Non-invasive infrared absorption spectrometer for the generation and capture of thermal gradient spectra from living tissue

• US 6,072,180 A
• Filed: 03/12/1997
• Issued: 06/06/2000
• Est. Priority Date: 10/17/1995
• Status: Expired due to Fees

• Current Assignee: OptiScan Biomedical Corporation
• Original Assignee: OptiScan Biomedical Corporation
• Inventors: Kramer, Charles E., Braig, James R., Sterling, Bernhard B., Shulenberger, Arthur M., Goldberger, Daniel S., King, Richard A., Trebino, Rick
• Primary Examiner(s): Hannaher, Constantine
• Application Number:
  US08/816,723
• Time in Patent Office: 1,182 Days
• Field of Search: 250/339.03, 250/341.6
• US Class Current: 250/341.6
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: G01N 21/35 using infrared light G01N21/39 takes precedence
• CPC Class Codes: G01N 21/71 thermally excited
• CPC Class Codes: G01N 25/72 Investigating presence of flaws

Abstract

A spectrometer for the non-invasive generation and capture of thermal gradient spectra from human or animal tissue. The spectrometer includes an infrared transmissive thermal mass for inducing a transient temperature gradient in the tissue by means of conductive heat transfer with the tissue, and cooling means in operative combination with the thermal mass for cooling the thermal mass. Also provided is an infrared sensor means for detecting infrared emissions emanating from the tissue as the transient temperature gradient progresses into the tissue, and for providing output signals proportional to the detected infrared emissions. Data capture means is provided for sampling the output signals received from the infrared sensor means as the transient temperature gradient progresses into the tissue.

Claims

1. A spectrometer for the non-invasive generation and capture of thermal gradient spectra from living tissue, comprising:

a solid infrared transmissive thermal mass for inducing a transient temperature gradient in the tissue by means of conductive heat transfer with the tissue;

cooling means in operative combination with the solid infrared transmissive thermal mass for cooling the solid infrared transmissive thermal mass;

infrared sensor means for detecting infrared emissions emanating from the tissue as the transient temperature gradient progresses into the tissue in use, and for providing output signals proportional to the detected infrared emissions; and

data capture means for sampling the output signals provided by the infrared sensor means as the transient temperature gradient progresses into the tissue.

2. A spectrometer according to claim 1 further comprising:

means for moving the solid infrared transmissive thermal mass relative to the tissue to bring the solid infrared transmissive thermal mass into a conductive heat transfer relationship with the tissue.

3. A spectrometer according to claim 2 wherein the means for moving the solid infrared transmissive thermal mass relative to the tissue comprises:

a housing in which the solid infrared transmissive thermal mass is contained, the housing defining an aperture therein over which the tissue can be placed; and

means for reducing the gas pressure in area between the tissue and the solid infrared transmissive thermal mass to draw the tissue into direct contact with the solid infrared transmissive thermal mass.

4. A spectrometer according to claim 3 wherein the means for moving the solid infrared transmissive thermal mass relative to the tissue further comprises:

linear actuating means coupled to the housing and to the solid infrared transmissive thermal mass, the linear actuating means being operable to advance and retract the solid infrared transmissive thermal mass relative to the aperture.

5. A spectrometer according to claim 3 wherein the means for moving the solid infrared transmissive thermal mass relative to the tissue further comprises:

rotary actuating means coupled to the housing and to the solid infrared transmissive thermal mass, the rotary actuating means being operable to rotate the solid infrared transmissive thermal mass between a position in which the solid infrared transmissive thermal mass is adjacent to the aperture and a position in which the solid infrared transmissive thermal mass is remote from the aperture.

6. A spectrometer according to claim 5 further comprising:

an additional thermal mass coupled to the rotary actuating means, the additional thermal mass for heating the tissue; and

heating means in operative combination with the additional thermal mass for heating the additional thermal mass, the rotary actuating means being operable to rotate the additional thermal mass between a position in which the additional thermal mass is adjacent to the aperture and a position in which the additional thermal mass is remote from the aperture.

7. A spectrometer according to claim 6 wherein the infrared sensor means comprises a single infrared detector positioned behind a rotatable variable filter wheel.

8. A spectrometer according to claim 3 further comprising a gas source in communication with the housing for supplying the interior of the housing with dry gas.

9. A spectrometer according to claim 1 further comprising:

homogenizing means through which the infrared emissions pass before being detected by the infrared sensor means, the homogenizing means for unfocusing the infrared emissions as they pass through the homogenizing means.

10. A spectrometer according to claim 9 wherein the homogenizing means comprises a tube having a reflective interior.

11. A spectrometer according to claim 9 wherein

the infrared sensor means comprises an array of infrared detectors, each infrared detector in the array being positioned behind a single wavelength infrared filter thereby to make each infrared detector sensitive to a particular band of infrared energy.

12. A spectrometer according to claim 1 wherein the data capture means further comprises data capture and control means including a power line phase sensor for synchronizing the operation of the spectrometer to the phase of power line interference.

13. A spectrometer according to claim 1 further comprising:

an airtight enclosure in which the solid infrared transmissive thermal mass is contained, the enclosure including an infrared transmissive window over which the tissue can be placed; and

means for moving the solid infrared transmissive thermal mass into contact with the window thereby to transfer heat from the tissue to the solid infrared transmissive thermal mass.

14. A spectrometer according to claim 13 wherein the means for moving the solid infrared transmissive thermal mass into contact with the window comprises:

linear actuating means coupled to the enclosure and to the solid infrared transmissive thermal mass, the linear actuating means being operable to advance and retract the solid infrared transmissive thermal mass relative to the window.

15. A spectrometer according to claim 14 further comprising:

heating means in operative combination with the window, for heating the window.

16. A spectrometer according to claim 15 wherein the enclosure is filled with dry gas.

17. A spectrometer according to claim 15 further comprising:

homogenizing means through which the infrared emissions pass before being detected by the infrared sensor means, the homogenizing means for unfocusing the infrared emissions as they pass through the homogenizing means.

18. A spectrometer according to claim 17 wherein the homogenizing means comprises a tube having a reflective interior.

19. A spectrometer according to claim 15 wherein

the infrared sensor means comprises an array of infrared detectors, each infrared detector in the array being positioned behind a single wavelength infrared filter thereby to make each infrared detector sensitive to a particular band of infrared energy.

20. A spectrometer according to claim 15 wherein the infrared sensor means comprises a single infrared detector being positioned behind a rotatable variable filter wheel.

21. A spectrometer according to claim 13 wherein the data capture means further comprises data capture and control means including a power line phase sensor for synchronizing the operation of the spectrometer to the phase of power line interference.

22. A spectrometer for the non-invasive generation and capture of thermal gradient spectra from living tissue, comprising:

a housing defining an aperture over which the tissue can be placed;

a first thermal mass for inducing a transient temperature gradient in the tissue by means of conductive heat transfer with the tissue, the first thermal mass being infrared transmissive;

cooling means in operative combination with the first thermal mass for cooling the first thermal mass;

a second thermal mass for heating the tissue by means of conductive heat transfer with the tissue;

heating means in operative combination with the second thermal mass for heating the second thermal mass;

drive means mounted in the housing for alternately positioning the first and second thermal masses adjacent to the aperture to alternately heat and cool the living tissue;

infrared sensor means for detecting infrared emissions emanating from the tissue as the transient temperature gradient progresses into the tissue in use, and for providing output signals proportional to the detected infrared emissions; and

data capture means for sampling the output signals provided by the infrared sensor means as the transient temperature gradient progresses into the tissue.

23. A spectrometer according to claim 22 wherein, in operation, the heating and cooling means are deactivated while the data capture means samples the output signals provided by the infrared sensor means as the transient temperature gradient progresses into the tissue.

24. A spectrometer for the non-invasive generation and capture of thermal gradient spectra from living tissue, comprising:

an enclosure including an infrared transmissive window over which the tissue can be placed;

a first thermal mass for inducing a transient temperature gradient in the tissue by means of conductive heat transfer with the tissue, the first thermal mass being infrared transmissive;

cooling means in operative combination with the first thermal mass for cooling the first thermal mass;

heating means in operative combination with the window for heating the window;

drive means mounted in the housing for alternately positioning the first thermal mass in a heat transfer relationship with the window;

infrared sensor means for detecting infrared emissions emanating from the tissue as the transient temperature gradient progresses into the tissue in use, and for providing output signals proportional to the detected infrared emissions; and

data capture means for sampling the output signals provided by the infrared sensor means as the transient temperature gradient progresses into the tissue.

25. A spectrometer according to claim 24 wherein, in operation, the heating and cooling means are deactivated while the data capture means samples the output signals provided by the infrared sensor means as the transient temperature gradient progresses into the tissue.

26. A method for the non-invasive generation and capture of thermal gradient spectra from living tissue, comprising the steps of:

cooling a solid infrared transmissive thermal mass;

placing the solid infrared transmissive thermal mass into a conductive heat transfer relationship with the tissue thereby to generate a transient temperature gradient in the tissue;

detecting infrared emissions emanating from the tissue and passing through the solid infrared transmissive thermal mass;

providing output signals proportional to the detected infrared emissions; and

sampling the output signals as the transient temperature gradient progresses into the tissue.

27. A method according to claim 26 wherein the step of placing the solid infrared transmissive thermal mass into a conductive heat transfer relationship further comprises the step of making direct contact between the tissue and the solid infrared transmissive thermal mass.

28. A method according to claim 26 wherein the conductive heat transfer relationship consists of contact between the solid infrared transmissive thermal mass and a relatively thin infrared transmissive window which is in direct contact with the tissue.

29. A method according to claim 26 further comprising the step of preheating the tissue before placing the solid infrared transmissive thermal mass into a conductive heat transfer relationship with the tissue.