Method and device for noninvasive measurements of concentrations of blood components
First Claim
1. A method for measuring concentrations of blood components and analytes including at least one of glucose, cholesterol, albumin, hemoglobin, alcohol or drugs, the method comprising the steps of:
- (a) irradiating near infrared light onto skin of a subject containing blood-containing tissues and blood vessels;
(b) receiving the near infrared light containing information on the blood component concentration, back scattered from or transmitted through the blood-containing tissues and blood vessels;
(c) selectively outputting the light of at least three wavelengths from the received near infrared light;
(d) converting the light of the at least three outputted wavelengths electrical signals, respectively; and
(e) computing the blood component concentration using the electrical signals,wherein in step (c), assuming that Aic, i=1, 2,. . . , n, are absorption values of light of n wavelengths for the blood component being measured, the requirements for selection of the wavelengths are;
(1) A1c is the maximum among A1c, A2c, A3c,. . . , Anc, and A2c, A3c, . . . , Anc are negligible when compared to A1c ; and
(2) for other components, with the exception of the blood component being measured, the relation ##EQU14## is satisfied, where Aij is absorption value of wavelength i for blood component j, and n is the number of selected wavelengths.
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Abstract
A method and device for noninvasive measurement of blood component concentrations utilizes pulsed polychromatic light source emitting, light in the near infrared range 800-1850 nm. The light is back scattered from or transmitted through a part of a patient'"'"'s body. Back scattered light from blood-containing tissues and blood vessels has information on blood component concentrations. That light is collected to avoid the surface reflection from the skin surface and to minimize the effects of changes in the scattering background. The concentrations of blood components are calculated from the spectral analysis based on selected wavelengths by a defined algorithm. A microprocessor calculates and determines the blood component concentrations by comparing a ratio with a calibration curve stored in a memory of the microprocessor. The calculated concentration values are displayed on a display.
300 Citations
24 Claims
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1. A method for measuring concentrations of blood components and analytes including at least one of glucose, cholesterol, albumin, hemoglobin, alcohol or drugs, the method comprising the steps of:
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(a) irradiating near infrared light onto skin of a subject containing blood-containing tissues and blood vessels; (b) receiving the near infrared light containing information on the blood component concentration, back scattered from or transmitted through the blood-containing tissues and blood vessels; (c) selectively outputting the light of at least three wavelengths from the received near infrared light; (d) converting the light of the at least three outputted wavelengths electrical signals, respectively; and (e) computing the blood component concentration using the electrical signals, wherein in step (c), assuming that Aic, i=1, 2,. . . , n, are absorption values of light of n wavelengths for the blood component being measured, the requirements for selection of the wavelengths are; (1) A1c is the maximum among A1c, A2c, A3c,. . . , Anc, and A2c, A3c, . . . , Anc are negligible when compared to A1c ; and (2) for other components, with the exception of the blood component being measured, the relation ##EQU14## is satisfied, where Aij is absorption value of wavelength i for blood component j, and n is the number of selected wavelengths. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A device for measuring blood component concentrations comprising:
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means for irradiating near infrared light onto skin of a subject containing blood-containing tissues and blood vessels; means for receiving the near infrared light containing information on the blood component concentration, back scattered from or transmitted through blood-containing tissues and blood vessels; means for selectively outputting the light of at least three wavelengths from the received near infrared light; means for converting the light of the at least three output wavelengths into electrical signals, respectively, and means for computing the blood component concentration using the electrical signals; wherein assuming that Aic, i=1, 2 . . . , n, are absorption values of light of n wavelengths for the blood component being measured the requirements for wavelengths selection are; (1) A1c is the maximum among Aic, A2c, A3c, . . . , Anc, and A2c, A3c, . . . , Anc are negligible when compared to A1c, and (2) for other components, with the exception of the blood component being measured, the relation ##EQU15## is satisfied, where Aij is absorption value of wavelength i for blood component j and n is the number of selected wavelengths. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A method for measuring concentrations of blood components and analytes including at least one of glucose, cholesterol, albumin, hemoglobin, alcohol and drugs, the method comprising the steps of:
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(a) irradiating near infrared light onto skin of a subject containing blood-containing tissues and blood vessels; (b) receiving the near infrared light containing information on the blood component concentration, back scattered from or transmitted through blood-containing tissues and blood vessels; (c) selectively outputting the light of at least three wavelengths from the received near infrared light; (d) converting the light of the at least three output wavelengths into electrical signals, respectively; (e) calculating a ratio D using the electrical signals, represented by the following formula ##EQU17## wherein Ti =Ji /Jio, where i=1, 2, . . . , n, Ji and Jio are intensities of the back scattered or transmitted light and incident light, corresponding to the wavelength i, respectively; and (f) calculating blood component concentration using the calculated ratio D. - View Dependent Claims (20, 21, 22)
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23. A device for measuring blood component concentrations comprising:
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means for irradiating near infrared light onto skin of a subject containing blood-containing tissues and blood vessels; means for receiving the near infrared light containing information on the blood component concentration, back scattered from or transmitted through blood-containing tissues and blood vessels; means for selectively outputting the light of at least three wavelengths from the received near infrared light; means for converting the light of the at least three output wavelengths into electrical signals, respectively; and means for computing the blood component concentration using the electrical signals, wherein the means for irradiating includes irradiation channels and the means for receiving includes reception channels, the irradiation channels and the reception channels being spatially separated and said receiving means is spaced from an irradiation point by a predetermined distance. - View Dependent Claims (24)
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Specification