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Device to determine volume of fluid dispensed

  • US 10,369,299 B2
  • Filed: 10/01/2015
  • Issued: 08/06/2019
  • Est. Priority Date: 02/09/2006
  • Status: Active Grant
First Claim
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1. An apparatus for determining a volume of fluid dispensed comprising:

  • an acoustic volume sensor comprising;

    a structure containing a fixed-volume chamber, a first port, and a measurement chamber, wherein the first port comprises a first tube portion and acoustically couples the fixed-volume chamber to the measurement chamber to form an acoustically contiguous region, the measurement chamber having a gas-filled measurement region;

    a printed circuit board disposed within the structure, the printed circuit board defining the fixed-volume chamber within the structure and the printed circuit board including;

    a loudspeaker acoustically coupled to the fixed-volume chamber, wherein the loudspeaker excites the acoustically contiguous region;

    a reference microphone acoustically coupled to the fixed-volume chamber, the reference microphone producing a first pressure signal based on the response of the fixed-volume chamber to excitement by the loudspeaker; and

    a sensing microphone acoustically coupled to the measurement chamber via a second port comprising a second tube portion, the sensing microphone producing a second pressure signal based on the response of the measurement chamber to excitement by the loudspeaker;

    a dispensing chamber, containing a variable fluid volume, an exit channel and a resilient membrane, wherein the dispensing chamber is attached to the structure and the resilient membrane defines a boundary of the gas-filled measurement region; and

    a processor in communication with the loudspeaker, the reference microphone and the sensing microphone, the processor comprising;

    receiving the first pressure signal and the second pressure signal at a first instance;

    receiving the first and second pressure signals at a second instance;

    determining a change in volume of the gas-filled measurement region associated with the first and second pressure signals at the first instance and the first and second pressure signals at the second instance; and

    determining the volume of fluid dispensed from the dispensing chamber to the exit channel associated with the change in the volume of the measurement region.

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