Analysis of small deflection touch mode behavior in capacitive pressure sensors

Fragiacomo, Giulio; Ansbæk, Thor; Pedersen, Thomas; Hansen, Ole; Thomsen, Erik Vilain

doi:10.1016/j.sna.2010.04.030

Cited by 45 publications

(25 citation statements)

References 7 publications

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“…Applications of these microdevices included pressure sensing, automatic control, biotechnology research, ultrasonic imaging and chemical detection [2]- [6]. In order to facilitate the design and optimization of these microplate-based electrostatic devices, numerous investigations have been directed towards understanding, predicting and controlling their mechanical responses to an electrostatic force [7]- [9].…”

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confidence: 99%

An Improved Method for the Mechanical Behavior Analysis of Electrostatically Actuated Microplates Under Uniform Hydrostatic Pressure

Zhao

Jiang

et al. 2015

J. Microelectromech. Syst.

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Microplates are essential components of the most electrostatically actuated microdevices. Their mechanical behavior is influenced not only by electrostatic force, but by hydrostatic pressure of the environment. This paper presents an improved reduced-order model for an electrostatically actuated microplate under uniform hydrostatic pressure with a novel method for treating the electrostatic force. The model was developed using the Galerkin method and turns the partial-differential equation governing the plate into an ordinary equation system. Using an axisymmetric deflection function and the first-order Taylor series expansion of the electrostatic force, explicit expressions for the deflection and pull-in voltage of the microplate under the electrostatic force alone, and under both electrostatic force and hydrostatic pressure, were derived. The expressions with only the electrostatic force considered can predict the pull-in voltage with a higher accuracy and the deflection within a large range (from the undeformed state to the pull-in position) compared with literature. The expressions for both types of loadings show a better prediction accuracy when the pressure changes in the lower pressure range. The derived expressions are applicable to the electrostatically actuated configurations where the ratio of the plate diameter to its thickness varies from 100 to 40, and the electrode distance is smaller than or equal to the thickness. These theoretical analyses were validated with finite element method simulations and previous literature.[ 2014-0012]Index Terms-Capacitance variation, electrostatically actuated microplate, electrostatic force, pull-in voltage, static deflection, uniform hydrostatic pressure.

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confidence: 99%

An Improved Method for the Mechanical Behavior Analysis of Electrostatically Actuated Microplates Under Uniform Hydrostatic Pressure

Zhao

Jiang

et al. 2015

J. Microelectromech. Syst.

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“…It has also been proved by [4] and [5] that a good approximation for the plate shape in touch mode is…”

Section: Transducer Model and Designmentioning

confidence: 94%

“…when the top electrode collapses on the substrate [2]. Theoretical models for devices which work in both operation modes have been widely investigated [3][4][5]. We have previously presented [6] a touch mode capacitive pressure sensor (TMCPS) that eases the design of a conditioning circuit given its large capacitive signal.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic low hysteresis touch mode capacitive pressure sensor

et al. 2010

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Hysteresis has always been one of the main concerns when fabricating touch mode capacitive pressure sensors (TMCPS). This phenomenon can be fought at two different levels: during fabrication or after fabrication with the aid of a dedicated signal conditioning circuit. We will describe a microfabrication step that can be introduced in order to reduce drastically the hysteresis of this type of sensors without compromising their sensitivity. Medium-high range (0 to 10 bar absolute pressure) TMCPS with a capacitive signal span of over 100pF and less than 1 % hysteresis in the entire pressure range have been obtained. Temperature characterization was performed and showed a decrease in capacitance as the temperature increases. The maximum output variation, relative to room temperature, has been found to be 0.15 %/°C at 80 °C, while an almost constant variation of 0.044 %/°C is achieved if working in the touch mode region.

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“…4). The deflection of a circular diaphragm and the change in capacitance are estimated (Fragiacomo et al 2010;Schellin et al 1994;Timoshenko and Woinowsky-Krieger 1959). The deflection caused by the applied pressure is determined by the rigidity and residual stress of the membrane.…”

Section: Introductionmentioning

confidence: 99%

Polymer-based miniature flexible capacitive pressure sensor for intraocular pressure (IOP) monitoring inside a mouse eye

Vries

John

et al. 2011

Biomed Microdevices

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This paper presents an ultra-thin and flexible polymer-based capacitive pressure sensor for intraocular pressure (IOP) monitoring in a mouse eye. Due to the size limitation of the anterior chamber in the mouse eye, a volume of approximately 700 × 700 × 150 μm(3) on a small substrate is available for the MEMS capacitive pressure sensor. Moreover, the sensor would ideally be easily injectable into place. Further complicating the sensing is the need to operate the device on the curved surface of the anterior chamber with minimum damage to the eye tissue. Therefore, a thin and flexible substrate is required. We fabricate sensors by exploiting Parylene as a biocompatible structural material in a suitable form factor and 25 μm thick liquid crystal polymer (LCP) as a soft and flexible host substrate. Using our approach, the flexibility and small form factor necessary for a mouse eye implant is achieved, along with the sensitivity required to monitor IOP fluctuations. This device will allow better study of glaucoma through close monitoring in mice after integration with other components.

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Analysis of small deflection touch mode behavior in capacitive pressure sensors

Cited by 45 publications

References 7 publications

An Improved Method for the Mechanical Behavior Analysis of Electrostatically Actuated Microplates Under Uniform Hydrostatic Pressure

An Improved Method for the Mechanical Behavior Analysis of Electrostatically Actuated Microplates Under Uniform Hydrostatic Pressure

Intrinsic low hysteresis touch mode capacitive pressure sensor

Polymer-based miniature flexible capacitive pressure sensor for intraocular pressure (IOP) monitoring inside a mouse eye

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