A surface-micromachined shear stress imager

Jiang, Feifei; Tai, Yu‐Chong; Gupta, Bhagwati P.; Goodman, R.M.; Tung, Steve; Huang, Jin-Biao; Ho, Chih‐Ming

doi:10.1109/memsys.1996.493838

Cited by 38 publications

(10 citation statements)

References 9 publications

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“…This includes prototypes with alternative sensing element configurations and materials [19][20][21][22][23], and investigations of sensor characteristics such as thermal insulation, frequency response, pressure sensitivity and noise floor spectra [24][25][26]. In addition, MEMS shear-stress sensors have been fabricated in arrays on rigid [27] and flexible substrates [28,29], integrated with signal conditioning circuitry [23,28,29] and applied to flow sensing and control in both air [30] and water [31]. Recently, there have also been numerical simulations on MEMS thermal shear-stress sensors to study the effect of natural convection on the fluid velocity profile [32] as well as the effect of heat conduction in the sensor substrate on frequency response [33].…”

Section: Introductionmentioning

confidence: 99%

“…Thermal shear-stress sensors exploit the dependence of heat transfer from a heated sensing element (or hot wire) on the applied shear stress and classical theory states that the rate at which heat is removed from the hotwire by the flow is proportional to the 1/3-power of the shear stress [7]. This theory has been applied to MEMS shear-stress sensors in the past due to the lack of a microscale sensor theory [21,23,26,27]. However, we have observed that this law is often inconsistent with experimental data.…”

Section: Introductionmentioning

confidence: 99%

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Experiments and simulations of MEMS thermal sensors for wall shear-stress measurements in aerodynamic control applications

Lin

Jiang²,

Wang

et al. 2004

J. Micromech. Microeng.

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MEMS thermal shear-stress sensors exploit heat-transfer effects to measure the shear stress exerted by an air flow on its solid boundary, and have promising applications in aerodynamic control. Classical theory for conventional, macroscale thermal shear-stress sensors states that the rate of heat removed by the flow from the sensor is proportional to the 1/3-power of the shear stress. However, we have observed that this theory is inconsistent with experimental data from MEMS sensors. This paper seeks to develop an understanding of MEMS thermal shear-stress sensors through a study including both experimental and theoretical investigations. We first obtain experimental data that confirm the inadequacy of the classical theory by wind-tunnel testing of prototype MEMS shear-stress sensors with different dimensions and materials. A theoretical analysis is performed to identify that this inadequacy is due to the lack of a thin thermal boundary layer in the fluid flow at the sensor surface, and then a two-dimensional MEMS shear-stress sensor theory is presented. This theory incorporates important heat-transfer effects that are ignored by the classical theory, and consistently explains the experimental data obtained from prototype MEMS sensors. Moreover, the prototype MEMS sensors are studied with three-dimensional simulations, yielding results that quantitatively agree with experimental data. This work demonstrates that classical assumptions made for conventional thermal devices should be carefully examined for miniature MEMS devices.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experiments and simulations of MEMS thermal sensors for wall shear-stress measurements in aerodynamic control applications

Lin

Jiang²,

Wang

et al. 2004

J. Micromech. Microeng.

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show abstract

“…In the indirect-type sensors, indirect measures of the shear stress, for example heat transfer from a Joule heated element subjected to the fluid flow, are sensed. Indirect sensors are predominantly heat transfer based [19][20][21], and are invasive to the fluid flow. They are very popular because they are simpler to fabricate and package and are generally more robust than direct sensors.…”

Section: State Of the Art In Shear Stress Sensingmentioning

confidence: 99%

Design and fabrication of a direction sensitive MEMS shear stress sensor with high spatial and temporal resolution

Desai

Haque

2004

J. Micromech. Microeng.

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Shear stress at the fluid–wall interface is one of the most frequently studied parameters in fluid dynamics. It is also a parameter of very small magnitude and calls for high resolution force sensors. Macroscopic sensors compromise dynamic bandwidth for the required high resolution and therefore cannot resolve shear stress data in space and/or time, which is very important for fundamental understanding in non-laminar fluid dynamics. We exploit the linear reduction in stiffness accompanied by cubic reduction in mass by miniaturization to design and fabricate a novel micro-electro-mechanical sensor (MEMS) for direct measurement of shear stress along and across the direction of fluid flow, with 0.01 Pa resolution and 50 kHz bandwidth along the flow. The mechanical component of the sensor is a floating beam element and capacitive comb drives supported by an in-plane torsional spring. A resonant RLC circuit, capable of sub-femtofarad capacitive sensing, is used to sense the displacement in the floating beam under shear. Fabrication of the sensor is demonstrated using silicon-on wafer (SOI) technology. The small overall size of the sensor, wide range of measurement, large bandwidth and high spatial and temporal resolution will make it useful in a wide variety of civil and military applications such as aerospace, automotive, marine and biomedical.

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“…A micro-shear-stress imaging chip, which is composed of multiple micro-shear-stress sensors (Jiang et al, 1996), is shown in Fig. 1.…”

Section: Micro-shear Stress Imaging Chipmentioning

confidence: 99%

Measurements of wall shear stress of a turbulent boundary layer using a micro-shear-stress imaging chip

Kimura¹,

Tung²,

Lew³

et al. 1999

Fluid Dyn. Res.

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Measurements of wall shear-stress streaks of a turbulent boundary layer in the channel ow were carried out using a MEMS-based micro-shear-stress imaging chip, which contains about 100 sensors. The chip is designed and fabricated by surface micromachining technology. One arrray of 25 micro-shear-stress sensors in the chip that covers a length of 7.5 mm is used to measure the instantaneous spanwise distribution of the surface shear stress. The statistics of high shear-stress streaks were established. Based on the measurement, the physical quantities associated with the high shear-stress streaks, such as their length, width and peak shear-stress level, were obtained. We found out that a high correlation exists between the peak shear-stress level and front-end shear-stress slope of a high shear-stress streak. This important property is currently being applied to the design of a real-time ow control logic.

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A surface-micromachined shear stress imager

Cited by 38 publications

References 9 publications

Experiments and simulations of MEMS thermal sensors for wall shear-stress measurements in aerodynamic control applications

Experiments and simulations of MEMS thermal sensors for wall shear-stress measurements in aerodynamic control applications

Design and fabrication of a direction sensitive MEMS shear stress sensor with high spatial and temporal resolution

Measurements of wall shear stress of a turbulent boundary layer using a micro-shear-stress imaging chip

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