Non-invasive method of determining oxygen concentration in a sealed package
First Claim
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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Abstract
The invention is a method of measuring oxygen concentration in a package having an oxygen sensitive product disposed therein. The method includes exposing a luminescent compound that is disposed in an interior of the package to light having a wavelength that is absorbed by the luminescent compound so that the luminescent compound is promoted into an excited state. When the exposure of the light is terminated, the excited luminescent compound emits light that is detectable by a detector positioned outside of the package. The intensity of the emitted light is inversely proportional to the oxygen concentration and is used in conjunction with mathematical function that describes the luminescent intensity of the luminescent compound as a function of oxygen concentration and temperature to calculate the oxygen concentration. The method may be used to verify and track the oxygen concentration of a package as it moves through a distribution system.
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Citations
14 Claims
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1. A method of verifying the oxygen concentration of a sealed package comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification