SYSTEMS FOR ENABLING TELEMETRY IN AN IMPLANTABLE MEDICAL DEVICE

• US 20100204759A1
• Filed: 04/16/2010
• Published: 08/12/2010
• Est. Priority Date: 06/09/2006
• Status: Active Grant

• Current Assignee: Bart A. Carey, Jason J. Edwardson, Timothy J. Christman
• Original Assignee: Bart A. Carey, Jason J. Edwardson, Timothy J. Christman
• Inventors: Christman, Timothy J., Edwardson, Jason J., Carey, Bart A.
• Granted Patent: US 8,352,044 B2
• Time in Patent Office: Days
• US Class Current: 607/60
• CPC Class Codes: A61N 1/37229 Shape or location of the implanted or external antenna
• CPC Class Codes: A61N 1/3758 Packaging of the components within the casing
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 9/30 with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence
• CPC Class Codes: H01Q 9/42 with folded element, the folded parts being spaced apart a small fraction of the operating wavelength

Abstract

A system for enabling telemetry in implantable medical devices is provided. One aspect of this disclosure relates to an implantable medical device having radio-frequency telemetry capabilities. The device includes a housing and electronic circuitry contained within the housing. The device also includes an antenna connected to the electronic circuitry, the antenna having a helical portion and a whip portion, the whip portion separate from a feed conductor and adapted to enhance a radiation pattern of the antenna. According to various embodiments, the antenna and circuitry are adapted to facilitate transmission and reception of modulated radio-frequency energy at a specified carrier frequency. At least a portion of the antenna is embedded in a dielectric compartment, according to various embodiments. Other aspects and embodiments are provided herein.

Claims

1. An implantable medical device, comprising:

a telemetry circuit;

an implantable housing configured to contain at least a portion of the telemetry circuit;

an antenna electrically connected to the telemetry circuit, the antenna including a helical portion and a non-helical portion, the antenna configured to wirelessly transfer information electromagnetically using a specified range of operating frequencies and using an antenna mode having an off-axis radiation efficiency greater than or equal to an on-axis radiation efficiency;

wherein the axis is the longitudinal axis of the helical portion; and

wherein the helical portion is physically and electrically shorter than a quarter of a wavelength of an electromagnetic wave propagating through a tissue medium having a relative dielectric constant greater than a free space relative dielectric constant.

2. An implantable medical device, comprising:

a telemetry circuit;

an implantable housing configured to contain at least a portion of the telemetry circuit; and

an antenna electrically connected to the telemetry circuit, the antenna including a helical portion and a non-helical portion, the antenna configured to wirelessly transfer information electromagnetically using a specified range of operating frequencies and using a mode having an off-axis radiation efficiency greater than or equal to an on-axis radiation efficiency, and wherein the axis is the longitudinal axis of the helical portion.

3. The implantable device of claim 2, wherein the helical portion is physically and electrically shorter than a quarter of a wavelength of an electromagnetic wave propagating through a tissue medium having a relative dielectric constant greater than a free space relative dielectric constant.

4. The implantable device of claim 3, wherein the tissue medium includes muscle tissue.

5. The implantable device of claim 2, comprising a header mechanically attached to the housing, wherein the header includes a first dielectric material.

6. The implantable device of claim 5, wherein the antenna is contained within the header.

7. The implantable device of claim 5, wherein the header includes a second dielectric material configured to surround at least a portion of the antenna.

8. The implantable device of claim 7, wherein the second dielectric material includes a ceramic sleeve having a greater relative dielectric constant than the first material.

9. The implantable device of claim 7, wherein the second dielectric material includes a medical adhesive.

10. The implantable device of claim 2, wherein the specified operating frequency range includes a frequency range between 300 MHz and 1 GHz.

11. The implantable device of claim 10, wherein the specified range of operating frequencies includes 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;

or

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

12. The implantable device of claim 2, wherein the housing includes a conductive portion electrically connected to the telemetry circuit.

13. The implantable device of claim 12, wherein the antenna includes a shunt stub to electrically connect the antenna to the housing at a specified location along the length of the antenna, the shunt stub configured to adjust an input impedance of the antenna.

14. The implantable device of claim 13, wherein an adjusted input impedance of the antenna including the shunt stub enhances return loss as compared to an input impedance of the antenna lacking the shunt stub.

15. The implantable device of claim 2, wherein the specified range of frequencies is determined at least in part by a physical arrangement of:

(1) the helical portion of the antenna with respect to at least one of the non-helical portion of the antenna or the housing;

or

(2) the non-helical portion of the antenna with respect to at least one of the helical portion of the antenna or the housing.

16. A method, comprising:

providing an implantable medical device comprising an antenna including a helical portion and a non-helical portion;

providing an electrical connection between the antenna and a telemetry circuit, the telemetry circuit at least partially contained within a housing of the implantable medical device;

transferring information wirelessly using the antenna and the telemetry circuit, the transferring using a specified range of operating frequencies and using an antenna mode having an off-axis radiation efficiency greater than or equal to an on-axis radiation efficiency; and

wherein the axis is the longitudinal axis of the helical portion.

17. The method of claim 16, wherein the providing the medical device comprising the antenna includes providing a helical portion physically and electrically shorter than a quarter of a wavelength of an electromagnetic wave propagating through a tissue medium having a relative dielectric constant greater than a free space relative dielectric constant.

18. The method of claim 16, wherein the specified range of operating frequencies includes 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;

or

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

19. The method of claim 16, comprising providing a shunt stub to electrically connect the antenna to a conductive portion of the housing at a specified location along the length of the antenna;

and

adjusting an input impedance of the antenna using the shunt stub to enhance return loss as compared to an input impedance of the antenna lacking the shunt stub.

20. The method of claim 16, wherein the specified range of frequencies is determined at least in part by a physical arrangement of:

(1) the helical portion of the antenna with respect to at least one of the non-helical portion of the antenna or the housing;

or

(2) the non-helical portion of the antenna with respect to at least one of the helical portion of the antenna or the housing.