Heater for optical gas sensors, gas sensors including the heater, and methods

• US 6,888,101 B2
• Filed: 05/31/2002
• Issued: 05/03/2005
• Est. Priority Date: 05/31/2001
• Status: Active Grant

• Current Assignee: RIC INVESTMENTS LLC (Respironics Incorporated)
• Original Assignee: Respironics Incorporated
• Inventors: Davis, Raymond G
• Primary Examiner(s): Jeffery, John A.
• Application Number:
  US10/160,566
• Publication Number:
  US 20030006223A1
• Time in Patent Office: 1,068 Days
• Field of Search: 219/201, 219/522, 219/543, 219/203, 359/512, 2503381-342, 250/504.R, 250/352, 600/529, 600/537, 600/532, 73/232, 73/233, 73/250.5, 733/350.1, 73/310.5, 128/200.24, 128/201.15
• US Class Current: 219/201
• CPC Class Codes: A61B 5/083 Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption
• CPC Class Codes: G01N 21/0332 with temperature control control of temperature G05D23/00; cryostats F17C3/08
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: H05B 2203/003 using serpentine layout
• CPC Class Codes: H05B 3/84 Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields

Abstract

A heater for a window of an optical gas sensor is provided. The heater may be positioned over a portion of the window or may form at least a portion of the window. Alternatively, the heater may be separate from the optical gas sensor and positionable (e.g., by a transducer) over the window either in contact therewith or in close proximity thereto. The heater may be substantially transparent to the relevant wavelengths of electromagnetic radiation that are used in optical (e.g., infrared or luminescence quenching) monitoring of respiratory gases, anesthetic agents, or the like. Alternatively, the heater may be configured so as to provide a substantially unobstructed optical pathway through the window. Optical gas sensors and complementary transducers that include the healer are also disclosed.

Claims

1. A heater for use on an optical gas sensor, comprising:

a heating element that is substantially transparent to at least one wavelength of electromagnetic radiation to be used in an optical sensing technique for measurement of at least one gaseous or vaporized material, the heating element configured to be positioned across an optical path of the optical gas sensor without being directly secured to the optical gas sensor.

2. The heater of claim 1, wherein the optical gas sensor comprises an infrared sensor.

3. The heater of claim 1, wherein the optical gas sensor comprises a luminescence quenching sensor.

4. The heater of claim 1, wherein the gaseous or vaporized material comprises at least one of O₂, CO₂, N₂O and an anesthetic agent.

5. The heater of claim 1, wherein the heating element comprises an elongate member.

6. The heater of claim 5, wherein the elongate member has a substantially nonlinear configuration.

7. The heater of claim 6, wherein the substantially nonlinear configuration of the elongate member comprises a serpentine configuration.

8. The heater of claim 5, wherein the elongate member is substantially linear.

9. The heater of claim 1, wherein the heating element comprises at least one of a conductive metal oxide, candium sulfide and zinc oxyfluoride.

10. The heater of claim 9, wherein the heating element comprises a conductive metal oxide, and wherein the conductive metal oxide comprises at least one of tin oxide, indium tin oxide, antimony tin oxide, zinc oxide and indium zinc oxide.

11. The heater of claim 1, further comprising a temperature-conducting element.

12. The heater of claim 11, wherein the temperature-conducting element is in at least thermal communication with the heating element.

13. The heater of claim 11, wherein the temperature-conducting element comprises an elongate member.

14. The heater of claim 13, wherein the elongate member has a substantially nonlinear configuration.

15. The heater of claim 14, wherein the substantially nonlinear configuration of the elongate member comprises a serpentine configuration.

16. The heater of claim 13, wherein the elongate member is substantially linear.

17. The heater of claim 13, wherein a configuration of the elongate member of the temperature-conducting element substantially approximates a configuration of the beating element.

18. The heater of claim 11, further comprising a temperature-measuring component in communication with the temperature-conducting element.

19. The heater of claim 18, wherein the temperature-measuring component comprises a thermocouple or a temperature-sensing semiconductor device.

20. The heater of claim 1, further comprising a temperature-control element in communication with the heating element.

21. A heater for use on an optical gas sensor including at least one window comprising:

a heating element positioned over at least a portion of the at least one window of the optical gas sensor without being secured directly thereto, the heating element comprising transparent material positioned across an optical path of the optical gas sensor to provide a substantially unobstructed optical pathway through the at least one window.

22. The heater of claim 21, wherein the configuration of the heating element substantially approximates an outer periphery of the at least one window and has smaller dimensions than the outer periphery, and wherein the substantially unobstructed optical pathway is through a center of the heating element.

23. The heater of claim 21, wherein the heating element comprises at least a first element portion and a second element portion, and wherein the first and second element portions are in at least thermal communication with each other.

24. The heater of claim 23, wherein the first element portion and the second element portion are substantially L-shaped.

25. The heater of claim 23, wherein the first element portion and the second element portion are substantially C-shaped.

26. The heater of claim 21, wherein the heating element comprises a plurality of element portions.

27. The heater of claim 26, wherein each element portion of the plurality of element portions substantially approximates a dimension of a corresponding portion of an outer periphery of the at least one window.

28. The heater of claim 21, further comprising a temperature-conducting element.

29. The heater of claim 28, wherein the temperature-conducting element is in at least thermal communication with the heating element.

30. The heater of claim 28, wherein the heating element comprises a plurality of heating element portions forming a first configuration and the temperature-conducting element comprises a plurality of temperature-conducting element portions forming a second configuration, and wherein the second configuration substantially approximates the first configuration.

31. The heater of claim 28, further comprising a temperature-measuring component in communication with the temperature-conducting element.

32. The heater of claim 31, wherein the temperature-measuring component is a thermocouple or a temperature-sensing semiconductor device.

33. The heater of claim 21, further comprising a temperature-control element in communication with the heating element.

34. An optical gas sensor, comprising:

a body defining a respiratory sample flow path therethrough, the respiratory sample flow path comprising a portion of a mainstream breathing circuit configured to communicate with an airway of an individual;

at least one window in the body; and

a heating element over at least a portion of the at least one window.

35. The optical gas sensor of claim 34, wherein the heating element is substantially transparent to at least one wavelength of electromagnetic radiation to be used in an optical sensing technique that facilitates measurement of at least one gaseous or vaporized material.

36. The optical gas sensor of claim 34, wherein the heating element comprises an elongate member.

37. The optical gas sensor of claim 36, wherein the elongate member comprises a flexible, substantially transparent member.

38. The optical gas sensor of claim 34, further comprising a temperature-conducting element over at least a portion of the at least one window.

39. The optical gas sensor of claim 38, wherein the temperature-conducting element comprises an elongate member.

40. The optical gas sensor of claim 39, wherein the elongate member comprises a flexible, substantially transparent member.

41. The optical gas sensor of claim 39, wherein the elongate member of the temperature-conducting element substantially approximates a configuration of the heating element.

42. The optical gas sensor of claim 34, wherein the heating element is coupled to a transducer, the transducer being positioned in proximity 10 the at least one window upon assembly of the transducer with the body.

43. The optical gas sensor of claim 42, wherein the heating element is substantially aligned with at least a portion of the at least one window upon assembly of the transducer with the body.

44. The optical gas sensor of claim 43, wherein the heating element at least partially conforms to a shape of a surface of at least the portion of the at least one window upon assembly of the transducer with the body.

45. The optical gas sensor of claim 34, wherein the heating element has a configuration that permits a substantially unobstructed optical pathway through the at least one window.

46. The optical gas sensor of claim 45, wherein the configuration of the heating element substantially approximates a configuration of an outer periphery of the at least one window and has smaller dimensions than the outer periphery, and wherein the substantially unobstructed optical pathway is through a center of the heating element.

47. The optical gas sensor of claim 45, wherein the heating element comprises a plurality of element portions.

48. The optical gas sensor of claim 47, wherein each element portion substantially approximates at least one dimension of a corresponding portion of an outer periphery of the at least one window.

49. The optical gas sensor of claim 45, further comprising a temperature-conducting element.

50. The optical gas sensor of claim 49, wherein the temperature-conducting element is in at least thermal communication with the heating element.

51. The optical gas sensor of claim 49, wherein the heating element comprises a plurality of heating element portions forming a first configuration and the temperature-conducting element comprises a plurality of temperature-conducting element portions forming a second configuration, and wherein the second configuration substantially approximates the first configuration.

52. The optical gas sensor of claim 49, further comprising a temperature-measuring component in communication with the temperature-conducting element.

53. A transducer for use in an optical sensing technique for measuring at least one gaseous or vaporized material, the transducer comprising:

a transducer body configured to be removably secured to an optical gas sensor; and

a heating element that is substantially transparent to al least one wavelength of electromagnetic radiation coupled to the transducer body.

54. The transducer of claim 53, wherein upon assembly of the transducer with an optical gas sensor having at least one window therein, the heating element is positioned in proximity to the at least one window.

55. The transducer of claim 54, wherein the heating element is substantially aligned with at least a portion of the at least one window upon assembly of the transducer with the optical gas sensor.

56. A transducer for use in an optical sensing technique for measuring at least one gaseous or vaporized material, the transducer comprising:

a transducer body configured to be removably secured to an optical gas sensor; and

a heating element coupled to the transducer body, the heating element having a configuration that permits a substantially unobstructed optical pathway through at least one window of the optical gas sensor upon assembly of the transducer with the optical gas sensor.

57. The transducer of claim 56, wherein the heating element is substantially aligned with at least a portion of the at least one window upon assembly of the transducer with the optical gas sensor.

58. A method of heating an optical window of a gas sensor comprising:

providing an optical gas sensor having a body that defines a sample flow path therethrough, with the sample flow path being positioned along a mainstream breathing circuit that communicates with an airway of an individual, the body having at least one window therein, the optical gas sensor also including a heating element over at least a portion of the at least one window, the heating element being coupled to a source of electrical power;

introducing or sensing radiation through the heating element on the at least one window; and

supplying power to the heating element to heat the at least one window.

59. The method of claim 58, further comprising:

sensing a temperature of the at least one window.

60. The method of claim 59, further comprising:

varying an amount of power supplied to the heating element responsive to a sensed temperature.

61. The method of claim 58, further comprising:

contacting the at least one window with a transparent heating element that is separate therefrom.

62. The method of claim 58, wherein providing comprises positioning the heating element in close proximity to but out of contact with the at least one window.