SYRINGE PISTON WITH CHECK VALVE SEAL

• US 20110152785A1
• Filed: 12/17/2010
• Published: 06/23/2011
• Est. Priority Date: 12/22/2009
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: CHATTARAJ, Sarnath, DANG, Kiem, HOFFMAN, Lance P., GULATI, Poonam S.
• Granted Patent: US 8,574,201 B2
• Time in Patent Office: Days
• US Class Current: 604/222
• CPC Class Codes: A61M 5/31511 Piston or piston-rod constructions, e.g. connection of piston with piston-rod A61M5/5066 takes precedence
• CPC Class Codes: A61M 5/31513 Piston constructions to improve sealing or sliding
• CPC Class Codes: A61M 5/36 with means for eliminating or preventing injection or infusion of air into body dialysis systems, blood oxygenators A61M1/14; haemofiltration equipment A61M1/34; automatic tube cut-off A61M39/281
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

A fluid syringe of the type used with fluid infusion devices is presented here. The fluid syringe generally includes a barrel, a piston, and a check valve seal. The barrel has an interior wall and a sealed main fluid chamber. The piston is slidably coupled within the barrel, and the piston has a piston seal forming an interference fluid seal against the interior wall. The check valve seal is coupled to the piston, and it is located between the piston seal and the main fluid chamber. The check valve seal forms an interference fluid seal against the interior wall when the piston is unloaded, and it disengages the interior wall to allow gas flow from the main fluid chamber toward the piston seal when the piston is loaded.

Claims

1. A syringe piston comprising:

a piston body having a fluid end and an actuator end opposite the fluid end;

a piston seal coupled to the piston body and located between the fluid end and the actuator end, wherein the piston seal forms an interference fluid seal with an interior wall of a syringe barrel;

a check valve seal coupled to the piston body and positioned such that the piston seal is located between the check valve seal and the actuator end; and

a gas entrapment zone defined between the check valve seal and the piston seal, wherein the check valve seal allows one-way gas flow into the gas entrapment zone.

2. The syringe piston of claim 1, wherein the check valve seal comprises a flap that forms an interference fluid seal with the interior wall of the syringe barrel under nominal operating conditions.

3. The syringe piston of claim 1, wherein the check valve seal inhibits gas flow from the gas entrapment zone into the syringe barrel.

4. The syringe piston of claim 1, further comprising an end seal coupled around the piston body and positioned such that the piston seal is located between the check valve seal and the end seal.

5. The syringe piston of claim 4, wherein the piston seal inhibits gas flow from the gas entrapment zone toward the end seal.

6. The syringe piston of claim 1, wherein:

the piston seal is formed from a first resilient material having a first durometer; and

the check valve seal is formed from a second resilient material having a second durometer that is different than the first durometer.

7. The syringe piston of claim 1, wherein:

the check valve seal comprises a flap that cooperates with the interior wall of the syringe barrel;

the flap seals against the interior wall of the syringe barrel when the syringe barrel is closed and the syringe piston is uncompressed;

the flap disengages the interior wall of the syringe barrel when the syringe barrel is closed and the syringe piston is compressed; and

the flap seals against the interior wall of the syringe barrel when the syringe barrel is open and the syringe piston is compressed for purposes of dispensing fluid.

8. A fluid syringe comprising:

a syringe barrel comprising an interior wall and a sealed main fluid chamber;

a syringe piston slidably coupled within the syringe barrel, the syringe piston comprising a piston seal forming an interference fluid seal against the interior wall; and

a check valve seal coupled to the syringe piston and located between the piston seal and the main fluid chamber, the check valve seal forming an interference fluid seal against the interior wall when the syringe piston is unloaded, and the check valve seal disengaging the interior wall to allow gas flow from the main fluid chamber toward the piston seal when the syringe piston is loaded.

9. The fluid syringe of claim 8, wherein the check valve seal forms an interference fluid seal against the interior wall when the syringe barrel is unsealed and the syringe piston is loaded for purposes of dispensing fluid.

10. The fluid syringe of claim 8, wherein the syringe piston comprises a piston body having a fluid end near the main fluid chamber, and having an actuator end opposite the fluid end, wherein:

the piston seal is coupled to the piston body and located between the fluid end and the actuator end; and

the check valve seal is coupled to the piston body and positioned such that the piston seal is located between the check valve seal and the actuator end.

11. The fluid syringe of claim 8, further comprising a liquid medication within the sealed main fluid chamber.

12. The fluid syringe of claim 11, wherein the liquid medication comprises insulin.

13. The fluid syringe of claim 11, further comprising a gas entrapment zone defined between the check valve seal, the piston seal, and the interior wall, wherein the check valve seal allows gas trapped in the main fluid chamber to flow into the gas entrapment zone when the syringe piston is loaded.

14. The fluid syringe of claim 13, wherein the check valve seal inhibits gas flow from the gas entrapment zone into the main fluid chamber.

15. The fluid syringe of claim 8, wherein the syringe piston further comprises an end seal forming an interference fluid seal against the interior wall, wherein the piston seal is located between the check valve seal and the end seal.

16. The fluid syringe of claim 15, wherein the piston seal inhibits gas flow from the gas entrapment zone toward the end seal.

17. The fluid syringe of claim 8, wherein:

the piston seal is formed from a first resilient material having a first durometer; and

the check valve seal is formed from a second resilient material having a second durometer that is equal to the first durometer.

18. A method of manufacturing a fluid syringe, the method comprising:

fabricating a syringe assembly comprising a syringe barrel having an interior wall and a main fluid chamber, a sealing cap having a penetrable membrane, a syringe piston slidably coupled within the syringe barrel and partially defining the main fluid chamber, and a liquid within the main fluid chamber, the syringe piston comprising a piston seal forming an interference fluid seal against the interior wall, and comprising a check valve seal located between the piston seal and the main fluid chamber;

maintaining the syringe assembly in a position that allows gas in the main fluid chamber to accumulate and rise toward the syringe piston;

after the gas in the main fluid chamber has settled at the check valve seal, applying a force to the syringe piston to move the syringe piston into the syringe barrel while maintaining the syringe assembly in the position, such that the check valve seal allows the gas to flow from the main fluid chamber into an entrapment zone defined between the piston seal, the check valve seal, and the interior wall; and

after the gas flows past the check valve seal into the entrapment zone, removing the force from the syringe piston to return the check valve seal to an unbiased state, such that the check valve seal retains the gas in the entrapment zone.

19. The method of claim 18, wherein fabricating the syringe assembly comprises:

providing the syringe barrel in an empty state with the syringe piston slidably coupled within the syringe barrel at a filling position;

dispensing the liquid into a neck region of the syringe barrel until the syringe barrel is filled; and

installing the sealing cap onto the neck region to seal the liquid in the syringe barrel.

20. The method of claim 18, wherein the syringe assembly is maintained in an upright position with the check valve seal above the sealing cap, to allow gas bubbles in the liquid to rise, accumulate, and settle at the check valve seal.