Vivascan Corporation

Yi Wang

Yitzhak Mendelson

Hannu Harjunmaa

Brian D Gross

The present invention relates to the determination of an analyte or multiple analytes in blood using information derived from the differential optical absorption spectra of blood. Specifically, the information is derived from the differential spectra of tissue before and immediately after the volume of blood in the tissue has been changed.

Blood constituent determination based on differential spectral analysis

The present invention relates to the noninvasive measurement of blood hematocrit and hemoglobin content using differential optical absorption of two or more wavelengths of light during blood volume changes. The method is also useful for noninvasive measurements of other blood analytes, such as glucose, where variations in hematocrit or blood hemoglobin concentration cause errors in the measurement.

Noninvasive measurement of hematocrit and hemoglobin content by

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.

Electromagnetic method and apparatus to measure constituents of human or

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.

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Worcester, MA, United States of America

Yi Wang