Multi-directional energy harvester for implantable devices

Abstract

An energy harvesting mechanism for an implantable device is provided. In some embodiments, an apparatus includes a housing configured for implantation in a patient. The housing may have a proximal end, a distal end, and a longitudinal axis extending between the proximal end and the distal end. The apparatus may also include a power source positioned within the housing, and an energy harvesting mechanism positioned within the housing and configured to charge the power source. The energy harvesting mechanism may include a plurality of piezoelectric elements aligned with a longitudinal axis of the housing. Each piezoelectric element may face a different direction.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 496,471, filed April 17, 2023, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present technology relates generally to medical devices, and in particular to multi-directional energy harvesters for implantable devices. BACKGROUND

[0003] Various types of implantable medical devices have been developed for monitoring or treating one or more conditions of a patient. For example, a cardiac pacemaker can monitor the heart activity of a patient and provide therapeutic electrical stimulation to the heart via electrodes. The electrical stimulation provided by a cardiac pacemaker can include signals such as pacing pulses to address abnormal heart rhythms (e.g., bradycardia). Some types of cardiac pacemakers are implanted at a distance from the heart and are coupled to one or more leads that extend intravascularly into the heart to position electrodes in contact with heart tissue. However, the leads can be susceptible to breakage, which can result in unreliable or incorrect pacing and can require replacement of the leads or even the entire pacemaker.

[0004] Some types of cardiac pacemakers are sized to be implanted entirely in one of the chambers of the heart and can include electrodes integrated with or attached to a device housing rather than leads. Such pacemakers can be less invasive than traditional pacemakers and can avoid complications associated with lead breakage. However, the relatively small size of such pacemakers can limit the types of power sources that can be incorporated into the device. BRIEF DESCRIPTION OF DRAWINGS

[0005] Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Instead, emphasis is placed on clearly illustrating the principles of the present disclosure.

[0006] FIG. 1 A pacing device implanted in the heart of a patient is illustrated in accordance with embodiments of the present technology.

[0007] FIG. 2 is a perspective view of a pacing device configured in accordance with embodiments of the present technology.

[0008] FIG. 3 is a side view of another pacing device configured in accordance with embodiments of the present technology.

[0009] FIG. 4 is a schematic block diagram illustrating electronic components of a pacing device configured in accordance with embodiments of the present technology.

[0010] FIG. 5Ais a cross-sectional side view of a device including an energy harvesting mechanism according to embodiments of the present technology.

[0011] FIG. 5B is a perspective view of an energy harvesting mechanism of FIG. 5A

[0012] FIG. 5C is a partial schematic view of an energy harvesting mechanism in a flat configuration of FIG. 5A

[0013] FIG. 5D is a cross-sectional end view of an energy harvesting mechanism of FIG. 5A

[0014] FIG. 6 is a partial schematic end view of an energy harvesting mechanism in a plurality of different orientations according to embodiments of the present technology.

[0015] FIG. 7A is a partial schematic view of an energy harvesting mechanism in a flat configuration according to embodiments of the present technology.

[0016] FIG. 7B is a cross-sectional end view of an energy harvesting mechanism of FIG. 7A

[0017] FIG. 8A is a cross-sectional side view of a device including an energy harvesting mechanism according to embodiments of the present technology.

[0018] FIG. 8B is a perspective view of an energy harvesting mechanism of FIG. 8A

[0019] FIG. 8C is a top view of an energy harvesting mechanism of FIG. 8A

[0020] FIG. 8D is a side view of an energy harvesting mechanism of FIG. 8A

[0021] FIG. 8E is an end view of an energy harvesting mechanism of FIG. 8A

[0022] FIG. 9 is a perspective view of an energy harvesting mechanism configured according to embodiments of the present technology. DETAILED DESCRIPTION

[0023] ​​​​​​​​The present technology relates to energy harvesters for implantable devices. In some embodiments, for example, a device includes a housing configured for implantation within a patient (e.g., within a single chamber of a patient’s heart). The housing can have a proximal end, a distal end, and a longitudinal axis extending between the proximal end and the distal end. The device can include a power source positioned within the housing to power various operations (e.g., to provide electrical stimulation to the patient). The device can also include an energy harvesting mechanism positioned within the housing and configured to charge the power source. The energy harvesting mechanism can include a plurality of piezoelectric elements aligned with the longitudinal axis of the housing and that generate energy when mechanically deflected by physiological motion (e.g., cardiac motion) of the patient. In some embodiments, the piezoelectric elements are arranged to face in different directions and / or have different principal bending directions, providing efficient energy harvesting for many different input motion directions.

[0024] The present technology can provide a number of advantages over conventional approaches for powering implantable devices. For example, the use of kinetic energy harvesters that generate electrical energy from physiological motion as described herein can extend the lifetime of implantable devices by allowing for recharging in situ within the patient’s body. Conventional energy harvesters, however, often exhibit direction dependence in that the power output of the harvester is significantly affected by the orientation of the harvester relative to the direction of motion. For example, a piezoelectric beam typically generates maximum power when the direction of motion is perpendicular to the plane of the beam, resulting in maximum deflection of the beam. If the beam is not properly aligned with the direction of motion (e.g., the direction of motion is parallel to the plane of the beam), the beam can exhibit little or no deflection, resulting in negligible power output. Physiological motion, however, is often multidirectional and can vary over time (e.g., depending on the patient’s posture, activity, anatomy, etc.), making it difficult or impossible to predict the optimal alignment of the implantable device for energy harvesting purposes.

[0025] To address these and other challenges, the present technology provides implantable devices configured for harvesting energy from multiple directions of motion with high efficiency. In some embodiments, the energy harvesting mechanisms herein include a plurality of piezoelectric elements that are geometrically arranged such that the power output of each element is enhanced (e.g., maximized) for different directions of motion. In other words, each piezoelectric element can be oriented in a different direction such that for any direction of motion, at least one of the piezoelectric elements is “active” and exhibits significant deflection. This approach can increase the robustness of the energy harvesting mechanism to different directions of motion, thereby increasing the longevity and / or broadening the potential inclusion criteria of applicability of the implantable device. Additionally, the present technology allows implantation procedures to not need to consider the alignment of the device, which can reduce the complexity and duration of the implantation procedure. Furthermore, the embodiments herein can use a plurality of piezoelectric elements arranged in a folded and / or overlapping configuration to reduce the spatial requirements while also maintaining a low resonant frequency compatible with the frequencies present in physiological motion, thereby allowing the energy harvesting mechanism to be used for implantable devices with strict size limitations (e.g., devices implanted in a single heart chamber).

[0026] Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which like numerals refer to like elements throughout several figures, and in which an exemplary embodiment is shown. Embodiments of the claims may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The examples set forth herein are non-limiting examples and are merely examples of other possible examples.

[0027] As used herein, the terms “vertical,” “lateral,” “upper,” and “lower” can refer to the relative orientation or position of features of the embodiments disclosed herein in view of the orientation shown in the figures. For example, “upper” or “uppermost” can designate a feature positioned closer to the top of the page than another feature. However, these terms should be broadly construed to include embodiments having other orientations, such as inverted or tilted orientations, in which top / bottom, over / under, up / down, upper / lower, and left / right can be interchanged depending on the orientation.

[0028] The headings provided herein are solely for convenience of reference and do not interpret the extent or meaning of the technology claimed or sought to be protected. Embodiments under any one heading can be used in combination with embodiments under any other heading.

[0029] I. Overview of Implantable Pacing Device

[0030] FIGS. 1-4 An overview of implantable devices configured in accordance with embodiments of the present technology is provided. In particular, FIG. 1 A pacing device implanted in a patient’s heart is exemplified,FIG. 2 An example configuration of a pacing device is illustrated, FIG. 3 Another example configuration of a pacing device is illustrated, and FIG. 4 Electronic components that can be included in a pacing device are illustrated. FIGS. 1-4 Any feature of an embodiment can be combined with any other embodiment and / or with any other embodiment described herein.

[0031] Reference is first made to FIG. 1 which illustrates a pacing device 100 implanted in a heart H of a patient, the device 100 being configured to monitor activity of the heart H and to provide electrical stimulation (e.g., pacing signals) to the heart H. In some embodiments, the device 100 is a leadless cardiac pacemaker configured to be implanted entirely within a chamber of the heart, such as entirely within a right atrium (RA), entirely within a right ventricle (RV), entirely within a left atrium (LA), or entirely within a left ventricle (LV). The device 100 can be implanted at any of a variety of locations to sense and / or deliver therapy to any one or more chambers of the heart H. For example, as shown in FIG. 1 the device 100 can be a right atrial cardiac pacemaker implanted in a target implant region T (e.g., the Koch triangle) in the RA of the heart H of the patient. The target implant region T can be located between the bundle of His and the coronary sinus, and / or can be adjacent to the tricuspid valve. In other embodiments, the device 100 can instead be configured as a right ventricular cardiac pacemaker implanted in the RV of the heart H, with the target implant region T located at or near the apex of the RV along the endocardial wall.

[0032] The device 100 can include a housing 102 having a size and shape factor suitable for transvenous delivery to the heart H via a catheter. In the illustrated embodiment, the housing 102 has an elongated shape extending from a distal portion 104 to a proximal portion 106. The housing 102 can have a generally cylindrical shape (e.g., a pill or capsule shape), a generally prismatic shape (e.g., a rectangular prism), or any other suitable shape. The housing 102 can define an internal cavity that houses electronic components (e.g., circuitry, power source, sensors) of the device 100.

[0033] Device 100 can include a fixation mechanism 108 to secure device 100 to tissue of heart H. For example, fixation mechanism 108 can include one or more fixation elements configured to penetrate into tissue, such as one or more prongs, coils, barbs, etc. In the illustrated embodiment, fixation mechanism 108 is coupled to and extends outwardly from distal portion 104 of housing 102. Thus, when device 100 is implanted, distal portion 104 can be positioned in contact with or in close proximity to heart tissue, while proximal portion 106 can be spaced apart from heart tissue. However, in other embodiments, fixation mechanism 108 can be located at a different portion of device 100.

[0034] Device 100 also includes a plurality of electrodes configured to sense electrical activity of heart H and / or deliver electrical therapy to heart H. For example, device 100 can include two, three, four, five, six, seven, eight, nine, ten, or more electrodes. Each electrode can be positioned at any suitable portion of device 100, such as on or coupled to housing 102 (e.g., distal portion 104, proximal portion 106, an intermediate location between distal portion 104 and proximal portion 106), or on or coupled to fixation mechanism 108. In some embodiments, device 100 includes one or more electrodes (e.g., cathodes) that directly contact heart tissue (e.g., of a single heart chamber or of multiple heart chambers) to sense activity thereof and / or deliver electrical therapy thereto. For example, such electrodes can be located at distal portion 104 of housing 102 and / or incorporated into fixation mechanism 108. Device 100 can also include at least one electrode (e.g., an anode and / or a return electrode) that does not directly contact heart tissue. Such electrodes can be located at a portion of housing 102 that is spaced apart from heart tissue, such as proximal portion 106. Optionally, a single electrode can be used as a cathode for certain operations, and can be used as an anode and / or return electrode for other operations.

[0035] In some embodiments, device 100 communicates via bidirectional wireless communication (such as Bluetooth ®An external device 110 (shown schematically) can be operably coupled to the device 100 (e.g., via wireless telemetry via RF circuitry, Wi-Fi, medical implant communication service (MICS), or other RF communication techniques). The external device 110 can be a computing device or system located outside the patient's body and can be used in a healthcare environment (e.g., in a clinic, hospital, or other medical facility), in the patient's home, or suitable combinations thereof. The external device 110 can be configured to control various operational parameters of the device 100, such as therapy parameters (e.g., pacing control parameters such as pacing interval), sensing parameters, power management parameters, and the like. For example, the external device 110 can transmit control signals to the device 100 to program one or more operational parameters of the device 100. Optionally, the external device 110 can display information related to and / or received from the device 100, such as intracardiac electrogram (EGM) signals obtained by the device 100, motion sensor signals acquired by the device 100, operational parameters of the device 100, and the like. In some embodiments, the external device 110 transmits information received from the device 100 to another computing device or system (e.g., a computer, laptop, workstation, mobile device, server, remote patient management system) for display, processing, and / or storage using any suitable wired or wireless communication techniques. The external device 110 can serve as a "programmer" that allows an physician, patient, or other individual to monitor and / or control the operation of the device 100.

[0036] Although FIG. 1 A single device 100 is illustrated, but the present technology is also applicable to an implantable system that includes multiple devices 100 implanted at different locations in the heart H. For example, the implantable system can include a first device 100 in the RA and a second device 100 in the RV. In such embodiments, each device 100 can independently have any of the features described herein.

[0037] FIG. 2 is a perspective view of a pacing device 200 configured in accordance with embodiments of the present technology. The device 200 is configured for implantation within a chamber of a patient's heart to monitor activity of the heart and / or to provide electrical therapy (e.g., pacing therapy) to the heart. The device 200 includes a housing 202 having a size and shape factor that allows the device 200 to be implanted entirely within a single chamber of a patient's heart. In the illustrated embodiment, the housing 202 has an elongated shape (e.g., a generally cylindrical shape, a generally prismatic shape) extending between a distal end 204 and a proximal end 206. The housing 202 can define a hermetically sealed interior cavity for housing the electronic components of the device 200. The housing 202 can also include an attachment mechanism 208 (e.g., at the proximal end 206) configured for temporary engagement with a delivery tool during implantation and / or extraction of the device 200.

[0038] The housing 202 may be formed partially or entirely of a conductive material, such as titanium or titanium alloys, stainless steel, MP35N (a non-magnetic nickel-cobalt-chromium-molybdenum alloy), platinum alloys, or other biocompatible metals or metal alloys, or other suitable conductive materials. Alternatively or in combination, the housing 202 may be formed partially or entirely of a non-conductive (e.g., insulating) material, such as ceramics, glass, sapphire, silicone, polyurethane, epoxy resin, acetyl copolymer plastics, polyetheretherketone (PEEK), liquid crystal polymers, other biocompatible polymers, or other suitable non-conductive materials.

[0039] Device 200 may include a plurality of electrodes 210a-210c configured to sense electrical activity of the heart and / or deliver electrical stimulation to the heart. In an illustrative embodiment, for example, device 200 includes a first electrode 210a and a second electrode 210b at or near the distal end 204 of housing 202, and a third electrode 210c on housing 202. The first electrode 210a and the second electrode 210b may be configured as cathodes that directly contact cardiac tissue; for example, the distal end of the first electrode 210a may be configured to rest within the ventricular myocardium of a patient, and the second electrode 210b may be configured to contact the atrial endocardium of a patient. The third electrode 210c may be configured as an anode and / or a return electrode that does not directly contact cardiac tissue.

[0040] like FIG. 2 As shown, the first electrode 210a may be an elongated structure extending from the distal end 204 of the housing 202 to penetrate the wall tissue of a first cardiac chamber (e.g., the chamber in which the device 200 is implanted) and enter the wall tissue of a different second cardiac chamber. For example, in some embodiments, the device 200 is implanted in the RA, wherein the distal end 204 is oriented toward the LV (e.g., similar to...). FIG. 1The first electrode 210a can be configured to extend through the wall tissue of the RA and into the wall tissue of the LV. In the illustrated embodiment, the first electrode 210a is configured as a coil (e.g., a helical coil and / or a spiral coil), while in other embodiments the first electrode 210a can have a different form factor (e.g., an elongated dart, barb, fork, or other tissue penetrating element). The first electrode 210a can include a proximal end coupled to the distal end 204 of the housing 202, and a free distal end not attached to the housing 202. The distal end of the first electrode 210a can have a conical, hemispherical, or beveled edge distal tip with a narrow tip diameter (e.g., less than 1 mm) for penetrating into and through tissue layers. In some embodiments, the distal end of the first electrode 210a can have a sharp or angled tip and / or a sharp or beveled edge, although the sharpness can be constrained to avoid cutting action that can cause lateral displacement of the distal end of the first electrode 210a and undesirable tissue trauma.

[0041] The second electrode 210b can be a structure extending from the distal end 204 of the housing 202 to contact the wall tissue of the first heart chamber without penetrating the wall tissue. The second electrode 210b can be located proximally of the first electrode 210a. The second electrode 210b can be configured as a coil (e.g., a partial helical and / or spiral coil that does not form a complete turn), a ring, a button, a pad, or any other suitable form factor. The second electrode 210b can include a proximal end coupled to the distal end 204 of the housing 202, and can or can not be coupled to the distal end of the housing 202. In some embodiments, the second electrode 210b is configured to flexibly maintain contact with the wall tissue (e.g., the RA endocardium) of the heart chamber in which the device 200 is implanted, despite changes in distance in the tissue surface and / or between the distal end 204 of the housing 202 and the tissue surface, which can occur as the wall tissue moves during the cardiac cycle. Thus, the second electrode 210b can be flexible and / or have spring-like properties, e.g., the second electrode 210b can have a spring bias that urges at least a portion of the second electrode 210b away from the distal end 204 of the housing 202 and toward the wall tissue of the heart chamber to maintain consistent contact.

[0042] The first electrode 210a and the second electrode 210b can be formed of a conductive material, such as titanium, platinum, iridium, tantalum, or alloys thereof, respectively. The first electrode 210a can include one or more insulative coatings (e.g., parylene, polyurethane, silicone, epoxy) that reduce the conductive surface area of the first electrode 210a to define a first electroactive region 212 (e.g., at or near the distal end of the first electrode 210a). The second electrode 210b can include one or more insulative coatings (e.g., parylene, polyurethane, silicone, epoxy) that reduce the conductive surface area of the second electrode 210b to define a second electroactive region 214 (e.g., at an intermediate region between the proximal and distal ends of the second electrode 210b). This approach can increase the electrical impedance of the first electrode 210a and the second electrode 210b, and thereby reduce the current delivered during pacing pulses, which can conserve power used by the device 200. In some embodiments, the first electrode 210a and the second electrode 210b include a coating of conductive material (e.g., TiN) over the first electroactive region 212 and the second electroactive region 214, respectively, to define the active regions. The first electrode 210a and the second electrode 210b can be made of the same material, or can be made of different materials.

[0043] During pacing and / or sensing, all, substantially all, or a portion of the housing 202 can function as the third electrode 210c (e.g., an anode and / or a return electrode). In some embodiments, the third electrode 210c partially or completely encircles a portion of the housing 202 at or near the proximal end 206. Although FIG. 2 The third electrode 210c is illustrated as a single band, but in other embodiments, the third electrode 210c can include multiple segments spaced apart by a distance along the longitudinal axis 216 of the housing 202 and / or around the perimeter of the housing 202. Additionally, the third electrode 210c can also be located at other locations along the housing 202, such as at or near the distal end 204 or at other locations along the longitudinal axis 216.

[0044] In embodiments where the housing 202 is formed of an electrically conductive material, one or more portions of the housing 202 can be electrically insulated by a coating of a non-conductive material, such as parylene, polyurethane, silicone, epoxy, or other biocompatible polymer or other suitable material. For portions of the housing 202 that do not have a non-conductive material, one or more discrete regions of the housing 202 having an electrically conductive material can be exposed to define the third electrode 210c. In embodiments where the housing 202 is formed of a non-conductive material, an electrically conductive material can be applied to one or more discrete regions of the housing 202 to form the third electrode 210c. Optionally, the third electrode 210c can be a discrete component (e.g., a ring electrode) coupled to the housing 202.

[0045] The electrodes 210a-210c can be used to sense electrical activity of one or more chambers of the heart and / or deliver electrical stimulation to one or more chambers of the heart. For example, the first electrode 210a can be paired with the second electrode 210b or the third electrode 210c for sensing ventricular signals and delivering ventricular pacing pulses. As another example, the second electrode 210b can be paired with the first electrode 210a or the third electrode 210c for sensing atrial signals and delivering pacing pulses to atrial myocardium. In yet another example, the third electrode 210c can be paired with both the first electrode 210a and the second electrode 210b at different times for ventricular or atrial functions, respectively. As still another example, the first electrode 210a and the second electrode 210b can be paired with each other in different polarities for atrial and ventricular functions.

[0046] In some embodiments, the second electrode 210b is configured as an atrial cathode electrode for delivering pacing pulses to atrial tissue at a target implant region in conjunction with the third electrode 210c. The second electrode 210b and the third electrode 210c can also be used to sense atrial P-waves for controlling atrial pacing pulses (e.g., delivered in the absence of a sensed P-wave) and for controlling atrial synchronous ventricular pacing pulses delivered using the first electrode 210a as a cathode and the third electrode 210c as a return anode. FIG. 2 The illustrated configuration of the electrodes 210a-210c allows the device 200 to sense cardiac signals from one or more chambers of the heart and / or deliver cardiac pacing to one or more chambers of the heart. For example, the present technology can facilitate the delivery of A-V synchronous pacing using a single device 200 implanted within a single chamber of the heart (e.g., the RA).

[0047] Device 200 may include a fixation mechanism 218 configured to secure device 200 to cardiac tissue at a target implantation region (e.g., Koch's triangle). In an illustrated embodiment, a first electrode 210a and / or a second electrode 210b at the distal end 204 of housing 202 may serve as fixation mechanism 218. In other embodiments, fixation mechanism 218 may be a component distinct from the first electrode 210a and / or the second electrode 210b, such as one or more separate barbs, forks, coils, darts, etc.

[0048] FIG. 3 This is a side view of another pacing device 300 configured according to an embodiment of the present technology. Device 300 is configured for implantation within a cavity of a patient's heart to monitor cardiac activity and / or provide electrical therapy to the heart. FIG. 3 In the illustrated embodiment, the device 300 includes a housing 302, a plurality of fixed forks 304, a first electrode 306a, and a second electrode 306b.

[0049] The housing 302 may have size and shape factors that allow the device 300 to be fully implanted within a cavity in the patient's heart. For example, as FIG. 3 As shown, housing 302 has an elongated shape factor that is generally cylindrical (e.g., spherical or capsule-shaped) extending between the distal end 308 and the proximal end 310. Housing 302 houses the electronic components of device 300 and can be hermetically or nearly hermetically sealed to prevent fluid from entering housing 302. The materials used to form housing 302 may include those described above relative to... FIG. 2 The conductive material or the non-conductive material.

[0050] Device 300 may include a fixation mechanism configured to secure device 300 to cardiac tissue at a target implantation region (e.g., the endocardial wall near the apex of the RV). In an illustrated embodiment, device 300 includes a plurality of fixation forks 304 extending from a distal end 308 of housing 302 and configured to engage with cardiac tissue to secure housing 302 in a fixed position within the heart's ventricles. The fixation forks 304 may be configured to anchor housing 302 to cardiac tissue such that device 300 moves with cardiac tissue during cardiac contraction. Device 300 may include any suitable number of fixation forks 304, such as one, two, three, four, five, or more. The fixation forks 304 may be made of any suitable material, such as shape memory materials (e.g., nitinol). Alternatively or in combination, device 300 may be secured to cardiac tissue using other types of fixation mechanisms, such as, but not limited to, barbs, coils, darts, etc.

[0051] Optionally, the device 300 can include an attachment mechanism configured for temporarily coupling the device 300 to a delivery tool, e.g., for delivery and / or retrieval of the device 300. In the illustrated embodiment, for example, the proximal end 310 includes a flange 318 defining an opening. The flange 318 can be attached to a tether extending through an elongated shaft (e.g., a catheter) (e.g., by threading the tether through the opening) to implant or retrieve the device 300.

[0052] In some embodiments, the device 300 is configured for sensing electrical activity of the heart and / or delivering electrical stimulation to the heart via the first electrode 306a and the second electrode 306b (collectively, “electrodes 306”). The first electrode 306a can function as a cathode configured for electrically contacting heart tissue and delivering pacing pulses thereto, and the second electrode 306b can function as an anode and / or a return electrode. Optionally, the device 300 can be equipped with a plurality of cathode electrodes. Such a plurality of cathode electrodes can be configured for electrically contacting heart tissue of a single heart chamber or heart tissue of a plurality of heart chambers, and delivering pacing pulses to the heart tissue of the single heart chamber or the heart tissue of the plurality of heart chambers. In some such embodiments, the plurality of cathode electrodes are configured for electrically contacting heart tissue of different heart chambers, and delivering pacing pulses to the heart tissue of the different heart chambers. For example, one cathode electrode can be configured for electrically contacting atrial tissue and delivering pacing pulses thereto, and another cathode electrode can be configured for electrically contacting ventricular tissue and delivering pacing pulses thereto.

[0053] The electrodes 306 can be configured in a number of different ways. For example, one or both of the electrodes 306 can be a discrete component mechanically coupled to the housing 302. As another example, one or both of the electrodes 306 can be defined by an electrically conductive outer portion of the housing 302. The electrodes 306 can be electrically isolated from one another. In some embodiments, a portion of the housing 302 is covered by or formed from an insulating material to isolate the electrodes 306 from one another and / or to provide a desired size and shape for one or both of the electrodes 306. The electrodes 306 can be electrically coupled to at least some of the internal electronic components of the device 300 within the housing 302 (e.g., sensing circuitry, electrical stimulation circuitry, or both).

[0054] In the illustrated embodiment, the first electrode 306a is located at the distal end 308 of the housing 302. The first electrode 306a can be referred to as a tip electrode, and the fixation fork 304 can be configured to anchor the device 300 to cardiac tissue such that the first electrode 306a is maintained in contact with the cardiac tissue. In some examples, the housing 302 includes an endcap 312 at the distal end 308, and the endcap 312 includes a feedthrough assembly to electrically couple the first electrode 306a to electronics within the housing 302 while electrically isolating the first electrode 306a from the rest of the housing 302, e.g., including the second electrode 306b and / or other electrically conductive portions of the housing 302.

[0055] The second electrode 306b can be located on the housing 302 distally from the first electrode 306a, e.g., proximally of the first electrode. As shown, the housing 302 includes a first portion 314 and a second portion 316, with the first portion 314 located proximally of the endcap 312 and the second portion 316 located proximally of the first portion 314. The second portion 316 can optionally define at least a portion of a power source compartment that houses a power source, e.g., a battery, of the pacing device 300. In some embodiments, the second electrode 306b is located on the second portion 316, while in other embodiments, the second electrode 306b is located on the first portion 314. FIG. 3

[0056] In some embodiments, the second electrode 306b is an electrically conductive portion of the housing 302, e.g., a ring-shaped portion of the housing 302 that is partially or entirely made of an electrically conductive material. Additionally or alternatively, the second electrode 306b can be an electrically conductive material coated onto the material of the housing 302, or a discrete component coupled to the housing 302, e.g., a ring electrode. The remainder of the housing 302 can include or be coated with an insulating material such that the second electrode 306b is electrically isolated from the remainder of the housing 302 and / or from the first electrode 306a.

[0057] FIG. 4 is a schematic block diagram of electronic components of a pacing device 400 configured in accordance with embodiments of the present technology. FIG. 4 Any of the electronic components shown can be incorporated into any of the embodiments of implantable devices described herein, such as FIG. 1 the device 100 of FIG. 2 the device 200, or FIG. 3 the device 300.

[0058] As FIG. 4 ​As shown, the device 400 includes a plurality of electrodes 402a-402c electrically coupled to components within a housing 404 of the device 400. Although the device 400 is exemplified and described herein as having three electrodes 402a-402c (e.g., similar to the device 200 of FIG. 2 ), in other embodiments, the device 400 can be modified to include a different number of electrodes, such as two electrodes (e.g., similar to the device 300 of FIG. 3 ) or any other suitable number of electrodes.

[0059] At least some of the electrodes 402a-402c can be configured to contact tissue of one or more heart chambers, as described elsewhere herein. For example, as discussed above with respect to FIG. 2 , the first electrode 402a can be configured to electrically contact tissue of a first heart chamber (e.g., ventricular tissue) and deliver electrical signals to that tissue, and the second electrode 402b can be configured to electrically contact tissue of a different second heart chamber (e.g., atrial tissue) and deliver electrical signals to that tissue. The third electrode 402c can be an anode and / or a return electrode that does not electrically contact heart tissue. Optionally, the first electrode 402a or the second electrode 402b can be omitted, or the device 400 can include additional electrodes that electrically contact tissue of a heart chamber (e.g., the first heart chamber, the second heart chamber, or another heart chamber) and deliver electrical signals to that tissue.

[0060] The device 400 includes a plurality of electronic components within the housing 404, such as a switching circuit 406, a sensing circuit 408, a therapy generation circuit 410, one or more sensors 412, a processing circuit 414, a communication circuit 416, a memory 418, and / or a power source 420. The various circuits can be programmable or fixed function circuits or include programmable or fixed function circuits configured to perform the operations described herein. FIG. 4 One or more components of the device 400 as shown can be part of an electronics assembly. For example, one or more of the switching circuit 406, the sensing circuit 408, the therapy generation circuit 410, the sensors 412, the processing circuit 414, the communication circuit 416, and / or the memory 418 can be mounted on a circuit board of an electronics assembly of the device 400.

[0061] Switching circuit 406 can include one or more switches (e.g., a switch matrix, a switch array, or other collection of switches), multiplexers, transistors, and / or other circuitry. Switching circuit 406 can selectively couple one or more of electrodes 402a-402c to other components of device 400 (e.g., sensing circuit 408 and / or therapy generation circuit 410). The subset of electrodes 402a-402c to be used can depend on the particular operation of device 400 being performed, such as whether device 400 is sensing or delivering therapy, the location of the heart being monitored or treated, and the like. In some embodiments, processing circuit 414 determines which subset of electrodes 402a-402c should be used for a particular operation, and controls switching circuit 406 to selectively couple those electrodes to the appropriate components of device 400.

[0062] Sensing circuit 408 can monitor signals from at least one of electrodes 402a-402c to monitor electrical activity, impedance, and / or other electrical phenomena of the heart. Sensing can be performed to determine heart rate and / or heart rate variability; and / or to detect ventricular dyssynchrony, arrhythmias (e.g., tachyarrhythmias), and / or other electrical signals. Sensing circuit 408 can include filters, amplifiers, analog-to-digital converters, and / or other circuitry configured to sense cardiac electrical signals via one or more of electrodes 402a-402c.

[0063] In some embodiments, switching circuit 406, controlled by processing circuit 414, selectively couples sensing circuit 408 to selected combinations of electrodes 402a-402c, e.g., to selectively sense electrical activity of one or more chambers of the heart. For example, switching circuit 406 can couple each of first electrode 402a and second electrode 402b (in combination with third electrode 402c) to a respective sensing channel provided by sensing circuit 408 to sense electrical signals from cardiac tissue in electrical contact with first electrode 402a (e.g., ventricular tissue) and second electrode 402b (e.g., atrial tissue), respectively. In some embodiments, sensing circuit 408 is configured to detect events (e.g., depolarizations) within the cardiac electrical signals, and provide indications of the events to processing circuit 414. In this way, processing circuit 414 can determine the timing of atrial depolarizations and / or ventricular depolarizations, and can control the delivery of cardiac pacing (e.g., AV synchronous cardiac pacing) based on the timing.

[0064] Therapy generation circuit 410 can generate electrical stimulation signals, such as cardiac pacing pulses. Therapy generation circuit 410 can be electrically coupled to one or more of electrodes 402a-402c to deliver pulses to a portion of heart muscle within the heart via one or more of electrodes 402a-402c. In some embodiments, therapy generation circuit 410 delivers pacing stimulation in the form of electrical pulses. Therapy generation circuit 410 can include a charging circuit and one or more charge storage devices (e.g., capacitors). Optionally, therapy generation circuit 410 can include switches and / or other circuitry to control when the charge storage devices discharge to electrodes 402a-402c.

[0065] Switching circuit 406, controlled by processing circuit 414, can direct the electrical stimulation signals from therapy generation circuit 410 to selected combinations of electrodes 402a-402c having a selected polarity, e.g., to selectively deliver pacing pulses to the RA, RV, LV, and / or interventricular septum of the heart. For example, to pace one or both of the ventricles, switching circuit 406 can electrically couple first electrode 402a (e.g., that contacts the wall tissue of a ventricle or interventricular septum) to therapy generation circuit 410 as a cathode, and one or both of second electrode 402b or third electrode 402c to therapy generation circuit 410 as an anode. As another example, to pace the RA, switching circuit 406 can couple second electrode 402b (e.g., that contacts the RA endocardium) to therapy generation circuit 410 as a cathode, and one or both of first electrode 402a or third electrode 402c to therapy generation circuit 410 as an anode.

[0066] Processing circuit 414 can include one or more processors, such as microprocessors, controllers, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or equivalent discrete or integrated logic circuitry. In some embodiments, processing circuit 414 can include multiple components, such as any combination of one or more microprocessors, controllers, DSPs, ASICs, and / or FPGAs, as well as other discrete or integrated logic circuitry. The functions attributed to processing circuit 414 herein can be embodied as software, firmware, hardware, or any combination of software, firmware, and hardware.

[0067] Processing circuit 414 can control treatment generation circuit 410 to deliver stimulation therapy to the patient's heart according to treatment parameters, which can be stored in memory 418. For example, processing circuit 414 can control treatment generation circuit 410 to deliver electrical pulses with amplitude, pulse width, rate, frequency, and / or electrode polarity specified by the treatment parameters. In this way, treatment generation circuit 410 can deliver pacing pulses to the heart via one or more electrodes 402a-402c. Device 400 can use any combination of electrodes 402a-402c to deliver therapy and / or detect electrical signals from the patient.

[0068] Memory 418 (e.g., a data storage device or other non-transitory medium) may store computer-readable instructions that, when executed by processing circuitry 414, cause device 400 to perform the various operations described herein. Memory 418 may include any volatile, non-volatile, magnetic, optical, or electrical medium, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other digital or analog medium.

[0069] Sensor 412 may include one or more sensing elements that convert patient physiological activity into electrical signals to sense values ​​of corresponding patient parameters. Sensor 412 may include one or more motion sensors, optical sensors, chemical sensors, temperature sensors, pressure sensors, and / or any other type of sensor. Sensor 412 may output patient parameter values ​​to processing circuitry 414, which can be used as feedback to control the sensing and / or delivery of treatment by device 400.

[0070] For example, sensor 412 may include at least one motion sensor, such as one or more inertial measurement units (IMUs), accelerometers, gyroscopes, electric or magnetic field sensors, and / or other devices capable of detecting the motion and / or position of device 400. Motion of device 400 detected by the motion sensor may indicate cardiac events (e.g., ventricular pacing activation), blood flow through the heart, patient posture, patient activity, and / or noise. Processing circuitry 414 may control and / or monitor motion data generated by the motion sensor to identify one or more features of cardiac contraction within the signal (e.g., on a beat-by-beat basis or otherwise) to facilitate the delivery of treatment (e.g., delivery of ventricular pacing pulses in an atrial-synchronized manner). Optionally, processing circuitry 414 may use the motion data to detect the patient's current activity level, which may be used for rate-responsive pacing of the patient's heart.

[0071] The communication circuitry 416 is configured to allow device 400 to wirelessly communicate with another device, such as an external device 110 outside of the patient’s body (e.g., FIG. 1 and / or another device under the control of processing circuitry 414. For example, processing circuitry 414 can receive updates to operational parameters from another device, and / or can provide acquired data (e.g., sensed cardiac activity and / or other patient parameters) to another device via communication circuitry 416. Communication circuitry 416 can use radio frequency (RF) communication techniques (e.g., via an antenna) and / or any other suitable communication modalities.

[0072] Power source 420 delivers operating power to various components of device 400. Power source 420 can include one or more batteries, each of which can independently be rechargeable or non-rechargeable. Recharging of power source 420 can be accomplished through proximal inductive interaction between an external charger and an inductive charging coil within device 400. Alternatively or in combination, recharging of power source 420 can be accomplished using an energy harvesting mechanism 422 of device 400. Additional details of energy harvesting mechanisms suitable for use with the embodiments herein are provided in Section II below.

[0073] FIG. 4 The components of device 400 shown can be modified in a number of different ways. For example, FIG. 4 Any of the components shown can be combined with one another, e.g., switch circuitry 406 can be incorporated into sensing circuitry 408 and / or therapy generation circuitry 410. FIG. 4 Any of the components shown can be divided into smaller subcomponents. FIG. 4 Some of the components shown are optional and can be omitted (e.g., switch circuitry 406 and / or sensor 412). Device 400 can also include additional components not shown. For example, device 400 can include power management circuitry coupled to power source 420 to allow processing circuitry 414 to monitor the status (e.g., charge level, charging rate, net power going into and / or coming out of power source 420, remaining battery life) of power source 420. FIG. 4

[0074] FIG. 4 The components of device 400 shown represent functionality that can be included in any device of the present technology. FIG. 4 The components shown can include any discrete and / or integrated electronic circuitry implementing analog and / or digital circuitry capable of producing the functionality attributed to the components herein. For example, the components can include analog circuitry such as amplification, filtering, and / or other signal conditioning circuitry. The components can also include digital circuitry such as combinational or sequential logic circuits, memory devices, etc. The functionality attributed to the components herein is capable of being implemented in one or more of the components shown. FIG. 4 ​The functionality of a component of the FIG. 4 described as separate blocks in the FIG. 4 is intended to highlight different functional aspects and does not necessarily imply that such components must be realized by separate hardware or software components. Rather, functionality associated with one or more components can be performed by separate hardware or software components, or integrated within common or separate hardware or software components. For example, although illustrated as separate functional components in

[0075] II. Multi-directional Energy Harvesting Mechanism

[0076] In some embodiments, the present technology provides an implantable device that includes an energy harvesting mechanism (also referred to as an “energy harvester” or “harvester”). The power capacity of the power source of an implantable device can be limited due to size constraints, such as if the device is implanted within a small space within a patient’s body (e.g., within a single heart chamber), and / or for safety considerations to avoid the device interfering with normal physiological functions. To extend the useful life of such implantable devices, an energy harvesting mechanism can be used to generate energy in situ to recharge the power source.

[0077] FIGS. 5A-5D A device 500 that includes an energy harvesting mechanism 502 according to an embodiment of the present technology is illustrated. Specifically, FIG. 5A is a cross-sectional side view of the device 500, FIG. 5B is a perspective view of the energy harvesting mechanism 502, FIG. 5C illustrates the energy harvesting mechanism 502 in a flat configuration, and FIG. 5D is a cross-sectional end view of the energy harvesting mechanism 502.

[0078] Referring first to FIG. 5A , the device 500 can be an implantable device, such as a pacing device configured to monitor activity of a patient’s heart and provide electrical stimulation to the heart. In such embodiments, the device 500 can include any of the features of the devices described above in connection with FIGS. 1-4 However, in other embodiments, the device 500 can be a different type of implantable medical device.

[0079] Device 500 includes a housing 504 having a distal end 508 and a proximal end 510. Housing 504 can have an elongated shape having a longitudinal axis A extending from distal end 508 to proximal end 510. Housing 504 defines an interior cavity 506 that houses energy harvesting mechanism 502, as well as other components of device 500, such as a power source 512 and electronic assembly 514. Energy harvesting mechanism 502 generates energy from physiological motion when device 500 is implanted in a patient. For example, in some embodiments, device 500 is configured for implantation within a chamber of a patient’s heart, and generates energy from cardiac motion (e.g., motion of the heart wall to which device 500 is attached) and / or blood flow through the cardiac chamber. The energy generated by energy harvesting mechanism 502 can be used to charge power source 512, which in turn powers the operation of device 500 (e.g., electronic assembly 514).

[0080] Reference is next made to the drawings, in which FIGS. 5A-5D Energy harvesting mechanism 502 includes a plurality of piezoelectric elements 516a-c (collectively, “piezoelectric elements 516”) that convert mechanical energy to electrical energy via the piezoelectric effect. Although FIGS. 5A-5D Three piezoelectric elements 516 are illustrated, but in other embodiments, device 500 can include a different number of piezoelectric elements 516, as further described below. Each piezoelectric element 516 can be partially or entirely made of a piezoelectric material, such as a piezoelectric ceramic (e.g., lead zirconate titanate (PZT)), a single-crystal piezoelectric material (e.g., lead magnesium niobate-lead titanate (PMN-PT)), a piezoelectric polymer (e.g., polyvinylidene fluoride (PVDF)), or a piezoelectric composite material (e.g., piezoelectric ceramic embedded in a polymer matrix, such as a macro-fiber composite). In some embodiments, some or all of piezoelectric elements 516 are piezoelectric bimorphs (e.g., piezoelectric bimorph beams) that include two active layers (e.g., upper and lower layers) of piezoelectric material. Optionally, the piezoelectric bimorphs can include a passive layer made of a non-piezoelectric material (e.g., a polymer or a metal) that serves as a support for the active layers and electrical connections. However, in other embodiments, some or all of piezoelectric elements 516 can be piezoelectric monomorphs having a single active layer.

[0081] Piezoelectric elements 516 can have any suitable geometry. In some embodiments, each piezoelectric element 516 is a flexible elongated member (e.g., a beam, a plate, a shaft, a rod, a fiber) extending from a respective first (e.g., distal) end portion to a respective second (e.g., proximal) end portion. For example, as FIG. 5CAs shown, the first piezoelectric element 516a can have a distal end portion 518a and a proximal end portion 520a, with a first longitudinal axis Al extending between the distal end portion 518a and the proximal end portion 520a, and a first transverse axis Tl orthogonal to the first longitudinal axis Al. The second piezoelectric element 516b can have a distal end portion 518b and a proximal end portion 520b, with a second longitudinal axis A2 extending between the distal end portion 518b and the proximal end portion 520b, and a second transverse axis T2 orthogonal to the second longitudinal axis A2. The third piezoelectric element 516c can have a distal end portion 518c and a proximal end portion 520c, with a third longitudinal axis A3 extending between the distal end portion 518c and the proximal end portion 520c, and a third transverse axis T3 orthogonal to the third longitudinal axis A3. Although the piezoelectric elements 516 are each depicted as having a rectangular shape with uniform width and thickness, in other embodiments some or all of the piezoelectric elements 516 can have different shapes, such as a tapered shape with varying width and / or thickness.

[0082] Referring to FIGS. 1-3 together FIGS. 5A-5C In the illustrated embodiment, for example, the first piezoelectric element 516a can be mechanically and electrically coupled to the power source 512, which is charged by the electrical current generated by the deflection of the piezoelectric elements 516, and the power source 512 can be mounted at a fixed location within the housing 504. In other embodiments, the first piezoelectric element 516a can be mounted to an interior wall (e.g., a bulkhead) within the housing 504, and can be electrically coupled to the power source 512 via electrical interconnects (e.g., wires, traces, etc., or any suitable combination thereof) that extend through or along the wall. Optionally, the fixed region can be a bearing or similar component that allows the energy harvester 502 to be passively rotated to self-align with the direction of input motion, but is mounted at a fixed axial location within the housing 504, as described in U.S. Provisional Application No. [Attorney Docket No. A0009976US01; MDTCR.008P], entitled “Energy Harvester with Rotational Alignment,” filed April 17, 2023, which is incorporated herein by reference in its entirety.

[0083] The third piezoelectric element 516c can be coupled to a harvester mass 522 (also referred to as a “proof mass” or an “inertial mass”) that can move within an interior cavity 506 of the housing 504, as described in greater detail below. The third piezoelectric element 516c can be coupled to the harvester mass 522 via bonding, welding, mechanical connections (e.g., interference fit, snap fit), fasteners, and / or any other suitable attachment techniques.

[0084] In some embodiments, the piezoelectric elements 516 are coupled to one another in an end-to-end folded configuration (e.g., a fan-fold, zig-zag, or serpentine configuration). For example, a distal end portion 518a of the first piezoelectric element 516a can be fixed relative to the housing 504 (e.g., via a direct connection to the housing 504 or indirectly via another component, such as the power source 512 or an internal wall within the housing 504). A proximal end portion 520a of the first piezoelectric element 516a can be coupled to a proximal end portion 520b of the second piezoelectric element 516b (e.g., via a first joint 524a). A distal end portion 518b of the second piezoelectric element 516b can be coupled to a distal end portion 518c of the third piezoelectric element 516c (e.g., via a second joint 524b). A proximal end portion 520c of the third piezoelectric element 516c can be coupled to the harvester mass 522. The piezoelectric elements 516 can be arranged such that their respective longitudinal axes Al, A2, A3 are aligned with one another and / or with a longitudinal axis A of the housing 504 (e.g., parallel or within 10°, 5°, 2°, or 1° of parallel).

[0085] The joints 524a, 524b can be blocks, strips, plates, brackets, wires, interposers, or the like that mechanically couple the respective pairs of piezoelectric elements 516 to one another. The joints 524a, 524b can be sufficiently rigid to maintain the piezoelectric elements 516 in a desired spatial arrangement relative to one another and / or to reduce excessive flexing of the joints 524a, 524b that dissipates mechanical energy. Optionally, the joints 524a, 524b can have a degree of flexibility to provide an elastic springback effect that dynamically amplifies deflection of the piezoelectric elements 516 in response to a motion input.

[0086] In some embodiments, the links 524a, 524b comprise an electrically conductive material (e.g., metal, electrically conductive polymer) to electrically couple the piezoelectric elements 516 to one another. Thus, electrical current generated by the second and third piezoelectric elements 516b, 516c can be transmitted to the power source 512 via the links 524a, 524b. For example, the links 524a, 524b can be made entirely of metal (e.g., brass, copper) and can be attached to the corresponding piezoelectric elements 518 via brazing, soldering, electrically conductive adhesive, etc. As another example, the links 524a, 524b can be made from a combination of insulating material (e.g., polyimide, polycrystalline ceramic such as aluminum oxide) and electrically conductive material (e.g., conductive traces, fine wires) using techniques such as molding and hot isostatic pressing, and wire bonding. However, in other embodiments, one or both of the links 524a, 524b can be omitted, and the piezoelectric elements 516 can instead be connected directly to one another (e.g., via welding, adhesive, fastener) or integrally formed with one another.

[0087] The configuration of the piezoelectric elements 516 described herein can reduce the overall resonant frequency of the energy harvesting mechanism 502 to a range suitable for efficient harvesting from physiological motion, while also reducing the spatial footprint of the energy harvesting mechanism 502. For example, the resonant frequency of the energy harvesting mechanism 502 can be in the range of 1 Hz to 50 Hz, 1 Hz to 30 Hz, 1 Hz to 20 Hz, 1 Hz to 10 Hz, 5 Hz to 10 Hz, 5 Hz to 15 Hz, 10 Hz to 20 Hz, 10 Hz to 15 Hz, 10 Hz to 30 Hz, 15 Hz to 20 Hz, 15 Hz to 25 Hz, 20 Hz to 30 Hz, 20 Hz to 25 Hz, or 25 Hz to 30 Hz. The length of the energy harvesting mechanism 502 (not including the harvester mass 522) can be less than or equal to 30 mm, 25 mm, 20 mm, or 15 mm; and / or in the range of 10 mm to 30 mm, 10 mm to 20 mm, 14 mm to 18 mm, or 15 mm to 25 mm. The maximum cross-sectional dimension (e.g., maximum width and / or diameter measured orthogonal to the longitudinal axis A) of the energy harvesting mechanism 502 (not including the harvester mass 522) can be less than or equal to 15 mm, 12 mm, 10 mm, or 8 mm; and / or in the range of 5 mm to 15 mm, or 5 mm to 10 mm.

[0088] When the device 500 is subjected to an external force from physiological motion, the inertia of the harvester mass 522 can cause a deflection of the proximal end portion 520c of the third piezoelectric element 516c. Force can be transmitted to the second piezoelectric element 516b and the first piezoelectric element 516a by way of the interconnections between these components. As a result, some or all of the piezoelectric elements 516 can elastically deform relative to the housing 504 and relative to the fixed distal end portion 518a of the first piezoelectric element 516a. For example, some or all of the piezoelectric elements 516 can deform from a resting, straightened configuration (as shown) to a curved configuration. The mechanical strain generated in the piezoelectric elements 516 can produce an electric current that can be used to charge the power source 512. FIG. 5A

[0089] In some embodiments, each piezoelectric element 516 is characterized by a primary bending direction (which can also be interchangeably referred to as a "preferred bending direction," a "preferred flexing direction," or a "preferred axis of motion"). The primary bending direction of a piezoelectric element 516 can correspond to a direction of input motion that maximizes the power output of the piezoelectric element 516 and / or minimizes the amount of force used to deflect the piezoelectric element 516. When the direction of input motion deviates from the primary bending direction, the power output of the piezoelectric element 516 can decrease, and / or more force can be required to deflect the piezoelectric element 516. In some cases, the power output can be minimal when the direction of input motion is orthogonal to the primary bending direction. Thus, it can be advantageous to arrange the piezoelectric elements 516 to have different primary bending directions, such that at least one piezoelectric element 516 is sufficiently deflected to provide at least a minimal level of power output regardless of the direction of input motion. In some embodiments, the energy harvesting mechanism 502 produces a power output (e.g., a minimum and / or average power output) of at least 1 μW, 1.5 μW, 2 μW, 2.5 μW, 3 μW, 3.5 μW, 4 μW, 4.5 μW, 5 μW, 5.5 μW, 6 μW, 6.5 μW, 7 μW, 7.5 μW, 8 μW, 8.5 μW, 9 μW, 9.5 μW, or 10 μW for any arbitrary direction of input motion.

[0090] The primary bending direction of a piezoelectric element 516 can depend on the geometry of the piezoelectric element 516. For example, as shown in FIG. 6A, the primary bending direction of a piezoelectric element 516 can be parallel to the length of the piezoelectric element 516. In some cases, the primary bending direction of a piezoelectric element 516 can be orthogonal to the length of the piezoelectric element 516, as shown in FIG. 6B. In some cases, the primary bending direction of a piezoelectric element 516 can be parallel to the width of the piezoelectric element 516, as shown in FIG. 6C. In some cases, the primary bending direction of a piezoelectric element 516 can be orthogonal to the width of the piezoelectric element 516, as shown in FIG. 6D. In some cases, the primary bending direction of a piezoelectric element 516 can be parallel to the thickness of the piezoelectric element 516, as shown in FIG. 6E. In some cases, the primary bending direction of a piezoelectric element 516 can be orthogonal to the thickness of the piezoelectric element 516, as shown in FIG. 6F. FIG. 5D ​As shown, the piezoelectric elements 516 can each have a flat body (e.g., beam, strip, film, plate) that defines a respective plane, e.g., the first piezoelectric element 516a defines a first plane 526a aligned (e.g., parallel) with the first transverse axis T1 and the first longitudinal axis A1, the second piezoelectric element 516b defines a second plane 526b aligned (e.g., parallel) with the second transverse axis T2 and the second longitudinal axis A2, and the third piezoelectric element 516c defines a third plane 526c aligned (e.g., parallel) with the third transverse axis T3 and the third longitudinal axis A3. Thus, the primary bending direction of the first piezoelectric element 516a can be a first direction 528a orthogonal to the first plane 526a, the primary bending direction of the second piezoelectric element 516b can be a second direction 528b orthogonal to the second plane 526b, and the primary bending direction of the third piezoelectric element 516c can be a third direction 528c orthogonal to the third plane 526c.

[0091] In some embodiments, the piezoelectric elements 516 face different directions such that the primary bending directions of the piezoelectric elements 516 are different from one another, allowing for efficient energy harvesting from input motions in different directions. For example, the piezoelectric elements 516 can have different orientations such that the first plane 526a, the second plane 526b, and the third plane 526c are offset from one another, such as by an angle greater than or equal to 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, or 170°. Thus, the first direction 528a, the second direction 528b, and the third direction 528c are also offset from one another, such as by an angle greater than or equal to 5°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, or 120°. In the illustrated embodiment, the piezoelectric elements 516 are arranged radially around the longitudinal axis A of the housing 504 in a radially symmetric configuration such that the angle between adjacent planes is 60° and the primary bending directions are offset by 120°. However, in other embodiments, the piezoelectric elements 516 can be arranged differently, such as in a non-radially symmetric configuration, an overlapping configuration, etc.

[0092] Referring again to FIG. 5APower source 512 (shown schematically) can be or include one or more batteries (e.g., rechargeable batteries) that are electrically coupled to energy harvesting mechanism 502 to store energy generated by energy harvesting mechanism 502. In the illustrated embodiment, power source 512 is located distal to energy harvesting mechanism 502 and is interposed between energy harvesting mechanism 502 and electronic assembly 514 at distal end 508 of housing 504. However, in other embodiments, power source 512 can have a different shape and / or can be located at a different portion within housing 504. For example, power source 512 can be a tubular structure that surrounds at least a portion of energy harvesting mechanism 502, such as a distal portion of energy harvesting mechanism 502. In such embodiments, the tubular power source can include a lumen extending therethrough such that at least a portion of energy harvesting mechanism 502 is received within the lumen. This configuration can facilitate reducing the overall size of device 500 while maintaining sufficient space within internal cavity 506 to allow movement of harvester mass 522 and piezoelectric element 516.

[0093] Optionally, device 500 can include a power conditioning circuit (not shown) that is electrically coupled to and interposed between energy harvesting mechanism 502 and power source 512. The power conditioning circuit can be configured to perform operations such as rectification, filtering, voltage regulation, etc. on the electrical signal generated by energy harvesting mechanism 502 before it is transmitted to power source 512.

[0094] Power source 512 is electrically coupled to electronic assembly 514 to power its operation. Electronic assembly 514 can include electronic components of device 500, such as any of the components (e.g., switching circuit 406, sensing circuit 408, therapy generation circuit 410, sensor 412, processing circuit 414, communication circuit 416, and / or memory 418) described above with respect to device 100. FIG. 4

[0095] ​Optionally, the electronic assembly 514 can include components (e.g., processing circuitry 414 and / or other circuitry) that perform power management functions, such as monitoring the state of the power source 512 (e.g., the charge level of the power source 512; whether the charge level is increasing, decreasing, or constant; the net current and / or power into the power source 512), and / or monitoring the power output of the energy harvesting mechanism 502 (e.g., the amount of current and / or power generated by the energy harvesting mechanism 502), the power consumption of the electronic assembly 514, etc. In some embodiments, the polarity of each piezoelectric element 516 (e.g., the polarity of each active layer of each piezoelectric element 516 when a piezoelectric bimorph is used) varies depending on the orientation of the piezoelectric element 516 relative to the direction of the input motion. Accordingly, the electronic assembly 514 can include circuitry that monitors and independently adjusts the polarity of each piezoelectric element 516 to ensure the correct phase relationship between the piezoelectric elements 516. For example, such circuitry can include a full-bridge rectifier using low forward voltage diodes (e.g., Schottky diodes), a synchronous rectifier based on MOSFET switches and / or other passive components, and / or other suitable methods known to those skilled in the art.

[0096] FIGS. 5A-5D The configuration of the device 500 can be modified in many different ways. For example, although the piezoelectric elements 516 are depicted as being connected in series, in other embodiments the piezoelectric elements 516 can be connected in parallel, or each piezoelectric element 516 can be routed individually to the power source 512 to allow the active and inactive elements to be selectively enabled and disabled, respectively. Additionally, although the piezoelectric elements 516 are illustrated as discrete components that are connected to one another via the tabs 524a, 524b, in other embodiments the piezoelectric elements 516 can instead be a single integral component that is folded or otherwise formed into the FIGS. 5A-5D the folded configuration shown, such as an elongated metal strip having an upper piezoelectric layer and a lower piezoelectric layer. This approach can improve the reliability of the energy harvesting mechanism 502 by eliminating the need for tabs, adhesives, welds, bonding agents, etc. to connect the piezoelectric elements 516 to one another.

[0097] FIG. 6 are partial schematic end views of an energy harvesting mechanism in a plurality of different orientations 602a-602f in accordance with embodiments of the present technology. The energy harvesting mechanism includes three piezoelectric bimorph beams 604a-604c connected in series, similar to FIGS. 5A-5DThe energy harvesting mechanism 502 is configured as follows: A first beam 604a includes a first end connected to a vertical vibration table and a second end connected to a second beam 604b via a first joint; the second beam 604b includes a first end connected to the first beam 604a via a first joint and a second end connected to a third beam 604c via a second joint; and the third beam 604c includes a first end connected to the second beam 604b via a second joint and a second end connected to an end mass block. Beams 604a-604c are arranged in a triangular configuration, wherein each beam is offset by 60° from the adjacent beam.

[0098] The energy harvesting mechanism is excited by a mechanical input motion in the form of a 20Hz sine wave along the direction of movement D, and is targeted at... FIG. 6 The power output is measured in six orientations 602a-602f. In orientations 602a-602c, the first beam 604a, the third beam 604c, and the second beam 604b are respectively oriented perpendicular to the direction of movement D. In orientations 602d-602f, the first beam 604a, the second beam 604b, and the third beam 604c are respectively offset by 45° from the direction of movement D.

[0099] As shown in Table 1 below, the energy harvesting mechanism generates power in each orientation. The highest power output is observed in orientation 602a, where the first beam 604a is perpendicular to the direction of movement D, such that the direction of movement D is parallel to the principal bending direction of the first beam 604a. The lowest power output is observed in orientation 602e, where the first beam 604a is parallel to the direction of movement D, such that the direction of movement D is perpendicular to the principal bending direction of the first beam 604a.

[0100] Table 1: Test Results for Energy Harvesting Mechanisms in Different Orientations

[0101] Orientation Average Power Output (pW) 602a 8 602b 2.5 602c 4.5 602d 3 602e 1.5 602f 4

[0102] FIG. 7A and FIG. 7B This is a partial schematic diagram of another energy harvesting mechanism 702 configured according to an embodiment of this technology. Specifically, FIG. 7A An example is shown: an energy harvesting mechanism 702 in a flat configuration, and FIG. 7B This is a cross-sectional end view of the energy harvesting mechanism 702. The energy harvesting mechanism 702 can be incorporated into any device described herein (e.g., FIGS. 1-5D In the device. The energy harvesting mechanism 702 can be connected with FIGS. 5A-5D The energy harvesting mechanism 702 is largely similar to that of the piezoelectric element 502, except that it includes five piezoelectric elements 704a-704e (collectively referred to as "piezoelectric elements 704"). Therefore, the following discussion of the energy harvesting mechanism 702 will be limited to its similarity to that of the piezoelectric element 502. FIGS. 5A-5D The different features of the implementation schemes.

[0103] Referring first to FIG. 7A , the piezoelectric elements 704 can be coupled to one another in series such that the first piezoelectric element 704a is coupled to a fixed region 706 of a housing that houses the energy harvesting mechanism 502 and to the second piezoelectric element 704b (e.g., via a first joint 708a); the second piezoelectric element 704b is coupled to the third piezoelectric element 706c (e.g., via a second joint 708b); the third piezoelectric element 706c is coupled to the fourth piezoelectric element 704d (e.g., via a third joint 708c); the fourth piezoelectric element 704d is coupled to the fifth piezoelectric element 704e (e.g., via a fourth joint 708d); and the fifth piezoelectric element 704e is coupled to the harvester mass 710. The joints 708a-708d can mechanically and / or electrically interconnect adjacent pairs of piezoelectric elements 704 and can be the same as or substantially similar to the joints 524a, 524b of FIGS. 5A-5D . Alternatively, the piezoelectric elements 704a-704e can be connected in parallel, or each piezoelectric element can be individually routed to a power source to allow selective activation and deactivation of active and inactive elements, respectively. Further, the piezoelectric elements 704a-704e can alternatively be provided as a single unitary component that is bent or otherwise formed into the folded configuration shown in FIG. 7A and FIG. 7B .

[0104] The piezoelectric elements 704 can be arranged such that their respective longitudinal axes are aligned with one another and / or with a longitudinal axis of a housing that houses the energy harvesting mechanism 702 (e.g., parallel or within 10°, 5°, 2°, or 1° of parallel). When the piezoelectric elements 704 are in the assembled configuration (as shown in FIG. 7B ), the piezoelectric elements 704 can each face in different directions such that respective planes 712a-712e defined by the corresponding longitudinal and transverse axes of each piezoelectric element 704 are offset from one another, and / or respective principal bending directions 714a-712e of the piezoelectric elements 704 are offset from one another. In the illustrated embodiment, the piezoelectric elements 704 are arranged in a radially symmetric configuration (e.g., a pentagonal configuration) such that the angle between adjacent planes is 108° and the principal bending directions are offset by 72°. However, in other embodiments, the piezoelectric elements 704 can be arranged differently, such as in a non-radially symmetric configuration, an overlapping configuration, etc.

[0105] FIGS. 8A-8E A device 800 including an energy harvesting mechanism 802 according to an embodiment of the present technology is illustrated. Specifically, FIG. 8A is a cross-sectional side view of the device 800, FIG. 8B is a perspective view of the energy harvesting mechanism 802, FIG. 8C is a top view of the energy harvesting mechanism 802, FIG. 8Dis a side view of the energy-harvesting mechanism 802, and FIG. 8E is an end view of the energy-harvesting mechanism 802.

[0106] Referring first to FIG. 8A , the device 800 can be an implantable device, such as a pacing device configured to monitor activity of a patient’s heart and provide electrical stimulation to the heart. In such embodiments, the device 800 can include any of the features of the devices described above in connection with FIGS. 1-4 However, in other embodiments, the device 800 can be a different type of implantable medical device.

[0107] The device 800 can be generally similar to the device 500 of FIGS. 5A-5D For example, the device 800 can include a housing 804 defining an internal cavity 806 that houses the energy-harvesting mechanism 802, a power source 812, and electronic components 814. Accordingly, like reference numerals (e.g., housing 804 and housing 504) are used to identify similar or identical components, and the following discussion of the device 800 will be limited to those features that differ from the embodiments described in connection with FIGS. 5A-5D

[0108] Referring to FIG. 8A and FIG. 8B together, the energy-harvesting mechanism 802 includes a pair of piezoelectric elements 816a, 816b (collectively, “piezoelectric elements 816”). Each piezoelectric element 816 can be partially or entirely made of a piezoelectric material, such as a piezoelectric ceramic (e.g., PZT), a single-crystal piezoelectric material (e.g., PMN-PT), a piezoelectric polymer (e.g., PVDF), or a piezoelectric composite material (e.g., piezoelectric ceramic embedded in a polymer matrix, such as a macro-fiber composite). In some embodiments, some or all of the piezoelectric elements 816 are piezoelectric bimorphs (e.g., piezoelectric bimorph beams) that include two active layers (e.g., an upper layer and a lower layer) of piezoelectric material. Optionally, the piezoelectric bimorphs can include a passive layer made of a non-piezoelectric material (e.g., a polymer or a metal) that acts as a support for the active layers. However, in other embodiments, some or all of the piezoelectric elements 816 can be piezoelectric monomorphs having a single active layer.

[0109] The piezoelectric elements 816 can have any suitable geometry. In some embodiments, each piezoelectric element 816 is a flexible elongated member (e.g., a beam, a plate, a shaft, a rod, a fiber) extending from a respective first (e.g., distal) end portion to a respective second (e.g., proximal) end portion. For example, as FIG. 8B and FIG. 8C ​As shown, the first piezoelectric element 816a can have a distal end portion 818a and a proximal end portion 820a, with a first longitudinal axis A4 extending between the distal end portion 818a and the proximal end portion 820a, and a first transverse axis T4 orthogonal to the first longitudinal axis A4. As shown, the second piezoelectric element 816b can have a distal end portion 818b and a proximal end portion 820b, with a second longitudinal axis A5 extending between the distal end portion 818b and the proximal end portion 820b, and a second transverse axis T5 orthogonal to the second longitudinal axis A5. FIG. 8B and FIG. 8D As shown, the first piezoelectric element 816a can have a distal end portion 818a and a proximal end portion 820a, with a first longitudinal axis A4 extending between the distal end portion 818a and the proximal end portion 820a, and a first transverse axis T4 orthogonal to the first longitudinal axis A4. As shown, the second piezoelectric element 816b can have a distal end portion 818b and a proximal end portion 820b, with a second longitudinal axis A5 extending between the distal end portion 818b and the proximal end portion 820b, and a second transverse axis T5 orthogonal to the second longitudinal axis A5.

[0110] Referring again to FIG. 8A , the first piezoelectric element 816a can be coupled to a fixed region within the housing 804. The fixed region can be a portion of the housing 804 or a portion of another component in a fixed spatial configuration relative to the housing 804. In the illustrated embodiment, for example, the first piezoelectric element 816a can be mechanically and electrically coupled to the power source 812, which is charged by the electrical current generated by the deflection of the piezoelectric element 816, and the power source 812 can be mounted at a fixed location within the housing 804. In other embodiments, the first piezoelectric element 816a can be mounted to an interior wall (e.g., a bulkhead) within the housing 804 and can be electrically coupled to the power source 812 via an electrical interconnect (e.g., a wire) that extends through or along the wall. The second piezoelectric element 816b can be coupled to the first piezoelectric element 816a and to the harvester mass 822, which can be movable within the interior cavity 806 of the housing 804, as described in greater detail below.

[0111] Referring together to FIGS. 8A-8D , the piezoelectric elements 816 can be coupled to one another in an end-to-end, overlapping (e.g., interleaved and / or coaxial) configuration. For example, the distal end portion 818a of the first piezoelectric element 816a can be coupled to a fixed region within the housing 804 and to the second piezoelectric element 816b. The proximal end portion 802a of the first piezoelectric element 816a can be positioned proximate to but spaced apart from the harvester mass 822. The distal end portion 818b of the second piezoelectric element 816b can be coupled to the first piezoelectric element 816a and can be positioned proximate to but spaced apart from the fixed region. The proximal end portion 820b of the second piezoelectric element 816b can be coupled to the harvester mass 822. The piezoelectric elements 816 can be arranged such that their respective longitudinal axes A4, A5 are aligned with one another and / or with the longitudinal axis A of the housing 804 (e.g., parallel or within 10°, 5°, 2°, or 1° of parallel).

[0112] In some embodiments, the distal end portion 818a of the first piezoelectric element 816a includes an external structure coupled to the fixed region and an internal structure coupled to the second piezoelectric element 816b. As FIG. 8B and FIG. 8C As best seen, the first piezoelectric element 816a can include a pair of elongated slots 824 extending from the distal end portion 818a toward the proximal end portion 820a. The slots 824 can terminate prior to the proximal end portion 820a, defining a pair of external members 826 (e.g., external fins or tabs) and an internal member 828 (e.g., an internal fin or tab) between the external members 826. The distal ends of the external members 826 can be fixedly coupled to the housing 804 (e.g., via a direct connection or indirectly via another component), while the distal end of the internal member 828 can be coupled to the distal end portion 818b of the second piezoelectric element 816b (e.g., via a joint 830). The external members 826 and the internal member 828 can be movable relative to one another (e.g., in a direction orthogonal to the longitudinal axis A4 and the transverse axis T4) such that the components behave like two discrete piezoelectric elements connected in series at the proximal end portion 820a, as discussed further below. In the illustrated embodiment, the slots 824 are angled away from the first longitudinal axis A4 such that the internal member 828 is tapered, having a narrower distal end and a wider proximal end, and such that the external members 826 are tapered, having a wider distal end and a narrower proximal end. However, in other embodiments, the geometry of the slots 824, the external members 826, and the internal member 828 can be varied as desired.

[0113] As FIG. 8B and FIG. 8D As best seen in FIGS. 8A and 8B, the second piezoelectric element 816b can include an elongated opening 832 extending from the proximal end portion 820b toward the distal end portion 818b. The opening 832 can define a pair of external members 834 (e.g., fins, tabs). In some embodiments, the opening 832 terminates prior to the distal end portion 818b of the second piezoelectric element 816b such that the distal ends of the external members 834 are connected to one another. Alternatively, the opening 832 can extend to the distal end portion 818b such that there is a gap between the distal ends of the external members 834. In such embodiments, the joint 830 and / or the internal member 828 of the first piezoelectric element 816a can bridge the gap between the distal ends of the external members 834 to couple the external members 834 to one another. In the illustrated embodiment, the opening 832 has a tapered shape, having a wider proximal end and a narrower distal end, such that the external members 834 are tapered, having a wider distal end and a narrower proximal end. However, in other embodiments, the geometry of the opening 832 and the external members 834 can be varied as desired.

[0114] like FIGS. 5A-5D As shown, the first piezoelectric element 816a may be partially received within the opening 832 of the second piezoelectric element 816b, such that at least a portion of the first piezoelectric element 816a (e.g., the inner member 828) is positioned between the outer members 834 of the second piezoelectric element 816b. The distal end of the outer member 834 of the second piezoelectric element 816b may be coupled to the distal end of the inner member 828 of the first piezoelectric element 816a (e.g., via connector 830). The proximal end of the outer member 834 of the second piezoelectric element 816b may be coupled to the collector mass block 822. Thus, the outer member 826 of the first piezoelectric element 816a, the inner member 828 of the first piezoelectric element 816a, and the outer member 834 of the second piezoelectric element 816b can be effectively represented as a fan-shaped folded assembly with three “beams” connected in series. Specifically, the outer component 826 of the first piezoelectric element 816a can be used together as a first "beam" having a fixed distal end, the inner component 828 of the first piezoelectric element 816a can be used as a second "beam", and the outer component 834 of the second piezoelectric element 816b can be used together as a third "beam" having a proximal end connected to the collector mass block 822.

[0115] The connector 830 can be a block, cover, strip, plate, bracket, wire, intermediate layer, etc., that mechanically connects the first piezoelectric element 816a and the second piezoelectric element 816b to each other. The connector 830 can be used with... FIGS. 5A-5D The connectors of connectors 524a and 524b are generally similar and may include a combination FIG. 8A Any of the features described herein. For example, connector 830 may comprise a conductive material (e.g., a metal, a conductive polymer) to electrically connect the first piezoelectric element 816a to the second piezoelectric element 816b. However, in other embodiments, connector 830 may be omitted, and the first piezoelectric element 816a and the second piezoelectric element 816b may instead be directly connected to each other (e.g., via welding, adhesive, fasteners) or integrally formed with each other.

[0116] The configuration of the piezoelectric elements 816 described herein can lower the overall resonant frequency of the energy harvesting mechanism 802 to a range suitable for efficient harvesting from physiological motion, while also reducing the spatial footprint of the energy harvesting mechanism 802. For example, the resonant frequency of the energy harvesting mechanism 802 can be in the range of 1 Hz to 50 Hz, 1 Hz to 30 Hz, 1 Hz to 20 Hz, 1 Hz to 10 Hz, 5 Hz to 10 Hz, 5 Hz to 15 Hz, 10 Hz to 20 Hz, 10 Hz to 15 Hz, 10 Hz to 30 Hz, 15 Hz to 20 Hz, 15 Hz to 25 Hz, 20 Hz to 30 Hz, 20 Hz to 25 Hz, or 25 Hz to 30 Hz. The length of the energy harvesting mechanism 802 (not including the harvester mass 822) can be less than or equal to 30 mm, 25 mm, 20 mm, or 15 mm; and / or in the range of 10 mm to 30 mm, 10 mm to 20 mm, 14 mm to 18 mm, or 15 mm to 25 mm. The maximum cross-sectional dimension of the energy harvesting mechanism 802 (e.g., the maximum width and / or diameter measured orthogonal to the longitudinal axis A) (not including the harvester mass 822) can be less than or equal to 15 mm, 12 mm, 10 mm, or 8 mm; and / or in the range of 5 mm to 15 mm, or 5 mm to 10 mm.

[0117] When the device 800 is subjected to an external force from physiological motion, the inertia of the harvester mass 822 can cause deflection of the proximal end portion 820b of the second piezoelectric element 816b. Force can be transmitted to the first piezoelectric element 816a by way of the interconnections between these components. As a result, one or both of the piezoelectric elements 816 can elastically deform relative to the housing 804 and relative to the fixed distal end portion 818a of the first piezoelectric element 816a (e.g., the distal end of the outer member 826). For example, one or both of the piezoelectric elements 816 can deform from a resting, straightened configuration (as shown) to a curved configuration. The mechanical strain generated in the piezoelectric elements 816 can produce an electric current that can be used to charge the power source 812. FIG. 8E

[0118] ​In some embodiments, each piezoelectric element 816 is characterized by a principal bending direction. As described herein, the principal bending direction of the piezoelectric element 816 may correspond to the direction of an input motion that maximizes the power output of the piezoelectric element 816 and / or minimizes the amount of force used to deflect the piezoelectric element 816. The piezoelectric elements 816 may be arranged to have different principal bending directions such that at least one piezoelectric element 816 is sufficiently deflected to provide at least a minimum level of power output regardless of the direction of the input motion. In some embodiments, for any arbitrary direction of input motion, the energy harvesting mechanism 802 produces a power output (e.g., minimum and / or average power output) of at least 1 μW, 1.5 μW, 2 μW, 2.5 μW, 3 μW, 3.5 μW, 4 μW, 4.5 μW, 5 μW, 5.5 μW, 6 μW, 6.5 μW, 7 μW, 7.5 μW, 8 μW, 8.5 μW, 9 μW, 9.5 μW, or 10 μW.

[0119] The main bending direction of the piezoelectric element 816 can depend on the geometry of the piezoelectric element 816. For example, as FIGS. 8A-8E As shown, each piezoelectric element 816 may have a generally flat body (e.g., beam, strip, membrane, plate) defining a corresponding plane. For example, a first piezoelectric element 816a defines a first plane 838a aligned (e.g., parallel) to a first transverse axis T4 and a first longitudinal axis A4, and a second piezoelectric element 816b defines a second plane 838b aligned (e.g., parallel) to a second transverse axis T5 and a second longitudinal axis A5. Due to the overlapping configuration of the first piezoelectric element 816a and the second piezoelectric element 816b, the first plane 838a may intersect the second plane 838b. The main bending direction of the first piezoelectric element 816a may be a first direction 840a orthogonal to the first plane 838a, and the main bending direction of the second piezoelectric element 816b may be a second direction 840b orthogonal to the second plane 838b.

[0120] In some embodiments, the piezoelectric elements 816 face different directions such that the primary bending directions of the piezoelectric elements 816 are different from one another, allowing for effective energy harvesting from input motions in different directions. For example, the piezoelectric elements 816 can have different orientations such that the first plane 838a is offset from the second plane 838b, such as by an angle that is greater than or equal to 5°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, or 170°. As a result, the first direction 840a can also be offset from the second direction 840b, such as by an angle that is greater than or equal to 5°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, or 170°. In the illustrated embodiment, the piezoelectric elements 816 are arranged in a radially symmetric configuration such that the angles between the planes 838a, 838b and the primary bending directions 840a, 840b are 90°. However, in other embodiments, the piezoelectric elements 816 can be arranged differently, such as in a non-radially symmetric configuration, a non-overlapping configuration, etc.

[0121] FIGS. 8A-8E The configuration of the device 800 can be modified in a number of different ways. For example, although the piezoelectric elements 816 are illustrated as discrete components that are connected to one another via the joint 830, in other embodiments the piezoelectric elements 816 can instead be curved or otherwise formed as a single integral component of the configuration shown, such as a single elongated metal strip having an upper piezoelectric layer and a lower piezoelectric layer. FIG. 9

[0122] FIGS. 1-5D is a perspective view of an energy harvesting mechanism 902 configured in accordance with an embodiment of the technology. The energy harvesting mechanism 902 can be incorporated into any of the devices described herein (e.g., the device of FIG. 9 The energy harvesting mechanism 902 includes a plurality of piezoelectric elements coupled to one another in series, including a first piezoelectric element 904a coupled to a fixed region 906 within a housing that houses the energy harvesting mechanism 902, a second piezoelectric element 904b coupled to a harvester mass 908, and one or more third piezoelectric elements 904c connected in series between the first and second piezoelectric elements 904a, 904b. Although FIG. 9 Although a total of six piezoelectric elements 904a-904c (collectively, “piezoelectric elements 904”) are illustrated, in other embodiments the energy harvesting mechanism 902 can include a different number of piezoelectric elements 904, such as two, three, four, five, or more piezoelectric elements 904.

[0123] ​Each piezoelectric element 904 may be made partially or entirely of a piezoelectric material, such as piezoelectric ceramics (e.g., PZT), single-crystal piezoelectric materials (e.g., PMN-PT), piezoelectric polymers (e.g., PVDF), or piezoelectric composites (e.g., piezoelectric ceramics embedded in a polymer matrix, such as macrofiber composites). In some embodiments, some or all of the piezoelectric elements 904 are piezoelectric bicrystalline wafers, while in other embodiments, some or all of the piezoelectric elements 904 are piezoelectric monocrystalline wafers. Each piezoelectric element 904 may have any suitable geometry, such as a beam, plate, shaft, rod, fiber, or other elongated member.

[0124] like FIG. 9 As shown, piezoelectric elements 904 can be mechanically and / or electrically connected to each other in an end-to-end and / or unfolded configuration, such that the distal end portion of each piezoelectric element 904 is coupled to the proximal end portion of the adjacent piezoelectric element 904. Although the piezoelectric elements 904 are illustrated as being directly connected to each other, in other embodiments, some or all of the piezoelectric elements 904 may alternatively be connected to each other via connectors. As described herein, connectors may optionally provide electrical interconnection between adjacent piezoelectric elements 904.

[0125] The piezoelectric element 904 can be arranged such that its respective longitudinal axes are aligned with each other and / or with the longitudinal axis of the housing housing the energy harvesting mechanism 902 (e.g., parallel or within 10°, 5°, 2°, or 1° of parallel). In an illustrated embodiment, the piezoelectric element 904 is arranged in a helical configuration along the longitudinal axis of the energy harvesting mechanism 902. Each piezoelectric element 904 may be longitudinally and circumferentially offset from adjacent piezoelectric elements 904 such that the distal end surface of each piezoelectric element 904 only partially overlaps or does not overlap the proximal end surface of adjacent piezoelectric elements 904. The piezoelectric element 904 may each face different directions such that the respective planes of the piezoelectric element 904 face different directions, and each piezoelectric element 904 has a different respective principal bending direction. For example, as FIGS. 5A-9 As shown, each piezoelectric element 904 can face the central longitudinal axis of the helix, wherein the plane of each piezoelectric element 904 is at an angle relative to the plane of the adjacent piezoelectric element 904.

[0126] although FIGS. 5A-7BEmbodiments of the energy harvesting mechanism with three, five, two, and six piezoelectric elements, respectively, are illustrated, but the techniques described herein can be applied to energy harvesting mechanisms having any suitable number of piezoelectric elements, such as two, three, four, five, six, seven, eight, nine, 10, 15, 20, or more piezoelectric elements. Some or all of the piezoelectric elements can be oriented in different directions to allow energy harvesting from input motions in different directions, as described herein. For example, some or all of the piezoelectric elements can face in different directions, such that respective planes of the piezoelectric elements are offset from one another by an angle that is greater than or equal to 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, or 170°. Thus, respective principal bending directions of some or all of the piezoelectric elements can be offset from one another by an angle that is greater than or equal to 5°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, or 120°. The piezoelectric elements can be arranged in any suitable configuration, such as a radially symmetric configuration or a radially asymmetric configuration. Some or all of the piezoelectric elements can be spaced apart from one another (e.g., in a radially distributed and / or folded configuration, such as the configuration shown in FIGS. 8A-8E ), or some or all of the piezoelectric elements can overlap one another (e.g., in an interleaved and / or coaxial configuration, such as the configuration shown in FIGS. 5A-7B ).

[0127] In some embodiments, the energy harvesting mechanisms described herein include an odd number of piezoelectric elements. In such embodiments, the piezoelectric elements can be coupled in series, with the distal end portion of a first piezoelectric element coupled to a fixed region within the housing, the proximal end portion of a last piezoelectric element coupled to the harvester mass, and intermediate piezoelectric elements coupled at their respective proximal and distal end portions to adjacent piezoelectric elements. For example, with respect to the configuration described in FIGS. 8A-8E The configuration of piezoelectric elements described can be extended to energy harvesting mechanisms having seven piezoelectric elements, nine piezoelectric elements, eleven piezoelectric elements, etc. However, in other embodiments, some or all of the piezoelectric elements can instead be coupled in parallel, with respective distal end portions of the piezoelectric elements coupled to the fixed region, and respective proximal end portions of the piezoelectric elements coupled to the harvester mass. This approach can be used, for example, in embodiments in which the piezoelectric elements are sufficiently flexible, so that the resonant frequency of the energy harvesting mechanism remains suitable for harvesting from physiological motions, as described elsewhere herein.

[0128] In some embodiments, the energy harvesting mechanism described herein includes an even number of piezoelectric elements. In such embodiments, one or more of the piezoelectric elements can include a structure that allows the piezoelectric element to effectively behave as a set of components coupled in series. For example, any piezoelectric element can include two or more structures that are able to move relative to one another to act as a set of fan-folded beams, for example, as described with respect to FIG. 9 Additionally, in some embodiments, the piezoelectric elements can be coupled in series in an end-to-end unfolded configuration, for example, as described with respect to Example However, in other embodiments, some or all of the piezoelectric elements can instead be coupled in parallel, for example, in cases where the piezoelectric elements are sufficiently flexible, so that the resonant frequency of the energy harvesting mechanism remains suitable for harvesting from physiological motion, as described elsewhere herein.

[0129] Conclusion

[0130] The following examples are included to further describe some aspects of the present technology and are not intended to be limiting of the scope of the technology.

[0131] 1. An apparatus, comprising:

[0132] a housing configured for implantation within a patient, wherein the housing includes a proximal end, a distal end, and a longitudinal axis extending between the proximal end and the distal end;

[0133] a power source positioned within the housing; and

[0134] an energy harvesting mechanism positioned within the housing and configured to charge the power source, wherein the energy harvesting mechanism includes a plurality of piezoelectric elements aligned with the longitudinal axis of the housing, and wherein each piezoelectric element faces a different direction.

[0135] 2. The apparatus of embodiment 1, wherein the plurality of piezoelectric elements are arranged radially around the longitudinal axis of the housing.

[0136] 3. The apparatus of embodiment 1 or 2, wherein the plurality of piezoelectric elements are arranged in a radially symmetric configuration.

[0137] 4. The apparatus of any of embodiments 1-3, wherein each piezoelectric element has a flat body that defines a plane, and wherein the planes of the plurality of piezoelectric elements are offset from one another.

[0138] 5. The device of any one of embodiments 1-4, wherein each piezoelectric element has a flattened body that defines a plane, and wherein each piezoelectric element faces a different direction due to each such plane facing a different direction.

[0139] 6. The device of any one of embodiments 1-5, wherein the energy harvesting mechanism is coupled to the housing at a fixed region, and wherein the energy harvesting mechanism further comprises a harvester mass that is spaced apart from the fixed region.

[0140] 7. The device of embodiment 6, wherein the plurality of piezoelectric elements comprises:

[0141] a first piezoelectric element coupled to the fixed region, and

[0142] a second piezoelectric element coupled to the harvester mass.

[0143] 8. The device of embodiment 7, wherein the plurality of piezoelectric elements comprises at least one additional piezoelectric element that couples the first piezoelectric element to the second piezoelectric element.

[0144] 9. The device of embodiment 8, wherein the first piezoelectric element, the second piezoelectric element, and the at least one additional piezoelectric element are coupled to one another in series.

[0145] 10. The device of embodiment 7, wherein:

[0146] the first piezoelectric element comprises a first end portion coupled to the fixed region, and a second end portion opposite the first end portion, and

[0147] the second piezoelectric element comprises a first end portion coupled to the first end portion of the first piezoelectric element, and a second end portion opposite the first end portion and coupled to the harvester mass.

[0148] 11. The device of embodiment 10, wherein the first piezoelectric element comprises a pair of outer members coupled to the fixed region, and an inner member located between the pair of outer members and coupled to the first end portion of the second piezoelectric element.

[0149] 12. The device of any one of embodiments 1-11, wherein each piezoelectric element comprises a piezoelectric bimorph beam.

[0150] 13. The device of any one of embodiments 1-12, wherein the housing is configured for implantation in a heart of the patient, and wherein the device further comprises one or more electrodes configured for delivering electrical stimulation to the heart.

[0151] 14. The device of any one of embodiments 1-13, wherein the energy harvesting mechanism has a cross-sectional dimension that is orthogonal to the longitudinal axis of the housing, and the cross-sectional dimension is no more than 10 mm.

[0152] 15. A device, comprising:

[0153] a housing configured for implantation in a patient, wherein the housing comprises a proximal end, a distal end, and a longitudinal axis extending between the proximal end and the distal end;

[0154] a power source positioned within the housing; and

[0155] an energy harvester positioned within the housing and configured for charging the power source, wherein the energy harvester comprises a plurality of piezoelectric members extending along the longitudinal axis of the housing, and wherein each piezoelectric member has a different principal bending direction.

[0156] 16. The device of embodiment 15, wherein the principal bending direction of each piezoelectric member corresponds to a direction of motion that maximizes power output of the piezoelectric member.

[0157] 17. The device of embodiment 15 or 16, wherein the principal bending direction of each piezoelectric member corresponds to a direction of motion that minimizes an amount of force used to deflect the piezoelectric member.

[0158] 18. The device of any one of embodiments 15-17, wherein each piezoelectric member has a longitudinal axis and a transverse axis, and the principal bending direction of each piezoelectric member is orthogonal to the longitudinal axis and the transverse axis of the piezoelectric member.

[0159] 19. The device of any one of embodiments 15-18, wherein the energy harvester is coupled to the housing at a fixed region, and wherein the energy harvester further comprises a harvester mass that is spaced apart from the fixed region.

[0160] 20. The device of embodiment 19, wherein the plurality of piezoelectric members comprises:

[0161] a first piezoelectric member coupled to the fixed region, and

[0162] a second piezoelectric member coupled to the harvester mass.

[0163] 21. The apparatus of embodiment 20, wherein the plurality of piezoelectric members includes at least one additional piezoelectric member coupling the first piezoelectric member to the second piezoelectric member.

[0164] 22. The apparatus of embodiment 21, wherein the first piezoelectric member, the second piezoelectric member, and the at least one additional piezoelectric member are coupled to one another in an end-to-end configuration.

[0165] 23. The apparatus of embodiment 20, wherein:

[0166] the first piezoelectric member includes a first end portion coupled to the fixed region, and a second end portion opposite the first end portion, and

[0167] the second piezoelectric member includes a first end portion coupled to the first end portion of the first piezoelectric member, and a second end portion opposite the first end portion and coupled to the harvester mass.

[0168] 24. The apparatus of embodiment 23, wherein the first piezoelectric member includes an outer structure coupled to the fixed region, and an inner structure positioned between the outer structure and coupled to the first end portion of the second piezoelectric member.

[0169] 25. The apparatus of any one of embodiments 15-24, wherein each piezoelectric member includes a piezoelectric bimorph beam.

[0170] 26. The apparatus of any one of embodiments 15-25, wherein the housing is configured for implantation in a heart of the patient, and wherein the apparatus further comprises one or more electrodes configured for delivering electrical stimulation to the heart.

[0171] 27. The apparatus of any one of embodiments 15-26, wherein the energy harvester has a cross-sectional dimension orthogonal to the longitudinal axis of the housing, and the cross-sectional dimension is no more than 10 mm.

[0172] 28. An apparatus comprising:

[0173] a housing configured for implantation in a patient;

[0174] a power source positioned within the housing; and

[0175] an energy harvesting mechanism positioned within the housing and configured to charge the power source, wherein the energy harvesting mechanism comprises:

[0176] a plurality of piezoelectric elements, and

[0177] one or more joints mechanically and electrically serially coupling the plurality of piezoelectric elements to one another.

[0178] 29. The apparatus of embodiment 28, wherein the plurality of piezoelectric elements are each configured to generate an electrical current in response to movement of the apparatus, and wherein the one or more joints are each configured to transmit the electrical current from one of the piezoelectric elements to another of the piezoelectric elements.

[0179] 30. The apparatus of embodiment 28 or 29, wherein the energy harvesting mechanism is coupled to the housing at a fixed region, and wherein the energy harvesting mechanism further comprises a harvester mass spaced apart from the fixed region.

[0180] 31. The apparatus of embodiment 30, wherein the plurality of piezoelectric elements comprises:

[0181] a first piezoelectric element coupled to the fixed region,

[0182] a second piezoelectric element coupled to the harvester mass, and

[0183] a third piezoelectric element serially coupled between the first piezoelectric element and the second piezoelectric element.

[0184] 32. The apparatus of embodiment 31, wherein the one or more joints comprises:

[0185] a first joint mechanically and electrically coupling the first piezoelectric element to the third piezoelectric element, and

[0186] a second joint mechanically and electrically coupling the second piezoelectric element to the third piezoelectric element.

[0187] 33. The apparatus of embodiment 31, wherein:

[0188] the plurality of piezoelectric elements comprises a fourth piezoelectric element serially coupled between the first piezoelectric element and the second piezoelectric element, and

[0189] the one or more joints comprises:

[0190] a first joint mechanically and electrically coupling the first piezoelectric element to the third piezoelectric element, and

[0191] a second joint mechanically and electrically coupling the second piezoelectric element to the fourth piezoelectric element.

[0192] 34. The apparatus of any one of embodiments 28-33, wherein the one or more joints are each made from a combination of an electrically conductive material and an insulating material.

[0193] 35. The apparatus of any one of embodiments 28-33, wherein the one or more joints are each made entirely from an electrically conductive material.

[0194] 36. The apparatus of any one of embodiments 28-35, wherein the one or more joints are rigid.

[0195] 37. The apparatus of any one of embodiments 28-35, wherein the one or more joints are flexible.

[0196] 38. The apparatus of any one of embodiments 28-37, wherein each piezoelectric element faces a different direction.

[0197] 39. The apparatus of any one of embodiments 28-38, wherein each piezoelectric element has a different primary bending direction.

[0198] FIGS. 1-9

[0199] While many embodiments have been described above with respect to systems, devices, and methods for cardiac pacing, the present technology is also applicable to other applications and / or other methods, such as other therapies involving implantable devices. Moreover, other embodiments, in addition to those described herein, are within the scope of the present technology. Additionally, several other embodiments of the present technology can have different configurations, components, or procedures than those described herein. Accordingly, a person having ordinary skill in the art, upon attaining an understanding of the nature of the present technology, should be FIGS. 1-9 other embodiments of several of the features shown and described.

[0200] Embodiments of the present technology can be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, various embodiments can be implemented within one or more processors, including one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components, embodied in programmers, such as physician or patient programmers, stimulators, or other devices. The term "processor" or "processing circuitry" can generally refer to any of the foregoing logic circuitry, alone or in combination, or any other equivalent electrical circuitry.

[0201] Various processes described herein can be partially or fully implemented by program code, including instructions that can be executed by one or more processors of a computing system to perform a certain logic function or step in the process. The program code can be stored on any type of computer readable medium, such as a storage device including a disk or hard drive. A computer readable medium that contains code or portions of code, including a computer readable medium that is non-transitory, can include any appropriate media, including storage media and communication media. Storage media include both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage and / or transmission of information such as computer readable instructions, data structures, program code, or other data. Storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, solid state drives (SSDs) or other solid state storage devices, or any other medium that can be used to store the desired information and that can be accessed by a system device. Communication media typically embody computer readable instructions, data structures, program code, or other data in a modulated data signal such as a carrier wave or other transport mechanism and include any information delivery media. The term "modulated data signal" means a signal that has one or more of its characteristics changed or set in a manner so as to encode information in the signal. By way of example, and not limitation, communication media include wired media such as a wired network or direct-wired connection, and wireless media such as wireless networks, cellular telephone networks, Bluetooth® wireless networks, and other wireless media.

[0202] The description of embodiments of the present technology is not intended to be exhaustive or to limit the present technology to the precise form disclosed. To the extent that the context permits, singular or plural terminology can also include the plural or singular form, respectively. While the above detailed description has described particular embodiments and examples of the present technology for illustrative purposes, various equivalent modifications are possible within the scope of the present technology, as those skilled in the relevant art will recognize. For example, while steps are presented in a given order, alternative embodiments can perform steps in a different order. Various embodiments described herein can also be combined to provide additional embodiments.

[0203] As used herein, the terms "entirely," "substantially," "about," and similar terms are used as approximating terms not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values that would be recognized by those of ordinary skill in the art.

[0204] Furthermore, the word "or" as used in this document is used in the inclusive sense of "and / or," unless otherwise indicated expressly herein, such as when used in a list of items. As used herein, the phrase "and / or" in the form "A and / or B" refers to: (a) A alone, (b) B alone, and (c) A and B together. Additionally, the term "comprising" is used throughout to mean including at least the recited item, such that other items are not excluded.

[0205] In the event that any material incorporated by reference conflicts with that of the present disclosure, the present disclosure controls.

[0206] It should also be appreciated that specific embodiments have been described herein for illustrative purposes, but various modifications can be made without departing from the technology. Additionally, although advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments can also exhibit such advantages, and not all embodiments necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the present disclosure and associated technology can encompass other embodiments not expressly shown or described herein.

Claims

1. An apparatus, the apparatus comprising: A housing configured for implantation in a patient, wherein the housing includes a proximal end, a distal end, and a longitudinal axis extending between the proximal end and the distal end; A power source, which is located within the housing; and An energy harvesting mechanism is located within the housing and configured to charge the power source, wherein the energy harvesting mechanism includes a plurality of piezoelectric elements aligned with the longitudinal axis of the housing, and wherein each piezoelectric element faces a different direction.

2. The apparatus of claim 1, wherein the plurality of piezoelectric elements are arranged radially around the longitudinal axis of the housing.

3. The apparatus according to claim 1 or 2, wherein the plurality of piezoelectric elements are arranged in a radially symmetrical configuration.

4. The apparatus according to any one of claims 1 to 3, wherein each piezoelectric element has a flat body defining a plane, and wherein the planes of the plurality of piezoelectric elements are offset from each other.

5. The apparatus according to any one of claims 1 to 4, wherein each piezoelectric element has a flat body defining a plane, and wherein each piezoelectric element faces a different direction due to each corresponding plane facing a different direction.

6. The apparatus according to any one of claims 1 to 5, wherein the energy harvesting mechanism is coupled to the housing at a fixed region, and wherein the energy harvesting mechanism further comprises a harvester mass block spaced apart from the fixed region.

7. The apparatus of claim 6, wherein the plurality of piezoelectric elements comprises: A first piezoelectric element, the first piezoelectric element being connected to the fixed region, and A second piezoelectric element is connected to the collector mass block.

8. The apparatus of claim 7, wherein the plurality of piezoelectric elements includes at least one additional piezoelectric element that connects the first piezoelectric element to the second piezoelectric element.

9. The apparatus of claim 8, wherein the first piezoelectric element, the second piezoelectric element, and the at least one additional piezoelectric element are connected in series with each other.

10. The apparatus according to claim 7, wherein: The first piezoelectric element includes a first end portion coupled to the fixed region and a second end portion opposite to the first end portion, and The second piezoelectric element includes a first end portion connected to the first end portion of the first piezoelectric element, and a second end portion opposite to the first end portion and connected to the collector mass block.

11. The apparatus of claim 10, wherein the first piezoelectric element comprises a pair of external members and an internal member located between the pair of external members, the pair of external members being coupled to the fixed region, and the internal member being coupled to the first end portion of the second piezoelectric element.

12. The apparatus according to any one of claims 1 to 11, wherein each piezoelectric element comprises a piezoelectric bicrystalline beam.

13. The device according to any one of claims 1 to 12, wherein the housing is configured for implantation in the heart of the patient, and wherein the device further comprises one or more electrodes configured for delivering electrical stimulation to the heart.

14. The apparatus according to any one of claims 1 to 13, wherein the energy harvesting mechanism has a cross-sectional dimension orthogonal to the longitudinal axis of the housing, and the cross-sectional dimension does not exceed 10 mm.

15. The device according to any one of claims 1 to 14, wherein each piezoelectric element has a different principal bending direction.

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