High-energy capacitors for implantable defibrillators

• US 7,558,051 B2
• Filed: 03/24/2006
• Issued: 07/07/2009
• Est. Priority Date: 10/02/1998
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Poplett, James M., Tong, Robert R., Christenson, Luke J., O'Phelan, Michael J.
• Primary Examiner(s): Ha; Nguyen T
• Application Number:
  US11/277,399
• Publication Number:
  US 20060256505A1
• Time in Patent Office: 1,201 Days
• Field of Search: 361/508, 361509-512, 361516-519, 361523-525, 361528-540, 29/250.1, 29/250.3
• US Class Current: 361/508
• CPC Class Codes: A61N 1/3782 producing a voltage above the power source level
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
• CPC Class Codes: H01G 9/045 based on aluminium
• CPC Class Codes: H01G 9/055 Etched foil electrodes
• CPC Class Codes: Y10T 428/12431 Foil or filament smaller than 6 mils

Abstract

Implantable defibrillators are implanted into the chests of patients prone to suffering ventricular fibrillation, a potentially fatal heart condition. A critical component in these devices is an aluminum electrolytic capacitor, which stores and delivers life-saving bursts of electric charge to a fibrillating heart. To reduce capacitor size, manufacturers have developed special aluminum foils, such as core-etched and tunnel-etched aluminum foils. Unfortunately, core-etched foils don'"'"'t work well in multiple-anode capacitors, and tunnel-etched foils are brittle and tend to break when making some common types of capacitors. Accordingly, the inventors devised a new foil structure having perforations and cavities. In an exemplary embodiment, each perforation and cavity has a cross-sectional area, with the perforations having a larger, for example, 2 to 100 times larger, average cross-sectional area than the cavities. Other embodiments of the invention include foil assemblies, capacitors, and implantable defibrillators that benefit from properties of the new foil structure.

Claims

1. A capacitor comprising a foil having a foil thickness;

means, including at least eight perforations, for allowing passage of an electrolyte; and

one or more cavities having a depth less than the foil thickness.

2. The capacitor of claim 1, wherein the foil has first and second opposing sides, with one or more of the cavities on the first side and one or more of the cavities on the second side and wherein the average depth of the cavities is less than one-half the foil thickness.

3. The capacitor of claim 2, wherein the average depth of the cavities is about one-third or one-fourth of the foil thickness.

4. The capacitor of claim 1, wherein the perforations have an average cross-sectional area larger than an average cross-sectional area of the cavities.

5. The capacitor of claim 1, wherein each perforation has a generally circular shape.

6. The capacitor of claim 1, wherein the foil comprises at least one of aluminum, tantalum, hafnium, niobium, titanium, and zirconium.

7. The capacitor of claim 1, wherein at least a portion of the foil is rolled.

8. A capacitor comprising:

a foil having first and second opposing surfaces which define a foil thickness, with the first opposing surface having one or more cavities each having a maximum depth less than the foil thickness and the second opposing surface having one or more cavities each having a maximum depth less than the foil thickness; and

means, including at least six perforations, for allowing passage of electrolyte through the foil.

9. The capacitor of claim 8:

wherein the cavities of the first surface have a first average depth and the cavities of the second surface have a second average depth, with the first and second average depths being less than one-half the foil thickness;

or

wherein the perforations have an average cross-sectional area at least twice an average maximum cross-sectional area of the cavities;

or

wherein at least a portion of the foil is rolled.

10. The capacitor of claim 8, wherein the foil comprises at least one of aluminum, and titanium.

11. The capacitor of claim 8, wherein each perforation has a generally circular shape.

12. An aluminum electrolytic capacitor comprising:

at least one aluminum anode foil having first and second opposing surfaces which define a foil thickness, with the first opposing surface having one or more cavities and the second opposing surface having one or more cavities, the cavities of the first and second surfaces having an average maximum depth less than one half the foil thickness and having an average maximum cross-sectional area; and

means, including at least six perforations, for allowing passage of electrolyte through the aluminum anode foil, with the perforations having an average maximum cross-sectional area at least twice the average maximum cross-sectional area of the cavities.

13. The aluminum electrolytic capacitor of claim 12:

wherein the average depth of the cavities is about one-third or one-fourth the foil thickness;

or

wherein the perforations have an average maximum cross-sectional area about 2 to 100 times larger than the average maximum cross-sectional area of the cavities.

14. The capacitor of claim 13, wherein the foil comprises titanium.

15. The capacitor of claim 13, wherein each perforation has a generally circular shape.

16. A capacitor comprising:

at least one perforated-core-etched foil;

or

at least one perforated-core-etched foil adjacent at least one core-etched foil;

or

at least one perforated-core-etched foil, at least one core-etched foil, and at least one tunnel-etched foil;

wherein each perforated core-etched foil comprises;

first and second opposing surfaces which define a foil thickness, with the first opposing surface having one or more cavities each having a maximum depth less than the foil thickness and the second opposing surface having one or more cavities each having a maximum depth less than the foil thickness; and

means, including at least six perforations, for allowing passage of electrolyte through the foil.

17. The capacitor of claim 16 wherein the cavities of the first surface have a first average depth and the cavities of the second surface have a second average depth, with the first and second average depths being less than one-half the foil thickness.

18. The capacitor of claim 16, wherein the foil comprises titanium.

19. The capacitor of claim 16, wherein each perforation has a generally circular shape.