Thermal model of thin film anemometer

Giani, Alain; Mailly, F.; Bonnot, R.; Pascal‐Delannoy, F.; Foucaran, A.; Boyer, André

doi:10.1016/s0026-2692(02)00039-3

Cited by 17 publications

(5 citation statements)

References 13 publications

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“…As a sensor substrate material, a commercially available 4-inch wafer of Pyrex 7740 was used and an aluminum thin-film was sputtered and patterned on the Pyrex wafer by photolithography and chemical etching. Unlike other thin-film thermal sensors possessing thin membranes as support materials for the sensor film [22][23][24], we developed the Pyrex substrate based thin-film sensor because of far simpler fabrication and integration with the silicon-based microchannel reactor system.…”

Section: Introductionmentioning

confidence: 99%

A micromachined thin-film gas flow sensor for microchemical reactors

Shin¹,

Besser

2006

J. Micromech. Microeng.

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As microchemical systems (MCS) have gained in importance since their introduction in the last decade, it has become recognized that appropriate sensing and control capabilities are needed if MCS are to reach their potential. In this context, we present a study of the working behavior of a novel thin-film micro flow sensor which is integrated with a silicon microreactor with a submillimeter channel. A simple-to-fabricate device based on the concept of calorimetric sensing was chosen as a model structure to understand the important factors controlling sensor performance. Various design options for the sensor were explored by the use of computational fluid dynamics simulations. We found that sensitivity depends strongly on certain design factors. In summary, sensitivity is improved with (a) higher values of the resistors that detect flowinduced temperature changes, (b) shorter distances between the resistor that provides a source of heat and the thermally sensitive resistors and (c) higher input power to the heating resistor. Item (a) was found to have by far the strongest effect of the three. Reproducibility tests were conducted and the sensor exhibited consistent performance throughout the entire test range of 0 to 20 sccm which is an appropriate fit to the flow capacity of the microchannel. Finally, response time was assessed by simulating the transient behavior of the sensor with a thermal capacitance model, which yielded an accurate prediction of the experimental response of the device. The response time is approximately 70 msec at a typical flow rate of 10 sccm.According to the understanding gained by the model, the sensor response time can be improved by reducing the substrate thickness, using a lower density substrate material, and increasing the convective heat transfer coefficient in the channel.3

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Section: Introductionmentioning

confidence: 99%

A micromachined thin-film gas flow sensor for microchemical reactors

Shin¹,

Besser

2006

J. Micromech. Microeng.

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“…Furthermore, the small surface area and relatively low operating temperature are also good reasons to neglect the radiation contribution; whereas the conduction losses from the hot film to the substrate are minimized by embedding the aluminium film in the thin silicon dioxide membrane. As a result, most of the power due to Joule heating is convected to the fluid passing over the hot film [33]:

P_{J} = (G_{c o n d} + G_{c o n v} + G_{r a d}) (T - T_{a m b})

…”

Section: Multi-sensor Chip Designmentioning

confidence: 99%

An SOI CMOS-Based Multi-Sensor MEMS Chip for Fluidic Applications

Mansoor

Haneef

Akhtar

et al. 2016

Sensors

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An SOI CMOS multi-sensor MEMS chip, which can simultaneously measure temperature, pressure and flow rate, has been reported. The multi-sensor chip has been designed keeping in view the requirements of researchers interested in experimental fluid dynamics. The chip contains ten thermodiodes (temperature sensors), a piezoresistive-type pressure sensor and nine hot film-based flow rate sensors fabricated within the oxide layer of the SOI wafers. The silicon dioxide layers with embedded sensors are relieved from the substrate as membranes with the help of a single DRIE step after chip fabrication from a commercial CMOS foundry. Very dense sensor packing per unit area of the chip has been enabled by using technologies/processes like SOI, CMOS and DRIE. Independent apparatuses were used for the characterization of each sensor. With a drive current of 10 µA–0.1 µA, the thermodiodes exhibited sensitivities of 1.41 mV/°C–1.79 mV/°C in the range 20–300 °C. The sensitivity of the pressure sensor was 0.0686 mV/(Vexcit kPa) with a non-linearity of 0.25% between 0 and 69 kPa above ambient pressure. Packaged in a micro-channel, the flow rate sensor has a linearized sensitivity of 17.3 mV/(L/min)−0.1 in the tested range of 0–4.7 L/min. The multi-sensor chip can be used for simultaneous measurement of fluid pressure, temperature and flow rate in fluidic experiments and aerospace/automotive/biomedical/process industries.

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“…For this type of sensors, heat exchanges by convection are modified by the flow velocity "v" and it produces the variation of electric signal [7] . The moving gas absorbs heat from the heat source, therefore, the source temperature is reduced, and the temperature of the platinum film resistance changes simultaneously, the value of the platinum film resistance changes according to the resistivity and temperature-related features, and this eventually leads to the changes of the output voltage in the Wheatstone bridge circuit.…”

Section: Introductionmentioning

confidence: 99%

A hot platinum thin film anemometer

Liu

Luo

Zhang

et al. 2010

2010 11th International Conference on Electronic Packaging Technology &Amp; High Density Packaging

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In this paper, a platinum thin film thermal flow sensor was presented. Design, fabrication process and thermal analysis were presented and discussed. Compared with traditional structure of four supporting beams, the present structure can provide high sensitivity and good strength because of the unique thermal and mechanical design. The sizes of the flow sensor chip are 571 μ m × 280 μ m × 0.25 μ m. The experimental results show that this flow sensor is capable of measuring the flow rate and has a good linearity in the flowmeter capacity (0.1 to1 m 3 /h) and also the linearity of the sensor is less influenced by the resistance of the sensor and flow orientation at a constant input voltage. The sensors subjected to different voltage input have been tested and the results show that the sensor has better performance under 3V voltage input. It demonstrates that the micro-machined flow sensor has great potential to be used in detecting flow rates within 0.1 to1 m 3 /h.

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Thermal model of thin film anemometer

Cited by 17 publications

References 13 publications

A micromachined thin-film gas flow sensor for microchemical reactors

A micromachined thin-film gas flow sensor for microchemical reactors

An SOI CMOS-Based Multi-Sensor MEMS Chip for Fluidic Applications

A hot platinum thin film anemometer

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