Apparatus and method for sealing pressure sensor membranes

• US 7,021,148 B2
• Filed: 04/30/2002
• Issued: 04/04/2006
• Est. Priority Date: 04/30/2002
• Status: Expired due to Fees

• Current Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Original Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Inventors: Jensen, Jan, Prisco, Michael R., Cartwright, Jason, Kuhn, David, Ripley, Jerry, Chim, Ed
• Primary Examiner(s): Noori, Max
• Assistant Examiner(s): JENKINS, JERMAINE L
• Application Number:
  US10/136,411
• Publication Number:
  US 20030200812A1
• Time in Patent Office: 1,435 Days
• Field of Search: 73700-756, 73/491
• US Class Current: 73/715
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61M 1/3639 Blood pressure control, pressure transducers specially adapted therefor
• CPC Class Codes: A61M 1/3641 Pressure isolators
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: G01L 19/0023 for flowthrough systems having a flexible pressure transmitting element
• CPC Class Codes: G01L 19/0645 using isolation membranes, specially adapted for protection

Abstract

The present invention lessens the amount of air entering between mating membranes of a pressure sensor. The pressure sensor of the present invention includes a transducer portion and separate patient or medical fluid transfer portion or dome. The transducer portion is reusable and the dome is disposable. The dome defines a fluid flow chamber that is bounded on one side by a dome membrane. Likewise, the transducer is mounted inside a housing, wherein the housing defines a surface that holds a transducer membrane. The two membranes mate when the dome is fitted onto the transducer housing. The pressure sensor enhances the seal between the mated membranes by creating higher localized contact stresses. The pressure sensor also reduces the amount of gas that permeates from the fluid chamber across the dome membrane and between the interface by making the dome membrane from a material having a low vapor transmission.

Claims

1. A fluid pressure sensor comprising:

a housing having a first membrane;

a transducer positioned inside the housing;

a body including a fluid inlet and a fluid outlet removably coupled to the housing; and

a second membrane provided with the body that contacts at least a portion of the first membrane when the body is coupled to the housing, the second membrane including an integral sealing member projecting from the second membrane towards the housing.

2. The fluid pressure sensor of claim 1, wherein the second membrane includes a mounting ring that pressure fits into the body.

3. The fluid pressure sensor of claim 1, wherein the second membrane includes a material selected from the group consisting of butyl rubber, neoprene, polyurethane, Buna-N, saran, mylar, a sputter coating of metal, a metal film and any combination thereof.

4. The fluid pressure sensor of claim 1, wherein the second membrane includes a first member and a second member, the second member having a lower gas permeability than the first member.

5. The fluid pressure sensor of claim 1, wherein the integral sealing member compresses to a surface of the housing that surrounds the first membrane.

6. The fluid pressure sensor of claim 1, wherein the sealing member is selected from the group consisting of:

an O-ring, a delta-ring, a D-ring, a T-ring, a square-ring, a lobed-ring, a cored-ring, a hollow-ring and a K-ring.

7. A fluid pressure sensor comprising:

a housing having a first membrane;

a transducer positioned inside the housing;

a body including a fluid inlet and a fluid outlet removably coupled to the housing via a coupling mechanism;

a second membrane provided with the body that contacts at least a portion of the first membrane when the body is coupled to the housing; and

an apparatus in addition to the coupling mechanism that creates a localized contact force between the second membrane and a surface of the housing surrounding the first membrane.

8. The fluid pressure sensor of claim 7, wherein the second membrane includes a material selected from the group consisting of butyl rubber, neoprene, polyurethane, Buna-N, saran, mylar, a sputter coating of metal, a metal film and any combination thereof.

9. The fluid pressure sensor of claim 7, wherein the apparatus includes a groove in the surface of the housing and a sealing member integral to the second membrane that compresses into the groove.

10. The fluid pressure sensor of claim 9, wherein the surface of the housing defining the groove is metal.

11. The fluid pressure sensor of claim 7, wherein the apparatus includes a groove in the surface of the housing and a separate sealing member compressed between the second membrane and the groove.

12. The fluid pressure sensor of claim 11, wherein the separate sealing member pressure fits into the groove when the housing and the body are separated.

13. The fluid pressure sensor of claim 7, wherein the apparatus includes a raised portion extending from the surface of the housing contacting the second membrane.

14. The fluid pressure sensor of claim 13, wherein the surface and the raised portion are metal.

15. The fluid pressure sensor of claim 7, wherein the apparatus includes a raised portion extending from a surface of the body.

16. A fluid pressure sensor comprising:

a housing having a first surface and a first membrane;

a transducer positioned inside the housing;

a body including a second surface, a fluid inlet and a fluid outlet removably coupled to the housing; and

a second membrane provided with the body that contacts at least a portion of the first membrane when the body is coupled to the housing; and

a sealing member positioned between the first surface and the second surfaces.

17. The fluid pressure sensor of claim 16, wherein one of the first and second surfaces defines a groove that houses the sealing member.

18. The fluid pressure sensor of claim 16, wherein the second membrane includes a material selected from the group consisting of butyl rubber, neoprene, polyurethane, Buna-N, saran, mylar, a sputter coating of metal, a metal film and any combination thereof.

19. A fluid pressure sensor comprising:

a housing having a first membrane;

a transducer positioned inside the housing;

a body including a fluid inlet and a fluid outlet removably coupled to the housing; and

a second membrane provided with the body that contacts at least a portion of the first membrane when the body is coupled to the housing, the second membrane constructed at least partly of a synthetic and electrically resistive material that is at least five times less permeable to air at standard temperature and pressure than ethylene propylene diene methylene (“

EPDM”

).

20. The fluid pressure sensor of claim 19, wherein the material includes butyl rubber.

21. A fluid pressure sensor comprising:

a housing having a surface surrounding a first membrane;

a transducer positioned inside the housing;

a body including a fluid inlet and a fluid outlet and having a means for removably coupling to the housing; and

a second membrane provided with the body that contacts at least a portion of the first membrane when the body is coupled to the housing, the second membrane including a first material and a second material having a lower gas permeability than the first material.

22. The fluid pressure sensor of claim 21, wherein the second material is bonded to first material.

23. The fluid pressure sensor of claim 21, wherein the first material is selected from the group consisting of:

ethylene propylene diene methylene (EPDM), silicone, polyurethane and any combination thereof.

24. The fluid pressure sensor of claim 21, wherein the second member includes a material selected from the group consisting of:

metal foil, a sputter coating of metal, saran, mylar, SiO₂ glass film, EvOH barrier film and any combination thereof.

25. A medical infusion device comprising:

an enclosure; and

a pressure sensor mounted to the enclosure, the pressure sensor including

a housing having a first membrane,

a transducer positioned inside the housing,

a body including a fluid inlet and a fluid outlet removably coupled to the housing,

a second membrane provided with the body that contacts at least a portion of the first membrane when the body is coupled to the housing, and

an apparatus that creates a localized contact force between the second membrane and a surface of the housing surrounding the first membrane.

26. The medical infusion device of claim 25, wherein the housing is mounted to the enclosure.

27. A dialysis device comprising:

an enclosure; and

a pressure sensor mounted to the enclosure, the pressure sensor including

a housing having a first membrane;

a transducer positioned inside the housing;

a body including a fluid inlet and a fluid outlet removably coupled to the housing, and

a second membrane provided with the body that contacts at least a portion of the first membrane when the body is coupled to the housing, the second membrane constructed at least partly of a synthetic and electrically resistive material that is at least five times less permeable to air at standard temperature and pressure than ethylene propylene diene methylene (“

EPDM”

).

28. The dialysis device of claim 27, wherein the pressure sensor monitors pressure of a fluid selected from the group consisting of:

blood, dialysate, infusate, saline and any combination thereof.