Method and apparatus for determining analyte concentration using phase and magnitude detection of a radiation transfer function
First Claim
1. A method for detecting a concentration of a substance in a body, the method comprising:
- inducing a time-varying temperature on a surface of the body, the temperature varying according to a surface temperature modulation;
detecting radiation emitted from the surface of the body, the emitted radiation having an emitted radiation modulation;
defining a first transfer function relating the emitted radiation modulation to (i) the surface temperature modulation and (ii) an absorbance; and
determining the absorbance based on the first transfer function.
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Abstract
A method and apparatus of determining the analyte concentration of a test sample is described. A temperature gradient is introduced into the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. The modulation of the temperature gradient is controlled by a surface temperature modulation. A transfer function is determined that relates the surface temperature modulation to the modulation of the measured infrared radiation. Reference and analytical signals are detected. In the presence of the selected analyte, phase and magnitude differences in the transfer function are detected. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated and processed to determine analyte concentration in the sample.
168 Citations
27 Claims
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1. A method for detecting a concentration of a substance in a body, the method comprising:
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inducing a time-varying temperature on a surface of the body, the temperature varying according to a surface temperature modulation;
detecting radiation emitted from the surface of the body, the emitted radiation having an emitted radiation modulation;
defining a first transfer function relating the emitted radiation modulation to (i) the surface temperature modulation and (ii) an absorbance; and
determining the absorbance based on the first transfer function. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for detecting a concentration of a substance in a body, the apparatus comprising:
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a thermal device adapted to induce a time-varying temperature on a body surface;
a detector adapted to detect radiation emitted from the body surface, the emitted radiation having an emitted radiation modulation;
a controller configured to drive the thermal device such that the time-varying temperature varies according to a surface temperature modulation; and
a signal processor connected to the detector and adapted to detect a phase and magnitude of the emitted radiation modulation, the signal processor including a transfer function that relates the surface temperature modulation to the emitted radiation modulation. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for determining an optical absorbance of a tissue comprising:
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determining a thermal transfer function that relates a tissue surface temperature modulation to an internal tissue temperature modulation;
detecting radiation emitted from the tissue, the emitted radiation having an emitted radiation modulation;
defining a radiation transfer function that relates the emitted radiation modulation to the internal tissue temperature modulation, the radiation transfer function including the optical absorbance; and
determining a correlation between a phase or magnitude of the radiation transfer function and the optical absorbance. - View Dependent Claims (14)
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15. An apparatus for detecting a concentration of a substance in a body, the apparatus comprising:
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a thermal device adapted to induce a time-varying temperature on a body surface;
a detector adapted to detect radiation emitted from the body surface, the emitted radiation having an emitted radiation modulation;
a controller configured to drive the thermal device such that the time-varying temperature varies according to a surface temperature modulation; and
a signal processor connected to the detector and adapted to detect a phase and magnitude of the emitted radiation modulation, the signal processor including a plurality of model transfer functions that relate to a respective plurality of model responses between the surface temperature modulation and the emitted radiation modulation, wherein each model transfer function depends on a set of patient parameters. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A method for detecting a concentration of a substance in a body, the method comprising:
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inducing a time-varying temperature on a surface of the body, the temperature varying according to a surface temperature modulation;
detecting radiation emitted from the surface of the body, the emitted radiation having an emitted radiation modulation; and
determining an absorbance based on a first transfer function which relates the emitted radiation modulation to (i) the surface temperature modulation and (ii) the absorbance. - View Dependent Claims (23, 24, 25, 26, 27)
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Specification