Electromagnetic method and apparatus to measure constituents of human or animal tissue
AssigneeVivaScan Corporation
InventorsHannu Harjunmaa, Yitzhak Mendelson, Yi Wang
Life of this patent
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Abstract
To deterine glucose or other constituents of the human or animal body, near-infrared radiation containing two alternating wavelengths that have equal extinction coefficients in the tissue is directed onto a sample area of the body. The intensity relation of the two different wavelengths is adjusted so as to balance the two wavelength detected signals. The extracellular-to-intracellular fluid ratio of the tissue is changed or is allowed to change, and the alternating component of the transmitted beam power is measured. The amplitude of the alternating-current (AC) signal given by the detector represents glucose concentration or the difference from a preset reference concentration.
Claims28
A non-invasive method for measuring the concentration of analytes in living tissue containing fluids, comprising the steps of:
- a) illuminating the tissue with an electromagnetic beam comprised of alternate periods of monochromatic wavelengths, one of the alternate periods having a wavelength that is absorbed by the analyte, and the other alternate period having a wavelength selected so as to have an extinction coefficient in the tissue identical with that of the first wavelength;
- b) detecting the electromagnetic beam after reaction with the tissue to produce a first electrical signal;
- c) adjusting the intensity relation between wavelength periods of the illuminating beam so as to produce a substantially zero alternating component in the first electrical signal;
- d) varying the balance of analyte present in the tissue;
- and
- e) detecting an alternating component of the beam that has interacted with the tissue to generate a second electrical signal proportional to the concentration of analyte in the tissue;
- and
- f) calculating the concentration of the analyte in the tissue.
A non-invasive apparatus for measuring the concentration of analytes in a living tissue, comprising:
- a) a source of electromagnetic radiation for illuminating the tissue with an electromagnetic beam comprised of alternate periods of different wavelengths, one of the alternate periods having a first wavelength that is absorbed by the analyte, and the other alternate period having a wavelength selected so as to have an extinction coefficient in the tissue identical with that of said first wavelength;
- b) a detector means for detecting the electromagnetic beam after reaction with the tissue to produce a first electrical signal proportional to the intensity of said electromagnetic beam;
- and
- c) intensity control means for adjusting the intensity relation between wavelength periods of the illuminating beam so as to produce, a reference level component in the first electrical signal when a minimum level of analyte is present in the tissue;
- d) whereby the first electrical signal when analyte is present is proportional to the concentration of analyte in the tissue.
A non-invasive apparatus for measuring the concentration of analytes in a living tissue, comprising:
- a) a source of electromagnetic radiation for illuminating the tissue with an electromagnetic beam comprised of alternate periods of different wavelengths, one of the alternate periods having a first wavelength that is absorbed by the analyte, and the other alternate period having a wavelength selected so as to have an extinction coefficient in the tissue identical with that of said first wavelength;
- b) a detector means for detecting the electromagnetic beam after reaction with the tissue to produce a first electrical signal proportional to the intensity of said electromagnetic beam;
- and
- c) analyte level changing means for changing the level of analyte in the tissue;
- d) intensity control means for adjusting the intensity relation between wavelength periods of the illuminating beam so as to produce, a reference level component in the first electrical signal when a minimum level of analyte is present in the tissue whereby the first electrical signal when analyte is present is proportional to the concentration of analyte in the tissue;
- e) temperature control means for maintaining the temperature of the tissue substantially constant during measurement.
Dependencies are inferred from the claim text.