Magnetorheological fluid compositions and prosthetic knees utilizing same

• US 7,101,487 B2
• Filed: 11/25/2003
• Issued: 09/05/2006
• Est. Priority Date: 05/02/2003
• Status: Active Grant

• Current Assignee: Ossur hf
• Original Assignee: Ossur Engineering Incorporated
• Inventors: Bisbee, Charles R. III, Hsu, Henry, Prince, Stephen W., Lindsay, Michael W., Lukasiewicz, Ronald J., Palmer, Michael Lars
• Primary Examiner(s): KOSLOW, CAROL M
• Application Number:
  US10/722,313
• Publication Number:
  US 20040217324A1
• Time in Patent Office: 1,015 Days
• Field of Search: 252/62.52, 623/24, 623/26, 623/39
• US Class Current: 252/62.52
• CPC Class Codes: A61F 2/68 Operating or control means
• CPC Class Codes: A61F 2002/5004 operated by electro- or magnetorheological fluids
• CPC Class Codes: A61F 2002/503 for adjusting elasticity, flexibility, spring rate or mechanical tension
• CPC Class Codes: A61F 2002/5033 for adjusting damping damping means A61F2002/5003
• CPC Class Codes: A61F 2002/6818 for braking
• CPC Class Codes: C10M 171/001 Electrorheological fluids; smart fluids
• CPC Class Codes: C10M 2201/05 Metals; Alloys
• CPC Class Codes: C10M 2213/06 Perfluoro polymers
• CPC Class Codes: C10M 2213/0606 used as base material
• CPC Class Codes: C10N 2010/14 Group 7
• CPC Class Codes: C10N 2010/16 Groups 8, 9, or 10
• CPC Class Codes: C10N 2020/011 Cloud point
• CPC Class Codes: C10N 2020/02 Viscosity; Viscosity index
• CPC Class Codes: C10N 2020/06 Particles of special shape or size
• CPC Class Codes: C10N 2030/02 Pour-point; Viscosity index
• CPC Class Codes: C10N 2060/00 Chemical after-treatment of the constituents of the lubricating composition
• CPC Class Codes: C10N 2060/06 by epoxydes or oxyalkylation reactions
• CPC Class Codes: C10N 2060/09 Treatment with nitrogen containing compounds
• CPC Class Codes: C10N 2060/12 by phosphorus or a compound containing phosphorus, e.g. PxSy
• CPC Class Codes: H01F 1/447 characterised by magnetoviscosity, e.g. magnetorheological, magnetothixotropic, magnetodilatant liquids electrorheological fluids C10M171/001

Abstract

The present invention relates in one embodiment to magnetorheological fluids utilized in prosthetic joints in general and, in particular, to magnetorheological fluids utilized in controllable braking systems for prosthetic knee joints. Preferred magnetorheological fluids of the present invention comprises polarizable iron particles, a carrier fluid, and optionally an additive. Preferred additives include, but are not limited to functionalized carrier fluids as well as derivatized fluoropolymers. Preferred carrier fluids include, but are not limited, to perfluorinated polyethers.

Claims

1. A magnetorheological fluid comprising polarizable particles and a fluid component,

wherein the fluid component comprises a carrier fluid and an additive;

wherein the additive comprises a parafluoropropene and oxygen polymerized amide derivative.

2. The magnetorheological fluid of claim 1 wherein the polarizable particles comprise iron particles.

3. The magnetorheological fluid of claim 2 wherein the iron particles range in size from about 0.2 to about 50 microns.

4. The magnetorheological fluid of claim 3 wherein the iron particles range in size from about 0.4 to about 10 microns.

5. The magnetorheological fluid of claim 4 wherein the iron particles range in size from about 0.5 to about 9 microns.

6. The magnetorheological fluid of claim 2 wherein the iron particles comprise about 1 to about 60% (v/v) of the total magnetorheological fluid volume.

7. The magnetorheological fluid of claim 6 wherein the iron particles comprise about 10 to about 50% (v/v) of the total magnetorheological fluid volume.

8. The magnetorheological fluid of claim 7 wherein the iron particles comprise more preferably from about 20 to about 40% (v/v) of the total magnetorheological fluid volume.

9. The maguetorheological fluid of claim 1 wherein the carrier fluid is selected from the group consisting of silicone, hydrocarbon, esters, ethers, fluorinated esters, fluorinated ethers, mineral oil, unsaturated hydrocarbons, and combinations thereof.

10. The magnetorheological fluid of claim 9 wherein the carrier fluid comprises one or more perfluorinated polyethers.

11. The magnetorheological fluid of claim 1 wherein the additive comprises from about 0.1 to about 20% (v/v) of the fluid component.

12. The magnetorheological fluid of claim 11 wherein the additive comprises from about 1 to about 15% (v/v) of the fluid component.

13. The magnetorheological fluid of claim 12 wherein the additive comprises from about 2 to about 10% (v/v) of the fluid component.

14. The magnetorheological fluid of claim 1 comprising:

about 28% (v/v) iron particles; and

about 72% (v/v) fluid component;

wherein said fluid component comprises about 5% (v/v) additive and about 95% (v/v) perfluorinated polyether carrier fluid.

15. The magnetorheological fluid of claim 1 wherein the magnetorheological fluid is operable over a temperature range from about 10 to about 115°

F.

16. The magnetorheological fluid of claim 1 wherein the carrier fluid has a viscosity at 104°

F. of about 10 to about 100 cSt.

17. The magnetorheological fluid of claim 16 wherein the carrier fluid has a viscosity at 104°

F. of about 30 to about 80 cSt.

18. The magnetorheological fluid of claim 17 wherein the carrier fluid has a viscosity at 104°

F. of about 50 to about 70 cSt.

19. The magnetorheological fluid of claim 1 wherein the carrier fluid has a viscosity index from about 100 to about 340 based on kinematic viscosity at 104 and 212°

F.

20. The magnetorheological fluid of claim 19 wherein the carrier fluid has a viscosity index from about 120 to about 320 based on kinematic viscosity at 104 and 212°

F.

21. The magnetorheological fluid of claim 1 wherein the carrier fluid has a pour point ranging from about −

70°

C. to about −

40°

C.

22. The magnetorheological fluid of claim 1 wherein the carrier fluid ham a percent volatility at 121°

C. ranging from about 0.01% to about 20%.

23. A magnetorheological fluid consisting of polarizable particles and a fluid component,

wherein the fluid component consists essentially of a carrier fluid and an additive;

wherein the carrier fluid consists essentially of one of the group consisting of silicone, hydrocarbon, esters, ethers, fluorinated esters, fluorinated ethers, mineral oil, and unsaturated hydrocarbons; and

wherein the additive consists essentially of a functionalized perfluorinated polyether fluid.

24. A magnetorheological fluid comprising polarizable particles and a fluid component

wherein the fluid component consists essentially of a carrier fluid and an additive;

wherein the carrier fluid consists essentially of one of the group consisting of silicone, hydrocarbon, esters, ethers, fluorinated esters, fluorinated ethers, mineral oil, and unsaturated hydrocarbons; and

wherein the additive consists essentially of a functionalized perfluorinated polyether fluid

wherein the functionalized perfluorinated polyether fluid additive comprises a poly(hexafluoropropylene epoxide) with a carboxylic acid located on the terminal fluoromethylene group.

25. The magnetorheological fluid of claim 24 wherein the polarizable particles comprise iron particles.

26. The magnetorheological fluid of claim 25 wherein the iron particles range in size from about 0.2 to about 50 microns.

27. The magnetorheological fluid of claim 25 wherein the iron particles range in size from about 0.4 to about 10 microns.

28. The magnetorheological fluid of claim 25 wherein the iron particles range in size from about 0.5 to about 9 microns.

29. The magnetorheological fluid of claim 25 wherein the iron particles comprise about 1 to about 60% (v/v) of the total magnetorheological fluid volume.

30. The magnetorheological fluid of claim 29 wherein the iron particles comprise about 10 to about 50% (v/v) of the total magnetorheological fluid volume.

31. The magnetorheological fluid of claim 30 wherein the iron particles comprise more preferably from about 20 to about 40% (v/v) of the total magnetorheological fluid volume.

32. The magnetorheological fluid of claim 24 wherein the carrier fluid comprises one or more perfluorinated polyethers.

33. The magnetorheological fluid of claim 24 wherein the functionalized perfluorinated polyother fluid additive comprises one or more functional groups selected from the group consisting of silane, phosphate, hydroxyl, carboxylic acid, amine, dihydroxyl, ethoxy ether, isocyanate, aromatic, ester and alcohol functions.

34. The magnetorheological fluid of claim 24 wherein the additive comprises from about 0.1 to about 20% (v/v) of the fluid component.

35. The magnetorheological fluid of claim 34 wherein the additive comprises from about 1 to about 15% (v/v) of the fluid component.

36. The magnetorheological fluid of claim 35 wherein the additive comprises from about 2 to about 10% (v/v) of the fluid component.

37. A magnetorheological fluid comprising:

about 32% (v/v) polarizable iron particles; and

about 68% (v/v) fluid component;

wherein said fluid component consists essentially of about 5% (v/v) additive and about 95% (v/v) perfluorinated polyother carrier fluid;

wherein said additive consists essentially of poly(hexafluoropropylene epoxide) with a carboxylic acid located on the terminal fluoromethylene group.

38. The magnetorheological fluid of claim 37 wherein the iron particles range in size from about 0.2 to about 50 microns.

39. The magnetorheological fluid of claim 37 wherein the iron particles range in size from about 0.4 to about 10 microns.

40. The magnetorheological fluid of claim 37 wherein the iron particles range in size from about 0.5 to about 9 microns.

41. A magnetorheological fluid comprising polarizable particles and a fluid component,

wherein the fluid component comprises a carrier fluid and an additive;

wherein the additive comprises poly(hexafluoropropylene epoxide) with a carboxylic acid located on the terminal fluoromethylene group.

42. The magnetorheological fluid of claim 41 wherein the polarizable particles comprise iron particles.

43. The magnetorheological fluid of claim 42 wherein the iron particles range in size from about 0.2 to about 50 microns.

44. The magnetorheological fluid of claim 42 wherein the iron particles range in size from about 0.4 to about 10 microns.

45. The magnetorheological fluid of claim 42 wherein the iron particles range in size from about 0.5 to about 9 microns.

46. The magnetorheological fluid of claim 42 wherein the iron particles comprise about 1 to about 60% (v/v) of the total magnetorheological fluid volume.

47. The magnetorheological fluid of claim 46 wherein the iron particles comprise about 10 to about 50% (v/v) of the total magnetorheological fluid volume.

48. The magnetorheological fluid of claim 47 wherein the iron particles comprise more preferably from about 20 to about 40% (v/v) of the total magnetorheological fluid volume.

49. The magnetorheological fluid of claim 41 wherein the carrier fluid is selected from the group consisting of silicone, hydrocarbon, esters, ethers, fluorinated esters, fluorinated ethers, mineral oil, unsaturated hydrocarbons, and combinations thereof.

50. The magnetorheological fluid of claim 49 wherein the carrier fluid comprises one or more perfluorinated polyethers.

51. The magnetorheological fluid of claim 41 wherein the additive comprises from about 0.1 to about 20% (v/v) of the fluid component.

52. The magnetorheological fluid of claim 51 wherein the additive comprises from about 1 to about 15% (v/v) of the fluid component.

53. The magnetorheological fluid of claim 52 wherein the additive comprises from about 2 to about 10% (v/v) of the fluid component.

54. The magnetorheological fluid of claim 41 comprising:

about 32% (v/v) iron particles; and

about 68% (v/v) fluid component;

wherein said fluid component comprises about 5% (v/v) additive and about 95% (v/v) perfluorinated polyether carrier fluid.