Far-Field Short-Range Radio-Frequency Antenna on the Side of an Implantable Medical Device Case

Abstract

An Implantable Medical Device (IMD) is disclosed having a bi-directional short-range far-field Radio-Frequency (RF) data antenna, operable in accordance with a short-range RF standard such as Bluetooth for example. The antenna is neither located inside the conductive case of the IMD, nor in the non-conductive header of the IMD that includes the lead connectors. Instead, the antenna is outside of the case, proximate to and generally planar with a flat planar side of the case that faces outward of the patient when the IMD is implanted. Dielectric materials keep the antenna from shorting to the case and to the patient's tissue. Because the antenna is not located within the conductive case, data communications to and from the antenna are less subject to attenuation. Not locating the antenna in the header reserves room for the header's lead connectors, thus simplifying IMD design.

Claims

1. An implantable medical device, comprising: a case comprising electronic circuitry inside the case, wherein the case comprises a planar side; a header affixed to the case, wherein the header comprises at least one lead connector configured to receive an electrode lead; and a short-range far-field Radio-Frequency (RF) data antenna outside of the case, wherein the data antenna is proximate to and planar with the planar side of the case.

2. The implantable medical device of claim 1, wherein the case is conductive.

3. The implantable medical device of claim 2, wherein the data antenna comprises a monopole antenna, and wherein the conductive case is grounded and acts as a ground plane for the monopole antenna.

4. The implantable medical device of claim 2, further comprising a dielectric material outside the case and between the data antenna and the planar side of the case.

5. The implantable medical device of claim 1, further comprising an electrode feedthrough configured to pass at least one electrode feedthrough pin from the inside to an outside of the case, wherein the at least one electrode pin is coupled to the electronic circuitry.

6. The implantable medical device of claim 5, wherein the lead connector comprises at least one header contact, wherein each at least one header contact is connected outside the case to one of the at least one feedthrough pins.

7. The implantable medical device of claim 1, further comprising a hole in the planar side of the case, wherein the data antenna is coupled to the electronic circuitry through the hole.

8. The implantable medical device of claim 7, further comprising an antenna feedthrough pin passing through the hole and comprising a first end and a second end, wherein the antenna feedthrough pin is connected at the first end to the electronic circuitry and is connected outside of the case at the second end to the data antenna.

9. The implantable medical device of claim 8, wherein the antenna feedthrough pin is sintered within the hole to provide a hermetic seal between the inside and outside of the case.

10. The implantable medical device of claim 1, further comprising a dielectric overcoat over the data antenna outside of the case.

11. The implantable medical device of claim 10, wherein the dielectric overcoat and the header comprise the same material.

12. The implantable medical device of claim 11, wherein the dielectric overcoat and the header are formed at the same time.

13. The implantable medical device of claim 12, wherein the dielectric overcoat and the header are contiguous.

14. The implantable medical device of claim 1, wherein the data antenna comprises a wire.

15. The implantable medical device of claim 1, wherein the data antenna is serpentined.

16. The implantable medical device of claim 1, wherein the data antenna comprises a patch or slot antenna.

17. The implantable medical device of claim 1, further comprising a substrate outside of the case, wherein the data antenna is formed in or on the substrate.

18. The implantable medical device of claim 17, wherein the substrate is in contact with the planar side of the case.

19. The implantable medical device of claim 1, wherein the data antenna comprises a lithographed or printed data antenna.

20. The implantable medical device of claim 19, further comprising a dielectric material in contact with the planar side of the case, where the data antenna is lithographed or printed on the dielectric material.

21. The implantable medical device of claim 1, wherein the data antenna is configured to operate in accordance with a wireless communication standard comprising one or more of Bluetooth, BLE, NFC, Zigbee, WiFi, and MICS.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIGS. 1A and 1B respectively show an Implantable Medical Device (IMD) in plan and cross sectional views, in accordance with the prior art.

[0021] FIGS. 2A and 2B respectively show a dedicated remote control (RC) for communicating with an IMD, and a mobile device for communicating with an IMD, in accordance with the prior art.

[0022] FIGS. 3A and 3B respectively show an improved IMD in perspective and cross sectional views having an external short-range RF antenna affixed to a side of the IMD case, in accordance with an example of the invention.

[0023] FIG. 4 shows an improved IMD in a perspective view in which the header and an overcoat for the short-range RF antenna are integrally formed, in accordance with another example of the invention.

[0024] FIGS. 5A and 5B show an improved IMD in perspective and cross sectional views in which the external short-range RF antenna is lithographed or printed on the side of the IMD case, in accordance with an example of the invention.

[0025] FIGS. 6A and 6B show an improved IMD in perspective and cross sectional views in which the external short-range RF antenna is pre-formed on a substrate affixed to the side of the IMD case, in accordance with an example of the invention.

DETAILED DESCRIPTION

[0026] An improved Implantable Medical Device (IMD) such as an Implantable Pulse Generator (IPG) is disclosed having a bi-directional short-range far-field Radio-Frequency (RF) data antenna, operable in accordance with a short-range RF standard such as Bluetooth, BLE, NFC, Zigbee, WiFi (802.11x), or MICS. The short-range RF antenna is neither located inside the conductive case of the IMD, nor in the non-conductive header of the IMD that includes the lead connectors. Instead, the short-range RF antenna is outside of the case, proximate to and generally planar with a flat planar side of the case that faces outward of the patient when the IMD is implanted. Dielectric materials keep the antenna from shorting to the case and to the patient's tissue. Because the short-range RF antenna is not located within the conductive case, data communications to and from the antenna are less subject to attenuation. Not locating the antenna in the header reserves room for the header's lead connectors, thus simplifying IMD design.

[0027] FIGS. 3A and 3B show a first example of the improved IMD 100 in perspective and cross sectional views. IMD 100 includes a short-range RF antenna 102 which is located outside of the conductive case 30 of the IMD 100, but which is not located in its header 28. More specifically, the short-range RF antenna 102 is proximate to and generally planar with one of the flat planar sides 101 of the case 30 (on top case portion 30a ). Preferably, case side 101 comprises the side of the case 30 that faces outwards from the patient when IMD 100 is implanted. In this manner, communications between the IMD 100 and an external device are not attenuated by the case 30. Because data communications occur to and from the IMD 100 via the short-range RF antenna 102, data antennas internal to the case 30—such as coil antenna 42 and short-range RF antenna 42b (FIG. 1B)—are omitted from IMD 100. Omitting such antennas from the inside of the case 30, and from the header 28, is beneficial as it allows the IMD 100 to be made smaller while still reserving room in the header 28 for lead connectors 24.

[0028] IMD 100 in the illustrated example includes a charging coil 44 within the case 30 to allow for recharging of battery 36, although as noted earlier battery 36 may also be primary and non-rechargeable, mooting the need for charging coil 44. As shown, case side 101 which carries the short-range RF antenna 102 is on the opposite side of the PCB 40 from the charging coil 44. However, antenna 102 may also be placed on the same side (on the side of bottom case portion 30b ). Because the inside of the case 30 preferably lacks a data antenna, the structures within the case 30 such as the PCB 40, the battery 36, and the charging coil 44 could be moved to other convenient positions and otherwise integrated in different manners within the case 30.

[0029] An external device usable to communicate with IMD 100 can for example comprise the remote control (RC) 50 of FIG. 2A or the mobile device 60 of FIG. 2B, assuming that these devices have short range antennas 59b and 69 that are compliant with the communication standard employed by the IMD's short-range antenna 102. In a preferred example, the antennas 102, 59b, and 69 operate in accordance with the Bluetooth standard, and hence the external device 50 or 60 and the IMD 100 would include telemetry circuitry (e.g., Bluetooth chip sets) operable with that standard.

[0030] As shown, short-range RF antenna 102 is serpentine shaped, and has a length that is preferably optimized for the frequency (or frequency range) at which the antenna 102 is designed to operate. For example, Bluetooth communications occur generally at 2.4 GHz (or more specifically in a range of 2.4-2.4835 GHz allowing for the use of 79 1 MHz channels). This frequency (f) equates to a wavelength (λ) of λ=c/f=12 cm, where c equal the speed of light (3*10.sup.8 m/s). Because the speed of light slows in water (2.25*10.sup.8 m/s), with water being the primary component of the patient's tissue, a more accurate wavelength calculation would be on the order of 10 cm. Because short-range RF antenna 102 preferably comprises a monopole quarter-wavelength antenna, the length of the antenna 102 would thus be in the range of 2.5 to 3 centimeters. If this is too long to fit on case side 101 as a straight line, the antenna 102 can be serpentined as shown. However, this is not necessary, and instead the antenna 102 can be straight, or bent into other shapes.

[0031] In the example shown, short-range RF antenna 102 is formed of a conductive wire, although patch and slot antennas could also be used. As best shown in FIG. 3B, to insulate the antenna 102 from the case 30 (which is normally grounded), a dielectric material 106 is included between the antenna 102 and the case side 101. Dielectric material 106 could comprise different materials (plastics, ceramics, etc.), but in a preferred example comprises a thin layer of glass. Such glass material may comprise a thin film, or may be vapor deposited in the location that the antenna 102 will occupy on the case side 101. The conductive material of the case 30, which again is normally grounded, can act as a ground plane for antenna 102.

[0032] An antenna feedthrough pin 103 passes through a hole 107 in the case side 101 and couples to the PCB 40, and in particular to short-range RF telemetry circuitry. PCB 40 may include a pre-soldered socket 110 to assist in coupling the antenna feedthrough pin 103 to the PCB 40. A glass ferrule 108 is positioned in hole 107, which ferrule 108 includes its own hole for passage of the antenna feedthrough pin 103. The antenna feedthrough pin 103 can be connected to the short-range RF antenna 102 via a weld 105, which preferably comprises a laser weld.

[0033] Once the antenna feedthrough pin 103 is so positioned, the top case portion 30a can be heated to sinter (melt) the glass ferrule 108 to ensure a hermetic seal between the inside and outside of the case 30 at hole 107. Sintering can also further melt the dielectric material 106 to add further hermeticity at the location of the hole 107 if dielectric material 106 is meltable. Although not shown, hole 107 may include a more-complex feedthrough structure similar in nature to the electrode feedthrough 32 used to hermetically pass the electrode feedthrough pins 34 between the inside and outside of the case 30.

[0034] A dielectric overcoat 104 is formed over the short-range RF antenna 102 to further ensure good hermeticity, and to insulate the antenna 102 from the patient's tissue. In a preferred example, dielectric overcoat 104 comprises epoxy, and may comprise the same epoxy used to form the header 28. In fact, the header 28 and dielectric overcoat 104 may be molded over the lead connector 24 and the short-range RF antenna 102 at the same time. Further, header 28 and dielectric overcoat 104 may be formed as a single contiguous overmold, as shown in FIG. 4.

[0035] With the various components of IMD 10 introduced, its assembly can now be summarized. Construction preferably begins with top case portion 30a to which the short-range RF antenna 102 will be affixed. The top case portion 30a is preferably formed with the dielectric material 106 in place on the case side 101. The ferrule 108 is positioned within hole 107 and the antenna feedthrough pin 103 is passed through the ferrule 108 and the dielectric material 106 such that it protrudes above the dielectric material 106. The top case portion 30a with these components is then heated (sintered) to melt the ferrule 108 to the hole 107 and to the antenna feedthrough pin 103, and possibly also to melt and (better) adhere the dielectric material 106 to the case side 101.

[0036] At this point, the short-range RF antenna 102, preferably pre-formed with the appropriate length and shape, can be connected to the top of the antenna feedthrough pin 103 such that it rests on the top of the dielectric material 106. However, connection of the antenna 102 to the antenna feedthrough pin 103 can also occur after the case is seales, as explained below. Dielectric overcoat 104 can be added on top of the antenna 102 at this stage, or later as explain below.

[0037] In a separate assembly step, an electronics assembly is formed. This can begin by constructing an electrode feedthrough subassembly in which the electrode feedthrough pins 34 are formed and sintered through the electrode feedthrough 32, and then the lead connectors 24 and header contacts 26 are connected to first ends of the electrode feedthrough pins 34. The second ends of the electrode feedthrough pins 34 can then be soldered to be PCB 40, which PCB 40 has otherwise been completed with its components pre-attached (e.g., the charging coil 44, the battery 36, the antenna feedthrough pin socket 110, and various circuitry 46).

[0038] With the electronics assembly completed in this fashion, the electronic assembly can be placed in the bottom case portion 30b with the edge of the bottom case portion 30b meeting with the edge of the electrode feedthrough 32. Then, the top case portion 30a constructed as described above can be placed over the bottom case portion 30b and the electrode feedthrough 32, at which point the end of the antenna feedthrough pin 103 can be press fit into the socket 110 on the PCB 40. The case 30 may then be sealed by laser welding the case portions 30a and 30b to each other, and by welding each case portion to the electrode feedthrough 32. The antenna 102 can be connected to the antenna feedthrough pin 103 at this point if this did not occur earlier.

[0039] Thereafter, the header 28 can be molded over the lead connectors 24, and as mentioned above, this step may also include formation of the dielectric overcoat 104, either as a structure separate from the header 28 (FIG. 3A), or as integrated with the header (FIG. 4).

[0040] Short-range RF antenna 102 may be formed in other manners. For example, although not illustrated, the wire comprising antenna 102 can be bent at one end and passed through the hole 107 for connection to the PCB 40. In other words, this end of the antenna wire would be sintered in hole 107, and a separate antenna feedthrough pin 103 could be dispensed with.

[0041] Further, short-range RF antenna need not comprise a wire, but instead could comprise a lithographed or printed antenna. For example, and as shown in the IMD 100′ of FIGS. 5A and 5B, antenna 102 could be formed by sputtering/etching or printing a conductive material (e.g., conductive ink) directly on the dielectric material 106 in contact with the case side 101. If necessary this printed or lithographed antenna 102 could be soldered, welded or otherwise connected (105) to antenna feedthrough pin 103 to ensure good connectivity to the PCB 40 and its short-range RF telemetry circuitry.

[0042] In another alternative shown in the IMD 100″ of FIGS. 6A and 6B, the short-range RF antenna 102 can be pre-formed in or on a substrate 112, such as a printed circuit board (PCB). Substrate 112 could be placed over the dielectric material 106, but if the bottom surface of the substrate 112 is insulative, use of the dielectric material 106 can be omitted as shown in FIG. 6B because this bottom surface will prevent shorting of the antenna 102 to the case side 101. In the example shown, the antenna 102 is formed as a patterned trace in an inner conductive layer of the substrate 112. However, in other examples, the antenna 102 can be patterned on top of the substrate 112. Although in this example the antenna 102/substrate 112 would not be insulated on its top surface, the antenna 102 would still eventually be insulated by application of the dielectric overcoat 104.

[0043] Although particular embodiments have been shown and described, it should be understood that the above discussion is not intended to limit the present invention to these embodiments. It will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention. Thus, the present invention is intended to cover alternatives, modifications, and equivalents that may fall within the spirit and scope of the present invention as defined by the claims.