MEMS Based Acoustic Array

Embodiments of the present invention described and shown in the specification aid drawings include a combination responsive to an acoustic wave that can be utilized as a dynamic pressure sensor. In one embodiment of the present invention, the combination has a substrate having a first surface and an opposite second surface, a microphone positioned on the first surface of the substrate and having an input and a first output and a second output, wherein the input receives a biased voltage, and the microphone generates an output signal responsive to the acoustic wave between the first output and the second output. The combination further has an amplifier positioned on the first surface of the substrate and having a first input and a second input and an output, wherein the first input of the amplifier is electrically coupled to the first output of the microphone and the second input of the amplifier is electrically coupled to the second output of the microphone for receiving the output sinual from the microphone. The amplifier is spaced from the microphone with a separation smaller than 0.5 mm

Micro-sensor thin-film anemometer

A device for measuring turbulence in high-speed flows is provided which includes a micro-sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14.degree. half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a microphotolithography technique

Micro-sensor thin-film anemometer

A device for measuring turbulence in high-speed flows is provided which includes a micro-sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14 deg half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a microphotolithography technique

Mixed convection induced by MEMS-based thermal shear stress sensors

The effect of buoyancy caused by heat generation from a microelectromechanical system (MEMS)-based thermal shear stress sensor is investigated. Due to the small size and relatively low power consumption of such sensors, the buoyancy effect on the overall flow structure is generally negligible. However, its impact on the flow variables such as shear stresses can be significant because such quantities are local and depend on the gradients of the velocity profile next to the sensor. Due to the small dimension of the MEMS sensor, a multiscale modeling approach is adopted to examine the effect of buoyancy on the velocity and wall shear stress profiles. Full-length channel computations are initially performed with finer resolution near the sensor region. Using the boundary conditions derived from the full-length computations, another simulation is performed concentrating on a small region near the shear stress sensor. Based on the temperature distribution in the region of the sensor, the effective thermal length scale is several times the streamwise dimension of the sensor. For a state-of-the-art MEMS sensor dimension of 200μm, the effect of buoyancy on the accuracy of shear stress measurement can be noticeable

Effect of conjugate heat transfer on MEMS-based thermal shear stress sensor

The effect of conjugate heat transfer resulting from a Micro- electromechanical Systems (MEMS)-based thermal shear stress is investigated. Due to the length scale disparity and large solid-fluid thermal conductivity ratio, a two-level computation is used to examine the relevant physical mechanisms and their influences on wall shear stress. The substantial variations in transport properties between the fluid and solid phases and their interplay in regard to heat transfer and near-wall fluid flow structures are investigated. It is demonstrated that for the state-of-the-art sensor design, the buoyancy effect can noticeably affect the accuracy of the shear stress measurement. Copyright © 2005 by ASME

A Micromachined Geometric Moire Interferometric Floating-Element Shear Stress Sensor

This paper presents the development of a floating-element shear stress sensor that permits the direct measurement of skin friction based on geometric Moir interferometry. The sensor was fabricated using an aligned wafer-bond/thin-back process producing optical gratings on the backside of a floating element and on the top surface of the support wafer. Experimental characterization indicates a static sensitivity of 0.26 microns/Pa, a resonant frequency of 1.7 kHz, and a noise floor of 6.2 mPa/(square root)Hz