AeroMEMS Wall Hot-Wire Anemometer on Polyimide Foil for Measurement of High Frequency Fluctuations

Buder, U.; Berns, Andreas; Obermeier, Ε.; Petz, Ralf; Nitsche, W.

doi:10.1109/icsens.2005.1597756

Cited by 8 publications

(6 citation statements)

References 8 publications

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“…Indeed there are many papers that describe the different types of wind speed sensors, such as hot wire anemometers [5], [6], acoustic anemometers [7], however, most of them are large scale sensors. Besides, there are also some complicated and expensive sensors like ultrasonic anemometers [8], [9].…”

Section: Related Workmentioning

confidence: 99%

Low cost embedded weather station with intelligent system

Shaout

Zhou

et al. 2014

2014 10th International Computer Engineering Conference (ICENCO)

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This paper presents an embedded design of a low cost weather station. Three weather parameters; wind speed, wind directions and temperature are measured. The measured parameters are used to measure the wind chill temperature and dressing index through calculation and a build-in intelligent system. Only basic types sensors were used (a reflective optical sensor, potentiometer and a temperature sensor) so that the cost of this design is reduced.A small scale neural network was planted into the microcontroller for the post-processing. Taking the three measured data as inputs, the system gave out the dressing index as an output. All of the data were displayed on the LCD and also sent to computer from the serial port.

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Section: Related Workmentioning

confidence: 99%

Low cost embedded weather station with intelligent system

Shaout

Zhou

et al. 2014

2014 10th International Computer Engineering Conference (ICENCO)

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“…To be able to process a flexible substrate material in equipment designed for handling of rigid silicon wafers, the polyimide foil is attached to a 2-mm-thick wafer. The adhesive employed is a solvent-free thermoplastic, which provides high bond strength after being heated and subjected to high pressure in a vacuum press during bonding [27]. Using this specific adhesive is necessary to prevent outgassing of solvents in high-vacuum environments common in MEMS processing.…”

Section: Fabricationmentioning

confidence: 99%

Family of Micromachined Wall Hot-Wire Sensors on Polyimide Foil

Buder¹,

Berns²,

Klitzing³

et al. 2007

AIAA Journal

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Micromachined wall hot-wire sensors composed of a highly sensitive, nickel, thin-film resistor spanning an airfilled cavity in a mechanically flexible substrate are presented. Cavity design and sensor materials are optimized to reduce thermal losses, thus enabling measurement of high-frequency fluctuations in fluid flows. Successfully realized sensors featuring wire widths of 2 and 5 m, wire lengths from 400 to 2000 m, and various cavity dimensions were characterized in wind-tunnel experiments. Static sensor calibration, cutoff frequency determination using a sine sweep, and recording of angular characteristics were conducted at wall shear stresses of up to 1 N=m 2 , obtained at 20 m=s freestream velocity in an open wind tunnel on a flat plate with fully developed turbulent flow. An overheat ratio of 1.8 was used for hours without thermal failure of the sensors, and a maximum cutoff frequency in still air of 73 kHz was obtained. The highest average sensitivity of 0:196 V=N=m 2 was recorded for a sensor of 5-m wire width and a length-to-width ratio of 400 in a wall shear stress range from 0 to 1 N=m 2 with a power consumption of less than 30 mW. Nomenclature a W = overheat ratio of the hot wire d C = depth of the cavity, m k = yaw factor l C = length of the cavity, m l W = length of the hot wire, m P = electrical power consumption, W R W = electrical resistance of the hot wire in operation, R 0 = electrical resistance of the hot wire at room temperature, S = sensitivity of the sensor to changes in wall shear stress, V=N=m 2 T W = temperature of the heated wire, K T 0 = ambient fluid temperature, K t F = thickness of the polyimide foil, m t W = thickness of the hot wire, m U = anemometer output voltage with flow in constanttemperature operation, V U 0 = anemometer output voltage without flow in constanttemperature operation, V U 0 = anemometer output voltage with flow normal to the wire length in constant-temperature operation, V v = flow velocity at the hot wire, m=s v eff = flow velocity contributing to cooling of the hot wire, m=s v n = component of flow velocity normal to the hot-wire length, m=s v 1 = freestream velocity, m=s w C = width of the cavity, m w W = width of the hot wire, m = yaw angle, deg = wall shear stress, N=m 2

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“…Even though reducing sensor size potentially reduces disturbances, using sensors with bondpads on the top side of the polyimide, as presented in [10], electrical contacts will always be a source of flow disturbance. A process for through-foil metallization, yielding a system in which bondpads are relocated to the bottom side of the sensor and flow disturbances are solely caused by the measurement components of the sensor itself, substantially contributes to the quality of flow measurement.…”

Section: Introductionmentioning

confidence: 99%

AeroMEMS Wall Hot-Wire Anemometer on Polyimide Substrate Featuring Top Side or Bottom Side Bondpads

et al. 2007

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Design, manufacturing, calibration, and basic characterization of a microelectromechanical systems (MEMS) wall hotwire sensor on a flexible polyimide substrate are presented. A configuration exhibiting bondpads on the top side of the foil, as well as an improved setup featuring a through-foil metallization and bottom side bondpads were established. Both sensor designs make use of a highly sensitive nickel thin-film resistor spanning a reactive ion etched cavity in a polyimide substrate. The polyimide base material enables the sensor to be adapted to curved aerodynamic surfaces, e.g., airfoils and turbine blades. A mismatch of curvature of aerodynamic surface and silicon sensor surface, as observed with previously presented MEMS hot-wire anemometers is avoided. The combination of polyimide's low thermal conductivity and a cavity featuring FEM-optimized dimensions accounts for a very low-power consumption (<25 mW). Fluctuations in wall shear stress up to 85 kHz can be resolved in constant-temperature mode. An average sensitivity of 0.166 V/(N/m 2 ) is achieved in a wall shear stress range from 0 to 0.72 N/m 2 . The specifically designed through-foil metallization process allows for electrical contacts to be positioned on the backside of the substrate, thus effectively minimizing aerodynamic disturbances.Index Terms-Microelectromechanical systems (MEMS), polyimide, via, wall hot-wire.

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AeroMEMS Wall Hot-Wire Anemometer on Polyimide Foil for Measurement of High Frequency Fluctuations

Cited by 8 publications

References 8 publications

Low cost embedded weather station with intelligent system

Low cost embedded weather station with intelligent system

Family of Micromachined Wall Hot-Wire Sensors on Polyimide Foil

AeroMEMS Wall Hot-Wire Anemometer on Polyimide Substrate Featuring Top Side or Bottom Side Bondpads

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