Ammonia sensor and system for use

• US 20070161113A1
• Filed: 05/31/2006
• Published: 07/12/2007
• Est. Priority Date: 01/06/2006
• Status: Active Grant

• Current Assignee: Renal Solutions, Inc. (Fresenius SE & Co. KGaA)
• Original Assignee: Renal Solutions, Inc. (Fresenius SE & Co. KGaA)
• Inventors: Ash, Stephen
• Granted Patent: US 8,409,864 B2
• Time in Patent Office: Days
• US Class Current: 436/113
• CPC Class Codes: A61M 1/1609 after use, i.e. downstream of dialyser
• CPC Class Codes: A61M 1/1696 with dialysate regeneration
• CPC Class Codes: G01N 2021/775 Indicator and selective membrane
• CPC Class Codes: G01N 2021/7763 Sample through flow
• CPC Class Codes: G01N 2021/7773 Reflection
• CPC Class Codes: G01N 21/05 Flow-through cuvettes G01N21/09 takes precedence; handling fluid samples G01N1/10
• CPC Class Codes: G01N 21/783 for analysing gases
• CPC Class Codes: G01N 21/80 Indicating pH value
• CPC Class Codes: G01N 33/0054 Ammonia
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y10T 436/17 Nitrogen containing
• CPC Class Codes: Y10T 436/175383 Ammonia

Abstract

An ammonia gas sensing device includes a housing defining a fluid flow path. The fluid flow path includes a fluid inlet, a fluid outlet, and an access port. A gas permeable/liquid impermeable membrane is mounted on and sealed against the housing at the access port such that the membrane is exposed to the fluid flow path but fluid is blocked from flowing outward of the access port around rather than through the membrane. An ammonia sensor is mounted on the housing at the access port in a position outward of the membrane. A system for using the ammonia sensing device includes the ammonia gas sensing device, a light source directed at the ammonia sensor, a photo detector to measure the light reflected off the ammonia sensor from the light source, and a controller for controlling the light source and optical sensor.

Claims

1. An ammonia gas detecting device comprising:

a housing defining a fluid flow path including a fluid inlet, a fluid outlet, and an access port located between the fluid inlet and the fluid outlet;

a gas permeable/liquid impermeable membrane mounted on the housing at the access port such that the membrane is exposed to the fluid flow path;

a seal installed between the membrane and the housing to block fluid from flowing outward of the access port around rather than through the membrane; and

an ammonia sensor mounted on the housing at the access port in a position outward of the membrane.

2. An ammonia gas detecting device as defined in claim 1 wherein the fluid flow path has first and second sections intersecting at a corner, and the access port is located at the corner.

3. An ammonia gas detecting device as defined in claim 1 wherein the fluid flow path extends along a curve and the access port is located on an outer side of the curve.

4. An ammonia gas detecting device as defined in claim 1 wherein the housing is a unitary structure.

5. An ammonia gas detecting device as defined in claim 1 wherein the housing is made of plastic.

6. An ammonia gas detecting device as defined in claim 1 wherein the housing is configured to be connected to flexible tubing at the inlet and outlet ports.

7. An ammonia gas detecting device as defined in claim 1 wherein the seal is an O-ring.

8. An ammonia gas detecting device as defined in claim 1 wherein the access port comprises a cylindrical counterbore in which the seal, membrane, and ammonia sensor are installed.

9. An ammonia gas detecting device as defined in claim 1 wherein the ammonia sensor includes a mixture of bromocresol green and malonic acid.

10. An ammonia gas detecting device as defined in claim 1 further comprising a transparent adhesive securing the seal, membrane, and ammonia sensor to the housing.

11. An ammonia gas detecting device as defined in claim 1 further comprising a lens mounted on the housing at the access port in a position outward of the ammonia sensor.

12. An ammonia gas detecting device comprising:

a housing defining a fluid flow path including a fluid inlet, a fluid outlet, and an access port located between the fluid inlet and the fluid outlet, the access port comprising a cylindrical counterbore with a shoulder surface extending radially inward;

a gas permeable/liquid impermeable membrane installed in the counterbore such that the membrane is exposed to the fluid flow path and has an outer edge extending over the shoulder surface;

an ammonia sensor installed in the counterbore in a position outward of the membrane; and

a cylindrical lens installed in the counterbore in a position outward of the ammonia sensor such that a compressive force is exerted by and between an outer edge of the lens and the shoulder surface to seal the outer edge of the membrane against the shoulder surface and thereby to block fluid from flowing outward of the access port around rather than through the membrane.

13. An ammonia gas detecting device as defined in claim 12 wherein the fluid flow path has first and second sections intersecting at a corner, and the access port is located at the corner.

14. An ammonia gas detecting device as defined in claim 12 wherein the fluid flow path extends along a curve and the access port is located on an outer side of the curve.

15. An ammonia gas detecting device as defined in claim 12 wherein the lens has a cylindrical inner portion and a cylindrical outer rim portion, and the inner portion is thicker than the outer rim portion.

16. An ammonia gas detecting device as defined in claim 12 wherein the housing is a unitary structure.

17. An ammonia gas detecting device as defined in claim 12 wherein the housing is made of plastic.

18. An ammonia gas detecting device as defined in claim 12 wherein the housing is configured to be connected to flexible tubing at the inlet and the outlet ports.

19. An ammonia gas detecting device as defined in claim 12 wherein the ammonia sensor includes a mixture of bromocresol green and malonic acid.

20. An ammonia gas detecting device as defined in claim 12 further comprising a transparent adhesive securing the lens to the housing.

21. An ammonia gas detecting device as defined in claim 12 wherein the lens is secured to the housing by ultrasonic staking.

22. A system for monitoring the ammonia gas level in a fluid comprising:

a) a housing including;

i) a fluid flow path including a fluid inlet, a fluid outlet, and an access port located between the fluid inlet and the fluid outlet;

ii) a gas permeable/liquid impermeable membrane mounted on the housing at the access port such that the membrane is exposed to the fluid flow path;

iii) a seal installed between the membrane and the housing to block fluid from flowing outward of the access port around rather than through the membrane; and

iv) an ammonia sensor mounted on the housing at the access port in a position outward of the membrane;

b) a light source directed at the ammonia sensor;

c) a photo detector operative to measure light reflected off the ammonia sensor from the light source; and

d) a controller operative to control the light source and photo detector.

23. A system as defined in claim 22 wherein the fluid flow path has first and second sections intersecting at a corner, and the access port is located at the corner.

24. A system as defined in claim 22 wherein the fluid flow path extends along a curve and the access port is located on an outer side of the curve.

25. A system as defined in claim 22 wherein the housing is a unitary structure.

26. A system as defined in claim 22 wherein the housing is made of plastic.

27. A system as defined in claim 22 wherein the housing is configured to be connected to flexible tubing at the inlet and outlet ports.

28. A system as defined in claim 22 wherein the seal is an O-ring.

29. A system as defined in claim 22 wherein the access port comprises a cylindrical counterbore into which the seal, membrane, and ammonia sensor are installed.

30. A system as defined in claim 22 wherein the ammonia sensor includes a mixture of bromocresol green and malonic acid.

31. A system as defined in claim 22 further comprising a transparent adhesive securing the seal, membrane, and ammonia sensor to the fluid flow path.

32. A system as defined in claim 22 further comprising a lens mounted on the housing at the access port in a position outward of the ammonia sensor.

33. A system as defined in claim 22 wherein the ammonia sensor is functional to change from yellow to blue as the ammonia sensor is exposed to ammonia gas.

34. A system as defined in claim 22 wherein the light source is a LED.

35. A system as defined in claim 22 wherein the light source is a yellow LED.

36. A system as defined in claim 22 wherein the photo detector is a phototransistor.

37. A system as defined in claim 22 wherein the photo detector is a light sensitive diode.

38. A system for monitoring the ammonia gas level in a fluid comprising:

a) an ammonia gas detecting device comprising;

i) a housing defining a fluid flow path including a fluid inlet, a fluid outlet, and an access port located between the fluid inlet and the fluid outlet, the access port comprising a cylindrical counterbore with a shoulder surface extending radially inward;

ii) a gas permeable/liquid impermeable membrane installed in the counterbore such that the membrane is exposed to the fluid flow path and has an outer edge extending over the shoulder surface;

iii) an ammonia sensor installed in the counterbore in a position outward of the membrane; and

iv) a cylindrical lens installed in the counterbore in a position outward of the ammonia sensor such that a compressive force is exerted by and between an outer edge of the lens and the shoulder surface to seal the outer edge of the membrane against the shoulder surface and thereby to block fluid from flowing outward of the access port around rather than through the membrane;

b) a light source directed at the ammonia sensor;

c) a photo detector operative to measure light reflected off the ammonia sensor from the light source; and

d) a controller operative to control the light source and photo detector.

39. A system as defined in claim 38 wherein the fluid flow path has first and second sections intersecting at a corner, and the access port is located at the corner.

40. A system as defined in claim 38 wherein the fluid flow path extends along a curve and the access port is located on an outer side of the curve.

41. A system as defined in claim 38 wherein the lens has a cylindrical inner portion and a cylindrical outer rim portion, and the inner portion is thicker than the outer rim portion.

42. A system as defined in claim 38 wherein the housing is a unitary structure.

43. A system as defined in claim 38 wherein the housing is made of plastic.

44. A system as defined in claim 38 wherein the housing is configured to be connected to flexible tubing at the inlet and outlet ports.

45. A system as defined in claim 38 wherein the ammonia sensor includes a mixture of bromocresol green and malonic acid.

46. A system as defined in claim 38 further comprising a transparent adhesive securing the lens to the housing.

47. A system as defined in claim 38 wherein the lens is secured to the housing by ultrasonic staking.

48. A system as defined in claim 38 wherein the ammonia sensor is functional to change from yellow to blue as the ammonia sensor is exposed to ammonia gas.

49. A system as defined in claim 38 wherein the light source is a LED.

50. A system as defined in claim 38 wherein the light source is a yellow LED.

51. A system as defined in claim 38 wherein the photo detector is a phototransistor.

52. A system as defined in claim 38 wherein the photo detector is a light sensitive diode.