Non-invasive blood chemistry measurement by stimulated infrared relaxation emission
First Claim
1. A non-invasive, blood chemistry measurement apparatus for measuring a concentration of a selected blood component within a sample of blood, said apparatus comprising:
- a source of exposing light having a spectral peak at wavenumber k1 that will excite said blood component to a state from which it emits light, by stimulated relaxation emission, having a peak at a second wavenumber k2 different from k1 ;
means for imaging said exposing light through an area of epidermis of an animal into a portion of that animal'"'"'s blood adjacent to said area of epidermis on which this exposing light is incident;
means for detecting light that is emitted at wavenumber k2 from molecules of said selected blood component in response to exposing light from said source of light; and
means, responsive to said means for detecting, for calculating a concentration of said selected blood component.
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Abstract
An apparatus for measuring the concentration of a selected solute in a solution. This apparatus is particularly suitable for measuring the concentration of blood components, such as blood glucose. A beam of exposing light is imaged through a wall of a containment vessel onto a region of the sample adjacent to this wall to induce from said selected solute emission of light that includes at least one emission peak that can be used to calculate the concentration of this solute. At least one detector is positioned to maximize the strength of detected signal, if other components of this solution strongly absorb the emitted light. The exposing light is directed such that the detected signal is maximized as a function of the path of this exposing light. A particular embodiment is a non-invasive blood glucose tester that can be used painlessly by diabetics to monitor their blood glucose levels. In this embodiment, the containment vessel is preferably one of the patient'"'"'s fingers. At least two additional detected signals are monitored and processed at wavenumbers suitable for eliminating temperature and pressure effects on the calculated blood glucose levels.
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Citations
29 Claims
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1. A non-invasive, blood chemistry measurement apparatus for measuring a concentration of a selected blood component within a sample of blood, said apparatus comprising:
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a source of exposing light having a spectral peak at wavenumber k1 that will excite said blood component to a state from which it emits light, by stimulated relaxation emission, having a peak at a second wavenumber k2 different from k1 ; means for imaging said exposing light through an area of epidermis of an animal into a portion of that animal'"'"'s blood adjacent to said area of epidermis on which this exposing light is incident; means for detecting light that is emitted at wavenumber k2 from molecules of said selected blood component in response to exposing light from said source of light; and means, responsive to said means for detecting, for calculating a concentration of said selected blood component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A non-invasive, blood chemistry measurement apparatus for measuring a concentration of a selected blood component within a sample of blood, said apparatus comprising:
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a source of exposing light having a spectral peak at wavenumber k1 that will excite said blood component to a state from which it emits light, by stimulated relaxation emission, having a peak at a second wavenumber k2 different from k1 ; means for imaging said exposing light through an area of epidermis of an animal into a portion of that animal'"'"'s blood adjacent to said area of epidermis on which this exposing light is incident; means for detecting light that is emitted at wavenumber k2 from molecules of said selected blood component in response to exposing light from said source of light; and means, responsive to said means for detecting, for calculating a concentration of said selected blood component, wherein N=2, wherein said selected blood component is blood glucose, wherein S1 is proportional to an intensity of light within a band substantially centered on an emission peak of blood glucose substantially at a wavenumber of 1040 cm-1, wherein S2 is proportional to an intensity of light within a band substantially centered on an emission peak of haemoglobin produced by incident fight substantially at a wavenumber of 1109 cm-1 and wherein said means for calculating a concentration calculates a concentration of blood glucose that is corrected by use of S2 to take into account effects due to changes in blood volume intersected by the light from said light source.
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14. A non-invasive, blood chemistry measurement apparatus for measuring a concentration of a selected blood component within a sample of blood, said apparatus comprising:
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a source of exposing light having a spectral peak at wavenumber k1 that will excite said blood component to a state from which it emits light, by stimulated relaxation emission, having a peak at a second wavenumber k2 different from k1 ; means for imaging said exposing light through an area of epidermis of an animal into a portion of that animal'"'"'s blood adjacent to said area of epidermis on which this exposing light is incident; means for detecting light that is emitted at wavenumber k2 from molecules of said selected blood component in response to exposing light from said source of light; and means, responsive to said means for detecting, for calculating a concentration of said selected blood component, wherein S1 is proportional to an intensity of light within a band substantially centered on an emission peak of blood glucose substantially at a wavenumber of 1040 cm-1, wherein S2 is proportional to an intensity of light within a band substantially centered on an emission peak of haemoglobin produced by incident light substantially at a wavenumber of 1109 cm-1, wherein S3 is proportional to an intensity of light within a band that contains substantially only blackbody radiation from surrounding portions of this apparatus, and wherein said means for calculating a concentration calculates a concentration of blood glucose that is corrected by use of S2 and S3 to take into account effects due to changes in temperature and volume of blood intersected by the light from said source. - View Dependent Claims (15)
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16. A non-invasive, blood chemistry measurement apparatus for measuring a concentration of a selected blood component within a sample of blood, said apparatus comprising:
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a source of exposing light having a spectral peak at wavenumber k1 that will excite said blood component to a state from which it emits light, by stimulated relaxation emission, having a peak at a second wavenumber k2 different from k1 ; means for imaging said exposing light through an area of epidermis of an animal into a portion of that animal'"'"'s blood adjacent to said area of epidermis on which this exposing light is incident; means for detecting light that is emitted at wavenumber k2 from molecules of said selected blood component in response to exposing light from said source of light; means, responsive to said means for detecting, for calculating a concentration of said selected blood component; a temperature sensor means for measuring a temperature of a region from which light is received by said means for detecting; and means for maintaining a substantially constant, selected temperature T of a region of said apparatus that emits blackbody radiation to said means for detecting.
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17. A non-invasive, blood chemistry measurement apparatus for measuring a concentration of a selected blood component within a sample of blood, said apparatus comprising:
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a source of exposing light having a spectral peak at wavenumber k1 that will excite said blood component to a state from which it emits light, by stimulated relaxation emission, having a peak at a second wavenumber k2 different from k1 ; means for imaging said exposing light through an area of epidermis of an animal into a portion of that animal'"'"'s blood adjacent to said area of epidermis on which this exposing light is incident; means for detecting light that is emitted at wavenumber k2 from molecules of said selected blood component in response to exposing light from said source of light; means, responsive to said means for detecting, for calculating a concentration of said selected blood component; a flat plate that is transparent to the emitted light, positioned such that light emitted from the sample of blood passes through this plate before reaching said means for detecting; this plate providing a top surface against which a patient is to press a portion of the patient'"'"'s epidermis during a blood test with this apparatus. - View Dependent Claims (18, 19, 21)
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20. A non-invasive, blood chemistry measurement apparatus for measuring a concentration of a selected blood component within a sample of blood, said apparatus comprising:
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a source of exposing light having a spectral peak at wavenumber k1 that will excite said blood component to a state from which it emits light, by stimulated relaxation emission, having a peak at a second wavenumber k2 different from k1 ; means for imaging said exposing light through an area of epidermis of an animal into a portion of that animal'"'"'s blood adjacent to said area of epidermis on which this exposing light is incident; means for detecting light that is emitted at wavenumber k2 from molecules of said selected blood component in response to exposing light from said source of light; means, responsive to said means for detecting, for calculating a concentration of said selected blood component; and a flat plate, that is transparent to the emitted light, positioned such that light emitted from the sample of blood passes through this plate before reaching said means for detecting; this plate providing a top surface against which a patient is to press a portion of the patient'"'"'s epidermis during a blood test with this apparatus; wherein said flat plate is of a material selected from the class consisting of ZnS and ZnSe.
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22. A method of measuring the concentration of a selected blood component of an animal, said method comprising the steps of:
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(a) directing, through an epidermis of said animal, exposing light having at least one wavenumber selected to excite said selected blood component to emit light of wavenumber characteristic of that component; (b) detecting light that is emitted from said selected blood component in response to the exposing light which has a peak wavelength that produces stimulated emission of light from said selected blood component; and (c) calculating a concentration of said selected blood component. - View Dependent Claims (23, 24, 25, 26)
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27. A method of measuring the concentration of a selected blood component of an animal, said method comprising the steps of:
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(a) directing, through an epidermis of said animal, exposing light having at least one wavenumber selected to excite said selected blood component to emit light of wavenumber characteristic of that component; (b) detecting light that is emitted from said selected blood component in response to the exposing light; and (c) calculating a concentration of said selected blood component, wherein the exposing light is in the range from 0.6-1.5 microns, whereby a ratio of the absorbance by blood glucose to the total absorbance by blood haemoglobin and the animal'"'"'s epidermis is increased.
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28. A method of measuring the concentration of a selected blood component of an animal, said method comprising the steps of:
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(a) directing, through an epidermis of said animal, exposing light having at least one wavenumber selected to excite said selected blood component to emit light of wavenumber characteristic of that component; (b1) detecting emitted light at a first wavenumber k1 at which there is a significant level of emission from said selected blood component and from a second blood component; (b2) detecting emitted light at a second wavenumber k2 at which at least one of the selected blood component and the second blood component exhibits an emission peak; and (b3) detecting light at a wavenumber k3 at which there is a significant level of blackbody radiation; (c) calculating a concentration of said selected blood component utilizing the detected intensities at wavenumbers k1, k2 and k3.
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29. A method of measuring the concentration of a selected blood component of an animal, said method comprising the steps of:
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(a) directing, through an epidermis of said animal, exposing light having at least one wavenumber selected to excite said selected blood component to emit light of wavenumber characteristic of that component, wherein a portion of the epidermis through which the exposing light is directed is contained on a front surface of a person'"'"'s finger; (b) detecting light that is emitted from said selected blood component in response to the exposing light Which has a peak wavelength that produces stimulated emission of light from said selected blood component; and (c) calculating a concentration of said selected blood component, wherein the portion of epidermis through which the exposing light is directed is pressed into contact with a window through which said exposing light is directed, said method further comprising the step of; (d) sensing a pressure of contact between the window and the portion of the epidermis through which the exposing light is directed; and
, in step (c)adjusting the calculated concentration of the selected blood component, taking into account the effect of pressure on the measured intensities.
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Specification