Measurement of an analyte concentration in a scattering medium
First Claim
1. A method for measuring the concentration of an analyte in a scattering medium, the method comprising the steps of:
- illuminating a sample containing said analyte with broad spectrum radiation;
detecting an amount of transmitted, transflected, or reflected radiation from the sample with a detector;
associating a vector in a vector space with the amount of transmitted, transflected, or reflected radiation;
determining a correction vector from a measurement of a standard in a non-scattering medium as compared with the measurement of the same standard in the scattering medium; and
utilizing said correction vector and said vector associated with the amount of transmitted, transflected, or reflected radiation to identify and to obtain the concentration of the analyte in the scattering medium.
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Abstract
A non-invasive detection method for glucose and other constituents of interest in a sample is described. The apparatus and methods of the invention provide an analog of color perception of human vision, preferably in the near infrared region, replacing the spectrophotometers used in other non-invasive near infrared detection methods. A plurality of detection units are used, each covering a broad region of the detected spectrum, paralleling color perception and colorimetry. In some circumstances, a neural net is used for analysis, allowing the system to learn. Analyte concentrations in scattering mediums can be obtained by calibrating the results with in vitro measurements.
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Citations
38 Claims
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1. A method for measuring the concentration of an analyte in a scattering medium, the method comprising the steps of:
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illuminating a sample containing said analyte with broad spectrum radiation;
detecting an amount of transmitted, transflected, or reflected radiation from the sample with a detector;
associating a vector in a vector space with the amount of transmitted, transflected, or reflected radiation;
determining a correction vector from a measurement of a standard in a non-scattering medium as compared with the measurement of the same standard in the scattering medium; and
utilizing said correction vector and said vector associated with the amount of transmitted, transflected, or reflected radiation to identify and to obtain the concentration of the analyte in the scattering medium. - View Dependent Claims (2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
obtaining a second vector associated with a second spectral property of the standard in a second sample containing the scattering medium.
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14. The method of claim 13, wherein the first vector and the second vector both belong to a vector space whose dimension is equal to the number of detection units in the detection array.
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15. The method of claim 14, wherein the step of utilizing includes calculating a rotation that transforms the second vector into the first vector, said rotation specifying the correction vector.
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16. The method of claim 13, wherein the second sample is in vivo.
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17. The method of claim 1, wherein the standard in the non-scattering medium is in vitro.
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18. The method of claim 1, wherein the sample is in vivo.
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4. The method of claim I wherein said detecting step includes impinging the radiation transmitted, transflected, or reflected from the sample onto the detector that includes a plurality of filters, each of said filters allowing transmission of a specific region of a spectrum associated with the transmitted, transflected, or reflected radiation, the spectral response of each of said filters having at least partial overlap with the response of at least one other of said filters, wherein each of said filters is impinged on the radiation transmitted, transflected, or reflected from said sample or standard sequentially and the output from said detector is used to measure the concentration.
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19. The method of claim I, wherein the vector space has a dimension that is equal to the number of detection units.
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20. A system for measuring the concentration of an analyte in a scattering medium, the system comprising:
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a light source for illuminating a sample containing said analyte with broad spectrum radiation;
a detector for detecting an amount of transmitted, transflected, or reflected radiation from the sample;
a generator for generating a vector in a vector space that is associated with the amount of transmitted, transflected, or reflected radiation; and
an analyzer for determining a correction vector from a measurement of a standard in a non-scattering medium as compared with the measurement of the same standard in the scattering medium, and for utilizing said correction vector and said vector associated with the amount of transmitted, transflected, or reflected radiation to identify and to obtain the concentration of the analyte in the scattering medium. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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Specification