Method and apparatus for monitoring blood constituent levels in biological tissue
First Claim
1. A method of monitoring blood constituent concentration within a biological tissue comprising:
- providing light having scattering properties sensitive to the blood constituent concentration within the biological tissue;
directing the light over an area of the biological tissue;
causing a reflected portion of the light to interfere with a reference beam;
obtaining interferometric, non-image measurements from at least one tissue depth, the non-image measurements including at least scatter measurements of the light; and
processing the non-image measurements to determine the blood constituent concentration within the biological tissue.
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Abstract
In accordance with the invention, a low coherence interferometer is used to non-invasively monitor the concentration of glucose in blood by shining a light over a surface area of human or animal tissue, continuously scanning the light over a two dimensional area of the surface, collecting the reflected light from within the tissue and constructively interfering this reflected light with light reflected along a reference path to scan the tissue in depth. Since the reflection spectrum is sensitive to glucose concentration at particular wavelengths, measurement and analysis of the reflected light provides a measure of the level of glucose in the blood. The measurement of glucose is taken from multiple depths within blood-profused tissue, and sensitivity is preferably enhanced by the use of multiple wavelengths. Noise or speckle associated with this technique is minimized by continuously scanning the illuminated tissue in area and depth.
781 Citations
28 Claims
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1. A method of monitoring blood constituent concentration within a biological tissue comprising:
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providing light having scattering properties sensitive to the blood constituent concentration within the biological tissue; directing the light over an area of the biological tissue; causing a reflected portion of the light to interfere with a reference beam; obtaining interferometric, non-image measurements from at least one tissue depth, the non-image measurements including at least scatter measurements of the light; and processing the non-image measurements to determine the blood constituent concentration within the biological tissue. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for measuring blood constituent concentration of a human or animal subject comprising:
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at least one light source for providing a sample beam and a reference beam, the at least one light source providing at least one wavelength of light, the at least one light source configured to direct the sample beam to tissue of the subject; a phase shifter configured to adjust the phase path of the reference beam; a scanner to scan the sample beam over a two-dimensional area of the subject'"'"'s tissue; an interferometer to constructively interfere a reflected sample beam from the subject tissue with the reference beam; at least one photodetector to detect the interfered light; and a processor to calculate blood constituent concentration based at least partly on non-image measurements of the detected interfered light. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification