Implantable medical device with fractal antenna

• US 20070100385A1
• Filed: 10/28/2005
• Published: 05/03/2007
• Est. Priority Date: 10/28/2005
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Rawat, Prashant, Von Arx, Jeffrey
• Granted Patent: US 8,369,950 B2
• Time in Patent Office: Days
• US Class Current: 607/37
• CPC Class Codes: A61N 1/37229 Shape or location of the implanted or external antenna
• CPC Class Codes: A61N 1/375 Constructional arrangements, e.g. casings
• CPC Class Codes: A61N 1/37512 Pacemakers
• CPC Class Codes: A61N 1/37516 Intravascular implants
• CPC Class Codes: A61N 1/37518 Anchoring of the implants, e.g. fixation
• CPC Class Codes: H01Q 1/36 Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewithH01Q1/08, H01Q1/14 take precedence

Abstract

An apparatus and method for enabling an implanted fractal antenna for radio frequency communications between an implantable medical device and an external device. The fractal antenna may be disposed within or outside of a header assembly of the device housing. Various examples include a three dimensional patterned cylinder usable as a tissue anchor or stent. In another embodiment the antenna may be cast, molded, stamped, punched, milled, laser cut, etched or other methods to form a fractal pattern in conductive media. In another embodiment the antenna may be formed of a printed circuit board (PCB) either with or without an included ground reference plane. In another embodiment the antenna may be formed in a fractal pattern and then wrapped around a part of the implantable device.

Claims

1. A device, comprising:

a header coupled to an implantable housing, the housing having an electronic circuit configured to communicate via a modulated radio frequency carrier;

an antenna, at least a portion of the antenna disposed within, on, or adjacent the header and coupled to the electronic circuit; and

the antenna including at least one conductive segment forming at least one selected fractal pattern.

2. The device of claim 1, wherein the antenna is disposed within the header.

3. The device of claim 1, wherein the antenna is disposed on a surface of the header.

4. The device of claim 3, wherein the antenna is disposed within a groove formed on the surface of the header.

5. The device of claim 3, wherein the antenna is covered with a dielectric material having a selected dielectric constant.

6. The device of claim 3, wherein the antenna has a shape that is conformal to a portion of the surface of at least one of the header and the implantable housing.

7. The device of claim 6, wherein the antenna is disposed at a fixed distance away from at least one of the header and the implantable housing.

8. The device of claim 1, wherein the antenna is disposed at a fixed distance away from the header and the implantable housing.

9. The device of claim 8, wherein the antenna is disposed on a printed circuit board.

10. The device of claim 9, wherein the printed circuit board is covered with a bio-compatible coating selected from the list including polytetafluoroethylene (PTFE), expanded polytetafluoroethylene (ETFE), polyetheretherketone (PEEK), parylene, silicone, polyurethane, aromatic polyether thermoplastics and glass.

11. The device of claim 1, wherein the antenna includes a bent conductive wire.

12. The device of claim 11, wherein the wire is formed of a bio-compatible material selected from the list including platinum (Pt), iridium (Ir), osmium (Os), rhodium (Rh), niobium (Nb), gold (Au), silver (Ag), stainless steel and combinations thereof.

13. The device of claim 11, wherein the wire has a circular cross section.

14. The device of claim 1, wherein the antenna is formed of a sheet of conductive material stamped into the selected fractal pattern.

15. The device of claim 14, wherein the stamped pattern is one of folded, bent, formed, and combinations thereof into a three dimensional form.

16. The device of claim 1, wherein the antenna is formed of a sheet of conductive material that is at least one of sculpted, bent, hammered, heat treated, laser formed, stamped, punched, etched and combinations thereof into the selected fractal pattern.

17. The device of claim 1, wherein the antenna is formed of a conductive material that is at least one of twisted, folded, molded, cast, milled, cut, sawed, wire EDM, plunger EDM and combinations thereof into the selected fractal pattern.

18. The device of claim 1, wherein the antenna is formed of a patterned metal foil on a glass substrate patterned by photolithography and etching, wherein the metal is selected from a list including titanium (Ti), platinum (Pt), iridium (Ir), osmium (Os), rhodium (Rh), niobium (Nb), gold (Au), silver (Ag), stainless steel and combinations thereof.

19. The device of claim 1, wherein the antenna is formed of a three dimensional structure substantially wrapped around at least one of the implantable housing and the header.

20. An implantable medical device, comprising:

a programmable electronic circuit configurable to perform as at least one of a cardiac pacemaker, a cardioverter, and a defibrillator, disposed in an implantable housing with a plurality of hermetic electrical feed throughs to a header;

the housing having an electronic circuit configured to perform two way communication via a modulated radio frequency carrier with an external device capable of at least one of programming the implantable medical device, downloading history data logs from the implantable medical device, and recording and analyzing real time data from the implantable medical device; and

an antenna coupled to the electronic circuit including at least one conductive segment forming a fractal pattern.

21. The device of claim 20, wherein the far field distribution varies by less than 6 db in at least one plane from a minimum to a maximum field strength at a preselected radius from the antenna.

22. The device of claim 20, wherein the antenna has at least two resonant frequencies.

23. The device of claim 20, wherein the antenna has a broadband response and the electronic circuit in two way communication via the modulated radio frequency carrier does not include an adjustable tuning circuit.

24. A method, comprising:

providing a non-conductive header assembly adapted to provide electrical connections to a conductive walled implantable medical device housing through hermetic electronic feed throughs and adapted to provide communication with an external system via a modulated radio frequency carrier signal; and

connecting an antenna to the modulated radio frequency carrier signal, wherein the antenna has a fractal pattern of conductive lines.

25. The method of claim 24, wherein providing the header assembly includes forming a cavity to receive the antenna inside the header assembly.

26. The method of claim 24, wherein providing the header assembly includes forming a recess to receive the antenna on a surface of the header.

27. The method of claim 24, wherein providing the header assembly includes forming the antenna of an insulated conductor on an outside surface of the conductive walled housing.

28. The method of claim 27, wherein the conductive walled housing acts as a ground plane for the antenna to radiate against.

29. The method of claim 27, wherein the insulated conductor has a selected dielectric constant.

30. The method of claim 27, wherein forming the antenna includes forming a three dimensional structure wrapped around at least one of the conductive walled housing and the header.

31. The method of claim 24, wherein forming the antenna includes at least one of a wire, a strip line, a transmission line, a stamped patterned sheet of conductive material, a twisted wire, a bent wire, a sculpted conductor, an etched sheet of conductive material, an etched layer of conductive material deposited on a layer of glass, a bio-compatible coated printed circuit board, and combinations thereof.

32. The method of claim 24, wherein the modulated radio frequency carrier signal has at least two resonant bands, including the ranges of 400-450 Mhz and 863-928 Mhz.

33. The method of claim 32, wherein providing the modulated radio frequency carrier signal at a plurality of frequency bands further includes providing a single antenna and a single impedance matching circuit.

34. The method of claim 24, wherein providing the modulated radio frequency carrier signal at a plurality of frequency bands further includes a plurality of distinct feed points to the single antenna, with each distinct feed point resulting in a different operating frequency band.

35. The method of claim 24, wherein providing communication with an external system includes providing a fractal antenna connected to the external system.

36. The method of claim 35, wherein the external system provides at least one of programming the implantable medical device, downloading history data logs, recording and analyzing real time data from the implantable medical device, and externally controlling the implantable medical device in response to physician direction.

37. A method of using a fractal antenna to communicate between an implantable medical device and an external device, comprising:

disposing a first radio transceiver in a portion of the implantable medical device, the first radio transceiver having a circuit enabled to transmit and receive at least at one of a first radio frequency and a second radio frequency;

connecting the first radio transceiver to a first antenna having at least a portion formed in a fractal pattern, and disposed within, on, adjacent to, or distant from the implantable medical device;

transmitting information from the implantable medical device via modulation of either the first or second radio frequency to a second antenna connected to a second radio transceiver connected to the external device; and

receiving information from the external device via detecting modulation of either the first or second radio frequency from the antenna connected to the external device.

38. The method of claim 37, wherein transmitting information from the first antenna has at least two selectable feed line connections from the first radio transceiver, wherein selecting one of the feed lines connections results in a different one of the at least first radio frequency and second radio frequency.

39. The method of claim 38, wherein selecting one individual one of the feed lines is performed by a radio frequency switch, resulting in a radio frequency corresponding to an allowable radio frequency band in a selected geographical region.

40. The method of claim 38, wherein transmitting information from the first antenna includes impedance matching the radio frequency circuitry of the first transceiver to the first antenna without using a dynamically adjustable matching circuit.

41. The method of claim 40, wherein the second antenna has at least a portion formed in a fractal pattern.

42. A device, comprising:

an antenna having at least a portion of the antenna shape in the form of a fractal pattern for communicating between a first electrical device implanted inside a body and a second device that is external to the body.

43. The device of claim 42, wherein the antenna is implanted inside the body and coupled to the first electrical device via a non-conductive radome.

44. The device of claim 43, wherein the antenna uses the surface of the first electrical device as a ground reference plane.

45. The device of claim 43, wherein the radome is formed of a plastic having a selected dielectric constant.

46. The device of claim 45, wherein the radome is formed of tecothane®

.

47. The device of claim 43, wherein the radome is located on a surface of the electrical device at a point opposite to an electrical connection header location.

48. A device, comprising:

an implantable housing including an electronic circuit configured to communicate via a modulated radio frequency carrier;

at least one header coupled to the housing including a plurality of electrical signal feed throughs;

at least one radome coupled to the housing including at least one antenna feed through; and

the at least one antenna including at least one conductive segment forming a fractal pattern.

49. The device of claim 48, wherein the at least one radome is located at a location on the housing that is at least 90 degrees away from the at least one header.

50. The device of claim 48, wherein the at least one radome is located opposite the at least one header.

51. The device of claim 48, wherein the at least one radome is formed of a plastic material having a dielectric constant of from 4.0 to 7.0.

52. The device of claim 48, wherein the at least one radome is formed of tecothane®

.