EP0757243A1
Expired / Lapsed
EP
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Liquid correlation spectometry
Assignee: Sensys Medical Inc
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Filing: 1995-12-14
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Granted: —
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Expires: 2015-12-14
Abstract
Abstract A number of optically active elements are provided that enable the performance of accurate, dependable chemical analysis in a medium having varying matrix backgrounds and substantial component interferences. Optical transfer cells are provided that include positive correlation filter systems adapted to accept near-IR radiation and to pass a wavelength from that radiation having high correlation with a particular analyte. A near-IR spectrometer apparatus for the measurement of analyte concentration in a complex medium is also provided. The apparatus features an optical transfer cell constructed according to the invention. The apparatus can be used in the non-invasive determination of blood analyte concentrations in a variety of mediums. Methods of measuring the concentration of a blood analyte in a mammalian subject are also provided. The methods entail the use of reflective near-IR radiation to interrogate a medium to obtain spectrally modified radiation. The radiation thus obtained is passed through an optical transfer cell constructed according to the invention to obtain a wavelength having high correlation with an analyte of interest and substantially no correlation with interfering constituents present in the medium.
Inventors
- 👤 Kenneth J. Schlager
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 17:09
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/145; A61B5/1495; A61B5/14532; A61B5/1455; G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/35; G01N21/359
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
45 words
An optical transfer cell for use in the measurement of analyte concentration in a complex aqueous medium, comprising a positive correlation filter means adapted to accept near infrared radiation and to selectively pass a wavelength from said radiation having high correlation with the analyte concentration.
Claim 2
Dependent Claim
20 words
The optical transfer cell of claim 1, wherein the medium comprises body tissue and the analyte comprises a blood analyte.
Claim 3
Dependent Claim
36 words
The optical transfer cell of claim 2, wherein the blood analyte is selected from the group consisting of calcium, potassium, sodium, chloride, bicarbonate (CO 2 ), hydrogen ion concentration (pH), glucose, urea (BUN), hematocrit and hemoglobin.
Claim 4
Dependent Claim
23 words
The optical transfer cell of claim 3, wherein the near infrared radiation includes wavelengths in the range of approximately 1100 to 2500 nm.
Claim 5
Dependent Claim
31 words
The optical transfer cell of claim 1, wherein the positive correlation filter means is adapted to selectively pass a plurality of wavelengths, each having a high correlation with the analyte concentration.
Claim 6
Dependent Claim
47 words
The optical transfer cell of claim 1, wherein the positive correlation filter means further comprises a plurality of layers, each layer having a selected near infrared absorption characteristic such that said filter means passes a population of wavelengths, each having a high correlation with the analyte concentration.
Claim 7
Dependent Claim
37 words
The optical transfer cell of claim 6, wherein at least one layer further comprises wavelength weighting factor means, said weighting factor providing enhanced positive correlation of the passed wavelength to the analyte concentration in a selected medium.
Claim 8
Dependent Claim
26 words
The optical transfer cell of claim 7, wherein said weighting factor is determined using rotated principal component analysis of an original absorption spectrum of the analyte.
Claim 9
Dependent Claim
26 words
The optical transfer cell of claim 7, wherein said weighting factor is determined using a least squares analysis of an original absorption spectrum of the analyte.
Claim 10
Independent Claim
121 words
An apparatus for measurement of analyte concentration in a complex aqueous medium, said apparatus comprising: a source of near infrared radiation; means for reflectively transmitting the radiation to the aqueous medium and retransmitting spectrally modified radiation reflected from said aqueous medium; means for receiving and directing the spectrally modified radiation into a beam path; an optical transfer cell disposed in the beam path, said cell comprising positive correlation filter means adapted to accept the radiation beam and selectively pass a wavelength from said beam having high correlation with the analyte concentration; means for receiving the passed wavelength and for converting the same into a signal representative of the intensity of said wavelength; and means for calculating analyte concentration from the signal.
Claim 11
Dependent Claim
21 words
The apparatus of claim 10, wherein the means for calculating analyte concentration comprises application of a chemometrics algorithm to the signal.
Claim 12
Dependent Claim
40 words
The apparatus of claim 10, wherein the positive correlation filter means further comprises a plurality of layers, each layer having a selected absorption characteristic whereby said filter means passes a population of wavelengths having high correlation with the analyte concentration.
Claim 13
Dependent Claim
39 words
The apparatus of claim 12, wherein at least one layer of the filter means further comprises wavelength weighting factor means, said weighting factor providing enhanced positive correlation of the passed wavelength to the analyte concentration in a selected medium.
Claim 14
Dependent Claim
18 words
The apparatus of claim 13, wherein the medium comprises body tissue and the analyte comprises a blood analyte.
Claim 15
Dependent Claim
34 words
The apparatus of claim 14, wherein the blood analyte is selected from the group consisting of calcium, potassium, sodium, chloride, bicarbonate (CO 2 ), hydrogen ion concentration (pH), glucose, urea (BUN), hematocrit and hemoglobin.
Claim 16
Dependent Claim
21 words
The apparatus of claim 14, wherein the near infrared radiation includes wavelengths in the range of approximately 1100 to 2500 nm.
Claim 17
Dependent Claim
115 words
A non-invasive method of measuring the concentration of a blood analyte, comprising: (a) directing near infrared radiation to a medium containing the blood analyte; (b) causing the radiation to be reflected by the medium to provide a spectrally modified beam; (c) directing the modified beam into a path through an optical transfer cell disposed in the beam path, said cell comprising positive correlation filter means adapted to accept the beam and selectively pass a wavelength from said beam having high correlation with the analyte concentration; (d) measuring the intensity of the passed wavelength and generating a signal representative of the intensity of the wavelength; and (e) converting the signal into an indication of analyte concentration.
Claim 18
Dependent Claim
12 words
The method of claim 17, wherein the medium comprises an aqueous solution.
Claim 19
Dependent Claim
12 words
The method of claim 17, wherein the medium comprises a solid substrate.
Claim 20
Dependent Claim
118 words
A non-invasive method of measuring the concentration of a blood analyte, comprising: (a) directing near infrared radiation to the surface of a substrate containing the blood analyte; (b) causing the radiation to be reflected by the surface to provide a spectrally modified beam; (c) directing the modified beam into a path through an optical transfer cell disposed in the beam path, said cell comprising positive correlation filter means adapted to accept the beam and selectively pass a wavelength from said beam having high correlation with the analyte concentration; (d) measuring the intensity of the passed wavelength and generating a signal representative of the intensity of the wavelength; and (e) converting the signal into an indication of analyte concentration.
Claim 21
Dependent Claim
14 words
The method of claim 20, wherein the substrate comprises human skin or mucosal tissue.
Claim 22
Dependent Claim
27 words
The method of claim 17, wherein the step of converting the signal into an indication of analyte concentration comprises application of a chemometrics algorithm to the signal.
Claim 23
Dependent Claim
34 words
The method of claim 17, wherein the blood analyte is selected from the group consisting of calcium, potassium, sodium, chloride, bicarbonate (CO 2 ), hydrogen ion concentration (pH), glucose, urea (BUN), hematocrit and hemoglobin.
Claim 24
Dependent Claim
21 words
The method of claim 17, wherein the near infrared radiation includes wavelengths in the range of approximately 1100 to 2500 nm.
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