Method and apparatus for determination of analyte concentration
Inventors
Weinstein, Aharon • Primack, Harel
Assignees
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Publication Number
US-7952692-B2
Publication Date
2011-05-31
Expiration Date
Abstract
A method and system are presented for use in determination of the concentration of an analyte in a subject's medium. The medium is irradiated with at least two radiation components to produce detectable radiation responses of the medium thereto. These at least two radiation components are selected to have different mean wavelengths and such that the spectral bandwidth of at least one of said at least two radiation components is characterized by relatively high variability of the extinction coefficient of the analyte of interest across said spectral bandwidth. This enables analysis of data indicative of detected radiation responses of the medium to said at least two radiation components and determination of the concentration of said analyte.
Core Innovation
The invention provides a method for measurements of the concentration of an analyte in a medium having a certain extinction coefficient spectrum by providing at least first and second radiation components. The mean wavelength and spectral bandwidth of the first radiation component correspond to a first spectral region where the variation of an extinction coefficient, Δβ1, per volume fraction of the analyte across the spectral bandwidth of the first radiation component is higher than in other spectral regions, and the mean wavelength and second spectral bandwidth of the second radiation component correspond to a second spectral region where the variation of an extinction coefficient, Δβ2, per volume fraction of the analyte across the spectral bandwidth of the second radiation component is smaller than in other spectral regions.
At least one of the radiation components contains a plurality of wavelengths with radiation intensities in a fixed relation to each other during periods of the measurements. During a certain measurement time, the medium is irradiated with the at least first and second radiation components to produce detectable radiation responses of the medium thereto. The data indicative of the detected radiation responses is analyzed to determine the concentration of the analyte.
The invention further provides hematocrit concentration determination using radiation in different spectral regions of a hematocrit absorption coefficient spectrum. The spectral bandwidth of at least one source is selected such that the bandwidth lies within a first spectral region where variation of an absorption coefficient, Δβ1, per volume fraction of hematocrit as a function of wavelength is higher than in other spectral regions, and within a second spectral region where variation, Δβ2, is smaller than in other spectral regions.
Radiation transmitted through and/or reflected from the medium at the different spectral regions is measured, a measurable relation between the medium radiation responses to different wavelengths is derived, and analyzing the relation determines hematocrit concentration.
Claims Coverage
The document provides four independent claims covering a general analyte concentration measurement method, a hematocrit concentration determination method, an analyte concentration method with wavelength-structure constraints, and corresponding system implementations. Across these independent claims, the core inventive features are selecting mean wavelengths and spectral bandwidths to target extinction-coefficient variation regions, using radiation components with fixed intensity relations across multiple wavelengths, and deriving and analyzing a measurable relation from detected responses to obtain concentration.
Selecting radiation components based on extinction coefficient variation regions
Selecting at least first and second radiation components so that the mean wavelength and spectral bandwidth of the first radiation component correspond to a first spectral region of the extinction coefficient spectrum of the analyte where variation of an extinction coefficient, Δβ1, per volume fraction of the analyte across the spectral bandwidth is higher than in other spectral regions, and so that the mean wavelength and second spectral bandwidth of the second radiation component correspond to a second spectral region where variation of an extinction coefficient, Δβ2, per volume fraction of the analyte across the spectral bandwidth is smaller than in other spectral regions.
Using a fixed relation among plurality of wavelengths during measurement
At least one of the radiation components contains a plurality of wavelengths with radiation intensities in a fixed relation to each other during periods of said measurements, and the medium is irradiated with the at least first and second radiation components during a certain measurement time to produce detectable radiation responses.
Analyzing detected radiation responses to determine analyte concentration
Analyzing data indicative of detected radiation responses of the medium to the at least first and second radiation components to determine the concentration of the analyte.
Hematocrit bandwidth selection within higher- and smaller-variation regions and deriving a measurable relation
Providing at least two sources of electromagnetic radiation operable in different spectral regions of a hematocrit absorption coefficient spectrum; selecting an operating spectral bandwidth of at least one source such that the spectral bandwidth lies within a first spectral region where variation of an absorption coefficient, Δβ1, per volume fraction is higher than in other spectral regions and such that the spectral bandwidth lies within a second spectral region where variation of an absorption coefficient, Δβ2, per volume fraction is smaller than in other spectral regions, while containing a plurality of wavelengths with radiation intensities in a fixed relation during a measurement time; irradiating the medium; measuring transmitted through and/or reflected from intensity at different spectral regions; deriving from the transmitted and/or reflected intensity a measurable relation between medium radiation responses to different wavelengths; and analyzing the relation to determine hematocrit concentration.
Including multiple wavelengths spaced within a selected extinction-coefficient region
Selecting the at least two radiation components such that a first radiation component has a first mean wavelength and first spectral bandwidth and the second radiation component has a second mean wavelength and second spectral bandwidth, where the first component bandwidth lies within a first spectral region with higher variation Δβ1 than other regions and the second component bandwidth lies within a second spectral region with smaller variation Δβ2 than other regions, and at least the first radiation component contains a plurality of wavelengths including at least two wavelengths spaced apart along the first spectral region, with radiation intensity being in a fixed relation during the certain measurement time, the relation between the detected radiation responses being indicative of the concentration.
System with light source, detector unit, and control unit analyzing a measurable relation
A system comprising a light source unit producing at least first and second radiation components selected by mean wavelength and spectral bandwidth so that the first bandwidth lies within a first spectral region of the extinction coefficient spectrum with higher variation Δβ1 and the second bandwidth lies within a second spectral region with smaller variation Δβ2, and where the first bandwidth contains a plurality of wavelengths with radiation intensities in a fixed relation during a measurement time; a detector unit with one or more light detectors collecting light from the medium and generating data indicative thereof; and a control unit connectable to the light source unit and detector unit and configured for processing and analyzing said data to determine a measurable relation between detected radiation responses and derive analyte concentration therefrom.
Measurement system collecting transmitted/reflected components and deriving analyte concentration from a measurable relation
A system having a measurement unit and control unit where the measurement unit includes a light source unit operable to produce at least two radiation components with selected mean wavelengths and spectral bandwidths aligned to higher-variation Δβ1 and smaller-variation Δβ2 regions of the extinction coefficient spectrum, and at least one radiation component containing a plurality of wavelengths with radiation intensity in a fixed relation during measurement time; the light detector unit collecting radiation after being transmitted through and/or reflected from an illuminated subject’s medium and generating data indicative of collected light components; and the control unit analyzing the data to determine a measurable relation between collected light components and derive analyte concentration.
Across the independent claims, the document consistently focuses on selecting radiation components whose spectral bandwidths correspond to different regions of extinction- or absorption-coefficient variability, using plurality of wavelengths with fixed intensity relations during measurement, and using detector responses to derive and analyze a measurable relation to determine analyte concentration, including a dedicated hematocrit concentration determination.
Stated Advantages
Allows determination of analyte concentration by selecting radiation components based on extinction coefficient spectrum regions with higher and smaller variation.
Supports hematocrit concentration determination by selecting operating spectral bandwidths within regions of higher and smaller absorption-coefficient variation and deriving a measurable relation from transmitted and/or reflected intensity.
Documented Applications
Determining the concentration of an analyte in a medium using at least first and second radiation components and analyzing detected radiation responses.
Determining hematocrit concentration using at least two sources of electromagnetic radiation operable in different spectral regions of a hematocrit absorption coefficient spectrum.
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