TANK FILTERS PLACED IN SERIES WITH THE LEAD WIRES OR CIRCUITS OF ACTIVE MEDICAL DEVICES TO ENHANCE MRI COMPATIBILITY

• US 20070112398A1
• Filed: 11/09/2006
• Published: 05/17/2007
• Est. Priority Date: 11/11/2005
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Stevenson, Robert, Frysz, Christine, Dabney, Warren
• Granted Patent: US 7,945,322 B2
• Time in Patent Office: Days
• US Class Current: 607/63
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• 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
• CPC Class Codes: A61N 1/3754 Feedthroughs
• CPC Class Codes: H01F 2017/065 Core mounted around conductor to absorb noise, e.g. EMI filter
• CPC Class Codes: H01G 4/35 Feed-through capacitors or anti-noise capacitors
• CPC Class Codes: H01G 4/40 Structural combinations of fixed capacitors with other electric elements, the structure mainly consisting of a capacitor, e.g. RC combinations
• CPC Class Codes: H03H 1/0007 of radio frequency interference filters
• CPC Class Codes: H03H 2001/0042 Wound, ring or feed-through type capacitor
• CPC Class Codes: H03H 7/1766 Parallel LC in series path H03H7/1783 takes precedence
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49004 including measuring or testing of device or component part

Abstract

A TANK filter is provided for a lead wire of an active medical device (AMD). The TANK filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the lead wire of the AMD, wherein values of capacitance and inductance are selected such that the TANK filter is resonant at a selected frequency. The Q of the inductor may be relatively maximized and the Q of the capacitor may be relatively minimized to reduce the overall Q of the TANK filter to attenuate current flow through the lead wire along a range of selected frequencies. In a preferred form, the TANK filter is integrated into a TIP and/or RING electrode for an active implantable medical device.

Claims

1. A medical therapeutic device, comprising:

a tank filter according to the processes and apparatuses set forth above.

2. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry;

a tank filter placed in series with the conductor and having electrical inductance in parallel with capacitance, whereby the tank filter attenuates current flow at a selected frequency band; and

an RFID chip associated with the active medical device or the electrical conductor or the electrode for identifying the presence of the tank filter in the active medical device or the electrical conductor or the electrode.

3. The device of claim 2, wherein the RFID chip is incorporated into the active medical device having the tank filter associated therewith.

4. The device of claim 2, wherein the conductor comprises a lead wire, and wherein the RFID chip is incorporated into the lead wire.

5. The device of claim 2, wherein the RFID chip is implanted into a patient operably connected to the active medical device or a lead wire system thereof that includes the tank filter.

6. The device of claim 2, wherein the RFID tag identifies the selected frequency band.

7. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, a plurality of electrodes, and a plurality of electrical conductors for connecting each electrode to the electronic circuitry; and

a tank filter placed in series with each conductor, the tank filter having electrical inductance in parallel with capacitance, whereby the tank filter attenuates current flow at a selected frequency band.

8. The device of claim 7, wherein each electrical conductor includes a plurality of tank filters, each tank filter configured to attenuate current flow at a different selected frequency band.

9. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry; and

a plurality of tank filters placed in series with the conductor, each tank filter having electrical inductance in parallel with capacitance, wherein each tank filter attenuates current flow at a different selected frequency band.

10. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and a lead wire for connecting the electrode to the electronic circuitry; and

a tank filter having electrical inductance in parallel with capacitance for attenuating current flow at a selected frequency band;

wherein the tank filter comprises a tubular capacitor electrically connected to the electrode and the lead wire, and an inductor in parallel with the capacitor and electrically connected to the lead wire and the electrode.

11. The device of claim 10, wherein the inductor is disposed within the capacitor.

12. The device of claim 11, wherein the inductor comprises a spiral wound inductor or a chip inductor.

13. The device of claim 10, wherein the tubular capacitor includes a first metallization electrically connected to the lead wire, and a second metallization electrically connected to the electrode.

14. The device of claim 13, wherein the capacitor includes a first set of electrode plates electrically connected to the first metallization, and a second set of electrode plates electrically connected to the second metallization.

15. The device of claim 10, wherein the electrode comprises a high surface area distal TIP electrode.

16. The device of claim 10, wherein the electrode comprises an active fixation helix TIP electrode.

18. The device of claim 10, wherein the tubular capacitor comprises a monolithic discoidal feedthrough capacitor including a first set of electrode plates electrically connected to a first metallization, and a second set of electrode plates electrically connected to a second metallization, the first metallization electrically connected to the first segment of the conductor, and the second metallization electrically connected to the second segment of the conductor.

17. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and a conductor for connecting the electrode to the electronic circuitry; and

a tank filter having electrical inductance in parallel with capacitance for attenuating current flow at a selected frequency band;

wherein the conductor comprises a first segment extending from the active medical device to the tank filter, and a second segment extending from the tank filter to the electrode; and

wherein the tank filter comprises a tubular capacitor electrically connected to the first and second segments of the conductor, and an inductor in parallel with the capacitor and electrically connected to the first and second segments of the conductor.

19. The device of claim 17, wherein the inductor is disposed within the capacitor and extends between the first and second segments of the conductor.

20. The device of claim 19, wherein the inductor comprises a spiral wound inductor or a chip inductor.

21. The device of claim 17, wherein the electrode comprises an active fixation distal TIP including a helix coil selectively rotatably removed from a housing.

22. A medical therapeutic device, comprising:

an active medical device comprising a bion and including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with each conductor between the electronic circuitry and the electrode, the tank filter having electrical inductance in parallel with capacitance, whereby the tank filter attenuates current flow at a selected frequency band.

23. The device of claim 22, wherein the tank filter is disposed adjacent to the electrode.

24. The device of claim 22, wherein the bion active medical device includes multiple electrodes, and wherein a distinct tank filter is placed in series with the conductor and each electrode.

25. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry;

a tank filter placed in series with the conductor and having electrical inductance in parallel with capacitance, whereby the tank filter attenuates current flow at a selected frequency band;

wherein the tank filter comprises a circuit trace disposed on a capacitor or a substrate attached to the capacitor so as to be in parallel therewith.

26. The device of claim 25, wherein the circuit trace extends between wire bond pads electrically connected to the conductor.

27. The device of claim 25, wherein the circuit trace includes multiple turns over the length thereof.

28. A process for testing a tank filter placed in series with a conductor of an active medical device for therapy delivery or detection of biological signals, comprising the steps of:

disposing a meander circuit trace onto a capacitor;

forming a gap between an end of the circuit trace and a wire bond pad of the capacitor;

testing the capacitor; and

filling the gap with conductive material.

29. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with the conductor and having electrical inductance in parallel with capacitance, whereby the tank filter attenuates current flow at a selected frequency band;

wherein the tank filter comprises;

a tubular capacitor electrically connected to the conductor and the electrode;

an inductor electrically connected to the conductor and the electrode, the inductor comprising a spiral winding around a ferro-magnetic core disposed within the capacitor; and

a sleeve disposed over the inductor for creating a ferro-magnetic field to reduce or prevent saturation of inductor in presence of a static magnetic field.

30. The device of claim 29, wherein the sleeve is comprised of nickel.

31. The device of claim 29, wherein the capacitor is attached to a TIP electrode at one end and a cap at an opposite end to create a hermetic housing encasing the inductor and sleeve.

32. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with the conductor and having electrical inductance in parallel with capacitance, whereby the tank filter attenuates current flow at a selected frequency band;

wherein the tank filter comprises a capacitor having an inductor trace embedded therein so as to be in parallel with the capacitor.

33. The device of claim 32, wherein the capacitor comprises a multi-layer tubular or chip capacitor.

34. The device of claim 33, including first and second electrode plates, the inductor trace being embedded above or below the electrode plates.

35. The device of claim 32, wherein the inductor trace is disposed on a substrate embedded within the capacitor.

36. The device of claim 32, wherein the inductor trace includes multiple turns along a length thereof.

37. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with the conductor and having electrical inductance in parallel with capacitance, whereby the tank filter attenuates current flow at a selected frequency band;

wherein the tank filter comprises;

a capacitor; and

a substrate including an inductor trace attached to the capacitor.

38. The device of claim 37, wherein the inductor trace is disposed on a surface of the substrate.

39. The device of claim 38, wherein a second inductor trace is disposed on a generally opposite surface of the substrate.

40. The device of claim 37, wherein the inductor trace is embedded within the substrate.

41. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and a coiled lead wire for connecting the electrode to the electronic circuitry; and

a chip capacitor having wire bond pads disposed within the coiled lead wire, the coiled lead wire being electrically connected to the wire bond pads to form a tank filter having electrical inductance in parallel with capacitance, whereby the tank filter attenuates current flow at a selected frequency band.

42. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with the conductor and having an inductor in parallel with a capacitor, wherein values of capacitance and inductance are selected such that the tank filter attenuates current flow at a selected frequency band;

wherein the Q of the capacitor is relatively minimized by raising equivalent series resistance of the capacitor by any one of the following;

reducing thickness of electrode plates in the capacitor;

using high resistivity capacitor electrode materials;

adding dielectric powders to electrode ink;

providing apertures, gaps, slits or spokes in the electrode plates of the capacitor;

providing separate discrete resistors in series with the capacitor;

utilizing resistive electrical attachment materials to the capacitor;

utilizing capacitor dielectric materials that have high dielectric loss tangents at the selected frequency band;

or

providing capacitor electrode plates having a relative greater length than a width.

43. The device of claim 42, wherein the Q of the inductor is relatively maximized and the Q of the capacitor is relatively minimized to reduce the overall Q of the tank filter to attenuate current flow through the conductor along a range of selected frequencies.

44. The device of claim 43, wherein the range of selected frequencies includes a plurality of MRI pulsed frequencies.

46. The device of claim 44, wherein the capacitor comprises a chip capacitor.

47. The device of claim 44, wherein the first set of electrode plates extend to a plurality of first surface metallizations, and the second set of electrode plates extend to a plurality of second surface metallizations, and wherein a plurality of inductors are each electrically connected to distinct first and second metallizations.

49. The process of claim 47, wherein the physically modifying step comprises the step of removing or shorting at least a portion of the inductor.

50. The process of claim 49, wherein the inductor comprises a circuit trace having multiple turns, and wherein the physically modifying step comprises the step of electrically interconnecting at least one gap between a turn of the circuit trace.

51. The process of claim 49, wherein the inductor comprises a circuit trace having multiple turns interconnected with electrically conductive material, and wherein the physically modifying step comprises the step of removing the electrically conductive material between at least one turn of the circuit trace.

52. The process of claim 47, wherein the trimming step comprises the step of removing at least a portion of electrode plates of the capacitor.

53. The process of claim 47, wherein the trimming step is performed utilizing an abrasive microblaster or a laser.

45. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with the conductor and having an inductor in parallel with a capacitor, wherein values of capacitance and inductance are selected such that the tank filter attenuates current flow at a selected frequency band;

wherein the capacitor includes a first set of embedded electrode plates extending to a first surface metallization, and a second set of embedded electrode plates extending to a second surface metallization; and

wherein the inductor is electrically connected to the first and second surface metallizations.

48. A process for tuning a tank filter, comprising the steps of:

providing a tank filter having an inductor in parallel with a capacitor;

measuring frequency attenuation of the tank filter; and

physically modifying the tank filter until the measured frequency of the tank filter falls within a predetermined frequency band.

54. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with the conductor and having an inductor in parallel with a capacitor, wherein values of capacitance and inductance are selected such that the tank filter attenuates current flow at a selected frequency band;

wherein the tank filter is hermetically sealed from body fluids.

55. The device of claim 54, wherein the tank filter is encapsulated in a hermetically sealing material.

56. The device of claim 55, wherein the hermetically sealing material comprises glass.

57. The device of claim 54, wherein the tank filter is disposed within a hermetically sealed housing.

58. The device of claim 57, wherein the tank filter comprises a capacitor having an inductor circuit trace disposed on a surface thereof or embedded therein.

59. The device of claim 58, wherein the capacitor comprises a feedthrough capacitor, a tubular capacitor, or a chip capacitor.

60. The device of claim 57, wherein the housing comprises a conductive end cap electrically interconnected to the conductor of the active medical device and the tank filter.

61. The device of claim 58, wherein the housing further comprises an electrode tip generally opposite the conductive end cap and electrically connected to the tank filter.

62. The device of claim 61, wherein the housing comprises walls extending from the end cap to the electrode and hermetically sealed thereto.

63. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical lead wire for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with the conductor and having an inductor in parallel with a capacitor, wherein values of capacitance and inductance are selected such that the tank filter attenuates current flow at a selected frequency band;

wherein the tank filter comprises a feedthrough capacitor having an inductor circuit trace disposed thereon or embedded therein;

wherein the lead wire is electrically connected to a contact plate electrically connected to an inner metallization of the capacitor; and

wherein the electrode is electrically connected to an outer metallization of the capacitor.

64. A process for manufacturing a tank filter and electrode combination, the process comprising the steps of:

providing an electrode;

creating a stacked inductor, layer by layer, by placing one or more insulative layers on a surface of the electrode, each having an inductor circuit trace deposited on a surface thereof;

placing an insulative layer over the uppermost inductor circuit trace of the stacked inductor;

creating a stacked capacitor by placing, layer by layer, first and second capacitor electrodes, separated by insulative layers, the stacked capacitor being stacked, layer by layer, onto the stacked inductor.

65. The process of claim 64, wherein the layers of insulative material, inductor circuit traces, and capacitor electrodes are placed by a thick film deposition process.

66. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an active fixation distal TIP electrode, and an electrical lead wire for connecting the electrode to the electronic circuitry, wherein the active fixation distal TIP electrode includes a spline electrically connected to the lead wire and extending within a housing having a coiled helix TIP therein; and

a tank filter disposed in the housing and electrical connected to the spline and the coiled helix, the tank filter having an inductor in parallel with a capacitor, wherein values of capacitance and inductance are selected such that the tank filter attenuates current flow at a selected frequency band.

67. The device of claim 66, wherein an end of the spline is configured to at least partially surround the tank filter.

68. The device of claim 67, wherein the end of the spline is configured as a hollow cylinder, the tank filter being disposed therein.

69. The device of claim 68, wherein the tank filter includes a first metallization electrically connected to the spline, and a second metallization electrically connected to the coiled helix electrode.

70. The device of claim 68, wherein the tank filter is hermetically sealed within the end of the spline.

71. The device of claim 70, including a hermetic terminal assembly connected to a free end of the spline and disposed between the tank filter and the helix coil electrode.

72. The device of claim 71, wherein the hermetic terminal assembly comprises a ferrule attached to the cylinder end of the spline, a post extending between the tank filter and the helix coil electrode, and an insulator disposed between the ferrule and the post.

73. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with the conductor and having an inductor in parallel with a capacitor, wherein values of capacitance and inductance are selected such that the tank filter attenuates current flow at a selected frequency band;

wherein the inductor comprises a set of substrates in stacked relation, at least a plurality of the substrates having inductor traces on a surface thereof; and

wherein the inductor traces are electrically interconnected with one another.

74. The device of claim 73, wherein the inductor traces comprise spiral traces having a central end and an outer free end.

75. The device of claim 74, wherein the spiral trace is configured such so as to create parasitic capacitance between turns of the spiral trace.

76. The device of claim 74, wherein an aperture is formed through either the central or free end of a first inductor trace and underlying substrate so as to be aligned with a corresponding central or free end of an underlying circuit trace, the aperture being filled with conductive material so as to electrically connect the inductor circuit traces.

77. The device of claim 76, wherein at least one of the inductor circuit traces extends to an outer surface metallization of the inductor.

78. The device of claim 73, wherein the substrates are comprised of a low K ceramic material.

79. The device of claim 78, wherein the substrates are comprised of an alumina ceramic material having a K of between 60 and 90.

81. The device of claim 73, wherein the inductor traces comprise spiral traces having a central end and an outer free end, an aperture formed through either the central or free end of a first inductor trace and underlying substrate so as to be aligned with a corresponding central or free end of an underlying circuit trace, the aperture being filled with conductive material so as to electrically connect the inductor circuit traces.

82. The device of claim 81, wherein the spiral trace is configured such so as to create parasitic capacitance between turns of the spiral trace.

80. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical conductor for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with the conductor and having inductance in parallel with capacitance, wherein values of capacitance and inductance are selected such that the tank filter attenuates current flow at a selected frequency band;

wherein the tank filter is comprised of a set of stacked layers forming a unified structure;

wherein at least a plurality of the layers comprise insulative substrates having inductor traces on a surface thereof;

wherein the inductor traces are electrically interconnected with one another; and

wherein at least a plurality of the layers comprise electrode plates.

83. The device of claim 80, wherein at least one of the inductor circuit traces extends to an outer surface metallization of the inductor.

84. The device of claim 80, wherein the electrode plates comprise active and ground electrode plates.

85. The device of claim 80, wherein the substrates are comprised of a low K ceramic material.

86. The device of claim 85, wherein the substrates are comprised of an alumina ceramic material having a K of between 60 and 90.

87. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, a plurality of electrodes, and an electrical conductor for connecting the electrodes to the electronic circuitry; and

a plurality of tank filters placed in series with the conductor, a distinct tank filter associated with each electrode, each tank filter having inductance in parallel with capacitance, wherein values of capacitance and inductance are selected such that the tank filters attenuate current flow at a selected frequency band.

88. The device of claim 87, wherein the active medical device comprises a neurostimulation TIP, an ablation probe, or a catheter.

89. The device of claim 87, wherein each tank filter is configured to attenuate current flow at a different frequency band.

90. A medical therapeutic device, comprising:

an active medical device including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical lead wire for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with the lead wire within or adjacent to a header of the active medical device defining a lead wire ingress/egress, the tank filter having inductance in parallel with capacitance, wherein values of capacitance and inductance are selected such that the tank filter attenuates current flow at a selected frequency band.

91. The device of claim 90, wherein the tank filter is placed in series within the lead wire adjacent to the header of the active medical device.

92. The device of claim 90, wherein the header comprises a ferrule attached to a housing of the active medical device, a feedthrough capacitor disposed within the ferrule, a lead wire pin having first and second segments at least partially extending through the feedthrough capacitor, and an insulator disposed between the ferrule and at least a portion of the lead wire pin segments, and wherein the tank filter is disposed in series between the lead wire pin first and second segments.

93. A medical therapeutic device, comprising:

an active medical device comprising and EKG or EEG device and including electronic circuitry for therapy delivery or detection of biological signals, an electrode, and an electrical lead for connecting the electrode to the electronic circuitry; and

a tank filter placed in series with the electrical lead between the electronic circuitry and electrode of the active medical device, the tank filter having inductance in parallel with capacitance, wherein values of capacitance and inductance are selected such that the tank filter attenuates current flow at a selected frequency band.