Electromagnetic method and apparatus to measure constituents of human or animal tissue
First Claim
1. Non-invasive method for measuring the concentration of predetermined analytes in living body tissue, comprising the steps of:
- a) generating a combined beam of electromagnetic radiation comprised of alternate and repetitive periods of radiation having different wavelengths, the two wavelengths having different absorption coefficients for the analyte being sought, at least one of the wavelengths being tunable, and the repetitive periods forming a measurement cycle;
b) detecting the combined beam with a primary detector for generating a primary electrical signal proportional to the intensity of the combined beam;
c) detecting the combined beam with a reference detector for generating a reference signal proportional to the intensity of the combined beam and wherein the electrical response generated by the two period radiations in both detectors is substantially equal in magnitude, thus producing a substantially zero alternating component in the signals of both detectors,d) directing the combined beam on the subject tissue so that radiation transmitted or reflected by the tissue reaches the primary detector;
e) controlling the intensity relation between the periods using the reference signal and tuning the wavelength of one of the periods to obtain a substantially zero alternating component in the primary signal;
f) changing the ratio of extracellular fluid content to intracellular fluid content in the tissue; and
g) using the change in the primary signal produced by the principal detector as a result of the fluid ratio change to measure the concentration of the analyte in the tissue.
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Accused Products
Abstract
To determine glucose or other constituents of the human or animal body, a stabilized near-infrared radiation beam containing two alternating wavelengths that have approximately equal extinction coefficients in the tissue, is directed onto the sample area, the transmitted signal alternating component is zeroed by tuning one of the wavelengths, the extracellular-to-intracellular fluid ratio of the tissue is changed by exerting varying mechanical pressure on the tissue, or the ratio is allowed to change as a result of the natural pulsation. The alternating component of the transmitted beam power is measured in the changed fluid ratio state. The amplitude of the alternating-current (AC) signal given by the detector, is taken to represent glucose concentration or the difference from a preset reference concentration.
472 Citations
20 Claims
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1. Non-invasive method for measuring the concentration of predetermined analytes in living body tissue, comprising the steps of:
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a) generating a combined beam of electromagnetic radiation comprised of alternate and repetitive periods of radiation having different wavelengths, the two wavelengths having different absorption coefficients for the analyte being sought, at least one of the wavelengths being tunable, and the repetitive periods forming a measurement cycle; b) detecting the combined beam with a primary detector for generating a primary electrical signal proportional to the intensity of the combined beam; c) detecting the combined beam with a reference detector for generating a reference signal proportional to the intensity of the combined beam and wherein the electrical response generated by the two period radiations in both detectors is substantially equal in magnitude, thus producing a substantially zero alternating component in the signals of both detectors, d) directing the combined beam on the subject tissue so that radiation transmitted or reflected by the tissue reaches the primary detector; e) controlling the intensity relation between the periods using the reference signal and tuning the wavelength of one of the periods to obtain a substantially zero alternating component in the primary signal; f) changing the ratio of extracellular fluid content to intracellular fluid content in the tissue; and g) using the change in the primary signal produced by the principal detector as a result of the fluid ratio change to measure the concentration of the analyte in the tissue. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. Apparatus for non-invasive measurement of the in vivo concentration of a predetermined analyte in bodily tissue comprising:
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a) radiation means to generate an electromagnetic radiation probe beam containing two alternating wavelength portions where at least one of the wavelengths is tunable and the intensity of the radiation during at least one wavelength portion is controllable, b) optical means to transmit the beam to the tissue; c) reference detector means to detect a representative portion of the beam, prior to interaction with the tissue, and for generating a reference signal proportional to probe beam intensity; d) primary detector means to detect at least a portion of the beam radiation after interaction with the tissue and for generating a primary signal proportional to interacted probe beam intensity; e) electrical means to produce an off-set signal in response to the primary signal; f) electrical means to produce a control signal from the reference signal and the off-set signal; g) control means to control the intensity relation of the alternating portions of the probe beams, according to said control signal, h) computing means to convert the primary signal to the concentration value of the analyte sought. - View Dependent Claims (15, 16, 17)
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18. Non-invasive apparatus for measuring the concentration of predetermined analytes in living body tissue, comprising:
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a) transmission means for generating a combined beam of electromagnetic radiation comprised of alternate and repetitive periods of radiation having different wavelengths, the two wavelengths having different absorption coefficients for the analyte being sought, at least one of the wavelengths being tunable; b) a primary detector means for detecting the combined beam before and after interacting with the tissue and for generating a primary electrical signal proportional to the intensity of the combined beam before and after said interaction; c) a reference detector means for detecting the combined beam for generating a reference signal proportional to the intensity of the combined beam and wherein the electrical response generated by the two period radiations in both detectors is substantially equal in magnitude, thus producing a substantially zero alternating component in the signals of both detectors, d) coupling means for directing the combined beam onto the subject tissue so that radiation transmitted or reflected by the tissue is coupled to the primary detector means; e) control means for controlling the intensity relation between the radiation periods in response to the reference signal to tune the wavelength of one of the periods to obtain a substantially zero alternating component in the primary signal; f) change means for changing the ratio of extracellular fluid content to intracellular fluid content in the tissue; and g) display means responsive to the change, in the primary signal produced by the primary detector means as a result of the fluid ratio change to measure the concentration of the analyte in the tissue. - View Dependent Claims (19, 20)
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Specification