CONTINUOUS CONDUCTIVE MATERIALS FOR ELECTROMAGNETIC SHIELDING

• US 20080195186A1
• Filed: 02/14/2007
• Published: 08/14/2008
• Est. Priority Date: 02/14/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Li, Bernard, Chen, Xingfu, Cai, Chad
• Granted Patent: US 10,537,730 B2
• Time in Patent Office: Days
• US Class Current: 607/115
• CPC Class Codes: A61N 1/0551 Spinal or peripheral nerve electrodes
• CPC Class Codes: A61N 1/086 Magnetic resonance imaging [MRI] compatible leads
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents

Abstract

A medical electrical lead having a conductor assembly covered by an insulating layer, and a shield covering positioned adjacent or proximate to at least a portion of the insulating layer in order to shield the conductor assembly from one or more electromagnetic fields. The shield covering is formed of a material that is electrically conductive, where the material is in a wrapped or woven form. The material is selected so as to have an effective combination of small size and high conductive surface area, e.g., as opposed to metal wire or coatings thinner than metal wire. As such, the shield covering exhibits sufficient conductivity in the presence of one or more high frequency electromagnetic fields so that interference to the operation of the conductor assembly is minimized. The material can have a coating formed of one or more metals. The material can include carbon. In turn, the carbon can be formed of one or more of carbon fiber, carbon nanofiber, and single or multi-walled carbon nanotube.

Claims

1. A medical electrical lead, comprising:

a conductor assembly having one or more conductors covered by an insulating layer; and

a shield covering adjacent or proximate to at least a portion of the insulating layer to shield the conductors from one or more electromagnetic fields, the shield covering formed of a non-metallic material that is electrically conductive, the material being in a wrapped or woven form and having one or more conductive members each having an outer diameter that is no greater than about 20 μ

m, the shield covering having an effective combination of small size and high surface area for sufficient conductivity in presence of one or more high frequency electromagnetic fields so that interference to the operation of the one or more conductors is minimized.

2. The medical electrical lead of claim 1, wherein the material comprises carbon.

3. The medical electrical lead of claim 2, wherein the carbon is formed of carbon fiber, the one or more conductive members of the carbon fiber comprising a bundled plurality of individual strands, wherein each of the individual strands has an outer diameter ranging in size from about 5 μ

m to about 12 μ

m.

4. The medical electrical lead of claim 2, wherein the carbon is formed of one or more of carbon nanofiber and carbon nanotube, wherein the one or more conductive members of the carbon nanofiber comprise a plurality of individual strands, and wherein each of the individual strands and the carbon nanotube have an outer diameter that is no greater than about 1 μ

m.

5. The medical electrical lead of claim 2, wherein the carbon has a shielding coverage percentage over the conductor assembly that is higher than that obtained with metal wire.

6. The medical electrical lead of claim 5, wherein the carbon is in the wrapped form, the material extending across the conductor assembly via a plurality of turns, wherein consecutive turns are in contact with each other.

7. The medical electrical lead of claim 5, wherein the carbon is in the woven form, the material extending across the conductor assembly via a plurality of overlapping turns.

8. The medical electrical lead of claim 1, wherein the material has a higher skin depth than metal.

9. The medical electrical lead of claim 1, further comprising a coating formed of one or more metals, the coating formed or attached around the material, the coating and the shield covering providing an enhanced shielding effect for the one or more conductors.

10. The medical electrical lead of claim 1, further comprising a coating formed of one or more metals, the coating positioned external to the shield covering, the coating and the shield covering providing an enhanced shielding effect for the one or more conductors.

11. The medical electrical lead of claim 1, further comprising one or more additional layers, the one or more additional layers comprising a braided metal sheath or mesh and an optional insulation layer, the one or more additional layers positioned either internal or external to the shield covering, the one or more additional layers and the shield covering providing an enhanced shielding effect for the one or more conductors.

12. The medical electrical lead of claim 1, further comprising a further layer formed of a polymer based composite material, the further layer positioned either internal or external to the shield covering, the further layer and the shield covering providing an enhanced shielding effect for the one or more conductors.

13. The medical electrical lead of claim 12, wherein the composite material is a composite with conductive properties provided by discontinuous conductive fillers, the fillers comprising one or more of nano-sized metal structures and nano-sized non-metallic conductive structures.

14. The medical electrical lead of claim 13, wherein the discontinuous conductive fillers comprise at least the nano-sized non-metallic conductive structures, wherein the nano-sized non-metallic conductive structures are formed of carbon.

15. The medical electrical lead of claim 14, wherein the nano-sized non-metallic conductive structures comprise one or more of carbon nanofibers, carbon filaments, carbon nanotubes, and carbon nanoflakes.

16. The medical electrical lead of claim 13, wherein the discontinuous conductive fillers comprise at least the nano-sized non-metallic conductive structures, wherein the nano-sized non-metallic conductive structures each has an outer metal coating.

17. A medical electrical lead, comprising:

a conductor assembly having one or more conductors covered by an insulating layer; and

a shield covering adjacent or proximate to at least a portion of the insulating layer to shield the conductors from one or more electromagnetic fields, the shield covering formed of a non-metallic material that is electrically conductive, the material being in a wrapped or woven form and having one or more conductive members each having a higher skin depth than metal, the shield covering having an effective combination of small size and high surface area for sufficient conductivity in presence of one or more high frequency electromagnetic fields so that interference to the operation of the one or more conductors is minimized.

18. The medical electrical lead of claim 17, wherein the material comprises carbon.

19. The medical electrical lead of claim 18, wherein the carbon is formed of carbon fiber, the one or more conductive members of the carbon fiber comprising a bundled plurality of individual strands, wherein each of the individual strands has an outer diameter ranging in size from about 5 μ

m to about 12 μ

m.

20. The medical electrical lead of claim 18, wherein the carbon is formed of one or more of carbon nanofiber and carbon nanotube, wherein the one or more conductive members of the carbon nanofiber comprise a plurality of individual strands, and wherein each of the individual strands and the carbon nanotube have an outer diameter that is no greater than about 1 μ

m.

21. The medical electrical lead of claim 18, wherein the carbon has a shielding coverage percentage over the conductor assembly that is higher than that obtained with metal wire.

22. The metal electrical lead of claim 21, wherein the carbon is in the wrapped form, the non-metallic material extending across the conductor assembly via a plurality of turns, wherein consecutive turns are in contact with each other.

23. The medical electrical lead of claim 21, wherein the carbon is in the woven form, the non-metallic material extending across the conductor assembly via a plurality of overlapping turns.

24. The medical electrical lead of claim 17, further comprising a coating formed of one or more metals, the coating formed or attached around the material, the coating and the shield covering providing an enhanced shielding effect for the one or more conductors.

25. The medical electrical lead of claim 17, further comprising a coating formed of one or more metals, the coating positioned external to the shield covering, the coating and the shield covering providing an enhanced shielding effect for the one or more conductors.

26. The medical electrical lead of claim 17, further comprising one or more additional layers, the one or more additional layers comprising a braided metal sheath or mesh and an optional insulation layer, the one or more additional layers positioned either internal or external to the shield covering, the one or more additional layers and the shield covering providing an enhanced shielding effect for the one or more conductors.

27. The medical electrical lead of claim 17, further comprising a further layer formed of a polymer based composite material, the further layer positioned either internal or external to the shield covering, the further layer and the shield covering providing an enhanced shielding effect for the one or more conductors.

28. The medical electrical lead of claim 27, wherein the composite material is a composite with conductive properties provided by discontinuous conductive fillers, the fillers comprising one or more of nano-sized metal structures and nano-sized non-metallic conductive structures.

29. The medical electrical lead of claim 28, wherein the discontinuous conductive fillers comprise at least the nano-sized non-metallic conductive structures, wherein the nano-sized non-metallic conductive structures are formed of carbon.

30. The medical electrical lead of claim 29, wherein the nano-sized non-metallic conductive structures comprise one or more of carbon nanofibers, carbon filaments, carbon nanotubes, and carbon nanoflakes.

31. The medical electrical lead of claim 28, wherein the discontinuous conductive fillers comprise at least the nano-sized non-metallic conductive structures, wherein the nano-sized non-metallic conductive structures each has an outer metal coating.

32. An apparatus for alleviating the adverse effects of various health ailments of a patient comprising:

a medical device; and

an electrical lead connected to the medical device at a proximal end of the lead and having at least a distal end implanted within a patient'"'"'s body, the distal end of the electrical lead having one or more electrodes or electrical contacts for sensing and/or therapy delivery, the electrical lead comprising a conductor assembly having one or more conductors covered by an insulating layer and a shield covering adjacent or proximate to at least a portion of the insulating layer to shield the conductors from one or more electromagnetic fields, the shield covering formed of carbon, the carbon being in a wrapped or woven form, the carbon having an effective combination of small size and high surface area for sufficient conductivity in presence of one or more high frequency electromagnetic fields so that interference to the operation of the one or more conductors is minimized.

33. The apparatus of claim 32, wherein the carbon is formed of one or more of carbon fiber, carbon nanofiber, and carbon nanotube having one or more of single and multiple walls.

34. The apparatus of claim 32, wherein the carbon has one or more conductive members each having an outer diameter that is no greater than about 20 μ

m.

35. The apparatus of claim 32, wherein the carbon has a higher skin depth than metal.

36. The apparatus of claim 32, wherein the carbon has a coating formed of one or more metals, the coating formed or attached around the carbon, the coating and the shield covering providing an enhanced shielding effect for the one or more conductors.

37. The apparatus of claim 32, wherein the medical device is an implantable medical device, the device and the electrical lead being implanted within the patient.

38. The apparatus of claim 32, wherein the electrical lead further includes a lead extension electrically connecting the lead to the medical device, the shield covering positioned adjacent or proximate to at least a portion of the lead extension.