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Non-invasive method of determining oxygen concentration in a sealed package

  • US 7,749,768 B2
  • Filed: 03/13/2006
  • Issued: 07/06/2010
  • Est. Priority Date: 03/13/2006
  • Status: Expired due to Fees
First Claim
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1. A method of verifying the oxygen concentration of a sealed package comprising:

  • providing a sealed package defining an interior and having a luminescent compound provided in the interior of the sealed package the luminescent compound having a luminescent emission that is sensitive to quenching by oxygen;

    exposing the luminescent compound to light having a wavelength that is absorbed by the luminescent compound so that the luminescent compound is promoted into an excited state;

    terminating the exposure of the luminescent compound when the luminescent compound achieves a steady state between excitation and luminescence;

    measuring luminescent intensity over a period of time to produce an exponential decay curve;

    calculating the coefficient of the decay curve to determine tau;

    measuring a temperature that is indicative of the temperature of the luminescent compound;

    determining the oxygen concentration within the sealed package using the equation;


    [O2]=(ATa(T)2+BTa(T)+CTa)(tau)2+(ATb(T)2+BTb(T)+CTb)(tau)+(ATc(T)2+BTc(T)+CTc)wherein;

    T is the measured temperature;

    tau is the coefficient of the exponential decay curve; and

    ATa, BTa, CTa, ATb, BTb, CTb, ATc, BTc, and CTc are previously determined coefficients for the luminescent compound that describes the luminescent intensity of the luminescent compound as a function of oxygen concentration and temperature; and

    comparing the measured oxygen concentration to a predetermined minimum or maximum to verify that the measured oxygen concentration is within acceptable limits.

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