Rechargeable heart monitoring device

Abstract

Systems, apparatus, and methods allow for inductive recharging of a power source within or coupled to an implantable medical device (IMD) while the device is implanted in a patient. The IMD may include: a rechargeable battery having a battery housing; a non-metallic substrate attached to the battery housing, wherein the non-metallic substrate and the battery housing form an outer housing for the implantable medical device; control circuitry formed on the non-metallic substrate within the outer housing of the IMD; a receive coil within the outer housing of the IMD, the receive coil configured to receive energy from outside the outer housing of the IMD; and recharging circuitry within the outer housing of the IMD and coupled to the receive coil, the recharging circuitry configured to receive the energy from the receive coil and use the received energy to recharge the rechargeable battery.

Description

Technical Field

[0001] The present disclosure relates to implantable medical devices, and more particularly to implantable medical devices having a rechargeable power source. Background Art

[0002] Various implantable medical devices (IMDs) have been clinically implanted or proposed for therapeutically treating or monitoring one or more physiological and / or neurological conditions of a patient. Such devices may be suitable for monitoring or treating a condition or function related to the heart, muscles, nerves, brain, stomach, endocrine organs or other organs and their associated functions. Advances in the design and manufacture of miniaturized electronics and sensing devices have enabled the development of implantable devices with therapeutic and diagnostic functions, such as pacemakers, cardioverters, defibrillators, biochemical sensors, implantable loop recorders, and pressure sensors. Such devices may be associated with leads that position electrodes or sensors at desired locations, or may be leadless with electrodes integrated into the device housing. These devices may have the ability to wirelessly transmit data to another device implanted in the patient's body or to another instrument positioned outside the patient's body, or both.

[0003] Although the implantation of some devices requires surgery (e.g., pacemakers, defibrillators, etc.), other devices can be small enough to be delivered and placed at the intended implantation site in a relatively non-invasive manner, such as by percutaneous delivery catheters, intravenously, or using subcutaneous delivery tools. As an example, subcutaneous implantable monitors have been proposed and used to monitor heart rate and rhythm and other physiological parameters, such as patient posture and activity level. Such direct in vivo measurements of physiological parameters can provide clinicians with important information to facilitate diagnostic and treatment decisions. Summary of the Invention

[0004] The present disclosure describes implantable medical devices, including receiving coil configurations for implantable medical devices, and associated techniques, structures, and assemblies configured to provide recharging of a power source within a medical device that has been implanted in a patient. An implantable medical device (IMD) may include a receiving coil (also known as a secondary coil) located within a portion of the device housing. The receiving coil may be coupled to a recharging circuit system and configured to have a current induced thereon to provide a recharging current for recharging the power source of the IMD. The receiving coil may be made of one or more windings formed from separate electrical conductors, such as multiple strands of wire. Receive coil configurations include flat spirally wound coils and tubular coils as examples. The receiving coil configurations as described herein may provide a desired form factor and sufficient charging efficiency for an IMD.

[0005] In some examples, the receive coil may have a curved shape corresponding to an inner surface of a housing that is a portion of an IMD. The receive coil may be attached to a first surface of a flexible ferrite sheet. The flexibility of the ferrite sheet and the windings forming the receive coil allows the combination of the ferrite sheet and the attached receive coil to be attached at a second surface of the ferrite sheet, opposite the first surface, at a curvature relative to the inner surface of the housing that is a portion of the IMD. This arrangement allows the receive coil to occupy a desired space within the IMD while allowing a high level of inductive coupling efficiency between the receive coil and an externally generated magnetic field applied to the receive coil, which may be enhanced by the presence of the interposed ferrite sheet to provide inductive recharging for a power source (e.g., a battery or supercapacitor) located within the IMD.

[0006] When it is necessary to recharge the power supply of an IMD including a receive coil configuration as described herein, the device including the receive coil configuration can be placed within a magnetic field (or within a composite magnetic field formed by multiple magnetic fields). This magnetic field is generated by an external power supply device having one or more transmit coils (also known as primary coils), so that the magnetic field (or composite magnetic field) is applied to the receive coil of the IMD. The magnetic field applied to the device can be configured to induce currents into one or more windings of the receive coil. The one or more induced currents can be used to recharge the power supply of the IMD and / or provide power for directly operating the device.

[0007] Examples described in the present disclosure relate to an IMD that includes a rechargeable battery, the rechargeable battery comprising a battery housing; a non-metallic substrate attached to the battery housing, wherein the non-metallic substrate and the battery housing form a housing for the implantable medical device; a control circuit system formed on the non-metallic substrate and located within the housing of the implantable medical device, wherein the control circuit system is configured to control operation of the implantable medical device; a receive coil within the housing of the implantable medical device, the receive coil configured to receive energy from outside the housing of the implantable medical device; and a recharging circuit system within the housing of the implantable medical device and coupled to the receive coil, the recharging circuit system configured to receive energy from the receive coil and use the received energy to recharge the rechargeable battery.

[0008] Examples described in the present disclosure relate to a system for recharging a power source in an IMD implanted in a patient, the system comprising a power source; at least one recharging coil coupled to the power source and configured to generate a magnetic field having a magnetic field direction when energized by the power source; and an implantable medical device comprising a rechargeable battery, the rechargeable battery comprising a battery housing; a non-metallic substrate attached to the battery housing, wherein the non-metallic substrate and the battery housing form an outer housing of the implantable medical device; a control circuit system formed on the non-metallic substrate and located within the outer housing of the implantable medical device, wherein the control circuit system is configured to control operation of the implantable medical device; a receive coil within the outer housing of the implantable medical device, the receive coil configured to receive energy from the at least one recharging coil outside the outer housing of the implantable medical device; and a recharging circuit system within the outer housing of the implantable medical device and coupled to the receive coil, the recharging circuit system configured to receive the energy from the receive coil and use the received energy to recharge the rechargeable battery.

[0009] Examples described in the present disclosure relate to a method for recharging a power source in an IMD implanted in a patient, the method comprising receiving a magnetic field generated by at least one recharging coil located external to the patient at a receive coil configuration of the implantable medical device, wherein the magnetic field induces one or more currents in at least one receive coil forming the receive coil configuration, wherein the implantable medical device comprises a rechargeable battery, the rechargeable battery comprising a battery housing; a non-metallic substrate attached to the battery housing, wherein the non-metallic substrate and the battery housing form an outer housing of the implantable cardiac monitoring device; a control circuit system formed on the non-metallic substrate and located within the outer housing of the implantable medical device, wherein the control circuit system is configured to control operation of the implantable cardiac monitoring device; and a control circuit system within the outer housing of the implantable cardiac monitoring device. a receiving coil within the body of the implantable medical device, the receiving coil being configured to receive energy from the at least one recharging coil outside the outer housing of the implantable medical device; and a recharging circuit system within the outer housing of the implantable cardiac monitoring device and coupled to the receiving coil, the recharging circuit system being configured to receive the energy from the receiving coil and to recharge the rechargeable battery using the received energy; using the receiving coil configuration to generate one or more currents induced into the at least one receiving coil when an externally generated magnetic field is received at the at least one receiving coil; summing the one or more currents to form a recharging current through the recharging circuit system; and applying the recharging current to the rechargeable battery of the implantable medical device through the recharging circuit system to recharge the energy level stored in the rechargeable battery.

[0010] Examples described in the present disclosure relate to a system including an implantable cardiac monitoring device, the implantable cardiac monitoring device including a rechargeable battery, the rechargeable battery including a battery housing; a non-metallic substrate attached to the battery housing, wherein the non-metallic substrate and the battery housing form an outer housing of the implantable cardiac monitoring device; a control circuit system formed on the non-metallic substrate and located within the outer housing of the implantable medical device, wherein the control circuit system is configured to control operation of the implantable cardiac monitoring device; a receive coil within the outer housing of the implantable cardiac monitoring device, the receive coil configured to receive energy from at least one recharging coil external to the outer housing of the implantable medical device; and a recharging circuit system within the outer housing of the implantable cardiac monitoring device and coupled to the receive coil, the recharging circuit system configured to receive the energy from the receive coil and recharge the rechargeable battery using the received energy; wherein the at least one implantable pacemaker device is configured to transmit telemetry data to the implantable cardiac monitoring device; and the implantable cardiac monitoring device is configured to transmit the telemetry data to a mobile device via a short-range wireless communication protocol.

[0011] This summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the devices and methods described in detail in the following figures and description. The details of one or more aspects of the present disclosure are set forth in the figures and the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description, drawings, and claims.

[0013] Figure 1 is a conceptual diagram illustrating an example medical device system in conjunction with a patient according to various examples described in this disclosure.

[0014] Figure 2 is a conceptual diagram illustrating a magnetic field applied to a receiving coil attached to a ferrite sheet according to various examples described in the present disclosure.

[0015] Figure 3 It shows Figure 1 Functional block diagram of an exemplary configuration of an implantable medical device (IMD) for a medical system.

[0016] Figure 4 is an oblique view of an exemplary rechargeable implantable medical device with a receiving coil according to various examples of the present disclosure.

[0017] Figure 5yes Figure 4 An exploded view of an exemplary rechargeable implantable medical device.

[0018] Figures 6A to 6C Each includes a respective perspective view and a cross-sectional view, and each depicts a respective one of three exemplary arrangements of a receive coil and a rechargeable battery within an implantable medical device according to some examples of the present disclosure.

[0019] Figures 7A to 7C Depicted are three exemplary configurations of receive coils for rechargeable implantable medical devices according to some examples of the present disclosure.

[0020] Figure 8 is a top view of an exemplary rechargeable IMD having a tubular receive coil according to some examples of the present disclosure.

[0021] Figure 9A and 9B yes Figure 8 Cross-sectional view of an exemplary rechargeable IMD.

[0022] Figure 10A is an oblique view of an exemplary tubular receive coil for a rechargeable IMD according to some examples of the present disclosure, and Figure 10B It's a floor plan.

[0023] Figure 11 is a line graph depicting an exemplary mathematical relationship between magnetic field strength and the amount of power delivered to a rechargeable battery according to some examples of the present disclosure.

[0024] Figure 12 is a flowchart illustrating an exemplary method according to various examples described in this disclosure.

[0025] In the accompanying drawings, the use of the same reference numerals or the same reference numerals with letter extensions may be used to indicate the same or corresponding devices or elements when used in the same or different drawings. In addition, unless otherwise indicated, devices and / or other objects such as patients, implantable medical devices, or electrical devices (such as electrical coils) are not necessarily shown to scale relative to each other and / or relative to actual examples of the items shown. Specifically, the various figures provided in the present disclosure show "patients" represented by human-shaped outlines, and unless otherwise expressly indicated in the drawings, such as by size indicators or otherwise described, such as in the text of the present disclosure, it should not be considered that they are drawn to scale relative to actual human patients or other objects shown in the same figure. DETAILED DESCRIPTION

[0026] Various types of medical devices sense a patient's cardiac electrogram (EGM) and / or other physiological signals or parameters. Some medical devices that sense cardiac EGM and / or other patient signals or parameters are non-invasive, for example, using multiple electrodes placed in contact with an external portion of the patient, such as at various locations on the patient's skin, to sense the cardiac EGM. The electrodes used to monitor cardiac EGM in these non-invasive procedures can be attached to the patient using, for example, an adhesive, a strap, a belt, or a vest, and electrically coupled to a monitoring device, such as an electrocardiograph, a Holter monitor, or other electronic device. The electrodes are configured to sense electrical signals associated with the electrical activity of the patient's heart or other cardiac tissue and provide these sensed electrical signals to an electronic device for further processing and / or display of the electrical signals. Non-invasive devices and methods can be utilized on a temporary basis, for example, to monitor a patient during a clinical visit, such as during a doctor's appointment, or for example, over a predetermined period of time, such as a day (twenty-four hours), or over a period of several days.

[0027] External devices that can be used to non-invasively sense and monitor cardiac EGMs include wearable devices, such as patches, watches, or necklaces, having electrodes configured to contact the patient's skin. One example of a wearable physiological monitor configured to sense cardiac EGMs is the SEEQ, commercially available from Medtronic plc of Dublin, Ireland. TM Mobile cardiac telemetry systems. These external devices can facilitate relatively long-term monitoring of patients during normal daily activities and can periodically transmit the collected data to a web service, such as Medtronic's Carelink. TM network.

[0028] Some IMDs also sense and monitor cardiac EGMs. The electrodes used by the IMD to sense cardiac EGMs are typically integrated with the housing of the IMD and / or coupled to the IMD via one or more elongated leads. Example IMDs that monitor cardiac EGMs include pacemakers and implantable cardioverter-defibrillators, which may be coupled to intravascular or extravascular leads, as well as pacemakers having a housing configured for implantation within the heart, which may be leadless. An example of a pacemaker configured for intracardiac implantation is the Micra ® 1000 , available from Medtronic plc. TM Transcatheter pacing systems. Some IMDs that do not provide therapy (e.g., implantable patient monitors) sense cardiac EGMs. An example of such an IMD is the Reveal LINQ available from Medtronic plc. TMInsertable cardiac monitors (ICMs), which are inserted subcutaneously. These IMDs facilitate relatively long-term monitoring of patients during normal daily activities and can periodically transmit collected data to a web service, such as Medtronic's Carelink. TM network.

[0029] Conventional cardiac monitors, pacemakers, neurostimulators, and implantable loop recorders may use primary batteries with limited energy as internal power sources to power the operation of the device after the device is implanted in the patient. In various examples of IMDs, the primary (non-rechargeable) battery has a limited energy storage capacity that limits its operating life based on its size and energy density (for a given energy usage rate). This limits the useful duration of the implantable device. Once the primary battery is exhausted, the device may need to be replaced, which, although minimally invasive, may still pose surgical risks to the patient.

[0030] Furthermore, limitations on available battery energy may result in limited treatment and / or monitoring options for the device and / or patient. Furthermore, issues associated with IMDs may lead to the need for more energy-intensive device configurations, which further shortens the operating life of the IMD. For example, detectable cardiac events may occur more frequently in certain patients, requiring the IMD to process, store, and transmit data more frequently, leading to excessive battery drain and shortening the life of the IMD.

[0031] Rechargeable batteries conceptually provide semi-infinite energy storage, where the size of the battery and the energy density of the charge determine the recharge frequency rather than the operating life (under the assumption of negligible battery capacity decay). A consequence of the semi-infinite energy source is the opportunity to provide additional features and functionality that may otherwise be limited or unavailable under the constraints of a limited energy source. Another consequence of this semi-infinite energy source is the potential reduction or elimination of the need for surgically invasive device replacement procedures that would otherwise need to be performed due to exhaustion of the capacity of a primary (i.e., non-rechargeable) battery. The receive coil configuration as described herein can be incorporated into a relatively compact IMD, such as a LINQ TM ICM.

[0032] The ability to recharge the power supply of an IMD, for example, within a one-hour recharging period on a monthly or annual cycle, without having to remove the device to do so, allows for at least the benefits described above, including using a smaller power supply to help miniaturize the IMD itself, and providing more power and, therefore, greater functionality to the implantable medical device by providing an overall longer operating life for the device using a smaller power supply. Examples of the receive coil configurations described in this disclosure have been shown to safely deliver over 80 milliwatts of power to a rechargeable battery of an implantable device.

[0033] Throughout this disclosure, references to a "receive coil" refer to a coil winding formed of an electrical conductor that may or may not be coupled with one or more additional coil windings to form a receive coil for an implantable medical device. The term "receive antenna" may be used in place of or interchangeably with the term "receive coil" in any context involving a coil winding that is coupled to recharging circuitry of an implantable medical device and that may be configured to have current induced into the coil winding for the purpose of providing electrical energy to recharge a rechargeable power source of the implantable medical device and / or to provide electrical power to operate the circuitry of the implantable medical device for the purpose of operating the device.

[0034] Throughout this disclosure, reference is made to "one or more magnetic fields" in the context of one or more magnetic fields generated external to an IMD and applied to the IMD for inducing current into one or more coil windings of a receive coil of an implantable medical device. Typically, such one or more magnetic fields have a parameter (e.g., amplitude or phase) that varies with time or varies with respect to the magnetic field direction of the magnetic field, resulting in a time rate of change of a net magnetic flux intensity applied to the coil windings of the receive coil and a corresponding change in an electromotive force (emf) configured to generate one or more currents in the one or more coil windings.

[0035] Figure 1 is a conceptual diagram illustrating an exemplary medical system 10 in combination with a patient 12 according to various examples described in this disclosure. The systems, devices, and methods described in this disclosure may include an exemplary configuration of a receive coil 16 located within an IMD 14 for charging the IMD 14, as described with respect to FIG. Figure 1 As illustrated and described herein. For purposes of this description, an understanding of cardiovascular anatomy and function is assumed, and details are omitted except to the extent necessary or desirable to explain the context of the disclosed technology. System 10 includes a rechargeable IMD 14 having a receive coil 16, implanted at or near a heart 18 of a patient 12; a transmit coil 20 coupled to an external recharging device 22; and an external computing device 24. The systems, devices, and methods described herein can provide efficient inductive coupling of the external recharging device 22 with circuitry within the IMD 14.

[0036] The exemplary techniques may be used with IMD 14, which may communicate with external device 24 and Figure 1 In some instances, IMD 14 is implanted outside the chest of patient 12 (e.g., subcutaneously). Figure 1The IMD 14 may be positioned near the sternum of the patient 12 at or just below the level of the heart, for example, at least partially within the outline of the heart. The IMD 14 includes a plurality of electrodes 48 ( Figure 5 ) and is configured to sense a cardiac electrogram (EGM) via a plurality of electrodes. In some instances, the IMD 14 employs LINQ TM ICM form, or similar to LINQ TM Although primarily described in the context of IMD 14 being an example of an ICM, in various examples, IMD 14 may represent a cardiac monitor, a defibrillator, a cardiac resynchronization pacemaker / defibrillator, a pacemaker, an implantable pressure sensor, a neurostimulator, or any other implantable or external medical device.

[0037] External device 24 may be a computing device having a display viewable by a user and an interface (i.e., a user input mechanism) for providing input to external device 24. In some examples, external device 24 may be a laptop computer, a tablet computer, a workstation, one or more servers, a cellular phone, a personal digital assistant, or another computing device that can run an application that enables the computing device to interact with IMD 14. External device 24 is configured to communicate with IMD 14 and, optionally, with another computing device (e.g., a computer) via wireless communication. Figure 1 For example, the external device 24 may communicate via near field communication technology (e.g., inductive coupling, NFC, or other communication technology that can operate within a range of less than 10 to 20 cm) and far field communication technology (e.g., according to 802.11 or Bluetooth). RF telemetry based on a standard set, or other communication technologies that can operate at a range greater than near field communication technology).

[0038] External device 24 may be used to configure operating parameters of IMD 14. External device 24 may be used to retrieve data from IMD 14. The retrieved data may include values ​​of physiological parameters measured by IMD 14, indications of arrhythmia or other disease episodes detected by IMD 14, and physiological signals recorded by IMD 14. For example, external device 24 may retrieve a cardiac EGM segment recorded by IMD 14, e.g., because IMD 14 determined that an arrhythmia or other disease episode occurred during the segment, or in response to a request from patient 12 or another user to record the segment. In some instances, one or more remote computing devices may interact with IMD 14 in a manner similar to external device 24, e.g., to program IMD 14 and / or retrieve data from IMD 14 via a network.

[0039] In various instances, IMD 14 may include one or more additional sensor circuits configured to sense specific physiological or neural parameters associated with patient 12, or may include multiple sensor circuits that may be located at various and / or different positions relative to patient 12 and / or relative to each other and may be configured to sense one or more physiological parameters associated with patient 12.

[0040] For example, IMD 14 may include a sensor operable to sense the body temperature of patient 12 at the location of IMD 14 or at a location on the patient where a temperature sensor is coupled to IMD 14 by a lead. In another example, IMD 14 may include a sensor configured to sense motion, such as steps taken by patient 12, and / or the position or posture of patient 12. In various examples, IMD 14 may include a sensor configured to detect the respiration of patient 12. In various examples, IMD 14 may include a sensor configured to detect the heartbeat of patient 12. In various examples, IMD 14 may include a sensor configured to measure the systemic blood pressure of patient 12.

[0041] In some examples, one or more of the sensors comprising IMD 14 may be implanted within patient 12, i.e., implanted at least below the level of the patient's skin. In some examples, one or more sensors of IMD 14 may be located external to patient 12, e.g., as part of a cuff or as a wearable device, such as a device embedded in clothing worn by patient 12. In various examples, IMD 14 may be configured to sense one or more physiological parameters associated with patient 12 and transmit data corresponding to the sensed one or more physiological parameters to external device 24, as represented by a lightning bolt coupling IMD 14 to external device 24.

[0042] In various examples, the data transmission from IMD 14 to external device 24 can be performed by wireless transmission, e.g., using any of the formats described above for wireless communication. In various examples, IMD 14 can wirelessly communicate with an external device (e.g., one or more instruments) other than external device 24, such as a transceiver or access point that provides a wireless communication link between IMD 14 and a network. In various examples, the transceiver is a communication circuitry included within recharging circuitry 22, wherein the communication circuitry of external recharging device 22 is configured to communicate with IMD 14 during recharging, as further described below. Figure 1 Examples of communication technologies used by any of the described devices may include radio frequency (RF) telemetry, which may be via Bluetooth RF link established by Wi-Fi or Medical Implant Communication Service (MICS).

[0043] In some examples, system 10 may include Figure 1 More or fewer components may be shown. For example, in some instances, system 10 may include multiple additional IMDs implanted within patient 12, such as implantable pacemaker devices or other IMDs. In these instances, rechargeable IMD 14 may serve as a hub device for the other IMDs. For example, the additional IMDs may be configured to communicate with rechargeable IMD 14, which would then communicate with external device 24, such as a user's smartphone, via a low-energy telemetry protocol. Rechargeable IMD 14 may provide a theoretically unlimited energy capacity because IMD 14 may not need to be replaced or otherwise removed. Thus, IMD 14 may provide more frequent telemetry information and the ability to more proactively titrate therapy.

[0044] For the remainder of this disclosure, general references to medical device systems may collectively refer to any instance of medical device system 10, general references to IMD 14 may collectively refer to any instance of IMD 14, general references to sensor circuits may collectively refer to any instance of sensor circuits of IMD 14, and general references to external devices may collectively refer to any instance of external device 24.

[0045] Figure 2 FIG is a conceptual diagram showing a magnetic field 26 applied to the receiving coil 16 of the IMD. Figure 2 As shown, receive coil 16 is attached to a surface of ferrite sheet 28. Receive coil 16 includes an electrical conductor formed into a receive coil winding according to any receive coil described in this disclosure, including a flat spirally wound coil or a tubular coil winding. Receive coil 16 includes a pair of leads C1, C2 that can be coupled to recharging circuitry 30 of IMD 14, which in turn can be coupled to a rechargeable battery 32 of IMD 14. Receive coil 16 can be a single receive coil or one of multiple receive coils of an IMD according to various examples described throughout this disclosure.

[0046] like Figure 2 As shown, the receiving coil 16 is attached to the surface of the ferrite sheet 28. The ferrite sheet 28 can be configured to block external electromagnetic interference (EMI) and / or otherwise improve the efficiency of power transfer from the external recharging coil 20 to the receiving coil 16. In some examples, the ferrite sheet 28 can have a surface area having a perimeter (e.g., a rectangular or square area defined by height and width dimensions) along which the windings of the receiving coil 16 extend orthogonally to the thickness of the ferrite sheet 28. In other words, the height and width dimensions of the windings of the receiving coil 16 extend adjacent to the surface of the ferrite sheet 28, such that all or a portion of the windings are in direct contact with or adjacent to a portion of the surface of the ferrite sheet 28.

[0047] like Figure 2 As shown, the receiving coil 16 and ferrite sheet 28, as well as the recharging circuit system 30 and the rechargeable battery 32, can be incorporated into the implantable medical device 14, as shown in the dashed box. The transmitting coil 20 (also referred to as the "external recharging coil 20") is located somewhere near the IMD 14, such as Figure 2 The right side of the receiving coil 16. Figure 2 In the illustrated orientation, the receiving coil 16 is positioned between the first external recharging coil 20 and the ferrite sheet 28 .

[0048] The external recharging coil 20 includes a circuit configured to couple to the external recharging circuitry ( Figure 2 Not shown, but included for example in Figure 1 2 and 3. The external recharging circuitry of external recharging device 22 is configured to electrically energize external recharging coil 20 and, in turn, generate a magnetic field, illustratively represented by the arrow indicated by bracket 26. The magnetic field generated by external recharging coil 20 can be applied to an implantable medical device including receiving coil 16 in a direction indicated by the arrow (bracket 26) extending from external recharging coil 20 toward receiving coil 16. The magnetic field generated by external recharging coil 20 can induce current into the windings of receiving coil 16, which can then be coupled to the recharging circuitry of IMD 14, which is coupled to receiving coil 16.

[0049] In various examples of receive coil configurations described below, the receive coil can be bent or shaped into a curved configuration that extends around (e.g., conforms to) a portion of the interior surface of the housing of the IMD 14 to which the receive coil is mounted. Ferrite sheets 28 can be attached to receive coil 16 and oriented and / or shaped into a configuration that allows for their location within the IMD 14, and in some cases, allows for various orientations of the direction of the magnetic field 26 that can be applied to the IMD 14 to benefit from the increased level of inductive coupling efficiency associated with the use of ferrite sheet 28 as described above. Various arrangements of ferrite sheet 28, receive coil 16, and battery 32 that can be positioned within the IMD and configured to benefit from a "preferred orientation" of the receive coil / ferrite assembly relative to one or more magnetic fields applied to the implantable medical device are further detailed and described below. Furthermore, while several examples described herein include ferrite sheets, other exemplary receive coil configurations do not include ferrite sheets.

[0050] Figure 3 It shows Figure 1FIG2 is a functional block diagram of an exemplary configuration of an IMD 14 of medical system 10. In the illustrated example, IMD 14 includes receive coil 16, recharging circuitry 30, rechargeable power source 32, processing circuitry 34, memory 36, communication circuitry 38, communication antenna 40, sensing circuitry 42, sensor 44, accelerometer 46, and electrodes 48A and 48B (collectively, “electrodes 48”). Although the illustrated example includes two electrodes 48, in some examples, an IMD that includes or is coupled to more than two electrodes 48 may implement the techniques of this disclosure.

[0051] Processing circuitry 34 may include fixed-function circuitry and / or programmable processing circuitry. Processing circuitry 34 may include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or equivalent discrete or analog logic circuitry. In some examples, processing circuitry 34 may include multiple components, such as one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FPGAs, as well as any combination of other discrete or integrated logic circuitry. The functions attributed herein to processing circuitry 34 may be implemented as software, firmware, hardware, or any combination thereof.

[0052] The sensing circuit system 42 is coupled to the electrodes 48. The sensing circuit system 42 can sense signals from the electrodes 48, for example to generate cardiac EGMs to facilitate monitoring of the electrical activity of the heart. Sensing of cardiac EGMs can be performed to determine heart rate or heart rate variability, or to detect arrhythmias (e.g., tachyarrhythmias or bradycardias). The sensing circuit system 42 can also monitor impedance or other electrical phenomena through the electrodes 48. The sensing circuit system 42 can also monitor signals from the sensors 44, which, for example, can include one or more accelerometers 46, pressure sensors, and / or optical sensors. In some instances, the sensing circuit system 42 can include one or more filters and amplifiers for filtering and amplifying signals received from the electrodes 48 and / or sensors 44. In some instances, the sensing circuit system 42 can sense or detect physiological parameters, such as heart rate, blood pressure, respiration, and other physiological parameters associated with the patient.

[0053] Sensing circuitry 42 and / or processing circuitry 34 can be configured to detect cardiac depolarization (e.g., a P wave for atrial depolarization or an R wave for ventricular depolarization) when the cardiac EGM amplitude crosses a sensing threshold. For cardiac depolarization detection, in some instances, sensing circuitry 42 can include a rectifier, a filter, an amplifier, a comparator, and / or an analog-to-digital converter. In some instances, sensing circuitry 42 can output an indication to processing circuitry 34 in response to sensing of cardiac depolarization. In this manner, processing circuitry 34 can receive indications of detected cardiac depolarization that correspond to the presence of R waves and P waves detected in various chambers of the heart. Processing circuitry 34 can use the indications of detected R waves and P waves to determine depolarization intervals, heart rate, and detect cardiac arrhythmias, such as tachyarrhythmias and asystole.

[0054] Sensing circuitry 42 may also provide one or more digitized cardiac EGM signals to processing circuitry 34 for analysis, e.g., for cardiac rhythm discrimination. In some examples, processing circuitry 34 may store the digitized cardiac EGMs in memory 36. Processing circuitry 34 of IMD 14 and / or processing circuitry of another device that retrieves data from IMD 14 may analyze the cardiac EGMs.

[0055] Communication circuitry 38 may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device, such as external device 24, another networked computing device, or another IMD or sensor. Under the control of processing circuitry 34, communication circuitry 38 may receive downlink telemetry from external device 24 or another device via an internal or external antenna (e.g., antenna 40) and send uplink telemetry to external device 24 or another device. In addition, processing circuitry 34 may communicate with external devices (e.g., Figure 1 external devices 24) and such as Medtronic The antenna 40 and the communication circuitry 38 may be configured to transmit and / or receive signals via inductive coupling, electromagnetic coupling, near field communication (NFC), radio frequency (RF) communication, Bluetooth, Wi-Fi, or other proprietary or non-proprietary wireless communication schemes. The communication antenna 40 may be configured to transmit and / or receive signals via a computer network such as a Wi-Fi network. The communication antenna 40 may be configured to transmit and / or receive signals via a computer network such as a Wi-Fi network. The communication antenna 40 may be configured to transmit and / or receive signals via a high frequency telemetry data, such as approximately 2.4 gigahertz (GHz).

[0056] In some examples, memory 36 includes computer-readable instructions that, when executed by processing circuitry 34, cause IMD 14 and processing circuitry 34 to perform the various functions attributed herein to IMD 14 and processing circuitry 34. Memory 36 may include any volatile, nonvolatile, magnetic, optical, or electrical medium, such as random access memory (RAM), read-only memory (ROM), nonvolatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other digital media. As examples, memory 36 may store programmed values ​​for one or more operating parameters of IMD 14 and / or data collected by IMD 14, such as posture, heart rate, activity level, respiratory rate, and other parameters, as well as digitized versions of physiological signals sensed by IMD 14, for transmission to another device using communication circuitry 38.

[0057] IMD 14 includes a rechargeable power source 32 that is couplable to electronic circuitry provided in IMD 14 and configured to provide power to such circuitry. Power source 32 may be inductively recharged by applying one or more magnetic fields to IMD 14, where energy from these applied fields may induce electrical energy into receive coil 16 and, thereby, into recharging circuitry 30.

[0058] like Figure 3 As shown, device recharging circuitry 30 is coupled to power source 32 and may receive electrical energy induced in receive coil 16 by one or more electromagnetic fields applied to the coil and condition the energy to provide a level of energy that is provided to power source 32 for recharging power source 32 and / or powering other circuitry included as part of IMD 14. Device recharging circuitry 30 may perform various energy conditioning functions on the energy induced in receive coil 16, such as by providing rectification, voltage level conditioning, current level conditioning, and / or other signal processing functions, to generate “recharging energy” that is provided to power source 32.

[0059] In the illustrated example, IMD 14 includes processing circuitry 34 and associated memory 36, sensing circuitry 42, one or more sensors 44, and communication circuitry 38 coupled to antenna 40 as described above. However, IMD 14 need not include all of these components or may include additional components.

[0060] Processing circuitry 34 may be configured to provide information including charge status and / or temperature information associated with a battery (e.g., a battery located in IMD 14), determine an inductive coupling level (e.g., a level of energy generated in a receiving coil located in IMD 14 as a result of one or more electromagnetic fields applied to IMD 14), and generate information associated with the inductively received energy for transmission to a communication antenna of IMD 14 or a separate antenna and associated power conditioning circuitry.

[0061] In various examples, processing circuitry 34 is coupled to device recharging circuitry 30 and receives information such as the level of current induced in coil 16 as a result of electrical energy received by the antenna via magnetic energy applied to IMD 14 for recharging power source 32. Processing circuitry 34 may provide this information and other information, such as charge rate and temperature information associated with power source 32, in the form of output signals to communication circuitry 38 for transmission from IMD 14 to one or more external devices, such as external recharging device 22 ( Figure 1 ). This transmitted information can be used by an external device to control one or more aspects of the recharging process.

[0062] For example, this information transmitted from IMD 14 may be used to control the positioning and / or level of power applied to a recharging coil or pair of coils located external to IMD 14 and generating one or more magnetic fields applied to IMD 14. This information transmitted from IMD 14 may be used to control the settings of electrical parameters used to energize the coils of the coil pair that generate the one or more magnetic fields applied to IMD 14 to recharge power source 32. Furthermore, other information, such as temperature and field strength information transmitted from IMD 14, may be used to control the recharging process, e.g., by adjusting the field strength generated by the external coils, or, for example, by turning off the external coils to halt the recharging process.

[0063] Figure 4 1 is an oblique view of an exemplary configuration of a rechargeable IMD 14 having a receiving coil 16 according to various examples of the present disclosure. The IMD 14 may be an example of an insertable cardiac monitor (ICM) configured to receive a cardiac signal via one or more electrodes 48 ( Figure 3 and 5 ) to sense and monitor cardiac EGM. For example, IMD 14 may include RevealLINQ available from Medtronic plc TM Insertable cardiac monitors, which can be inserted subcutaneously. These IMDs can facilitate relatively long-term monitoring of patients during normal daily activities and can periodically transmit collected data to a web service, such as Medtronic's Carelink. TMnetwork. In the example shown, the receive coil 16 has a substantially planar configuration. In other examples, described in further detail below, the IMD may include a receive coil having a tubular configuration in which individual coil loops are stacked one on top of another. In either case, the receive coil 16 is configured to receive power from a separate external recharging coil 20 ( Figure 1 ) receives electromagnetic energy to power a rechargeable battery or other power source 32 ( Figure 2 ) for recharging.

[0064] In the example shown, the recharging circuitry 30 electrically connected to the two leads of the coil 16 is located near the exterior of the coil and is substantially coplanar with the receiving coil 16. The power source 32 is contained within a battery housing 50 below the receiving coil 16 and is located within the receiving coil 16. Figure 4 One or more side walls of the battery housing 50 define a recess within which the receiving coil 16 and the recharging circuit system 30 are located. Figure 4 , but IMD 14 may include a lid configured to be attached (e.g., sealed) to battery housing 50 and thereby form an outer housing (e.g., a cover) for IMD 14, within which receive coil 16 and recharging circuitry 30 are located. As will be described in more detail below, the circuitry may be formed on the lid and connected to power source 32 via electrical contacts 58.

[0065] Figure 5 yes Figure 4 14. An exploded view of an exemplary rechargeable IMD 14 is shown. IMD 14 includes at least a receive coil 16, recharging circuitry 30, a battery housing 50, and a cover 52. Recharging circuitry 30 is coupled to a rechargeable battery or other power source and can receive electrical energy induced in receive coil 16 by one or more electromagnetic fields applied to an antenna and condition the energy to provide a level of energy that is provided to the power source for recharging the power source and / or powering other circuitry included as part of IMD 14. Recharging circuitry 30 can perform various energy conditioning functions on the energy induced in receive coil 16, such as by providing rectification, voltage level conditioning, current level conditioning, and / or other signal processing functions, to generate "recharging energy" that is provided to the power source.

[0066] IMD 14 includes a barrel-shaped outer shell or battery housing 50. In some examples, battery housing 50 is formed of a material such as titanium or a titanium alloy and can be sealingly joined to lid 52. When joined, lid 52 and battery housing 50 can form a sealed housing or enclosure for the circuitry of IMD 14 (including receive coil 16 and recharging circuitry 30).

[0067] For lower frequency applications (e.g., magnetic fields having a frequency of 200 kHz or lower), battery housing 50 can be formed from a material including a titanium alloy that allows magnetic fields having these lower frequencies to pass through the housing and be applied to receive coil 16. In various examples, housing 50 can be formed from a biocompatible ceramic material. In some examples, grade 1 titanium is not a preferred material for housing 50 because grade 1 titanium may reduce power transfer efficiency and convert the drawn power into heat, which may cause IMD 14 to overheat at higher power transfer levels. Therefore, a material with higher electrical and thermal resistance for housing 50, such as grade 5 or higher titanium, can improve power transfer performance. For example, because grade 5 titanium can include a higher bulk resistivity than grade 1 titanium, using grade 5 titanium can reduce power losses caused by eddy currents.

[0068] In some, but not all, examples, the receive coil 16 can be attached to a ferromagnetic substrate 54. For example, the substrate 54 can include a flexible ferrite layer, which can improve the performance of the receive coil 16, particularly when the antenna 16 operates at relatively high frequencies. For example, the ferrite backing layer 54 can improve the performance of the receive coil 16 when driven at frequencies between approximately 400 kHz and several MHz.

[0069] In some examples, cover 52 comprises a relatively thin, planar wafer that is sealingly coupled to battery housing 50. Cover 52 can be formed from a non-metallic or non-conductive substrate material, such as a material having a relatively high resistivity value, which allows electromagnetic energy applied to IMD 14 for recharging purposes to penetrate and pass through cover 52 and reach receiver coil 16. Cover 52 can be formed from a "radio-transparent" material that also provides a low relative permittivity (i.e., high relative resistivity) and low magnetic permeability. In this way, cover 52 can provide a relatively more radio-transparent window for receiver coil 16 than battery housing 50.

[0070] Resistivity can be represented by the Greek letter ρ (rho) and in the International System (SI) the unit is measured in ohms (Ω-m) and can vary for a given material based on temperature. An example of a material (such as certain metals) that can be considered a good electrical conductor and therefore has a low resistivity value is copper, which has a ρ value of approximately 1.68x10 at 20 degrees Celsius (°C). -8 Ω-meter. Examples of materials that can be considered poor electrical conductors and therefore have high ρ values ​​(e.g., electrical insulators) can include glass, which has a ρ value in the range of 1x10 at 20°C. 10 to 1x10 14 Ω-meter. Another example of a material with a high ρ value is sapphire, which in some instances has a ρ value in the range of 1x10 at 23°C. 14Ω-cm. Examples of materials with low dielectric constant, high resistivity, and low magnetic permeability that can be used for portions of the housing 50 that include the receive coil configuration according to examples described in this disclosure may include grades 5, 9, 23, and 36 titanium alloys, which can provide sufficient levels of radio transmittance at lower frequencies (e.g., up to 200 kHz), or ceramic materials that can provide radio transmittance at these lower frequencies and in the frequency range above 200 kHz (e.g., up to 10 MHz). Cermets made using metal injection molding processes can also be used over a wide range of frequencies similar to the operating frequency range of ceramics.

[0071] To allow higher frequency magnetic fields to reach receive coil 16, at least cover 52 of IMD 14 may be formed from a material, such as sapphire, that has a high resistivity value at least at temperatures typically experienced by the device after implantation in a patient, e.g., temperatures on the outer surface of an implanted device typically do not exceed 39 to 40° C., even for brief periods of time, which may occur when the device is being recharged. To allow the use of higher frequency magnetic fields for recharging IMD 14, cover 52 may be formed from a material having a high resistivity (e.g., at 1×10 11 to 1x10 16 ohm-cm range) and a radio-transparent material with low magnetic permeability. A wide range of materials will meet these requirements, including commonly used examples such as sapphire, glass materials, or polymer materials having a dielectric constant ranging from approximately 1 to 12. Using sapphire or glass materials for cover 52 can allow higher frequency induced magnetic fields to be transmitted through cover 52 and applied to receive coil 16 relative to other materials that do not provide the same level or high value of resistivity. For example, by using cover 52 made of sapphire, magnetic fields with frequencies ranging from approximately 100 kHz to 10 MHz can be applied to IMD 14, where sapphire allows one or more applied magnetic fields having frequencies within this range to pass through cover 52 and induce currents in the electrical conductors forming the windings of receive coil 16.

[0072] As follows Figure 11 As shown, the ability to use a higher frequency magnetic field allows more energy, and thus a greater current, to be induced into the electrical conductors forming the windings of receive coil 16 at any given time or for a specific period of time when the higher frequency is applied to IMD 14, as compared to using a lower frequency magnetic field. Cover 52 is not limited to being formed from a visually transparent material. Examples of materials for forming cover 52 may include any type of material having a minimum resistivity value (e.g., a good electrical insulator with a low dielectric constant value) and low magnetic permeability, and meeting other manufacturing requirements and complying with any other applicable regulatory requirements for implantable medical devices, such as biocompatibility requirements.

[0073] Electrodes 48 are located, for example, formed on cover 52 and, in the illustrated example, are located at opposite ends of the wafer, as measured along the longitudinal axis of cover 52. In the illustrated example, electrodes 48 have a semicircular shape, e.g., conforming to the shape of the ends of cover 52. In other examples, IMD 14 may include more electrodes, electrodes of different shapes, and / or electrodes that are not necessarily formed on cover 52. IMD 14 may be configured to sense cardiac ECG signals and / or other electrical signals via electrodes 48. Electrodes 48 may be formed on a surface of cover 52 opposite control circuitry 56.

[0074] The spring contacts 58 may include one or more elongated conductive extensions configured to transfer power from the battery 32 to the control circuitry 56. For example, a first end of each spring contact 58 may be rigidly coupled to the battery 32, and a second end of each spring contact 58 may be configured to physically contact an electrical contact disposed on the same side of the cover 52 on which the control circuitry 56 is formed, via an internal spring mechanism.

[0075] IMD 14 includes control circuitry 56. Control circuitry 56 includes one or more processors such as Figure 3 processing circuitry 34), microchips, microprocessors, semiconductors, memory units (such as Figure 3 Memory 36) or other computing components configured to control the operation of IMD 14. Figure 5 As shown, control circuitry 56 may be formed on a non-metallic substrate of cover 52. Control circuitry 56 may be formed on a surface of cover 52 that is intended to be located inside the housing of IMD 14 when cover 52 is mounted on battery housing 50. Sensing circuitry 42, sensor 44, and communication circuitry 38 may similarly be formed on or attached to cover 52.

[0076] Figures 6A to 6CThree exemplary configurations and arrangements 60A-60C of planar receive coils 16A-16C and rechargeable batteries 32A-32C within battery housings 50A-50C of an IMD are depicted. Different sizes, shapes, and arrangements of the coils and batteries may be selected to conform to space constraints within the interior space of the enclosure formed by battery housing 50 and lid 52, and to meet other performance parameters of the IMD. For example, a larger battery size may correspond to a larger battery capacity, thereby allowing the IMD 14 to remain operational for longer periods between recharges. Similarly, a larger coil size may be desirable to increase the speed of a single recharge event (e.g., faster recharging). In some examples of the IMD 14, the coil and battery configuration may be selected to achieve a "1-1-1" configuration, wherein the receive coil can charge the battery in one hour, and wherein the battery has a capacity that allows for one year between recharges, with one year of reserve capacity remaining in the battery at each annual recharge (e.g., providing a total battery capacity for approximately two years of continuous use). It has been demonstrated that for batteries with a capacity between approximately 45 and 60 milliampere hours (mAh), two years of continuous use can be provided.

[0077] Figure 6A A first exemplary arrangement 60A is depicted. Figure 6A In the example shown, receive coil 16A includes a relatively small profile measured along the x- and y-axes so as to fit within a small compartment located near the top of housing 50 (measured along the z-axis), such as between certain circuitry formed on lid 52. Some exemplary dimensions for receive coil 16A include approximately 6 mm (along the x-axis) x 4 mm (along the y-axis) x 1.3 mm (along the z-axis).

[0078] In contrast, battery 32A comprises a relatively large profile that extends nearly the entire length and width (measured along the x and y axes, respectively) of device housing 50. Due to the larger size of battery 32A, Figure 6A The configuration depicted in FIG can exhibit a relatively long battery life (e.g., the usable life duration between required recharging events). However, due to the relatively small receive coil 16A, Figure 6A The configuration depicted in may also exhibit relatively long recharge cycles.

[0079] Figure 6B A second exemplary arrangement 60B is depicted. Figure 6B In the example shown, Figure 6A The length of battery 32B (measured along the x-axis) is reduced by approximately half compared to battery 32A. Thus, receiver coil 16B can be located below the plane where the circuitry formed on cover 52 is located along the z-axis, adjacent to battery 32B, and can include a relatively large profile measured along the x- and y-axes to fit within the housing formed by Figure 6ASome exemplary dimensions of the receiving coil 16B include approximately 15 to 25 mm (along the x-axis) x 6.5 mm (along the y-axis) x 1.7 mm (along the z-axis). Due to the smaller size of the battery 32B compared to the battery 32A, Figure 6B The configuration 60B depicted in FIG. 6B may exhibit a relatively short battery life. However, since the receive coil 16B is relatively large compared to the antenna 16A, Figure 6B The configuration depicted in may also exhibit relatively short recharge cycles.

[0080] Figure 6C A third exemplary arrangement 60C is depicted. Figure 6C In the example shown, Figure 6A The height of battery 32C (measured along the z-axis) is reduced by about half compared to battery 32A. Thus, the receiving coil 16C includes a relatively large profile measured along the x and y axes to fit within the housing formed by Figure 6A 52. In configuration 60C, antenna 16C and battery 32C both extend across most of the length and width of housing 50, as measured along the x- and y-axes, respectively. For example, receive coil 16C may have exemplary dimensions of approximately 33 mm (along the x-axis) x 7 mm (along the y-axis) x 0.4 mm (along the z-axis). Due to the smaller size of battery 32C compared to battery 32A, Figure 6C The configuration 60C depicted in FIG. 60C may exhibit a relatively short battery life. However, since the receive coil 16C is relatively large compared to the antenna 16A, Figure 6C The configuration depicted in may also exhibit relatively short recharge cycles.

[0081] Figures 7A to 7C Depicted are three exemplary electrical conductors configured to form a planar receive coil for a rechargeable IMD according to some examples of the present disclosure. Figure 7A As shown, the electrical conductor 71 is formed into a coil winding having a generally rectangular shape. The outermost winding of the electrical conductor 71 extends along a length dimension 74 and along a width dimension 75. The length dimension 74 has the same orientation as a longitudinal axis 76 extending across the receiving coil 70 parallel to the length dimension 74. A first end of the electrical conductor 71 is electrically coupled to a first lead 72. A second end of the electrical conductor 71 is electrically coupled to a second lead 73. The first lead 72 and the second lead 73 can extend to the receiving coil 70 and connect the receiving coil 70 to the recharging circuitry ( Figure 7A Not shown, but for example Figure 3This allows the current induced in the receive coil 70 by the magnetic field applied to the receive coil 70 to be used to recharge the power supply of the IMD coupled to the receive coil, or to power the operation of the device's circuitry.

[0082] like Figure 7A As shown, the windings of the receive coil 70 extending from the first lead 72 form the outermost windings of the receive coil, with additional windings gradually forming within the previous windings as the electrical conductor 71 extends toward the second lead 73. Thus, the overall thickness dimension of the receive coil 70 (e.g., the thickness dimension of the receive coil 70 perpendicular to both the length dimension 74 and the width dimension 75) can be the thickness of the diameter of the electrical conductor 71. In other words, the coil windings of the receive coil 70 can be configured as a flat, wound coil having a generally rectangular shape in both the length and width dimensions. Variations in the shape of the coil windings of the electrical conductor 71 can include rounded or curved corners where the direction of the electrical conductor changes from a longitudinal direction to a transverse direction, as illustratively shown by corner radius 78. Furthermore, the number of turns or windings included in the receive coil 70 is not limited to a specific number of turns and, in some examples, includes ten turns, where each turn includes a portion of the electrical conductor forming a four-sided winding of the receive coil 70.

[0083] like Figure 7A As shown, the first lead 72 and the second lead 73 are coupled to the electrical conductor 71 at the same corner of the coil winding, so that the first lead 72 and the second lead 73 extend from the coil winding in close proximity to each other. However, the positions of the first lead 72 and the second lead 73 are not limited to any particular arrangement, such as Figure 7A In some examples, leads 72 and 73 can extend from other locations of the coil winding of receive coil 70, including extending first lead 72 and second lead 73 from different portions of the coil winding such that the leads do not extend from portions of the receive coil that are immediately adjacent to each other.

[0084] The electrical conductor 71 is not limited to being formed from any particular type of material and can be formed from a conductive metal (such as copper) that is easily formed into a wire and can be easily bent to form the desired shape for forming the coil windings of the receiver coil 70. In some examples, the electrical conductor used to form the receiver coil 70 can include an insulating material (such as enamel) coated on the outer surface of the conductor to provide an insulation layer between the individual coil windings. In various examples, the electrical conductor used to form the receiver coil 70 is a multi-strand conductor (such as Litz wire), where the electrical conductor used to form each winding is insulated along the outer surface of the conductor using a coating (such as enamel) to reduce the skin effect of the conductor. The skin effect is a property of current flowing through an electrical conductor that causes the current to flow through the outer portion (e.g., the "skin" of the conductor) rather than through the inner portion of the conductor. The skin effect is more pronounced at higher frequencies. The use of Litz wire can help reduce the skin effect in the electrical conductor at higher frequencies.

[0085] An example of a receiving coil 70 may be maintained as Figure 7A The flat wound configuration shown is used as a receiving coil in an implantable medical device, such as the receiving coil 16 of the IMD 14. Figures 1 to 6C In other examples, the receiving coil 70 can be formed into a curved shape, such as Figure 7B When formed into a curved shape, the receiving coil 70 may or may not be attached to the ferrite sheet.

[0086] like Figure 7A As shown, in some examples, the outermost ring of the receiving coil 70 can be bent to form a rounded corner 78. For example, the receiving coil 70 can include one or more rounded corners 78 to conform to the battery housing 50 ( Figures 6A to 6C ) of the interior space, such as a bathtub-shaped housing 50. In some examples, a circular coil (e.g., a coil with rounded corners 78) may perform better mechanically than a rectangular coil with sharp corners.

[0087] like Figure 7B As shown, in some examples, the receiving coil 70 can be bent along the central longitudinal axis 76. Figure 5 In the example shown and described of a ferrite sheet 54, the amount of curvature of the receive coil 70 can be formed so that the receive coil 70 can be attached to the curved surface of the ferrite sheet. In the example where the receive coil 70 is not attached to the ferrite sheet, the receive coil 70 can be curved along the length of the longitudinal axis 76, as shown. Figure 7B For example, receiver coil 70 may be bent to conform to the curved interior surface of battery housing 50 of IMD 14 .

[0088] Figure 7C 1 shows electrical conductors 91 configured to form a receive coil 90 for an IMD according to various examples described in this disclosure. Figure 7C As shown, the electrical conductor 91 is formed into a coil winding having a circular or elliptical shape. The first end of the electrical conductor 91 is electrically coupled to the first lead 92 and the second end of the electrical conductor 91 is electrically coupled to the second lead 93. The first lead 92 and the second lead 93 can be configured to extend to the receiving coil 90 and connect the receiving coil 90 to the recharging circuit system ( Figure 7C Not shown in , but for example Figure 3 This allows the current induced into the receiving coil 90 by the magnetic field applied to the receiving coil 90 to be used to recharge the power supply of the implanted medical device coupled to the receiving coil, or to power the operation of the circuit system of the device.

[0089] like Figure 7C As shown, the windings of the receiving coil 90 extending from the first lead 92 form the outermost windings of the receiving coil, and as the electrical conductor 91 extends toward the second lead 93, additional windings are gradually formed within the previous windings. Therefore, the overall thickness dimension of the receiving coil 90 (e.g., the thickness dimension of the receiving coil 90) can be the thickness of the diameter of the electrical conductor 91. In other words, Figure 7C The coil windings of the illustrated receiver coil 90 can be configured as a flat-wound planar coil having a generally circular or elliptical shape. The number of turns or windings included in the receiver coil 90 is not limited to a particular number of turns, and in some examples includes ten turns, wherein each turn includes a portion of an electrical conductor forming a generally circular or elliptical winding of the receiver coil.

[0090] like Figure 7C As shown, the first lead 92 and the second lead 93 are coupled to the electrical conductor 91 at the same relative positions of the respective coil windings to which these leads are connected, so that the first lead 92 and the second lead 93 extend from the coil windings in close proximity to each other. However, the positions of the first lead 92 and the second lead 93 are not limited to any particular arrangement, for example Figure 7C In some examples, leads 92 and 93 can extend from other locations of the coil winding of receive coil 90, including extending first lead 92 and second lead 93 from different portions of the coil winding such that the leads do not extend from portions of the receive coil that are immediately adjacent to each other.

[0091] The electrical conductor 91 is not limited to being formed from any particular type of material and can be formed from any type of electrical conductor described above with reference to the electrical conductor 71, including conductive metals such as copper, that is easily formed into a wire and can be easily bent to form the desired shape for forming the coil windings of the receiving coil 70. In some examples, the conductor 91 is formed from any type of electrical conductor, including conductive metals such as copper. Figure 7C The electrical conductor of the receiver coil 90 in FIG. 1 may include an insulating material, such as enamel, coated on an outer surface of the conductor to provide an insulating layer between the individual coil windings. In various examples, the electrical conductor used to form the receiver coil 90 is a multi-strand conductor (e.g., Litz wire), wherein the electrical conductor used to form each winding is insulated along an outer surface of the conductor using a coating (e.g., enamel) to reduce the skin effect of the conductor.

[0092] Figure 8 is a top view of another exemplary rechargeable IMD 64 according to some examples of the present disclosure. Figure 8 In the example shown, the IMD 64 includes a tubular receiver coil 66, rather than the planar coil 16 shown in the previous example. Figure 9A and 9B As further depicted in FIG, the tubular coil 66 includes a plurality of coil loops or turns, each coil loop having the same shape and circumference as every other coil loop, wherein successive coil loops are stacked on top of each other, as shown in FIG. Figure 8 Measured along the z-axis.

[0093] Figure 9A Observed along line AA Figure 8 A cross-sectional view of an exemplary rechargeable IMD 64 is shown. Figure 9B BB observed along the line Figure 8 A cross-sectional view of an exemplary rechargeable IMD 64 is shown. Figure 9A and 9B As shown, the stacked coil windings of the tubular antenna 66 form a rectangular tubular shell extending upward along the z-axis. The rectangular shell defines an interior space into which the control circuitry 56, which may be coupled to the underside of the sapphire cover 52, may fit when the cover 52 is sealingly coupled to the housing 50.

[0094] Figure 10A yes Figure 8 An oblique view of an exemplary tubular receiving coil 66 is provided, and Figure 10B is a plan view. Specifically, Figure 10A and 10BSome exemplary dimensions of the tubular antenna 66 are depicted. For example, the tubular antenna 66 can include approximately 20 to 40 coils of wire, such as 36-gauge magnet wire. These coils can form a generally rectangular tube defining an outer length 78, measured along the x-axis, of approximately 1.22 to 1.26 inches; an inner length 80, measured along the x-axis, of approximately 1.20 to 1.24 inches; an outer width 82, measured along the y-axis, of approximately 0.264 to 0.268 inches; an inner width 84, measured along the y-axis, of approximately 0.244 to 0.248 inches; a first inner radius of curvature 86, of approximately 0.048 to 0.052 inches; a second inner radius of curvature 88, of approximately 0.028 to 0.032 inches; and a height 89, measured along the z-axis, of approximately 0.043 to 0.047 inches.

[0095] Figure 11 is a line graph depicting an exemplary mathematical relationship between magnetic field strength and the amount of power delivered to a rechargeable battery according to some examples of the present disclosure. Figure 11 As shown, under the applied magnetic field 26 ( Figure 2 ) and delivered to the rechargeable battery 32 ( Figure 3 ) there is an approximately linear relationship between the power delivered and the IMD 14. Thus, faster recharging may be achieved by applying a stronger magnetic field to receive coil 16. However, higher power delivery may also correspond to the generation of waste heat, which may need to be kept below a threshold level to avoid uncomfortable heating of IMD 14 when implanted in patient 12.

[0096] Figure 12 320 is a flow chart illustrating an exemplary method according to various examples described in the present disclosure. Method 320 includes a method for manufacturing a receive coil configuration for an IMD to be implanted in a patient according to the devices, systems, and techniques described herein. Method 320 is described as manufacturing a receive coil configuration for an IMD 14 ( Figure 1 ), the IMD 14 is designed to be implanted in a patient and includes a receive coil configuration configured to generate a recharge current when a magnetic field is applied to the antenna, the recharge current being used to recharge a power source (e.g., battery 32) of the device 14. However, the method 320 is not limited to manufacturing an implantable medical device 14 having the receive coil configuration shown and described, and may be applied to the manufacturing processes of various IMDs having receive coil configurations according to the examples described throughout this disclosure, and any equivalents thereof.

[0097] Method 320 includes forming a receive coil configuration for IMD 14 (block 322). The receive coil may include a coil winding formed of an electrical conductor as a helically wound planar coil, e.g., about Figures 7A to 7C The receiving coil 90 shown and described, or as a tubular coil, e.g. Figures 10A to 10BA receive coil 66 is shown and described.

[0098] The electrical conductor used to form the coil windings of the receive coil is not limited to any particular type of electrical conductor and can be any type of electrical conductor that can be used to form the receive coils described throughout this disclosure, including wires composed of conductive metals such as copper or stranded electrical conductors such as Litz wire. The coil windings can be formed using any technique that can be used to form receive coils, including any of the techniques described in this disclosure.

[0099] Reference again Figure 12 , method 320 includes attaching at least one receive coil of the antenna configuration to an inner surface of a portion of housing 50 of IMD 14 (block 326). In some examples, the portion of the housing including the inner surface is distinct from a separate cover portion 52. Attaching the at least one receive coil to the inner surface of housing 50 may include attaching the at least one receive coil directly to the inner surface such that coil windings forming the at least one receive coil are in contact with at least some portion of the inner surface. Attaching the at least one receive coil to the inner surface of the housing may include attaching the at least one receive coil to a first surface of a flexible ferrite sheet 54 (block 324), and then attaching a second surface of the ferrite sheet 54, opposite the first surface, to the inner surface of the housing such that the ferrite sheet is positioned between the inner surface and the coil windings of the at least one receive coil (block 326).

[0100] Attaching at least one receive coil to the inner surface of the housing can include attaching a plurality of receive coil windings directly to the inner surface of the housing 50 (e.g., without intervening ferrite sheet 54). In some examples, the plurality of receive coils includes a plurality of flat spirally wound coils forming a planar antenna. In some examples, the plurality of receive coils includes a plurality of stacked coils forming a tubular antenna. Attaching at least one receive coil to the inner surface of the housing can include positioning a second receive coil within an inner cavity at least partially surrounded by the inner surface.

[0101] Method 320 includes electrically coupling one or more receive coils of the receive coil configuration to recharging circuitry 30 of device 14 (block 328). Coupling the receive coil configuration may include coupling a first lead of each receive coil to a separate diode and coupling a second lead of each receive coil to a common voltage conductor. In the example of a receive coil configuration including multiple receive coils, coupling the receive coil configuration to recharging circuitry 30 may include coupling each receive coil to circuitry including an electrical diode so that any current generated in any receive coil can be added together to generate a recharging current, the recharging current comprising the sum of the currents generated by any and all receive coils at any given time.

[0102] Method 320 includes coupling the portion of housing 50 including the receive coil configuration to one or more additional portions of the housing of the implantable medical device (block 330). Coupling the portion of the housing including the receive coil configuration to the additional portion of the housing may include coupling cover 52 to housing portion 50. In some examples, method 320 may include forming control circuitry configured to control one or more functions of IMD 14 onto an inner surface of cover 52 before coupling cover 52 to the remainder of housing 50. Method 320 includes sealing the portion of the housing to cover 52 to create a sealed interior cavity including the receive coil configuration. Coupling housing 50 to cover 52 may include forming a sealed joint between the bottom side of cover 52 and housing portion 50 of IMD 14. Sealing the housing portion and / or antenna window may include using any material, such as an adhesive, and / or any type of welding or bonding process that can be used to provide a hermetic seal between the type of material used to form the housing portion and the type of material used to form cover 52.

[0103] The use of the devices, systems, and techniques described in this disclosure is not limited to use in a device solely during a recharging session applied to the device. Examples of receive coil configurations as described throughout this disclosure, or any equivalent thereof, may be included as part of a passive device. In some instances, a passive device may not include an internal power source capable of storing electrical energy for extended periods of time during which the device may be required to operate. The device may receive power from the external device, for example, via inductive coupling of electrical energy provided by an external device, to operate only during the time and period or time period when the device is energized from the external power source. When operating a passive device, the external device may include an external recharging coil that is configured to be energized to generate a magnetic field that is applied to a receive coil configuration incorporated within or coupled to the passive device. The applied magnetic field generates one or more currents in the receive coil configuration of the passive device, and additional circuitry of the passive device is configured to receive these induced currents to power and operate the passive device. These currents induced in the receive coil configuration may be referred to as "operating currents" because they are used to power and operate the passive implantable medical device.

[0104] Once powered by the induced current, the IMD can perform various functions, including sensing physiological parameters associated with the patient in order to monitor and / or diagnose the patient's condition, and / or providing treatment such as electrical stimulation therapy to the patient while powering the passive device through an applied magnetic field. In some cases, the need to operate the passive device may only require powering the device within short time intervals (e.g., a period of thirty minutes) and only periodically (e.g., once a day or once a week or once a month in other instances). By eliminating the need to locate the power supply within or as part of the passive device, the overall size and / or dimensions of the passive device can be reduced relative to similar devices that include a power supply as part of the device. The smaller size of the passive device can allow for less invasive implantation to implant the passive device at the implant site, and can contribute to patient comfort after implantation of the device due to the smaller size of the implantable device.

[0105] The technology of the present disclosure can be implemented in a variety of computing devices, medical devices or any combination thereof. Any of the units, modules or components described can also be implemented together or individually as discrete but interoperable logic devices. Depicting different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be implemented by separate hardware or software components. On the contrary, the functions associated with one or more modules or units can be performed by separate hardware or software components, or integrated in shared or separate hardware or software components.

[0106] The techniques described in this disclosure may be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, various aspects of the techniques may be implemented within one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combination of these components, embodied in a programmer (e.g., a physician or patient programmer), a stimulator, or other device. The terms "processor," "processor circuitry," "processing circuitry," "controller," or "control module" may generally refer to any of the aforementioned logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry, alone or in combination with other digital or analog circuitry.

[0107] For various aspects implemented in software, at least some of the functionality attributed to the systems and devices described in this disclosure may be embodied as instructions on a tangible computer-readable storage medium (e.g., random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), electrically erasable programmable read-only memory (EEPROM), flash memory, magnetic media, optical media, etc.). Computer-readable storage media may be referred to as non-transitory. A server, client computing device, or any other computing device may also contain a more portable type of removable memory to enable easy data transfer or offline data analysis. The instructions may be executed to support one or more aspects of the functionality described in this disclosure.

[0108] In some instances, computer-readable storage media include non-transitory media. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier wave or propagated signal. In some instances, non-transitory storage media may store data that may change over time (e.g., in RAM or cache).

[0109] Various aspects of the disclosure have been described. These and other aspects are within the scope of the following claims.

Claims

1. An implantable medical device comprising: a rechargeable battery comprising a battery housing; a non-metallic substrate attached to the battery housing, wherein the non-metallic substrate and the battery housing form an outer housing of the implantable medical device; control circuitry formed on the non-metallic substrate and located within the outer housing of the implantable medical device, wherein the control circuitry is configured to control operation of the implantable medical device; a receiving coil within the outer housing of the implantable medical device, the receiving coil being configured to receive energy from outside the outer housing of the implantable medical device; and A recharging circuit system is within the outer body of the implantable medical device and coupled to the receiving coil, the recharging circuit system being configured to receive the energy from the receiving coil and use the received energy to recharge the rechargeable battery.

2. The implantable medical device of claim 1, wherein the implantable medical device comprises a cardiac monitor and the control circuit system is configured to monitor at least one cardiac parameter of the patient.

3. The implantable medical device of claim 1, wherein the non-metallic substrate comprises sapphire.

4. The implantable medical device of any of the preceding claims, wherein the rechargeable battery extends a majority of the length and width of the outer housing, and wherein the receiver coil is positioned between the battery housing and the non-metallic substrate.

5. The implantable medical device of claim 4, wherein the receiving coil comprises dimensions of approximately 6 mm x 4 mm x 1.3 mm.

6. The implantable medical device of claim 4, wherein the receive coil extends a majority of the length and the width of the outer housing.

7. The implantable medical device of claim 6, wherein the receiving coil comprises dimensions of approximately 33 mm x 7 mm x 0.4 mm.

8. The implantable medical device of claim 1 , wherein the receiving coil and the rechargeable battery each extend a respective portion of the length of the outer housing, and wherein the receiving coil and the rechargeable battery are substantially coplanar.

9. The implantable medical device of claim 1, 2, or 3, wherein the receiving coil comprises dimensions of approximately 1.7 mm x 6.5 mm x 15 mm to 25 mm.

10. The implantable medical device of any one of claims 1-3, wherein the receiving coil is attached to a ferrite sheet.

11. The implantable medical device of claim 10, wherein the ferrite sheet is formed of a flexible material.

12. The implantable medical device of any one of claims 1-3, wherein the receiving coil comprises a helically wound planar coil.

13. The implantable medical device of claim 9, wherein the receiving coil is bent to conform to an inner surface of the battery housing.

14. The implantable medical device of any one of claims 1 to 3, wherein the receiving coil comprises a helically wound tubular coil.

15. A system for recharging a rechargeable battery in an implantable medical device implanted in a patient, the system comprising: power supply; at least one external recharging coil coupled to the power source and configured to generate a magnetic field having a magnetic field direction when energized by the power source; and An implantable medical device according to any one of the preceding claims.

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