Magnetorheological fluid compositions and prosthetic knees utilizing same

• US 20060178753A1
• Filed: 03/15/2006
• Published: 08/10/2006
• Est. Priority Date: 05/02/2003
• Status: Active Grant

• Current Assignee: Ossur hf
• Original Assignee: Ossur hf
• Inventors: Bisbee, Charles R. III, Hsu, Henry, Prince, Stephen W., Lindsay, Michael W., Lukasiewicz, Ronald J., Palmer, Michael Lars
• Granted Patent: US 7,335,233 B2
• Time in Patent Office: Days
• US Class Current: 623/26
• 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 prosthetic knee system comprising a magnetorheological fluid and a prosthetic knee, the fluid being provided within the prosthetic knee;

wherein the magnetorheological fluid comprises polarizable particles and a fluid component;

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

wherein the additive comprises a parafluoropropene and oxygen polymerized amide derivative and/or a functionalized perfluorinated polyether fluid.

2. The prosthetic knee system of claim 1, wherein the prosthetic knee operates in shear mode.

3. The prosthetic knee system of claim 1, wherein the polarizable particles comprise iron particles.

4. The prosthetic knee system of claim 1, wherein the polarizable particles range in size from about 0.2 to about 50 microns.

5. The prosthetic knee system of claim 4, wherein the polarizable particles range in size from about 0.4 to about 10 microns.

6. The prosthetic knee system of claim 5, wherein the polarizable particles range in from about 0.5 to about 9 microns.

7. The prosthetic knee system of claim 1, wherein the polarizable particles comprise about 1 to about 60% (v/v) of the total magnetorheological fluid volume.

8. The prosthetic knee system of claim 7, wherein the polarizable particles comprise about 10 to about 50% (v/v) of the total magnetorheological fluid volume.

9. The prosthetic knee system of claim 8, wherein the polarizable particles comprise more preferably from about 20 to about 40% (v/v) of the total magnetorheological fluid volume.

10. The prosthetic knee system 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.

11. The prosthetic knee system of claim 10, wherein the carrier fluid comprises one or more perfluorinated polyethers.

12. The prosthetic knee system of claim 1, wherein the additive comprises a parafluoropropene and oxygen polymerized amide derivative.

13. The prosthetic knee system of claim 1, wherein the additive comprises a functionalized perfluorinated polyether.

14. The prosthetic knee system of claim 13, wherein the functionalized perfluorinated polyether 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.

15. The prosthetic knee system of claim 14, wherein the functionalized perfluorinated polyether fluid additive comprises a poly(hexafluoropropylene epoxide) with a carboxylic acid located on the terminal fluoromethylene group.

16. The prosthetic knee system of claim 1, wherein the additive comprises from about 0.1 to about 20% (v/v) of the fluid component.

17. The prosthetic knee system of claim 16, wherein the additive comprises from about 1 to about 15% (v/v) of the fluid component.

18. The prosthetic knee system of claim 17 wherein the additive comprises from about 2 to about 10% (v/v) of the fluid component.

19. The prosthetic knee system of claim 1, comprising:

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

about 72% (v/v) fluid component;

wherein said fluid component comprises about 5% (v/v) poly(hexafluoropropylene epoxide) with a carboxylic acid located on the terminal fluoromethylene group additive and about 95% (v/v) perfluorinated polyether carrier fluid.

20. The prosthetic knee system of claim 1, comprising:

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

about 72% (v/v) fluid component;

wherein said fluid component comprises about 5% (v/v) parafluoropropene and oxygen polymerized amide derivative additive and about 95% (v/v) perfluorinated polyether carrier fluid.

21. A prosthetic joint system comprising a magnetorheological fluid and a prosthetic joint, the fluid being provided within the prosthetic joint;

wherein the magnetorheological fluid comprises polarizable particles and a fluid component;

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

wherein the additive comprises a parafluoropropene and oxygen polymerized amide derivative and/or a functionalized perfluorinated polyether fluid.

22. The prosthetic joint system of claim 21, wherein the prosthetic joint is a knee.

23. The prosthetic joint system of claim 21, wherein the polarizable particles comprise iron particles.

24. The prosthetic joint system of claim 21, wherein the additive comprises a parafluoropropene and oxygen polymerized amide derivative.

25. The prosthetic joint system of claim 21, wherein the additive comprises a functionalized perfluorinated polyether.