LOADED RF ANTENNA FOR IMPLANTABLE DEVICE

• US 20090228075A1
• Filed: 03/03/2009
• Published: 09/10/2009
• Est. Priority Date: 03/04/2008
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Dion, Philip G.
• Granted Patent: US 8,588,924 B2
• Time in Patent Office: Days
• US Class Current: 607/60
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61N 1/37229 Shape or location of the implanted or external antenna
• CPC Class Codes: G08C 17/04 using magnetically coupled devices
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 1/40 Radiating elements coated with or embedded in protective material
• CPC Class Codes: H01Q 5/321 within a radiating element or between connected radiating elements

Abstract

This document discusses, among other things, a system and method for wirelessly transferring information electromagnetically at a first specified operating frequency range and at a second specified operating frequency range using an implantable antenna. In certain examples, the implantable antenna can include a first non-coiled segment and a first coiled segment, and the first specified operating frequency range and the second specified operating frequency range can be provided at least in part by a physical arrangement of the first coiled segment with respect to the first non-coiled segment.

Claims

1. A system comprising:

an implantable telemetry circuit;

an implantable antenna electrically connected to the implantable telemetry circuit, the implantable antenna comprising;

a first non-coiled segment; and

a first coiled segment attached to the first non-coiled segment; and

wherein the implantable antenna is configured to wirelessly transfer information electromagnetically using a first specified operating frequency range and a second specified operating frequency range, and wherein the first specified operating frequency range and the second specified operating frequency range are provided at least in part by a physical arrangement of the first coiled segment with respect to the first non-coiled segment.

2. The system of claim 1, wherein:

the implantable antenna comprises a second non-coiled segment attached to the first coiled segment; and

the first and second specified operating frequency ranges are provided at least in part by a physical arrangement of the second non-coiled segment with respect to the first coiled segment, and with respect to the first non-coiled segment.

3. The system of claim 2, wherein the implantable antenna comprises a second coiled segment attached to the second non-coiled segment, wherein the second non-coiled segment is located between the second coiled segment and the first coiled segment;

and

wherein the first specified operating frequency range and the second specified operating frequency range are provided at least in part by a physical arrangement of the second coiled segment with respect to the first coiled segment, the first non-coiled segment, and the second non-coiled segment.

4. The system of claim 1, wherein a first mid-band frequency, centered in the first specified operating frequency range, is offset from a second mid-band frequency, centered in the second operating frequency range, by at least an octave.

5. The system of claim 4, wherein the first and second specified operating frequency ranges are selected from a list including at least one of:

(1) a Medical Implant Communications Service (MICS) band range extending from approximately 402 MHz. to approximately 405 MHz.;

(2) a Short Range Device (SRD) band range extending from approximately 862 MHz. to approximately 870 MHz.;

(3) a first Industrial-Scientific-Medical (ISM) band range extending from approximately 902 MHz. to approximately 928 MHz.;

or

(4) a second ISM band range extending from approximately 2400 MHz. to approximately 2500 MHz.

6. The system of claim 1, wherein a longest linear physical dimension of the implantable antenna is less than or equal to a quarter of a longest specified operating wavelength of the implantable antenna in a biological medium.

7. The system of claim 1, wherein the implantable antenna exhibits a higher radiation efficiency in at least one of the first and second operating frequency ranges than would be obtained when the first coiled segment is replaced by a similar length non-coiled segment.

8. The system of claim 1, wherein the physical arrangement of the first coiled segment with respect to the first non-coiled segment is configured such that the implantable antenna in a biological medium approximates a conjugate match to an output impedance of the implantable telemetry circuit for at least one of the first and second operating frequency ranges.

9. The system of claim 8, wherein the implantable telemetry circuit includes an impedance matching element, connected to the implantable antenna, and wherein the first coiled segment is configured to inductively load the implantable telemetry circuit without requiring the matching element to include a discrete inductor.

10. The system of claim 1, wherein the implantable antenna exhibits less directivity in at least one of the first and second operating frequency ranges than would be obtained when the first coiled segment is replaced by a similar length non-coiled segment.

11. The system of claim 1, comprising:

an implantable housing sized and shaped for implant within a human or animal body, the implantable housing comprising a conductive material and containing at least a portion of the implantable telemetry circuit, wherein the conductive material is electrically connected to the implantable telemetry circuit; and

an implantable dielectric compartment sized and shaped for implant within a human or animal body, the implantable dielectric compartment containing at least a portion of the implantable antenna, and wherein the implantable dielectric compartment is coupled to the housing.

12. The system of claim 1, comprising:

an external telemetry module comprising;

an external antenna; and

an external telemetry circuit electrically connected to the external antenna;

wherein the implantable antenna and the external antenna are wirelessly coupled; and

wherein the external antenna is configured to wirelessly transfer information electromagnetically between the implantable medical assembly and the external telemetry module using at least one of the first or second specified operating frequency ranges.

13. The system of claim 1, wherein a longest linear dimension of the first coiled segment is shorter than or equal to a longest linear dimension of the first non-coiled segment.

14. A method, comprising:

wirelessly transferring information electromagnetically at a first specified operating frequency range and at a second specified operating frequency range using an implantable antenna, the implantable antenna comprising;

a first non-coiled segment; and

a first coiled segment attached to the first non-coiled segment; and

wherein the first specified operating frequency range and the second specified operating frequency range are provided at least in part by a physical arrangement of the first coiled segment with respect to the first non-coiled segment.

15. The method of claim 14, wherein the implantable antenna comprises a second non-coiled segment attached to the first coiled segment, wherein the wirelessly transferring information electromagnetically using the implantable antenna includes using the second non-coiled segment, and wherein the first specified operating frequency range and the second specified operating frequency range are provided at least in part by a physical arrangement of the second non-coiled segment with respect to the first coiled segment and the first non-coiled segment.

16. The method of claim 15, wherein the implantable antenna comprises a second coiled segment attached to the second non-coiled segment, wherein the second non-coiled segment is located between the second coiled segment and the first coiled segment, wherein the wirelessly transferring information electromagnetically using the implantable antenna includes using the second coiled segment, and wherein the first specified operating frequency range and the second specified operating frequency range are provided at least in part by a physical arrangement of the second coiled segment with respect to the first coiled segment, the first non-coiled segment, and the second non-coiled segment.

17. The method of claim 14, wherein the wirelessly transferring information electromagnetically includes using the first specified operating frequency range having a first mid-band frequency and the second specified operating frequency range having a second mid-band frequency, and wherein the first mid-band frequency is offset from the second mid-band frequency by at least an octave.

18. The method of claim 14, wherein the wirelessly transferring information electromagnetically includes using an implantable antenna having a longest linear dimension of the first coiled segment shorter than or equal to a longest linear dimension of the first non-coiled segment.

19. The method of claim 14, comprising substantially matching a conjugate impedance of the implantable antenna in a biological medium using the implantable telemetry circuit.

20. The method of claim 19, wherein the substantially matching includes inductively loading the implantable telemetry circuit using the coiled segment.

21. The method of claim 14, comprising:

driving the implantable antenna using the implantable telemetry circuit, wherein the implantable telemetry circuit is contained within an implantable conductive housing, and wherein the antenna is located outside of the conductive housing; and

wherein the wirelessly transferring information electromagnetically includes wirelessly transferring information electromagnetically between the implantable antenna and an external telemetry module antenna using at least one of the first specified operating frequency range or the second specified operating frequency range.