/or it is uniform elsewhere.…”

Section: Introductionmentioning

confidence: 99%

Computation of capacitance and electrostatic forces for the electrostatically driving actuators considering fringe effects

et al. 2014

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A method to extract the lateral and normal components of motion from the capacitance change of a moving MEMS comb drive

Cited by 12 publications

References 10 publications

The Leiden MEMS Tribometer: Real Time Dynamic Friction Loop Measurements With an On-Chip Tribometer

The Leiden MEMS Tribometer: Real Time Dynamic Friction Loop Measurements With an On-Chip Tribometer

In-Plane MEMS Acoustic Emission Sensors Development and Experimental Characterization

Computation of capacitance and electrostatic forces for the electrostatically driving actuators considering fringe effects

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