Optical bubble detection system

• US 6,531,708 B1
• Filed: 04/16/2001
• Issued: 03/11/2003
• Est. Priority Date: 04/16/2001
• Status: Expired due to Term

• Current Assignee: Zevex (Moog Incorporated)
• Original Assignee: Zevex (Moog Incorporated)
• Inventors: Beck, Kent F., Miles, Scott D., Malmstrom, James A.
• Primary Examiner(s): Epps; Georgia
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US09/836,840
• Time in Patent Office: 694 Days
• Field of Search: 250/573,574,575,576 356/246,436,440,442
• US Class Current: 250/573
• CPC Class Codes: A61M 2205/12 with interchangeable cassettes forming partially or totally the fluid circuit
• CPC Class Codes: A61M 5/14232 Roller pumps
• CPC Class Codes: A61M 5/365 Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626

Abstract

An optical sensor includes a sample cell through which a fluid flows, an optical sensor formed by an optical emitter and an optical detector. The sample cell and the optical sensor use light refraction to determine the presence and size of a bubble passing through the sample cell. A housing may also be included to provide better control over light refraction and to protect the optical sensor.

Claims

1. A sample cell for monitoring the flow of a liquid, the sample cell comprising, a cell wall defining a conduit, the conduit having a triangular cross-section, and a base portion positioned adjacent the conduit and along the cell wall, the base portion extending away from the conduit and being configured for the passage of light therethrough without passing through the conduit.

2. The sample cell for monitoring the flow of a liquid according to claim 1, wherein the conduit has a cross-sectional shape of an inverted equilateral triangle.

3. The sample cell for monitoring the flow of a liquid according to claim 1, wherein the cell wall has a generally triangular exterior.

4. The sample cell for monitoring flow of a fluid according to claim 3, wherein the cell wall forms an inverted equilateral triangle.

5. The sample cell for monitoring flow of a fluid according to claim 4, wherein the base portion is positioned at the bottom of the equilateral triangle.

6. The sample cell according to claim 5, wherein sample cell is configured for light to be directed at the sample cell along a path, and wherein at least one side of the base portion forms a wall perpendicular to said path.

7. The sample cell according to claim 1, wherein the base portion extends in a direction transverse to the cell walls defining the conduit.

8. The sample cell according to claim 1, wherein the cell wall has a first wall and a second wall disposed at an angle of between 45 and 100 degrees from one another, and wherein the base portion extends tangentially from both sidewalls.

10. The device according to claim 6, wherein the housing has a pair of sidewalls disposed in parallel to the sidewalls of the sample cell.

11. The device according to claim 10, wherein the sidewalls of the sample cell and the sidewalls of the housing are disposed at an angle of between about 47 and 70 degrees relative to one another.

12. The device according to claim 11, wherein the sidewalls of the sample cell are offset from one another at an angle of about 60 degrees.

13. The device according to claim 10, wherein the sidewalls of the sample cell and the sidewalls are disposed at an angle of about 60 degrees from a horizontal plane.

30. A bubble detection system comprising the sample cell according to claim 1, and further comprising an optical signal emitter and an optical signal detector.

31. The device according to claim 30, wherein the base portion of the sample cell is disposed to transmit light between the optical emitter and the optical detector uninterrupted by contents of the conduit.

9. A device for monitoring fluids comprising:

a sample cell having a cell wall defining a conduit, the cell wall having first and second sidewalls disposed tangentially to ane another, and

a housing disposed adjacent to, but spaced apart from the sample cell.

14. The device according to claim 9, wherein the housing is spaced from the sample cell to define an air chamber.

15. The device according to claim 9, wherein the housing further comprises an upper flange portion.

16. The device according to claim 9, wherein the housing further comprises a generally horizontal base portion.

17. The device according to claim 16, wherein the housing is formed as a channel wall of an enteral feeding pump.

18. The device according to claim 9, wherein the device further comprises an anti-freeflow mechanism.

19. The device according to claim 9, wherein the device further comprises a cartridge having a tube attached thereto.

20. The device according to claim 9, further comprising an optical emitter and an optical detector.

21. The device according to claim 20, wherein the sample cell has a base portion which is not intersected by the conduit of the sample cell, and which is disposed between the optical emitter and the optical detector for allowing light to be transmitted from the optical emitter to the optical detector regardless of contents in the conduit.

22. The device according to claim 20, wherein the housing has a base portion which is disposed between the optical emitter and the optical detector for allowing light to be transmitted from the optical emitter to the optical detector.

23. The device according to claim 20, wherein the sample cell and the housing each have sidewalls disposed at an angle of about 60 degrees from a plane extending between the optical emitter and the optical detector.

24. A device for monitoring the flow of a liquid, the device comprising:

a sample cell having a cell wall with at least two sidewalls disposed at an angle of between 45 and 100 degrees from one another and defining a conduit;

a housing disposed adjacent to but spaced apart from the sample cell so as to define an air chamber between the housing and the sample cell.

25. The device according to claim 24, further comprising an optical emitter and an optical detector disposed on opposing sides of the housing.

26. The device according to claim 24, wherein the housing has at least two sidewalls disposed substantially parallel to the sidewalls of the cell wall.

27. The device according to claim 24, consisting of a single optical detector.

28. The device according to claim 27, wherein the device comprises means for determining if the sample cell is properly positioned in the housing, means for determining if the optical emitter is working, and means for determining if there is air or liquid in the conduit.

29. The device according to claim 28, wherein the means for determining if the sample cell is properly positioned in the housing, the means for determining if the optical emitter is working, and the means for determining if there is air or liquid in the conduit is the single optical emitter.

32. A sample cell for use in monitoring of air bubbles in an infusion set, the sample cell comprising a conduit and a base portion extending from the sample cell configured to allow light to pass therethrough regardless of contents of the conduit.

33. The sample cell of claim 32, wherein the sample cell comprises first and second sidewalls disposed tangentially to one another at an angle of between about 45 to 100 degrees.

34. The sample cell according to claim 33, wherein the base portion is configured to allow light to pass therethrough generally horizontally with minimal refraction.

35. An air bubble sensor system comprising a sample cell in accordance with claim 32, further comprising an optical signal emitter and an optical signal detector.

36. The air bubble sensor system according to claim 35, wherein the optical signal emitter is disposed adjacent the first sidewall and wherein the optical signal detector is disposed adjacent the second sidewall.

37. The air bubble sensor system according to claim 36, wherein a light emission plane extends from the optical signal emitter to the optical signal detector, and wherein each sidewall has an acute angle from the light emission plane which is substantially the same as the acute angle from the light emission plane of the other sidewall.

38. The air bubble sensor system according to claim 37, wherein both the first and second sidewalls are disposed 60 degrees from the light emission plane.

39. The air bubble sensor system according to claim 35, further comprising a housing disposed adjacent to the sample cell.

40. The air bubble sensor system according to claim 39, wherein the housing is disposed between the sample cell and the optical signal emitter and the optical signal sensor.

41. The air bubble sensor system according to claim 40, wherein the housing has a sidewall disposed generally parallel to the first sidewall of the sample cell and a second sidewall disposed generally parallel to the second sidewall of the sample cell.

42. The sample cell of claim 32, wherein the sample cell defines a conduit, the conduit having a triangular cross-section.

43. The sample cell according to claim 32, wherein the sample cell defines a conduit and wherein the conduit has a generally diamond shaped cross-section.

44. A method for monitoring a conduit for supplying a liquid, the method comprising:

positioning the conduit between an optical emitter and an optical detector;

emitting a signal from the optical emitter to the optical detector; and

utilizing the optical signal received by the optical detector to determine at least two of the group consisting the presence of the conduit;

the presence of air in the conduit; and

that optical emitter is sending the optical signal.

45. The method according to claim 44, wherein the method comprises determining that the conduit is in place by detecting an amount of the optical signal less than an amount detected when the conduit is not in place.

46. The method according to claim 44, wherein the method comprises, detecting air in the conduit by detecting an amount of the optical signal received by the optical detector which is greater than the amount received when there is liquid in the conduit.

47. The method according to claim 44, wherein confirmation that the optical emitter is sending an optical signal is determined by the optical detector receiving a portion of the optical signal regardless of whether the conduit is in place and regardless of whether the conduit has air therein.

48. The method according to claim 47, wherein the method comprises passing a portion of the signal through a base portion formed by a wall defining the conduit, the base portion being configured to allow light to pass therethrough with minimal refraction regardless of the contents of the conduit.

49. The method according to claim 44, wherein the method comprises positioning the optical emitter and the optical detector so that the optical detector receives less optical signal when the conduit is in place than when the conduit is not in place, and less optical signal when the conduit is filled with liquid than when the conduit is filled with air.

50. The method according to claim 49, wherein the method comprises positioning the conduit, the optical detector and the optical sensor, so that the optical detector always senses some optical signal from the optical emitter when the optical emitter is working.

51. The method according to claim 44, wherein the method comprises using a single optical detector and optical emitter to determine presence of the conduit, whether the conduit has air therein, and whether the optical emitting is emitting optical signals.

52. A method for monitoring air bubbles in an infusion set, the method comprising;

selecting a sample cell having a first sidewall and a second sidewall, the first and second sidewall being disposed at an angle relative to one another between about 45 and 100 degrees and having a conduit formed therein;

transmitting light from an optical signal emitter toward an optical signal detector and into the sample cell and refracting a greater amount of light toward the optical signal detector if air is present in the conduit; and

directing light through the sample cell such that the optical detector always receives light if the optical emitter is working.

53. The method according to claim 52, wherein the method comprises;

more specifically, selecting a sample cell having sidewalls which are offset from one another at an angle of about 60 degrees.

54. The method according to claim 52, wherein the method comprises passing some light from the optical signal emitter to optical signal detector through the sample cell, but not through the conduit.

55. The method according to claim 52, wherein the method further comprises disposing a housing adjacent the sample cell for refracting light.

56. A method for detecting bubbles in a sample cell, the method comprising;

selecting a sample cell having a conduit, an optical signal emitter and an optical signal detector;

determining whether the sample cell is properly positioned between the optical signal emitter and the optical signal detector by the amount of light detected by the optical signal detector; and

causing different amounts of light to be refracted towards the optical signal detector depending, on whether the conduit is filled with air or is filled with a liquid.

57. The method according to claim 56, wherein the method comprises transmitting the light along a plane and refracting the light with a sample cell wall disposed at an angle less than normal to the plane.

58. The method according to claim 56, wherein the method comprises stopping the transmission of light with an opaque liquid in the sample cell.

59. The method according to claim 58, wherein the method comprises directing some light to the optical signal detector regardless of the contents of the sample cell.

63. The method according to claim 59, wherein the sample cell has a pair of sidewalls through which the light passes, and wherein the sidewalls are angled away from each other at an angle of 45 to 110 degrees.

64. The method according to claim 59, wherein the method comprises positioning the optical sensors to maximize detection of refracted light.

60. A method for forming a sample cell from flexible tubing the method comprising:

selecting a sample cell container having a channel formed therein defining a pair of sidewalls sloping toward one another and being disposed at an angle offset from each other of between about 45 and 100 degrees; and

engaging the flexible tube with the pair of sidewalls to deform the flexible tube so that the flexible tube has sidewalls disposed generally parallel to the pair of sidewalls of the sample cell container, and so that a base portion is formed for passing light therethrough with minimal refraction.

61. A sample cell container for forming a sample cell from a piece of flexible tubing, the sample cell container comprising;

a lower portion having a channel formed therein, the channel having a pair of inwardly sloping sidewalls disposed tangentially to one another at an angle of between about 45 and 100 degrees, and a base portion formed at a bottom end of the inwardly sloping sidewalls; and

an upper portion having a protrusion for nesting into the lower portion to deform the flexible tubing.

62. A method for determining the presence of air in a sample cell, the method comprising;

selecting a sample cell having a sidewall;

directing light from an optical emitter along a plane toward the sample cell such that the sidewall of the sample cell is at an angle of less than normal from the plane; and

selectively refracting the light through the sample cell so that the light is directed to an optical detector when the sample cell is substantially filled with air;

directing a portion of the light through the sample cell with minimal refraction to indicate that the light has been emitted into the sample cell.

65. A method for monitoring for bubbles, the method comprising;

selecting a sample cell having a first sidewall and a second sidewall on opposite sides of a conduit;

passing a portion of the light through the sample cell so that said portion is subject to minimal refraction regardless of the contents of the conduit; and

refracting light through the first sidewall, the conduit and the second sidewall such that the light reaches an optical signal detector when the sample cell has an air bubble disposed therein, and so that substantially none of the light passing through the conduit reaches the optical detector when the sample cell is filled with liquid.

66. The method according to claim 65, wherein the method comprises, emitting light along a plane, and disposing the first sidewall at an angle less than normal to the plane.

67. The method according to claim 65, wherein the method comprises selecting a sample cell with the first and second sidewalls disposed at an angle between about 45 and 100 degrees from one another.

68. The method according to claim 65, wherein the method further comprises using a single sensor to determine whether light has been emitted and to determine if the sample cell has air herein.

69. The method according to claim 68, wherein the method further comprises refracting a different amount of light to said sensor when the sample cell is in a proper position for monitoring.