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FLUID SENSOR AND METHODS OF MAKING COMPONENTS THEREOF

  • US 20090120169A1
  • Filed: 11/12/2007
  • Published: 05/14/2009
  • Est. Priority Date: 11/12/2007
  • Status: Abandoned Application
First Claim
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1. A fluid sensor for determining properties of a fluid, the sensor comprising:

  • a header assembly comprising an electrically grounded header and a plurality of feedthrough conductors extending through the header between opposite ends of the header, each of the feedthrough conductors being surrounded by an electrically insulating sheath, the feedthrough conductors being fused to the sheaths and the sheaths being fused to the header;

    a tuning fork resonator having a base portion and a pair of tines extending from the base portion, each of the tines including a piezoelectric substrate and electrodes on the substrate for applying an electric field to the substrate, some of the feedthrough conductors being in conductive electrical contact with the electrodes;

    a temperature sensor in conductive electrical contact with some of the feedthrough conductors, the temperature sensor being spaced from the tuning fork resonator a distance that is no more than about 2 mm;

    an electrically grounded shroud partially enclosing the tuning fork resonator and temperature sensor, the shroud comprising a substantially cylindrical wall extending circumferentially around the tuning fork resonator and temperature sensor, the shroud including a plurality of openings in the wall for allowing said fluid to enter the shroud and contact the tuning fork resonator and temperature sensor, the shroud being secured to the header assembly;

    a fitting adapted to be installed in an opening of a support structure, the fitting having a central opening, the header assembly being received in the central opening and secured to the fitting;

    a printed circuit board in conductive electrical contact with the feedthrough conductors, the printed circuit board including an ASIC chip operable to transmit a variable frequency signal to the electrodes on the tuning fork resonator through the feedthrough conductors to energize the electrodes so the tines oscillate in opposite phase and to monitor impedance of the tuning fork resonator as a function of frequency, the ASIC chip being spaced from the feedthrough conductors a distance of no more than about 2 mm, the printed circuit board being spaced from the electrodes on the tuning fork a distance of no more than about 20 mm.

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