Optimization of a thermal flow sensor for acoustic particle velocity measurements

J.W. van Honschoten, Vitaly Svetovoy, Gijsbertus J.M. Krijnen, Michael Curt Elwenspoek

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    In this paper, a thermal flow sensor consisting of two or three heated wires, the Microflown, is treated for application to acoustic measurements. It is sensitive to flow ("particle velocity"), contrary to conventional microphones that measure acoustic pressures. A numerical analysis, allowing for detailed parametric studies, is presented. The results are experimentally verified. Consequently, improved devices were fabricated, and also sensors with a new geometry consisting of three wires, instead of the usual two, of which the central wire is relatively most heated. These devices are the best performing Microflowns to date with a frequency range extending from 0 to over 5 kHz and a minimum detectable particle velocity level of about 70 nm/s at 2 to 5 kHz (i.e., 3 dB PVL or SPL, corresponding to a pressure of 3.1/spl middot/10/sup -5/ Pa at a free field specific acoustic impedance).
    Original languageUndefined
    Pages (from-to)436-443
    Number of pages8
    JournalJournal of microelectromechanical systems
    Volumevolume 14
    Issue numberno.3/no. 3
    Publication statusPublished - Jun 2005


    • IR-52575
    • METIS-224194
    • EWI-9802

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