Device for capturing thermal spectra from tissue

• US 20040242975A9
• Filed: 08/06/2002
• Published: 12/02/2004
• Est. Priority Date: 03/10/1999
• Status: Active Grant

• Current Assignee: OptiScan Biomedical Corporation
• Original Assignee: Hercules Technology Growth Capital, Inc.
• Inventors: Braig, James R., Hartstein, Philip C., Rule, Peter, Goldberger, Daniel S., Witte, Kenneth G., Cortella, Julian M., Agostino, Mark D., Smith, Heidi M., Herrera, Roger O.
• Granted Patent: US 6,959,211 B2
• Time in Patent Office: Days
• US Class Current: 600/309
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/061 Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body A61B1/00158 takes precedence
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: G01J 3/0286 Constructional arrangements for compensating for fluctuations caused by temperature, humidity or pressure, or using cooling or temperature stabilization of parts of the device; Controlling the atmosphere inside a spectrometer, e.g. vacuum
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01N 2021/0389 Windows
• CPC Class Codes: G01N 21/01 Arrangements or apparatus for facilitating the optical investigation
• CPC Class Codes: G01N 21/35 using infrared light G01N21/39 takes precedence
• CPC Class Codes: G01N 2201/021 Special mounting in general
• CPC Class Codes: G01N 2201/0245 with insertable-removable part

Abstract

A device and method are provided for use with a noninvasive optical measurement system, such as a thermal gradient spectrometer, for improved determination of analyte concentrations within living tissue. In one embodiment, a wearable window is secured to a patient'"'"'s forearm thereby isolating a measurement site on the patient'"'"'s skin for determination of blood glucose levels. The wearable window effectively replaces a window of the spectrometer, and thus forms an interface between the patient'"'"'s skin and a thermal mass window of the spectrometer. When the spectrometer must be temporarily removed from the patient'"'"'s skin, such as to allow the patient mobility, the wearable window is left secured to the forearm so as to maintain a consistent measurement site on the skin. When the spectrometer is later reattached to the patient, the wearable window will again form an interface between the spectrometer and the same location of skin as before.

Claims

1. A device for use with a noninvasive optical measurement system for capturing thermal spectra from living tissue, said device comprising:

a window holder; and

a window connected to said window holder, said window comprising a material of high thermal conductivity so as to permit thermal spectra to pass through said window;

said device defining a skin contact surface configured for placement in intimate thermal contact with the skin of a patient;

said device further defining a system contact surface opposite said skin contact surface;

said system contact surface being configured for removable placement against said noninvasive optical measurement system.

2. The device of claim 1, wherein said window holder has an aperture allowing unimpeded transmission of thermal spectra through said window holder.

3. The device of claim 1, wherein said window holder is made of injection-molded plastic.

4. The device of claim 1, wherein said material is polycrystalline float zone silicon.

5. The device of claim 1, wherein said material has a thickness of about 0.25 millimeters.

6. The device of claim 1, further comprising a heating element disposed upon said window.

7. The device of claim 6, wherein said heating element comprises a grid structure.

8. The device of claim 7, wherein said grid structure comprises a plurality of bridging sub-busses spaced apart from one another and a plurality of heating wires spaced apart from one another, and at least two busses disposed on opposite sides of said heating

9. The device of claim 8, wherein said sub-busses each has a width of about 50 micrometers.

10. The device of claim 8, wherein said sub-busses are spaced apart from one another by about 1.0 millimeters on center.

11. The device of claim 8, wherein said heating wires each has a width of about 20 micrometers.

12. The device of claim 8, wherein said heating wires are spaced apart from one another by about 0.5 millimeters on center.

13. The device of claim 8, wherein said busses comprise an electrical connection whereby electrical communication is established between said heating element and a power supply.

14. The device of claim 13, wherein said power supply is in operative communication with a timed switching device which intermittently supplies electrical power to said heating element via said electrical connection.

15. A device for consistently interfacing a noninvasive optical measurement system with a location of skin on a patient for capturing thermal spectra therefrom, said device comprising:

a window holder having an aperture;

a window covering said aperture on said window holder, said window comprising a material of high thermal conductivity so as to permit thermal spectra to pass through said window; and

a heating element disposed upon said window, said heating element comprising a grid structure which includes a plurality of bridging sub-busses, a plurality of heating wires, and at least two busses disposed on opposite sides of said heating element.

16. The device of claim 15, wherein said device defines a skin contact surface configured for placement in intimate thermal contact with said predetermined location of skin on the patient, said device further defining a system contact surface opposite said skin contact surface;

said system contact surface being configured for removable placement against said noninvasive optical measurement system.

17. The device of claim 15, wherein said sub-busses each has a width of about 50 micrometers.

18. The device of claim 15, wherein said sub-busses are spaced apart from one another by about 1.0 millimeters on center.

19. The device of claim 15, wherein said heating wires each has a width of about 20 micrometers.

20. The device of claim 15, wherein said heating wires are spaced apart from one another by about 0.5 millimeters on center.

21. The device of claim 15, wherein said busses comprise an electrical connection whereby electrical communication is established between said heating element and a power supply.

22. The device of claim 21, wherein said power supply is in operative communication with a timed switching device which intermittently supplies electrical power to said heating element via said electrical connection.

23. The device of claim 15, wherein said heating element comprises a gold layer deposited over an alloy layer which is affixed to said window, said gold layer and said alloy layer being formed into said grid structure.

24. The device of claim 23, wherein said gold layer has a thickness of about 4000 Angstroms.

25. The device of claim 23, wherein said alloy layer has a thickness ranging between about 300 Angstroms and about 500 Angstroms.

26. The device of claim 15, wherein said window holder is made of injection-molded plastic.

27. The device of claim 15, wherein said material is polycrystalline float zone silicon.

28. The device of claim 15, wherein said window has a thickness of about 0.25 millimeters.

29. A method for interfacing a noninvasive optical measurement system with skin of a patient for capturing thermal spectra therefrom, said method comprising:

mounting a wearable window onto the skin of the patient, said wearable window comprising a window holder having an aperture, a window covering said aperture, said window comprising a material of high thermal conductivity so as to permit thermal spectra to pass through said window, and a heating element disposed upon said window;

establishing an electrical connection between said heating element and a power source; and

placing said noninvasive optical measurement system in intimate thermal contact with said window.

30. The method of claim 29, wherein said power source supplies electric power to said heating element via said electrical connection so as to apply intermittent heating to the skin of the patient.

31. The method of claim 30, wherein said power supply is under operational control of said noninvasive optical measurement system.

32. The method of claim 29, wherein said mounting comprises using a fastening strap to press said wearable window against the skin of the patient.

33. The method of claim 32, wherein said fastening strap comprises at least two fixed ends and at least two adjustable ends, said fixed ends each attachable to said window holder and said adjustable ends removably attachable to one another.

34. The method of claim 29, wherein pressure between said wearable window and the skin of the patient causes said window holder to grip the skin such that relative motion between the skin of the patient and said wearable window is minimized.

35. An apparatus for use with a noninvasive optical measurement system for capturing thermal spectra from living tissue, said apparatus comprising:

a wearable window comprising a window holder having an aperture, a window covering said aperture, said window comprising a material of high thermal conductivity so as to permit thermal spectra to pass through said window, and a heating element disposed upon said window;

a first electrical connection comprising at least two contacts molded into the surface of said window holder, said contacts being in electrical communication with said heating element;

an interface surface of said noninvasive optical measurement system, said interface surface including a window aperture; and

a second electrical connection comprising at least two pins, each slidably retained within a socket of said interface surface and spring biased in a protruded state relative to said interface surface, said pins being in electrical communication with a power supply;

wherein pressing said wearable window against said interface surface pushes said pins into said sockets while urging said pins against said contacts.

36. The apparatus of claim 35, wherein said pins each corresponds with one of said contacts so as to form a closed circuit between said power supply and said heating element when said wearable window is pressed against said interface surface of said noninvasive optical measurement system.

37. The apparatus of claim 35, wherein said contacts are made of an electrically conducting material.

38. The apparatus of claim 35, wherein said window aperture directly corresponds with said aperture within said window holder.

39. The apparatus of claim 35, wherein said window aperture permits thermal spectra to pass through said interface surface.

40. The apparatus of claim 35, wherein said interface surface is made of a semi-compliant material which grips said wearable window so as to minimize relative motion therebetween.

41. The apparatus of claim 40, wherein said semi-compliant material is rubber.

42. The apparatus of claim 35, wherein pressure between said wearable window and the skin of the patient causes said window holder to grip the skin, thereby minimizing relative motion between the skin and the wearable window.

43. The apparatus of claim 35, wherein said power supply is in operational communication with a timed switching device whereby electrical power is intermittently applied to said heating element.

44. A method for interfacing a noninvasive optical measurement system with skin of a patient, said method comprising:

providing a wearable window comprising a window holder having an aperture, a window covering said aperture, said window comprising a material of high thermal conductivity so as to permit thermal spectra to pass through said window, and a heating element disposed upon said window;

mounting said wearable window onto the skin of the patient such that said heating element is placed into intimate contact with the skin of the patient;

positioning said wearable window on an interface surface of said noninvasive optical measurement system such that a window aperture within said interface surface is centered and aligned with said aperture within the window holder; and

establishing an electrical connection between said heating element and a power source.

45. The method of claim 44, wherein pressure between said wearable window and the skin of the patient causes said window holder to grip the skin, thereby minimizing relative motion between the skin and said wearable window.

46. The method of claim 44, wherein said window aperture permits thermal spectra to pass through said interface surface.

47. The method of claim 44, wherein said power source supplies electrical power intermittently to said heating element.

48. The method of claim 44, wherein said electrical connection comprises a first set of contacts on the surface of said window holder and a second set of contacts on said interface surface, said first set of contacts being in electrical communication with said heating element, said second set of contacts being in electrical communication with said power source, wherein pressing said wearable window against said interface surface places said first set of contacts in electrical contact with said second set of contacts.

49. The method of claim 48, wherein said second set of contacts comprises at least two pins each slidably retained within a socket of said interface surface and spring biased in a protruded state relative to said interface surface.