Implantable antenna arrangement

Abstract

Various antenna configurations are disclosed. An implantable antenna, such as shown and described herein, can include a segmented conductive portion placed in proximity to a sensor electrode included as a portion of an implantable device. Such an antenna can be loaded by the sensor electrode, such as altering a radiation efficiency, directivity, or impedance of the implantable antenna. Collectively, such aspects of antenna operation can be referred to as antenna characteristics. Use of a segmented configuration as shown and described herein can facilitate tuning antenna performance to achieve specified characteristics supporting communication in both a free-space (e.g., air) environment, such as prior to implant, and in situ where the implantable antenna is surrounded by tissue. Such a configuration can also be arranged to reduce or minimize loading or other effects associated with proximity of a segmented conductive portion of the antenna assembly to the sensor electrode.

Description

IMPLANTABLE ANTENNA ARRANGEMENTRELATED APPLICATIONSThis application claims priority to United States Provisional Application SerialNumber 63 / 550,275 (Docket No.: OCL-004-PR1), titled “IMPLANTABLE ANTENNA ARRANGEMENT”, filed February 6, 2024, the content of which is incorporated by reference in its entirety.This application is related to United States Provisional Application Serial Number 62 / 853,899 (Docket No.: OCL-001-PR1), titled “IMPLANTABLE CARDIAC MONITOR”, filed May 29, 2019, the content of which is incorporated by reference in its entirety.This application is related to United States Patent Application Serial Number 17 / 611,335 (Docket No.: OCL-001-US), titled “IMPLANTABLE CARDIAC MONITOR”, filed November 15, 2021, United States Publication Number 2022-0192600, published June 23, 2022, the content of which is incorporated by reference in its entirety.This application is related to International PCT Patent Application Serial Number PCT / US2020 / 035171 (Docket No.: OCL-001-PCT), titled “IMPLANTABLE CARDIAC MONITOR”, filed May 29, 2020, Publication Number WO2020 / 243463, published December 3, 2020, the content of which is incorporated by reference in its entirety.This application is related to United States Provisional Application Serial Number 63 / 321,936 (Docket No.: OCL-002-PR1), titled “IMPLANTABLE CARDIAC MONITOR”, filed March 21, 2022, the content of which is incorporated by reference in its entirety.This application is related to United States Patent Application Serial Number 18 / 846,871 (Docket No.: OCL-002-US), titled “IMPLANTABLE CARDIAC MONITOR”, filed September 13, 2024, the content of which is incorporated by reference in its entirety.This application is related to International PCT Patent Application Serial Number PCT / US2023 / 015734 (Docket No.: OCL-002-PCT), titled “IMPLANTABLE CARDIAC MONITOR”, filed March 21, 2023, Publication Number WO2023 / 183278, published September 28, 2023, the content of which is incorporated by reference in its entirety.This application is related to United States Provisional Application Serial Number 63 / 259,912 (Docket No.: OCL-003-PR1), titled “IMPLANTABLE ANTENNA ANDSENSOR CONFIGURATIONS”, filed July 28, 2021, the content of which is incorporated by reference in its entirety.This application is related to United States Patent Application Serial Number 18 / 579,994 (Docket No.: OCL-003-US), titled “IMPLANTABLE ANTENNA AND SENSOR CONFIGURATIONS”, filed January 17, 2024, the content of which is incorporated by reference in its entirety.This application is related to International PCT Patent Application Serial Number PCT / US2022 / 038653 (Docket No.: OCL-003-PCT), titled “IMPLANTABLE ANTENNA AND COEXISTING SENSOR CONFIGURATIONS”, filed July 28, 2022, Publication Number W02023 / 009707, published February 2, 2023, the content of which is incorporated by reference in its entirety.FIELD OF THE DISCLOSURE

[0001] This document pertains generally, but not by way of limitation, to antenna configurations, and more particularly to antennas that can be used in implantable devices, such as coexisting with a sensor.BACKGROUND

[0002] Active implantable medical devices can include circuitry to sense one or more physiologic signals. In addition, or instead, such implantable medical devices can include circuitry to provide electrostimulation or trigger drug therapy, as illustrative examples. Monitoring features of an active implantable medical device can include detection of physiologic events or logging of received physiologic signals. In one approach, retrieval of stored representations of such signals or real-time transmission of monitored signals can be accomplished using a near-field magnetic telemetry scheme, such as providing one-way or bi-directional communication between an implantable device and a nearby coupled pickup device (e.g., a wand located externally to the body, at most a few centimeters away from the implantable device). Such a near-field scheme can be used for configuration or control of the active implantable device.SUMMARY OF THE DISCLOSURE

[0003] A near-field communication scheme for transfer of information from or to an implantable device can prove cumbersome for use by a caregiver or patient. A caregiver or patient may be requested to place a wand or other pickup at a specified location nearby animplantable device or communication cannot occur. Use of a wand may entirely preclude retrieval of data from an implantable device in a passive manner without requiring intervention by a patient or caregiver. Instead, when a wand or other user interaction is required, inconvenience or extra costs may be incurred at follow-up, or locations may be limited in terms of where online / remote follow up can be performed. Accordingly, the present inventor has developed, among other things, an antenna configuration suitable for use in an implantable device to facilitate longer-range (radiative) communication with other devices. For example, such an implantable antenna configuration can be sized and shaped to facilitate use of an operating frequency range allocated within an Industrial, Scientific, and Medical (ISM) band, as an illustrative example. In an illustrative example, an active implantable medical device such as an implantable monitoring device, can include a transceiver certified for compatibility with a Bluetooth® standard, such as conforming to a Bluetooth® Low Energy (BLE) specification.

[0004] Use of the antenna configurations described herein can facilitate longer-range (e.g., meters or even tens of meters) communication without requiring a near-field “repeater” or other intermediary device external to the patient. Moreover, compatibility of antenna configurations described herein with standard communication schemes such as BLE facilitates potential interoperability with a broad range of BLE-enabled devices, such as cellular devices, tablets, mobile devices, portable or desktop computers, or applicationspecific monitoring devices such as BLE-enabled bed-side monitors.

[0005] An implantable antenna, such as shown and described herein, can be placed in proximity to a sensor electrode included as a portion of an implantable device. The present inventor has recognized, among other things, that such an antenna can be loaded by the sensor electrode, such as altering a radiation efficiency, directivity, or impedance of the implantable antenna. Collectively, such aspects of antenna operation can be referred to as antenna characteristics. Constitutive properties of a medium surrounding the implantable antenna can also affect one or more such characteristics. The present inventor has also recognized, among other things, that use of an antenna arrangement having segments that are neither parallel nor perpendicular to nearby edges of the electrode structure can help to enhance antenna performance (e.g., in terms of avoiding degradation of radiation efficiency, directivity, or impedance matching). The present inventor has also recognized that use of a segmented configuration as shown and described herein can facilitate tuning antenna performance to achieve specified characteristics supporting communication in both a free- space (e.g., air) environment, such as prior to implant, and in situ where the implantableantenna is surrounded by tissue.

[0006] In an example, an implantable antenna assembly can include or define a feed location, a dielectric portion, and a conductive structure located on or within the dielectric portion, the conductive structure coupled to the feed location. The conductive structure can include or define a first segment initiating at the feed location and extending in a first direction having a footprint that partially overlaps with a sensor electrode located on or within the dielectric portion, the first direction neither parallel nor perpendicular to lateral edges of the sensor electrode closest to the first segment, and a second segment initiating at an end of the first segment distal to the feed, the second segment extending in a different second direction and having a footprint that partially overlaps with the sensor electrode, the second direction neither parallel nor perpendicular to the lateral edges of the sensor electrode closest to the second segment.

[0007] In an example, an implantable device can include an antenna assembly, the implantable device comprising a conductive housing, defining a feed location, a dielectric portion mechanically coupled to the conductive housing, a sensor electrode located on or within the dielectric portion, and an antenna structure defined by a conductive structure located on or within the dielectric portion, the conductive structure comprising a first segment initiating at the feed location and extending in first direction having a footprint that partially overlaps with the sensor electrode, the first direction neither parallel nor perpendicular to lateral edges of the sensor electrode closest to the first segment, and a second segment initiating at an end of the first segment distal to the feed, the second segment extending in a different second direction and having a footprint that partially overlaps with the sensor electrode, the second direction neither parallel nor perpendicular to the lateral edges of the sensor electrode closest to the second segment.

[0008] In an example, a system can include an implantable device as mentioned above, and an external device communicatively coupled with the implantable device using an antenna structure of the implantable device, the antenna structure configured to support communication with the external device when the dielectric portion is surrounded by different media. For example, the antenna structure can be configured to support communication with the external device when the dielectric portion is surrounded by a tissue medium and when the dielectric portion is surrounded by air.

[0009] According to various examples, the first segment, the second segment, and the third segment of the implantable antenna mentioned in the example above can each be neither parallel nor perpendicular to a surface of the conductive housing to which the dielectricportion is coupled. In addition or instead, the first segment, the second segment, and the third segment can be located in the same plane, such as parallel to a plane of a surface of a sensor electrode and orthogonal to a top surface of the conductive housing.

[0010] This summary is intended to provide an overview of subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the present patent application.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

[0012] FIG. 1 illustrates generally a system that can include an active implantable medical device comprising an implantable antenna assembly.

[0013] FIG. 2A and FIG. 2B illustrate respective examples such as different views of an implantable antenna assembly, such as can be included in an active implantable medical device or form a portion of an active implantable medical device.

[0014] FIG. 3 illustrates an illustrative example of a portion of an implantable antenna assembly, such as can be included in an active implantable medical device or form a portion of an active implantable medical device.

[0015] FIG. 4 illustrates generally another illustrative example of a portion of an implantable antenna assembly, comprising two segments, such as can be included in an active implantable medical device or form a portion of an active implantable medical device.DETAILED DESCRIPTION

[0016] The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to generally as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventor also contemplates examples in which only those elements shown or described are provided. Moreover, the present inventor also contemplates examples using any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

[0017] In the event of inconsistent usages between this document and any documents so incorporated by reference, the usage in this document controls.

[0018] In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain- English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

[0019] The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0020] Active implantable medical devices can include communication circuitry to support monitoring or control, such as facilitating transfer of data between an implanted medical device and an external assembly. Various challenges can be presented in relation to use ofradiating communication antenna configurations on or within active implantable medical devices. For example, a relative dielectric constant (e.g., relative permittivity) of muscle tissue, or a combination of muscle and fat tissue, is generally much greater than unity at frequencies normally used for wireless communications (e.g., from a range of 10s of megahertz (MHz.) to about 5 gigahertz (GHz.)). Muscle tissue is also generally lossy and dispersive (e.g., such a medium can present a much higher conductivity than free space and the dielectric properties of such material vary substantially with respect to frequency). A tissue medium may also exhibit different propagation characteristics depending on a dominant polarization of an implantable antenna configuration.

[0021] The present inventor has recognized, among other things, that an implantable antenna assembly can be arranged to coexist with sensor circuitry such as one or more nearby sensor electrodes located within a dielectric portion shared with or nearby the implantable antenna assembly. Antenna configurations as shown and described herein can be compact, such as facilitated by a shorter “effective wavelength” of electromagnetic waves within the specified operating frequency range, taking into account a higher relative dielectric constant of the surrounding tissue medium.

[0022] Generally, the phrase “effective wavelength” refers to a wavelength as seen by the antenna when surrounded by an inhomogeneous medium, such as layers comprising free space, muscle and / or fat tissue, and a dielectric housing. The effective wavelength is generally an intermediate value reflecting an effective relative dielectric constant that is between a relative dielectric constant of a housing and that of the tissue medium (and generally greater in magnitude than the relative dielectric constant of the housing).

[0023] Generally, a length of an antenna structure (e.g., an effective length as determined either along a conductive structure of the antenna or defined by a diameter of a sphere bounding the largest dimension of the antenna structure) can be specified based at least in part upon an intended operational frequency range. For a monopole antenna structure or monopole-like structure, an overall length of the antenna structure can be specified to be a quarter of an effective wavelength, or an odd multiple thereof. For a dipole antenna structure, or a dipole-like structure, an overall length of the antenna structure can be specified to be half an effective wavelength.

[0024] A tradeoff can exist between antenna length, efficiency, and proximity of the antenna to the tissue interface. For example, if an antenna is embedded further within a dielectric housing, the effective wavelength can be longer (and hence the antenna structure is physically larger to achieve a quarter or half wavelength criterion), because the effective relativedielectric constant sees a greater contribution from the dielectric housing relative to a contribution from the tissue medium. Conversely, if the antenna is located in closer proximity to tissue, the effective wavelength is shorter, and the antenna can be made physically smaller. Generally, the antenna configurations disclosed herein can be used in a variety of configurations such as at different depths within a dielectric housing, where the antenna elements can be increased or decreased in physical length in accordance with a determined effective wavelength (either via simulation or empirically, or both). The configurations shown herein can provide improved performance even when located at or near a surface of a dielectric compartment, such as in part by providing tunability by using segments or portions that can have a length that is easily adjusted (e.g., “trimmed”) without inducing additional loading by a nearby sensor electrode structure.

[0025] Lengths of respective antenna segments can be established such as by considering a current distribution during operation. For a simulated or empirically determined radiation pattern, antenna portions can be sized to achieve a more uniform (e.g., isotropic) radiation profile or specified directivity. Various examples herein show a monopole configuration, but the structures and techniques described herein can be implemented to provide a dipole antenna configuration, such as by providing two arms having similar or symmetrical geometries, such as a first arm defined by a first conductive structure and a second arm defined by a second conductive structure, such as where the conductive structures are fed using a balanced port configuration.

[0026] FIG. 1 illustrates generally a system 100 that can include an active implantable medical device 102 comprising an implantable antenna assembly 110. The implantable antenna assembly 110 can include a monopole configuration such as embedded in a dielectric portion 108A (e.g., a dielectric compartment or header). A counterpoise can be provided by a separate conductive structure or even by a housing 106 of the active implantable medical device 102. The dielectric portion 108 A can be mechanically coupled to the housing 106, such as using an adhesive or other technique, such as via welding or use of a fastener, or a combination of various techniques. In an example, the implantable antenna assembly 110 can include two separate arms to provide a dipole configuration. In yet another example, a second dielectric portion 108B can be located at an end of the active implantable medical device 102 opposite the dielectric portion 108 A. The second dielectric portion 108B can house an antenna separate from the implantable antenna assembly 110 in the dielectric portion 108 A or forming another arm or element thereof.

[0027] In an illustrative example the active implantable medical device 102 can include an implantable monitoring device, such as implantable in a subcutaneous pectoral location 118 within a subject 114 (e.g., a person as shown in FIG. 1 as an illustration, but such a monitoring device can also be implanted in an animal such as for agricultural or veterinary use, as illustrative examples). The active implantable medical device 102 can include one or more physiologic sensors, such as having sensor electrodes located on or within one of: the dielectric portion 108 A or the second dielectric portion 108B, or using one or more conductive portions of the housing 106.

[0028] The system 100 can include or can be communicatively coupled with one or more external devices, such as an external device 120 (e.g., a bedside monitor, a mobile device, a tablet, a portable or desktop computer, or the like). The external device can include a first transceiver 122 for communication with the active implantable medical device 102. As mentioned above, the first transceiver 122 can conform to a Bluetooth® specification or other standard, such as to facilitate communication using a BLE protocol at or around 2.45 GHz. The external device 120 can use the first transceiver 122 or another transceiver such as a second transceiver 124 to communicate with other devices, such as a cloud-based repository 126 or other remote repository. For example, the second transceiver 124 can include a wireless networking transceiver or cellular modem, as illustrative examples. Generally, retrieved physiologic data or operating data relating to the active implantable medical device 102 can be stored, such as for retrieval, review, reporting, or alerting, as illustrative examples. The implantable antenna assembly 110 can include aspects as shown in other examples herein, such as shown and discussed below in FIG. 2A, FIG. 2B, FIG. 3, or FIG. 4. As mentioned above, various electrode configurations can co-exist with such antenna configurations.

[0029] FIG. 2A and FIG. 2B illustrate respective examples such as different views of an implantable antenna, such as can be included in an active implantable medical device 102 or form a portion of an active implantable medical device 202. The active implantable medical device 202 can include a housing 206 (e.g., a conductive housing such as comprising titanium or another material), and a dielectric portion 208 (e.g., a header or dielectric compartment, such as comprising a biocompatible polymer such as a polyether-based thermoplastic urethane or an epoxy). The dielectric portion can house a conductive structure 210 forming a portion of the implantable antenna assembly. The conductive structure 210 can have a wireshaped or ribbon-shaped (e.g., rectangular) profile, as illustrative examples.

[0030] As shown illustratively in FIG. 2 A (e.g., a front view) and FIG. 2B (e.g., a side view), the conductive structure 210 can be defined by two or more segments, such as a first segment SI initiating at a feed location 228 (e.g., an antenna port coupled with a transceiver circuit within the housing 206). A second segment S2 can extend from an end of the first segment SI distal to the feed location 228. Optionally, a third segment S3 can extend from an end of the second segment S2 distal to the junction between the first segment SI and the second segment S2. One or more sensor electrodes such as a sensor electrode 250 fed by a sensor feedthrough 254 can be located on or within the dielectric portion 208. Because the sensor electrode 250 is generally conductive, the conductive structure 210 of the antenna assembly can be affected by proximity with the sensor electrode 250. The present inventor has recognized, among other things, that the first segment SI and the second segment S2 can be oriented in different directions, such as where the first segment SI extends in a first direction and the second segment S2 extends in a different second direction. In this manner, a physical length of the conductive structure 210 can be extended while still reducing or minimizing overlap between a footprint of the conductive structure 210 (noted as “F”) projected onto a surface of the sensor electrode 250. As shown in FIG. 2A, FIG. 2B, FIG. 3, and FIG. 4, a footprint of the conductive structure 210 partially overlaps with the sensor electrode 250.

[0031] As discussed below in relation to the arrows indicative of surface current distribution shown in FIG. 3, in examples herein such as shown in FIG. 2A, FIG. 2B, FIG. 3, and FIG. 4, the first segment SI and the second segment S2 extend in directions that are neither perfectly parallel nor perfectly perpendicular to nearby lateral edges of the sensor electrode 250. This orientation of the first segment SI and the second segment S2 can help to avoid inducing mirroring current distributions in the sensor electrode 250 that would tend to load the antenna structure, such as affecting one or more of radiation efficiency, directivity, or impedance matching performance. For example, the first segment SI generally extends in a direction that is neither perpendicular nor parallel to either of the lateral edges El and E2 of the sensor electrode 250 closest to the first segment SI. Similarly, the second segment S2 generally extends in a direction that is neither perpendicular nor parallel to either of the lateral edges E2 and E3 of the sensor electrode 250 closest to the second segment S2. A similar consideration can apply to a surface 230 of the housing 206.

[0032] For example, the first segment SI and the second segment S2 can be oriented to extend in directions that are neither parallel nor perpendicular to the surface 230 (e.g., a top surface) of the housing 206 coupled with the dielectric portion 208, such as to avoid unwanted loading or coupling of the conductive structure 210 with the housing 206, thoughthe housing can serve as a counterpoise for a monopole antenna configuration as shown in FIG. 2A, FIG. 2B, FIG. 3, and FIG. 4. If present, the third segment S3 can also be oriented in such a way that it also is neither parallel nor perpendicular to respective lateral edges El, E2, and E3 of the sensor electrode 250, and neither parallel nor perpendicular to the surface 230 of the housing 206. Referring to FIG. 2A, specifically, one or more of the first segment SI, the second segment S2, or the third segment S3 can be coplanar (e.g., all arranged in the same plane), such as a plane Pl parallel to a plane P2 (as shown in Fig. 2B) defined by a surface of the sensor electrode 250.

[0033] As discussed briefly elsewhere herein, a depth of the conductive structure 210 from a surface of the dielectric portion 208 can impact antenna performance. For example, antenna characteristics can be dominated more by a relative dielectric constant of the dielectric portion 208 and interaction between the conductive structure 210 and the sensor electrode 250 as a distance D2 between the conductive structure 210 and the sensor electrode 250 decreases and as a distance Di increases. Conversely, as D2 is increased, an influence by the sensor electrode 250 can be decreased (along with other considerations concerning segment direction and overlap as discussed above), and as Di decreases, the effective dielectric constant “seen” by the conductive structure 210 becomes more dominated by a medium surrounding the antenna assembly.

[0034] If the medium is tissue, such an effective dielectric constant can be much higher than the relative dielectric constant of the dielectric portion 208. An effective electrical length of the antenna assembly in tissue is generally longer than an equivalent electrical length in an air medium. If the implantable antenna is optimized for tissue operation, a loss of efficiency and potential de-tuning of the antenna (e.g., a shift in resonant frequency) can occur when the active implantable medical device 202 is not (yet) implanted. Accordingly, specification of distance Di (and corresponding distance D2) can be used to trade-off stability in antenna characteristics versus implant medium, along with use of a two-segment or three-segment configuration as shown and described herein.

[0035] FIG. 3 illustrates an illustrative example of a portion of an implantable antenna assembly, such as can be included in an active implantable medical device 302 or form a portion of an active implantable medical device 302. The configuration shown in FIG. 3 is similar to FIG. 2A and FIG. 2B, where a conductive structure can be defined by three segments SI, S2, and S3 (e.g., a ribbon conductor such as stamped or otherwise formed). In the example of FIG. 3, dimensions are provided in millimeters corresponding to anoperational frequency centered at about 2.45 GHz, and where a dielectric material surrounding the conductive structure has a relative dielectric constant that ranges between 2.9 and 3.6 across a range of frequencies extending from 2 GHz to 3 GHz, with a relative dielectric constant of about 3.062 at 2.45 GHz. As shown in the illustrative example of FIG. 3, an angle between the first segment SI and the second segment S2 can be about 76 degrees and can be larger than an angle between the second segment S2 and the third segment S3 (where such a second angle is about 31.3 degrees). A length of the third segment S3 can be shorter than each of the first segment SI and the second segment S2, such as less than a third of a total length of the first segment SI, plus the second segment S2, plus the third segment S3. As shown by arrows in FIG. 3, a current distribution (e.g., surface current density) can be larger nearest the feed location 328 and can diminish along a length of the conductive structure. Accordingly, reduction of interaction between the first segment SI and a sensor electrode 350 and the second segment S2 and the sensor electrode 350 can provide greater influence on antenna performance, such as avoiding inducing complementary current densities (as shown by arrows on the surface of the sensor electrode 350). Similarly, orienting and locating the first segment SI and the second segment S2 away from a surface 330 can avoid inducing unwanted loading or strong coupling between the conductive structure and the housing 306.

[0036] FIG. 4 illustrates generally another illustrative example of a portion of an implantable antenna assembly, comprising two segments (e.g., a first segment SI and a second segment S2), such as can be included in an active implantable medical device 402 or form a portion of an active implantable medical device 402. Similar to FIG. 3, dimensions are provided in millimeters, and an angle between the first segment SI and the second segment S2 can be the same as shown in FIG. 3. In the example of FIG. 4, the second segment S2 is shortened to providing tuning of the antenna structure for a specified tissue environment. Such an approach can be used to compensate for variation between simulated and actual dielectric (or other constitutive) parameters associated with antenna operation, or to optimize the antenna configuration if a higher effective dielectric constant occurs in use (e.g., if a relative dielectric constant of a dielectric portion as shown in other examples is higher than designed or expected at the intended operating frequency), or if tissue effects cause a higher effective dielectric constant. Generally, the configurations shown herein can include dimensions and orientations of the respective segments to deliver specified performance in an implanted environment, where the implantable antenna is surrounded by tissue. Performance in non-tissue environment may be less optimal with such an arrangement, but because tissue is a scattering and absorbing medium, such degraded non-tissue performance may still provide adequate range when the implantable assembly is operated in free space (such as prior to implant for configuration or after explant).

Claims

WHAT IS CLAIMED IS:

1. An implantable antenna assembly, comprising: a feed location; a dielectric portion; and a conductive structure located on or within the dielectric portion, the conductive structure coupled to the feed location, the conductive structure comprising: a first segment initiating at the feed location and extending in first direction having a footprint that partially overlaps with a sensor electrode located on or within the dielectric portion, the first direction neither parallel nor perpendicular to lateral edges of the sensor electrode closest to the first segment; and a second segment initiating at an end of the first segment distal to the feed location, the second segment extending in a different second direction and having a footprint that partially overlaps with the sensor electrode, the second direction neither parallel nor perpendicular to the lateral edges of the sensor electrode closest to the second segment.

2. The implantable antenna assembly of claim 1, wherein the first segment and the second segment are each neither parallel nor perpendicular to all lateral edges of the sensor electrode.

3. The implantable antenna assembly of claim 1, wherein the conductive structure comprises a third segment initiating at the end of the second segment distal to the first segment, the third segment extending in a third direction different from the first direction and the second direction.

4. The implantable antenna assembly of claim 3, wherein the third segment is different in length than the first segment and the second segment.

5. The implantable antenna assembly of claim 4, wherein the third segment is shorter than first segment and the second segment.

6. The implantable antenna assembly of claim 3, wherein an angle between the third segment and the second segment is different from an angle between the second segment andthe first segment.

7. The implantable antenna assembly of claim 3, wherein the first segment, the second segment, and the third segment are coplanar.

8. The implantable antenna assembly of claim 7, wherein a plane in which the first segment, the second segment, and the third segment are located is parallel to the plane of a surface of the sensor electrode.

9. The implantable antenna assembly of claim 1, wherein the conductive structure is trimmed to establish a specified resonant frequency when the implantable antenna assembly is surrounded by a specified medium.

10. The implantable antenna assembly of claim 9, wherein the specified medium is tissue.

11. The implantable antenna assembly of claim 1, wherein the first segment comprises more than one third of a total length of the conductive structure.

12. The implantable antenna assembly of claim 11, wherein the second segment comprises more than one third of a total length of the conductive structure.

13. The implantable antenna assembly of claim 1, wherein the conductive structure is embedded within the dielectric portion.

14. The implantable antenna assembly of claim 1, wherein the conductive structure comprises a ribbon conductor.

15. An implantable device comprising an antenna assembly, the implantable device comprising: a conductive housing, defining a feed location; a dielectric portion mechanically coupled to the conductive housing; a sensor electrode located on or within the dielectric portion; and an antenna structure defined by a conductive structure located on or within the dielectric portion, the conductive structure comprising:a first segment initiating at the feed location and extending in a first direction having a footprint that partially overlaps with the sensor electrode, the first direction neither parallel nor perpendicular to lateral edges of the sensor electrode closest to the first segment; and a second segment initiating at an end of the first segment distal to the feed location, the second segment extending in a different second direction and having a footprint that partially overlaps with the sensor electrode, the second direction neither parallel nor perpendicular to the lateral edges of the sensor electrode closest to the second segment.

16. The implantable device of claim 15, wherein the conductive structure comprises a third segment initiating at the end of the second segment distal to the first segment, the third segment extending in a third direction different from the first direction and the second direction.

17. The implantable device of claim 16, wherein the first segment, the second segment, and the third segment are each neither parallel nor perpendicular to a surface of the conductive housing to which the dielectric portion is coupled.

18. The implantable device of claim 17, wherein a plane in which the first segment, the second segment, and the third segment are located is parallel to the plane of a surface of the sensor electrode.

19. A system, comprising: an implantable device, the implantable device comprising: a conductive housing, defining a feed location; a dielectric portion mechanically coupled to the conductive housing; a sensor electrode located on or within the dielectric portion; and an antenna structure defined by a conductive structure located on or within the dielectric portion, the conductive structure comprising: a conductive structure located on or within the dielectric portion, the conductive structure coupled to the feed location, the conductive structure comprising: a first segment initiating at the feed location and extending infirst direction having a footprint that partially overlaps with the sensor electrode, the first direction neither parallel nor perpendicular to lateral edges of the sensor electrode closest to the first segment; and a second segment initiating at an end of the first segment distal to the feed location, the second segment extending in a different second direction and having a footprint that partially overlaps with the sensor electrode, the second direction neither parallel nor perpendicular to the lateral edges of the sensor electrode closest to the second segment; and an external device communicatively coupled with the implantable device using the antenna structure of the implantable device, the antenna structure of the implantable device configured to support communication with the external device when the dielectric portion is surrounded by different media.

20. The system of claim 19, wherein the antenna structure is configured to support communication with the external device when the dielectric portion is surrounded by a tissue medium and when the dielectric portion is surrounded by air.

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