High Dielectric Substrate Antenna For Implantable Miniaturized Wireless Communications and Method for Forming the Same

• US 20100109958A1
• Filed: 12/31/2008
• Published: 05/06/2010
• Est. Priority Date: 10/31/2008
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Mateychuk, Duane N., Yamamoto, Joyce K., Haubrich, Gregory J.
• Granted Patent: US 8,497,804 B2
• Time in Patent Office: Days
• US Class Current: 343/718
• 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: H01Q 1/27 Adaptation for use in or on movable bodies H01Q1/08, H01Q1/12, H01Q1/18 take precedence
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 9/30 with feed to end of elongated active element, e.g. unipole H01Q9/44 takes precedence
• CPC Class Codes: Y10T 29/49016 Antenna or wave energy "plumbing" making

Abstract

An antenna structure for an implantable medical device (IMD) is provided including a lower dielectric biocompatible antenna portion positioned on a body side of the structure and a high dielectric portion including at least one dielectric substrate having a high dielectric constant positioned on a device side of the structure. The biocompatible antenna portion is derived from an antenna layer, a biocompatible surface layer, and at least one layer of biocompatible dielectric material (e.g., high temperature cofire ceramic (HTCC) material) that provides a matching gradient between the antenna and the surrounding environment. The high dielectric portion may include at least one layer of low temperature cofire ceramic (LTCC) material. The high dielectric portion may be bonded to the biocompatible antenna portion or cofired with the biocompatible antenna portion to form a single bilayer monolithic antenna structure having a lower dielectric HTCC biocompatible antenna portion and a high dielectric LTCC portion.

Claims

1. A multi-layer antenna for an implantable medical device (“

IMD”

), comprising;

a biocompatible antenna portion including;

an antenna formed from a biocompatible conductive material, and

at least one layer of biocompatible dielectric material; and

a high dielectric portion including;

a ground plane, and

at least one high dielectric substrate having a high dielectric constant positioned between the antenna and the ground plane,

wherein the at least one layer of biocompatible dielectric material in the biocompatable antenna portion includes a lower dielectric constant than the at least one high dielectric substrate in the high dielectric portion.

2. The multi-layer antenna of claim 1, wherein the at least one high dielectric substrate is formed from a high dielectric ceramic material.

3. The multi-layer antenna of claim 2, wherein the at least one high dielectric substrate comprises a low temperature co-fire ceramic (LTCC) material having a melting point between about 850°

C. and 1150°

C. and a cofireable paste having a high dielectric constant.

4. The multi-layer antenna of claim 1, wherein the high dielectric portion is physically and electrically connected to the biocompatible antenna portion.

5. The multi-layer antenna of claim 4, wherein the high dielectric portion is joined to the biocompatible portion through at least one bond that comprises one of a solder, a conductive epoxy and a metallurgical-based bond.

6. The multi-layer antenna of claim 1, wherein the biocompatible portion and high dielectric portion are separately formed monolithic structures that are connected together.

7. The multi-layer antenna of claim 3, wherein the at least one layer of biocompatible dielectric material in the biocompatible antenna portion comprises a high temperature co-fire ceramic (HTCC) material having a melting point between about 1100°

C. and 1700°

C.,

further wherein the biocompatible antenna portion and the high dielectric portion are joined together to form a single bilayer monolithic antenna structure having a lower dielectric HTCC biocompatible antenna portion and a LTCC high dielectric portion.

8. The multi-layer antenna of claim 7, wherein the HTCC biocompatible antenna portion and a LTCC high dielectric portion are joined together by an adhering material.

9. The multi-layer antenna of claim 7, wherein the HTCC biocompatible antenna portion and a LTCC high dielectric portion are cofired together.

10. The multi-layer antenna of claim 1, wherein the ground plane in the high dielectric portion further provides a shielding layer for providing electromagnetic shielding between the antenna and the IMD to which the antenna is connected.

11. The multi-layer antenna of claim 1, wherein the high dielectric portion further includes a layer of electromagnetic bandgap material.

12. The antenna of claim 1, wherein the antenna conductor is formed from a biocompatible conductive material.

13. A method for fabricating a multi-layer antenna structure for an implantable medical device (“

IMD”

), comprising;

forming a biocompatible antenna portion by cofiring together an antenna formed from a biocompatible conductive material and at least one layer of biocompatible dielectric material having a low dielectric constant; and

forming a high dielectric portion by joining together a ground plane shielding layer and at least one high dielectric substrate having a high dielectric constant,

wherein the at least one layer of biocompatible dielectric material in the biocompatable antenna portion includes a lower dielectric constant than the at least one high dielectric substrate in the high dielectric portion.

14. The method of claim 13, further comprising physically and electrically connecting the biocompatible antenna portion to the high dielectric portion.

15. The method of claim 14, further comprising connecting the biocompatible antenna portion to the high dielectric portion by joining the biocompatible portion to the high dielectric portion through at least one bond comprises one of a solder, a conductive epoxy and a metallurgical-based bond.

16. The method of claim 13, further comprising forming the biocompatible antenna portion and the high dielectric portion as separate monolithic structures that are connected together.

17. The method of claim 13, further comprising cofiring the biocompatible antenna portion and the high dielectric portion together to form a single monolithic antenna structure.

18. The method of claim 17, further comprising forming the at least one high dielectric substrate from a high dielectric ceramic material.

19. The method of claim 18, further comprising forming the at least one high dielectric substrate from a low temperature co-fire ceramic (LTCC) material having a melting point between about 850°

C. and 1150°

C.

20. The method of claim 19, further comprising:

forming the at least one layer of biocompatible dielectric material in the biocompatible antenna portion from a high temperature co-fire ceramic (HTCC) material having a melting point between about 1100°

C. and 1700°

C.; and

cofiring the biocompatible antenna portion together at a temperature between about 1100°

C. and 1700°

C. prior to cofiring the high dielectric portion; and

cofiring the high dielectric portion together with the cofired biocompatible antenna portion at a temperature between about 850°

C. and 1150°

C. to form a single monolithic antenna structure having a lower dielectric HTCC biocompatible antenna portion and a LTCC high dielectric portion.

21. The method of claim 13, further comprising depositing an outermost layer of biocompatible material over the at least one layer of biocompatible dielectric material in the biocompatible antenna portion prior to cofiring the layers together.

22. The method of claim 13, further comprising depositing a layer of electromagnetic bandgap material in the high dielectric portion prior to cofiring the high dielectric portion.