Apparatus and methods of raman spectroscopy for analysis of blood gases and analytes
AssigneeMassachusetts Institute of Technology
InventorsAndrew J. Berger, James F. Brennan, III, Ramanchandra R. Dasari, Michael S. Feld, Irving Itzkan, Kaz Tanaka, Yang Wang
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Abstract
The present invention relates to systems of methods of measuring selected analytes in blood and tissue using Raman spectroscopy to aid in diagnosis. More particularly, Raman spectra are collected and analyzed to measure the concentration of dissolved gases and other analytes of interest in blood. Methods include in vivo transdermal and continuous monitoring as well as in vitro blood analysis.
Claims38
A method of measuring a dissolved gas in blood comprising the steps of:
- irradiating blood with laser radiation having a wavelength such that Raman scattering occurs in a dissolved gas in the irradiated blood;
- collecting Raman scattered light from the dissolved gas;
- and
- detecting the collected Raman-scattered light from the dissolved gas in response to the laser radiation.
A method of spectroscopic analysis of blood comprising the steps of:
- transdermally irradiating blood through a portion of tissue with laser radiation having an excitation wavelength;
- and
- detecting Raman-scattered light from the blood in response to the laser radiation, the Raman-scattered light having a wavelength different from the excitation wavelength of the laser radiation.
A method of spectroscopically monitoring blood comprising the steps of:
- positioning a probe in proximity to a lumen containing the blood of a patient;
- periodically irradiating a region of the blood within the lumen with laser radiation having an excitation wavelength;
- and
- detecting Raman-scattered light from the blood in response to the periodic laser radiation, the Raman-scattered light having a wavelength different from the wavelength of the excitation laser radiation.
A method of spectroscopic analysis of blood comprising the steps of:
- irradiating a dissolved gas in blood with laser radiation;
- detecting a spectrum of Raman-scattered light returning from the dissolved gas in response to the laser radiation, the Raman-scattered light having a plurality of wavelengths different from the wavelength of the excitation laser radiation;
- and
- subtracting a background spectrum from the detected spectrum.
A transdermal spectroscopic diagnostic system for analyzing human blood comprising:
- a laser emitting radiation in the infrared spectrum at
- a wavelength to penetrate a layer of tissue;
- a fiber optic device optically coupled to the laser for delivering the infrared radiation through the layer of tissue to irradiate a region of blood underlying the tissue;
- a first optical filter having an input end coupled to a distal end of the fiber optic device that filters light, and an output end for passing the laser radiation;
- an optical concentrator which comprises a cavity that reflects light and an aperture at a distal end that collects light, including the Raman-scattered light from blood over a range of incident angles, and an output path at the proximal end having a diameter larger than that of the aperture for transmitting collected light, coupled to the output end of the first filter;
- a fiber optic bundle having an input end coupled to a second optical filter for passing the Raman-scattered light and an output end for delivering the Raman-scattered light, and
- a detector coupled to the output end of the fiber optic bundle for detecting the Raman-scattered light;
- and a data processor that determines a concentration level of an analyte in blood.
A method of measuring a dissolved gas in blood comprising the steps of:
- irradiating blood with laser radiation having a wavelength in the range of 700 to 1300 nm such that Raman scattering occurs in a dissolved gas in the irradiated blood;
- collecting Raman scattered light from the dissolved gas;
- and
- detecting the collected Raman-scattered light from the dissolved gas in response to the laser radiation.
Dependencies are inferred from the claim text.