Force sensor assembly for an infusion pump

• US 6,347,553 B1
• Filed: 02/28/2000
• Issued: 02/19/2002
• Est. Priority Date: 02/28/2000
• Status: Expired due to Term

• Current Assignee: Carefusion 303 Incorporated (Becton, Dickinson & Co)
• Original Assignee: ALARIS Medical Systems, Inc. (Becton, Dickinson & Co)
• Inventors: Morris, Matthew Gerald, Schwartz, Donald Frederic
• Primary Examiner(s): NOORI, MAX H
• Application Number:
  US09/514,532
• Time in Patent Office: 722 Days
• Field of Search: 737/63, 737/68, 737/74, 737/81, 738/18, 737/60
• US Class Current: 73/781
• CPC Class Codes: A61M 5/14228 with linear peristaltic action, i.e. comprising at least three pressurising members or a helical member
• CPC Class Codes: A61M 5/14232 Roller pumps
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: F04B 43/082 the tubular flexible member being pressed against a wall by a number of elements, each having an alternating movement in a direction perpendicular to the axes of the tubular member and each having its own driving mechanism
• CPC Class Codes: F04B 51/00 Testing machines, pumps, or pumping installations
• CPC Class Codes: G01L 1/2268 Arrangements for correcting or for compensating unwanted effects

Abstract

A force sensor assembly for use in peristaltic pumps includes a housing and a load cell at least partially disposed within the housing. A plunger, pivotable about an axis, has an upper surface and an underside surface distal from the upper surface. The underside surface cooperates with the load cell. The force sensor further includes a mechanism to reduce the load cell'"'"'s sensitivity to the positioning of an applied force on the upper surface.

Claims

1. A force sensor assembly for use in peristaltic pumps, comprising:

a housing;

a load cell at least partially disposed within said housing;

a plunger, pivotable about an axis, where said plunger comprises;

an upper surface; and

an underside surface distal from said upper surface where said underside surface cooperates with said load cell; and

a means for reducing said load cell'"'"'s sensitivity to the positioning of an applied force on said upper surface.

2. A force sensor assembly according to claim 1, wherein said means for reducing said load cell'"'"'s sensitivity, comprises an upper surface for receiving an intravenous tube perpendicular to said axis.

3. A force sensor assembly according to claim 2, wherein said upper surface is shaped to compensate for variations in measured force caused by the misalignment of said applied force.

4. A force sensor assembly according to claim 3, wherein said upper surface shape is selected from a group consisting of the following shapes:

circular, square or hourglass.

5. A force sensor assembly according to claim 1, wherein said means for reducing said load cell'"'"'s sensitivity, comprises an upper surface for receiving an intravenous tube parallel to said axis.

6. A force sensor assembly according to claim 5, wherein said upper surface is shaped to compensate for variations in measured force caused by the misalignment of said applied force.

7. A force sensor assembly according to claim 6, wherein said upper surface shape is selected from a group consisting of the following shapes:

circular, teardrop or triangular.

8. A force sensor assembly according to claim 1, wherein said plunger further comprises:

a free end; and

a pivot end located at said axis.

9. A force sensor assembly according to claim 8, wherein said pivot end is rotatably coupled to said housing.

10. A force sensor assembly according to claim 8, wherein said pivot end is rotatably coupled to a body proximate said housing.

11. A force sensor assembly according to claim 8, wherein said pivot end is rotatably coupled to said housing by means of a hinge.

12. A force sensor assembly according to claim 11, wherein said is hinge is a living hinge.

13. A force sensor assembly according to claim 12, wherein said living hinge is a resilient metal strip.

14. A force sensor assembly according to claim 12, wherein said living hinge is a resilient plastic strip.

15. A force sensor assembly according to claim 11, wherein said hinge is a small pin pivot hinge.

16. A force sensor assembly according to claim 15, wherein said hinge has low mechanical friction.

17. A force sensor assembly according to claim 1, wherein said load cell is a pressure transducer.

18. A force sensor assembly according to claim 1, wherein said load cell has low internal mechanical friction.

19. A force sensor assembly according to claim 1, wherein said load cell itself has a reduced sensitivity to the positioning of the applied force on said upper surface.

20. A force sensor assembly according to claim 1, wherein said underside of said plunger is shaped to contact with said load cell at a single point.

21. A force sensor assembly according to claim 1, wherein said plunger is biased away from said load cell.

22. A force sensor assembly adapted to reduce a load cell'"'"'s sensitivity to the positioning of an applied force, comprising:

a housing;

a load cell at least partially disposed within said housing; and

a plunger rotatably coupled to said housing by means of a hinge said plunger further comprising;

an upper surface which is shaped to compensate for variations in measured force caused by the misalignment of said applied force; and

an underside surface distal from said upper surface,

such that in use a force applied to said upper surface of said plunger is transferred to said load cell by said underside of said plunger pivoting into contact with said load cell.

23. A force sensor assembly according to claim 22, wherein said hinge is a living hinge.

24. A force sensor assembly according to claim 23, wherein said hinge is a small pin pivot hinge.