MEMS Pressure Sensor Array for Aeroacoustic Analysis of the Turbulent Boundary Layer

Krause, Joshua S.; White, Robert D.; Moeller, Mark J.; Jong, Richard De

doi:10.2514/6.2009-1905

Cited by 3 publications

(5 citation statements)

References 10 publications

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“…Laser vibrometer measurements shown elsewhere [10] indicate that the first resonant frequency of the microphone is greater than 400 kHz, suggesting that the microphones can be used at frequencies up to 400 kHz, although this has not been confirmed by acoustic calibration. The bandwidth of the electronics sets the upper limit of operation of the current system at 40 kHz, although this could be increased with minor changes to the electronics.…”

Section: Calibrationmentioning

confidence: 93%

“…Nano Fabrication Facility. Fabrication has been described previously [10,11]. Briefly, fabrication begins at Memscap by first depositing the silicon nitride isolation layer, then depositing and patterning of the 600 nm thick polysilicon lower electrode and interconnect layer (Poly0).…”

Section: Design and Fabricationmentioning

confidence: 99%

“…The computational model for this device has been described previously [10], and follows many of the same methods described by Doody et al for MEMS cMUT devices [13], with the notable exception that the transducer described here has holes through the diaphragm. A lumped element scheme is adopted as shown in Figure 3, and is valid up to the first resonant frequency at approximately 430 kHz.…”

Section: Modeling and Electronicsmentioning

confidence: 99%

“…The model includes the laminate plate diaphragm stiffness and mass, Z dia , the acoustic compliance of the backing cavity, Z cav , the damping of the diaphragm holes, Z holes , the acoustic input impedance of the environment for the circular bending modeshape of the transducer, Z env , and electrostatic coupling to the electrical domain. For the details of the various mechanical and acoustic impedances, refer to [10,13]. The model can be used to compute the output voltage, V out , that is expected for a given fluctuating pressure at the surface of the diaphragm, P in .…”

Section: Modeling and Electronicsmentioning

confidence: 99%

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MEMS Microphone Array on a Chip for Turbulent Boundary Layer Measurements

White

Krause

Jong

et al. 2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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A MEMS microphone array has been designed and applied to the measurement of wall pressure spectra under the turbulent boundary layer in flow duct testing at Mach numbers from 0 to 0.6. The array was micromachined onto a single chip in the PolyMUMPS surface micromachining process, allowing high spatial resolution and low surface roughness. The chip measures 1 cm by 1 cm, and is flush mounted into the wind tunnel wall. Individual elements are 0.6 mm in diameter, with element to element spacing of 1.11 mm in the crossflow direction and 1.26 mm in the flow direction. The 64 element array has 59 working elements, 58 of which are matched to within ± 2.5 dB at 1 kHz. Phase matching between the 59 elements is ± 6.5 degrees at 1 kHz. The array has been calibrated from 100 Hz to 4 kHz in a plane wave tube. The transducer bandwidth is greater than 400 kHz as determined by laser vibrometry measurements. Sensor nonlinearity of less than 0.36% is observed at a sound pressure level of 150 dB SPL. Board level electronics allow the array to be reconfigured on the fly using computer controlled CMOS switches. Multipoint wall pressure spectra were measured in 38 array configurations at the wall of a 6 inch by 6 inch flow duct at Mach numbers from 0.0 to 0.6. The array shows excellent agreement with Kulite and Bruel & Kjaer microphone measurements in the 300 Hz to 10 kHz band, and appears to be able to measure turbulent pressure spectra at frequencies as high as 40 kHz.

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Section: Calibrationmentioning

confidence: 93%

Section: Design and Fabricationmentioning

confidence: 99%

Section: Modeling and Electronicsmentioning

confidence: 99%

Section: Modeling and Electronicsmentioning

confidence: 99%

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MEMS Microphone Array on a Chip for Turbulent Boundary Layer Measurements

White

Krause

Jong

et al. 2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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“…In addition, for large arrays of MEMS microphones, yield issues were dominated by wire bond integrity problems. These two issues were the primary motivation for developing the low profile conductive ink process [4].…”

Section: Introductionmentioning

confidence: 99%

Low Profile Packaging for MEMS Aero-acoustic Sensors

2012

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This paper describes a semi-automated conductive ink process used for packaging MEMS devices. The method is applied to packaging of MEMS sensors for wind tunnel testing. The primary advantage of the method is a reduction in surface topology between the package and the integrated MEMS sensors. In this paper we explore the relationship between trace dimensions, resistivity, and deposition parameters such as feed rate, tip-substrate separation and tip diameter. Using this procedure it is possible to generate interconnects between a PC board and MEMS sensor chip with a topology of less than 25 micrometers.Introduction:

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A Microphone Array on a Chip for High Spatial Resolution Measurements of Turbulence

Krause

Gallman

Moeller

et al. 2014

J. Microelectromech. Syst.

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A microelectromechanical systems-based microphone array on a chip has been developed and applied to aeroacoustic measurements. The array is designed to measure the fluctuating pressures present under a turbulent boundary layer (TBL). Each chip measures 1 cm 2 and contains 64 individually addressable capacitively sensed microphones, with a center to center pitch of ∼1.25 mm. Surface topology, including the packaging, is kept to less than 0.13 mm. Element-to-element sensitivity variation in the array is less than ±2.5 dB from least to most sensitive, and phase variation is less than ±6.5°( at 1 kHz). The microphone 3-dB bandwidth is 700 Hz to 200 kHz, and the microphones are linear to better than 0.3% at sound pressure levels up to 150-dB SPL. A unique switched architecture system electronics and packaging method are employed to reduce data acquisition channel count requirements, and to maintain a low surface roughness. The array has been applied to the measurement of single point turbulence spectra under a flat plate TBL in a flow duct at Mach numbers up to 0.6 and Reynolds numbers based on plate length of 10 7 .

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MEMS Pressure Sensor Array for Aeroacoustic Analysis of the Turbulent Boundary Layer

Cited by 3 publications

References 10 publications

MEMS Microphone Array on a Chip for Turbulent Boundary Layer Measurements

MEMS Microphone Array on a Chip for Turbulent Boundary Layer Measurements

Low Profile Packaging for MEMS Aero-acoustic Sensors

A Microphone Array on a Chip for High Spatial Resolution Measurements of Turbulence

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