Optimisation of a two-wire thermal sensor for flow and sound measurements

J.W. van Honschoten, Gijsbertus J.M. Krijnen, Vitaly Svetovoy, V.B. Svetovoi, H.E. de Bree, Michael Curt Elwenspoek

    Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

    15 Citations (Scopus)
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    The Microflown is an acoustic sensor measuring particle velocity instead of pressure, which is usually measured by conventional microphones [2, 3, 4]. In this paper an analytical model is presented to describe the physical processes that govern the behaviour of the sensor and determine its sensitivity. The Microflown consists of two heaters that act simultaneously as sensors. Forced convection by an acoustic wave leads to a small perturbation of this temperature profile, resulting in a temperature difference between the two sensors. This temperature difference, to which the sensitivity is proportional, is calculated with perturbation theory. Consequently the frequency dependent behaviour of the sensitivity is analysed; it is found that there are two important corner frequencies, the first related to the time constant velocity of heat diffusion between the sensors, the second related to the heat capacity of the heaters. The developed model is verified by experiments. In [12] a very good model is given for the performance of the Microflown in a channel, i.e. with both heaters between fixed walls walls in the positive and negative z-direction. Here, a model is presented that describes the situation of the present used sensors: without walls under and above them. Model predictions are compared to experimental results.
    Original languageUndefined
    Title of host publicationProceedings of the IEEE Micro Electro Mechanical Systems (MEMS)
    Place of PublicationPiscataway
    PublisherIEEE Computer Society
    Number of pages4
    ISBN (Print)0-7803-5998-4
    Publication statusPublished - 2001
    EventInterlaken, Zwitserland: Proceedings of Micro Electro Mechanical Sensors (MEMS) Conference -
    Duration: 21 Jan 200125 Jan 2001

    Publication series



    ConferenceInterlaken, Zwitserland


    • METIS-200241
    • EWI-12896
    • IR-42033

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