Cable configurations for a medical device

Patent metadata

Field	Value
Publication number	US-9409008-B2
Application number	US-201113092402-A
Country	US
Kind code	B2
Filing date	Apr 22, 2011
Priority date	Apr 22, 2011
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

Techniques are disclosed related to cables that may be used within a medical device. According to one example, a cable may comprise multiple wires. Each wire may be formed of a biocompatible beta titanium alloy having an elastic modulus ranging from 30 GigaPascals (GPa) to 90 GPa and comprising at least two elements selected from a group of titanium, molybdenum, niobium, tantalum, zirconium, chromium, iron and tin. The cable may be heated to a stress-relieve temperature of the beta titanium alloy to allow the cable to retain a desired configuration while remaining ductile. The cable may be included within a medical device, such as a medical electrical lead.

First claim

What is claimed is:

1. An implantable medical device (IMD), comprising:
multiple wires, each of the wires having an outer diameter of between 0.001 inches and 0.01 inches, and each being formed of a biocompatible beta titanium alloy having an elastic modulus ranging from 30 GigaPascals (GPa) to 90 GPa and comprising at least two elements selected from a group consisting of titanium, molybdenum, niobium, tantalum, zirconium, chromium, iron and tin, the wires being twisted together to form a cable and heated to a stress-relieve temperature of the beta titanium alloy so that stress within the beta titanium alloy presented by force used to twist the wires is removed; and
a structural body carrying the cable.

2. The IMD of claim 1 , wherein the cable is heated to between 600° C. and 650° C. for less than 10 seconds.

3. The IMD of claim 1 , wherein the cable is heated to between 500° C. and 650° C. for less than 20 seconds.

4. The IMD of claim 1 , wherein the cable has a lay of between 0.019 inches and 0.06 inches.

5. The IMD of claim 4 , wherein the cable includes at least three wires and has a lay of between 0.019 inches and 0.04 inches.

6. The IMD of claim 4 , wherein the cable comprises at least seven wires and has a lay of between 0.038 inches and 0.06 inches.

7. The IMD of claim 1 , further comprising an insulating layer surrounding the cable.

8. The IMD of claim 1 , wherein none of the wires lies substantially along a longitudinal axis of the cable.

9. The IMD of claim 1 , wherein the multiple wires are twisted together to form multiple cables.

10. The IMD of claim 9 , wherein the structural body carries multiple elements, each of the elements being electrically coupled to a different respective one of the multiple cables.

11. The IMD of claim 9 , wherein the structural body comprises multiple lumens, each of the multiple cables being positioned within a different respective one of the multiple lumens.

12. The IMD of claim 11 , wherein one of the multiple lumens carries a steering device.

13. The IMD of claim 9 , wherein the multiple wires are twisted together to form at least three cables, each comprising between three and five wires.

14. The IMD of claim 9 , wherein the multiple wires are twisted together to form eight cables, each comprising between three and five wires.

15. The IMD of claim 1 , wherein one or more of the multiple wires comprises a low-resistance core formed of a material have a resistivity of less than 25 micro-ohm-cm.

16. The IMD of claim 15 , wherein the core is formed of silver.

17. The IMD of claim 15 , wherein the core is formed of a material having a resistivity of between 10 and 20 micro-ohm-cm.

18. The IMB of claim 15 , further comprising an electrically-conductive element that is electrically coupled to the cable, wherein for each of the one or more of the multiple wires, a fraction of a cross-sectional area of the core to an outer diameter of the wire is selected so that a resistance of the cable matches a resistance of the electrically-conductive element.

19. The IMB of claim 15 , wherein a fraction of the cross-section area of the core of each of the one or more wires is selected so that a resistance of each of the one or more wires is between 3.5 ohms and 15 ohms per 4 inches of wire.

20. The IMD of claim 1 , wherein each of the wires has an outer diameter of between 0.0010 inches and 0.0025 inches.

21. The IMD of claim 1 , wherein all of the wires that are twisted together to form the cable are formed of the biocompatible beta titanium alloy having an elastic modulus ranging from 30 GPa to 90 GPa and comprising at least two elements selected from a group consisting of titanium, molybdenum, niobium, tantalum, zirconium, chromium, iron and tin.

22. The IMB of claim 1 , further comprising circuitry coupled to the structural body to generate electrical stimulation waveforms to be delivered to a patient.

23. A method, comprising:
twisting multiple wires together to form a cable, each of the wires having an outer diameter ranging between 0.001 inches and 0.01 inches and being formed of a biocompatible beta titanium alloy having an elastic modulus ranging from 30 GigaPascals (GPa) to 90 GPa and comprising at least two elements selected from a group of titanium, molybdenum, niobium, tantalum, zirconium, chromium, iron and tin;
heating the cable to a stress-relieve temperature of the beta titanium alloy so that stress within the beta titanium alloy presented by force used to twist the wires is removed; and
including the cable within a medical device.

24. The method of claim 23 , wherein heating the cable comprises heating the cable to between 500° C.-650° C. for less than 20 seconds.

25. The method of claim 23 , wherein heating the cable comprises heating the cable to between 600° C.-650° C. for less than 10 seconds.

26. The method of claim 23 , wherein twisting multiple wires comprises twisting multiple wires to a lay of between 0.019 inches and 0.06 inches.

27. The method of claim 23 , wherein twisting multiple wires comprises twisting three wires to a lay of between 0.019 inches and 0.04 inches.

28. The method of claim 23 , wherein twisting multiple wires comprises twisting at least seven wires to a lay of between 0.038 inches and 0.06 inches.

29. The method of claim 23 , further comprising forming an insulating layer surrounding the cable.

30. The method of claim 23 , wherein twisting multiple wires comprises twisting all wires such that none of the wires lies substantially along a longitudinal axis of the cable.

31. The method of claim 23 , wherein twisting multiple wires comprises twisting multiple wires to form multiple cables, and further comprising coupling each of the multiple cables to a different respective electrically-conductive element.

32. The method of claim 31 , further comprising providing a lead body that carries the electrically-conductive elements and the multiple cables.

33. The method of claim 31 , wherein twisting multiple wires comprises twisting multiple wires to form at least three cables, each comprising between three and five wires and further comprising positioning each of the cables in the medical device.

34. The method of claim 31 , wherein twisting multiple wires comprises twisting multiple wires to form at least eight cables, each comprising between three and five wires, and further comprising positioning each of the cables in the medical device.

35. The method of claim 23 , wherein one or more of the wires further comprises a low-resistance core formed of a material have a resistivity of less than 25 micro-ohm-cm.

36. The method of claim 35 , wherein a dimension of the core of the one or more of the wires is selected to tune a resistance of the cable.

37. The method of claim 23 , further comprising:
cold drawing each of the multiple wires to obtain a wire of a desired dimension; and
heating each of the multiple wires to a beta transit temperature of the beta titanium alloy.

38. The method of claim 37 , further comprising including a low-resistance core within each of the wires.

39. The method of claim 37 , further comprising repeating cold drawing each of the multiple wires

Assignees

• Li Bernard Q
• Wang Ling
• Medtronic Inc

Inventors

• Li Bernard Q
• Wang Ling

Classifications

• H01B7/048

  for implantation into a human or animal body, e.g. pacemaker leads · CPC title

• A61N1/0551

  Spinal or peripheral nerve electrodes · CPC title

• A61N1/05 Primary

  for implantation or insertion into the body, e.g. heart electrode (A61N1/06 takes precedence) · CPC title

• C22F1/183

  of titanium or alloys based thereon · CPC title

• A61N1/0529

  Electrodes for brain stimulation · CPC title