Electret enhanced automatic IV drip chamber shutoff

• US 20060135939A1
• Filed: 12/17/2004
• Published: 06/22/2006
• Est. Priority Date: 12/17/2004
• Status: Active Grant

• Current Assignee: Carefusion 303 Incorporated (Becton, Dickinson & Co)
• Original Assignee: Cardinal Health 303 Incorporated (Cardinal Health, Inc.)
• Inventors: Brown, Houston
• Granted Patent: US 7,338,475 B2
• Time in Patent Office: Days
• US Class Current: 604/500
• CPC Class Codes: A61M 2205/0288 Electro-rheological or magneto-rheological materials
• CPC Class Codes: A61M 5/1411 Drip chambers A61M5/162, A61M5/1689, A61M5/40 take precedence
• CPC Class Codes: A61M 5/40 using low-level float-valve to cut off media flow from reservoir position detection of a floating member A61M5/1685

Abstract

An automatic stop valve formed in a container of a medical fluid administration system includes an electrical field that attracts the float and valve seat together to shut off flow from the exit port of the container when the fluid within the container is reduced to a predetermined level. One or both of the float and valve seat creates an electric field that attracts the other, which is made of a non-magnetic dielectric, into engagement. In one embodiment, the valve seat is formed of an electret that creates the electric field attracting the float to it to stop flow. In another embodiment, the float comprises an electret that attracts the float to the dielectric valve seat. In yet another embodiment, both the float and valve seat include electrets of opposite polarity that attract each other into engagement. The lack of magnetic and metallic materials makes the shut off valve suitable for use in an MRI environment.

Claims

1. An automatic shut off valve for use in regulating the flow of medical fluid, comprising:

a container having an upstream end, a downstream end, and an exit orifice at the downstream end;

a stop member disposed within the container and formed of a non-magnetic and dielectric material; and

a valve seat disposed adjacent the exit orifice at the downstream end of the container and formed of a non-magnetic and dielectric material;

wherein at least one of the stop member and the valve seat produces an electrical field that attracts the other of the stop member and the valve seat tending to move the stop member and the valve seat into contact with each other to shut off flow of medical fluid through the container.

2. The automatic shut off valve of claim 1 wherein the stop member has buoyancy and the attraction of the stop member and the valve seat to one another by means of the electric field is selected to overcome the buoyancy of the stop member when a predetermined level of medical fluid remains within the container.

3. The automatic shut off valve of claim 1 wherein both the stop member and the valve seat produce an electrical field that attracts each other tending to move the stop member and the valve seat into contact with each other.

4. The automatic shut off valve of claim 1 wherein the electrical field attractive force is produced as a result of at least one of the stop member and the valve seat comprising an electrical charge.

5. The automatic shut off valve of claim 4 wherein the electrical charge is permanently affixed to the bulk of the at least one of the stop member and the valve seat.

6. The automatic shut off valve of claim 4 wherein the electrical field is produced as a result of the stop member comprising a first electrical charge and the valve seat comprising a second electrical charge, the first and second electrical charges being opposite and attracting each other.

7. The automatic shut off valve of claim 6 wherein both the first and second electrical charges are permanently affixed to the bulk of the stop member and the valve seat respectively.

8. The automatic shut off valve of claim 4 wherein the material producing the electrical charge is disposed so that it does not have direct contact with medical fluid located in the container.

9. The automatic shut off valve of claim 1 wherein the at least one of the stop member and the valve seat that produces the electric field comprises an electret.

10. The automatic shut off valve of claim 1 wherein both the stop member and the valve seat comprise an electret.

11. The automatic shut off valve of claim 1 wherein the at least one of the stop member and the valve seat that produces the electric field comprises a ferroelectric polymer.

12. The automatic shut off valve of claim 1 wherein the stop member has a density that is less than a density of the fluid contained in the container whereby the stop member floats with the level of the medical fluid in the container.

13. The automatic shut off valve of claim 1 wherein the stop member and the valve seat comprise a nonpolar polymer.

14. The automatic shut off valve of claim 4 wherein the first electrical charge is permanently affixed to the surface of the at least one of the stop member and the valve seat comprising an electrical charge.

15. The automatic shut off valve of claim 6 wherein both the first and second electrical charges are permanently affixed to the surface of the stop member and the valve seat respectively.

16. The automatic shut off valve of claim 1 wherein the downstream end of the container is tapered to guide the stop member toward the center of the valve seat.

17. The automatic shut off valve of claim 1 wherein the stop member is hollow.

18. The automatic shut off valve of claim 1 wherein the stop member includes an inert gas.

19. A method of automatically shutting off flow of medical fluid from a container having an upstream end and a downstream end with an exit orifice and a valve seat at the downstream end and a float located within the container that has sufficient buoyancy to float in the medical fluid and having a size selected to stop flow through the exit orifice when fully engaged with the valve seat, said method comprising:

producing an electrical field from at least one of the float and valve seat;

forming the other of the float and valve seat from a dielectric material that is attracted by an electrical field;

whereby the float and the valve seat are attracted to one another by means of the electrical field and tend to fully engage each other and thereby stop flow through the exit orifice.

20. The method of automatically shutting off flow of claim 19 wherein the steps of producing an electrical field comprises the step of creating an attraction between the float and valve seat that will overcome a buoyancy of the float in the medical fluid so that the flat fully engages the valve seat and stops flow through the exit orifice when only a predetermined quantity of medical fluid remains in the container.

21. The method of automatically shutting off flow of claim 19 further comprising the step of permanently affixing an electrical charge to the bulk of at least one of the float and valve seat.

22. The method of automatically shutting off flow of claim 19 wherein the other of the float and valve seat is formed of a nonpolar polymer that is attracted by an electrical field

23. The method of automatically shutting off flow of claim 19 wherein the step of producing an electrical field from at least one of the float and valve seat comprises forming the at least one of the float and valve seat from an electret.

24. The method of automatically shutting off flow of claim 19 wherein the step of producing an electrical field from at least one of the float and valve seat comprises forming the at least one of the float and valve seat from a ferroelectric polymer.