HEAT DISPERSION FOR IMPLANTABLE MEDICAL DEVICES

• US 20130197608A1
• Filed: 01/27/2012
• Published: 08/01/2013
• Est. Priority Date: 01/27/2012
• Status: Active Grant

• Current Assignee: Cirtec Medical Corp.
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: EIGER, Jay H.
• Granted Patent: US 9,981,137 B2
• Time in Patent Office: Days
• US Class Current: 607/61
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 1/3787 from an external energy source

Abstract

An implantable medical device that includes electrical circuitry for providing a therapy to a patient. The device also includes a housing forming an inner chamber that is adapted for receiving, at least a portion of the electrical circuitry. The device further includes a thermally conductive material that is configured to disperse heat from a first portion of the implantable medical device that is located in proximity to a heat generating component of the electrical circuitry, to a second portion of the implantable medical device that is not located in proximity to said heat generating component. The thermally conductive material is a discrete component separate from the electrical circuitry and the housing.

Claims

1. An implantable medical device, comprising:

electrical circuitry;

a housing forming an inner chamber that is adapted for receiving at least a portion of the electrical circuitry; and

a thermally conductive material that is specifically configured to disperse heat from a first portion of the implantable medical device that is located in proximity to a heat generating component of the electrical circuitry, to a second portion of the implantable medical device that is not located in proximity to said heat generating component, wherein the thermally conductive material is a discrete component or treatment separate from the electrical circuitry and the housing.

2. The implantable medical device of claim 1, wherein the thermally conductive material is a non-metallic material.

3. The implantable medical device of claim 1, wherein the thermally conductive material is at least one of:

located within the inner chamber of the housing between the housing and the heat generating component of the electrical circuitry,

located within a wall of the housing as an integrated housing component, or

located on the exterior of the housing as a coating between the housing and a tissue that surrounds the implantable medical device.

4. The implantable medical device of claim 3 wherein the thermally conductive material is located within the inner chamber and is disposed between the housing and the electrical circuitry, and wherein the thermally conductive material is comprised of a thermally conductive material sheet that is form fitted to, at least, a portion of the inner chamber.

5. The implantable medical device of claim 4, wherein the thermally conductive material sheet has an in plane thermal conductivity greater than 1000 W/m-K, an out of plane thermal conductivity less than 10 W/m-K, and a thickness between 1 micron and 2 mm.

6. The implantable medical device of claim 1, wherein the thermally conductive material comprises a highly ordered pyrolytic graphite with an in plane thermal conductivity of greater than 1000 W/mK and an out of plane thermal conductivity of less than 10 W/m-K.

7. The implantable medical device of claim 1, wherein the electrical circuitry further comprises:

a therapeutic electrical circuitry for providing electrical signals to a therapeutic electrical lead external to the housing;

a temperature sensor for determining a surface temperature of the housing; and

a recharging circuitry for recharging a power source that provides power to the therapeutic electrical circuitry, wherein the recharging circuitry includes an implant coil that is implanted in a patient for receiving an inductive power signal from an external charger.

8. The implantable medical device of claim 7,

wherein the inductive power signal from the external charger passes through, at least, a patient'"'"'s skin, the thermally conductive material, and the housing before reaching the implant coil, and

wherein the thermally conductive material and a material of the housing are selected to have low magnetism to allow the inductive power signal to pass through the housing and the thermally conductive material to the implant coil.

9. The implantable medical device of claim 8,

wherein the material of the housing and the thermally conductive material is further selected to be safely implanted in a human body, and

wherein the material of the housing is configured to include the inner chamber that is hermetically sealed.

10. The implantable medical device of claim 9,

wherein the thermally conductive material comprises a thermally conductive pyrolitic graphite sheet, and

wherein the thermally conductive pyrolitic graphite sheet is partially segmented to reduce eddy currents from the inductive power signal.

11. The implantable medical device of claim 10, wherein the therapeutic electrical lead is a neuro-stimulator lead and at least a portion of the electrical circuitry is a neuro-stimulator electrical circuitry.

12. The implantable medical device of claim 11, wherein a housing material comprises a titanium alloy with high electrical resistance, and wherein the titanium alloy is one or more of:

titanium grade 9 and titanium grade 23.

13. An implantable medical device comprising:

electrical circuitry;

a housing forming an inner chamber that is adapted for receiving at least a portion of the electrical circuitry; and

a sheet of highly ordered pyrolytic graphite disposed between said electrical circuitry and said housing.

14. The implantable medical device of claim 13, wherein said sheet of highly ordered pyrolytic graphite is adapted for conducting heat generated by said electrical circuitry for dispersing across a large portion of said housing.

15. An implantable medical device, comprising:

electrical circuitry adapted for providing a pulse stimulation therapy;

a plurality of electrodes electrically connected to said electrical circuitry and adapted to provide electrical pulses to a therapy region of a patient;

a housing forming an inner chamber that is adapted for receiving said electrical circuitry sealed therein; and

a sheet of highly ordered pyrolytic graphite disposed between said electrical circuitry and said housing and sealed within said housing that is configured to disperse heat from one or more heat generating components of the electrical circuitry to a portion of the housing that is not located in proximity to said one or more heat generating components.

16. A method for providing a therapy with an implantable medical device, comprising:

implanting the implantable medical device including an electrical componentry, wherein the electrical componentry is located inside a housing of the implantable medical device;

providing a therapeutic operation with the electrical componentry;

generating heat with the electrical componentry; and

dispersing said generated heat of the electrical componentry with a thermally conductive layer from a first portion of the housing that is located in proximity to said generating heat of the electrical componentry to a second portion of the housing that is not located in proximity to said generated heat of the electrical componentry.

17. The method for providing the therapy of claim 16,

wherein the thermally conductive layer is, one or more of:

located within the housing between the housing and said generated heat of the electrical componentry,

located within a wall of the housing as an integrated housing component, and

located on the exterior of the housing as a coating between the housing and a tissue that surrounds the implantable medical device.

18. The method for providing the therapy of claim 17,

dispersing heat generated by the electrical componentry with the thermally conductive layer, further comprises:

dispersing heat with a first plane thermal conductivity of greater than 1000 W/m-K; and

dispersing heat with a second plane thermal conductivity of less than 10 W/m-K.

19. The method for providing the therapy of claim 18,

wherein the thermally conductive layer comprises a thermally conductive pyrolytic graphite with an in plane thermal conductivity of greater than 1000 W/m-K and an out of plane thermal conductivity of less than 10 W/m-K.

20. The method for providing the therapy of claim 16,

wherein said generated heat of the electrical componentry is caused, at least in part, by recharging of an implant battery of the implantable medical device, wherein recharging of the implant battery comprises:

receiving an inductive power signal with an implant coil, wherein the inductive power signal is provided by an external coil of an external charger;

converting the inductive power signal with at least a portion of the electrical componentry to a charging current;

providing the charging current to the implant battery.

21. The method for providing the therapy of claim 16,

wherein providing a therapeutic operation

stimulating tissue of a patient with an implanted electrical lead connected to the electrical componentry;

reading electrical signals from tissue of a patient with an implanted electrical lead connected to the electrical componentry;

22. A method of transferring heat in an implantable medical device, comprising:

providing a therapeutic operation with the implantable medical device;

generating heat with a component of the implantable medical device; and

dispersing heat generated by the component with a thermally conductive material from a first portion of the implantable medical device that is located in proximity to said heat generating component to a second portion of the implantable medical device that is not located in proximity to said generated heat of the component.

23. The method of transferring heat in the implantable medical device of claim 22, further comprising:

dispersing said generated heat of the component with the thermally conductive material that is comprised of a thermally conductive pyrolytic graphite with an in plane thermal conductivity of greater than 1000 W/m-K and an out of plane thermal conductivity of less than 10 W/m-K.

24. The method of transferring heat in the implantable medical device of claim 23,

wherein said component is an electrical component,

wherein the implantable medical device includes a rechargeable battery,

wherein said generated heat of the electrical component is caused, at least in part, by recharging of the rechargeable battery through transdermal inductive charging.

25. The method of transferring heat in the implantable medical device of claim 24, further comprising:

providing an electrical therapeutic operation with the implantable medical device,

wherein providing said electrical therapeutic operation includes one or more of;

stimulating tissue of a patient with an implanted electrical lead connected to the electrical component; and

reading electrical signals from tissue of a patient with an implanted electrical lead connected to the electrical component.

26. A method of manufacturing an implantable medical device comprising:

providing a titanium alloy metal sheet;

heating the titanium alloy metal sheet to a superplastic forming temperature;

providing a die comprising a plurality of housing forming areas each corresponding to one of said housing portions;

forcing the heated titanium alloy metal sheet onto the die and over each one of the plurality of housing forming areas simultaneously, thereby superplastically forming a workpiece comprising a plurality of joined and simultaneously integrally formed implantable medical device housing portions;

separating the plurality of integrally formed implantable medical device housing portions into separate housing portions;

cutting a plurality of feed through holes into at least one of the housing portions and installing pulse generation circuitry therein, including aligning feed through pins with the plurality of feed through holes;

inserting a thermally conductive material sheet within an inner chamber between the at least one of the housing portions and an another housing portion from said or another workpiece, wherein the thermally conductive material sheet is disposed between an electrical circuitry in the inner chamber and a wall of the inner chamber; and

welding the at least one of the housing portions to the another housing portion.

27. An implantable medical device, comprising:

electrical circuitry;

a housing forming an inner chamber that is adapted for receiving at least a portion of the electrical circuitry; and

a thermally conductive material that is specifically configured to transfer heat from a location in proximity to a heat generating component of the electrical circuitry to another location of the implantable medical device that is not located in proximity to said heat generating component, wherein the thermally conductive material is comprised of a thermally conductive non-metallic material.

28. The device of claim 27, wherein said thermally conductive material is a coating provided on said housing.

29. The device of claim 27, wherein said thermally conductive material is a sheet of material provided within said inner chamber.

30. The device of claim 27, wherein said thermally conductive material is a material provided within said inner chamber and is provided in contact with said housing.