EP4698269A1

EP4698269A1 - Energy harvester with rotational alignment

Info

Publication number: EP4698269A1
Application number: EP24714574.1A
Authority: EP
Inventors: Can Cinbis; Martin G. Hieb; Andrew J. Ries
Original assignee: Medtronic Inc
Current assignee: Medtronic Inc
Priority date: 2023-04-17
Filing date: 2024-03-19
Publication date: 2026-02-25
Also published as: WO2024218590A1; CN120957785A

Abstract

A device with an energy harvester arrangement can include a housing configured for implantation in a human body, and an energy harvester arranged at least partially in the housing and configured to produce energy from motion of the housing. The energy harvester can include a member having a first end, a second end movable along a flexing axis relative to the first end, and a longitudinal axis extending between the first and second ends, where the member is configured to passively rotate around the longitudinal axis to self-align the flexing axis with motion of the housing.

Description

ENERGY HARVESTER WITH ROTATIONAL ALIGNMENT

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63/496,488, filed April 17, 2023, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

[0002] The present technology generally relates to medical devices, and in particular, to devices and methods for enhancing energy harvesting.

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 a patient’ s heart activity and provide therapeutic electrical stimulation to the heart via electrodes. The electrical stimulation provided by the cardiac pacemaker can include signals such as pacing pulses to address abnormal cardiac rhythms (e.g., bradycardia). Some types of cardiac pacemakers are implanted a distance from the heart and are coupled to one or more leads that extend intravascularly into the heart to position the electrodes in contact with cardiac tissue. However, the leads may be prone to fracture, which may result in unreliable or incorrect pacing, and may require replacement of the lead or even the entire pacemaker.

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

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Many aspects of the present 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 illustrating clearly the principles of the present disclosure.

[0006] FIG. 1 illustrates an example pacing device implanted in the heart of a patient, in accordance with embodiments of the present technology.

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

[OOOSj FIG. 3 is a side view of an example pacing device configured in accordance with embodiments of the present technology.

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

[0010] FIG. 5 is a side cross-sectional view of an example device including an energy harvesting mechanism, in accordance with embodiments of the present technology.

[0011 ] FIG. 6A is a perspective view of an example energy harvesting mechanism with rotational alignment configured in accordance with embodiments of the present technology.

[0012] FIGS. 6B and 6C are illustrative schematics of an example energy harvesting mechanism in different rotational states.

[0013] FIGS. 7A-7C are illustrative schematics of various example bearing arrangements for an energy harvesting mechanism configured in accordance with embodiments of the present technology.

[0014] FIG. 8A is an illustrative schematic of an example energy harvesting mechanism having radial asymmetry, in accordance with embodiments of the present technology.

[0015[ FIGS. 8B-8D are illustrative schematics of an example energy harvesting mechanism in different rotational states, in accordance with embodiments of the present technology. [0016| FIGS. 9A-9C are illustrative schematics of example energy harvesting mechanism with preferential bias, configured in accordance with embodiments of the present technology.

[0017] FIG. 10A is an illustrative schematic of an example energy harvesting mechanism configured in accordance with embodiments of the present technology.

[0018] FIG. 10B is an illustrative schematic of an example energy harvesting mechanism with one or more stops, configured in accordance with embodiments of the present technology.

[0019] FIG. 11 is an illustrative schematic of an example energy harvesting mechanism with electrical leads, configured in accordance with embodiments of the present technology.

[ 020[ FIGS. 12A and 12B are side view and cross-sectional views, respectively, of an example energy harvesting mechanism with electrical leads, configured in accordance with embodiments of the present technology.

[0021] FIGS. 13A and 13B are plots illustrating simulated probability distribution of power generated by an energy harvesting mechanism configured in accordance with embodiments of the present technology.

DETAILED DESCRIPTION

[0022[ The present technology relates to energy harvester mechanisms, such as for use in implantable devices (e.g., implantable medical devices such as cardiac pacemakers).

[0023] Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings in which like numerals represent like elements throughout the several figures, and in which example embodiments are 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 among other possible examples.

[0024] As used herein, the terms “vertical,” “lateral,” “upper,” and “lower” can refer to relative directions or positions of features of the embodiments disclosed herein in view of the orientation shown in the Figures. For example, “upper” or “uppermost” can refer to a feature positioned closer to the top of a page than another feature. These terms, however, should be construed broadly to include embodiments having other orientations, such as inverted or inclined orientations where top/bottom, over/under, above/below, up/down, and left/right can be interchanged depending on the orientation.

[0025] The headings provided herein are for convenience only and do not interpret the scope or meaning of the claimed present technology. Embodiments under any one heading may be used in conjunction with embodiments under any other heading.

I. Overview of Implantable Pacing Devices

]0026| FIGS. 1-4 provide a general overview of implantable devices configured in accordance with embodiments of the present technology. Specifically, FIG. 1 illustrates a pacing device implanted in a patient’s heart, FIG. 2 illustrates an example configuration for a pacing device, FIG. 3 illustrates another example configuration for a pacing device, and FIG. 4 illustrates electronic components that can be included in a pacing device. Any of the features of the embodiments of FIGS. 1-4 can be combined with each other and/or with any of the other embodiments described herein.

[0027] Referring first to FIG. 1, which illustrates a pacing device 100 implanted in the heart H of a patient, the device 100 is configured to monitor activity of the heart H and provide electrical stimulation (e.g., pacing signals) to the heart H. In some embodiments, the device 100 is a leadless intracardiac pacemaker configured to be implanted entirely within a heart chamber, such as entirely within the right atrium (RA), entirely within the right ventricle (RV), entirely within the left atrium (FA), or entirely within the left ventricle (EV). The device 100 can be implanted at any of a variety of locations to sense and/or deliver therapy to any chamber or chambers of the heart H. For example, as shown in FIG. 1, the device 100 can be a right atrial intracardiac pacemaker that is implanted in the RA of the patient’s heart H in a target implant region T (e.g., the triangle of Koch). The target implant region T can lie 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 intracardiac pacemaker that is implanted in the RV of the heart H, with the target implant region T lying along the endocardial wall at or near the apex of the RV. [0028| The device 100 can include a housing 102 having a size and form factor suitable for transvenous delivery into the heart H via a catheter. In the illustrated embodiment, the housing 102 has an elongate shape extending from a distal portion 104 to a proximal portion 106. The housing 102 can have a generally cylindrical shape (e.g., pillshaped or capsule-shaped), a generally prismatic shape (e.g., a rectangular prism), or any other suitable shape. The housing 102 can define an interior cavity that contains the electronic components of the device 100 (e.g., circuitry, power source, sensors).

[0029] The device 100 can include a fixation mechanism 108 to secure the device 100 to the tissue of the heart H. For example, the fixation mechanism 108 can include one or more fixation elements configured to penetrate into tissue, such as one or more tines, coils, barbs, etc. In the illustrated embodiment, the fixation mechanism 108 is coupled to and extends outwardly from the distal portion 104 of the housing 102. Accordingly, when the device 100 is implanted, the distal portion 104 can be positioned in contact with or in close proximity to the cardiac tissue, while the proximal portion 106 can be spaced apart from the cardiac tissue. In other embodiments, however, the fixation mechanism 108 can be located at a different portion of the device 100.

[0030] The device 100 also includes a plurality of electrodes configured to sense electrical activity of the heart H and/or deliver electrical therapy to the heart H. For example, the 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 the device 100, such as on or coupled to the housing 102 (e.g., the distal portion 104, the proximal portion 106, an intermediate location between the distal portion 104 and proximal portion 106), or on or coupled to the fixation mechanism 108. In some embodiments, the device 100 includes one or more electrodes (e.g., cathodes) that directly contact the cardiac tissue (e.g., of a single heart chamber or multiple heart chambers) to sense the activity thereof and/or deliver electrical therapy thereto. Such electrode(s) can be located at the distal portion 104 of the housing 102 and/or incorporated into the fixation mechanism 108, for example. The device 100 can also include at least one electrode (e.g., an anode and/or return electrode) that does not directly contact cardiac tissue. Such electrode(s) can be located at portions of the housing 102 that are spaced apart from cardiac tissue, such as the proximal portion 106. Optionally, a single electrode may serve as a cathode for certain operations, and may serve as an anode and/or return electrode for other operations. [00311 In some embodiments, the device 100 is operably coupled to an external device 110 shown schematically) via bidirectional wireless communication, such as BLUETOOTH®, Wi-Fi, Medical Implant Communication Service (MICS), or other radiofrequency communication technique. The external device 110 can be a computing device or system that is located outside of the patient’s body, and can be used in a healthcare setting (e.g., in a clinic, hospital or other medical facility), at 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, etc. For instance, 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 relating 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, etc. 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 technique. The external device 110 can serve as a “programmer” that allows a physician, patient, or other individual to monitor and/or control the operations of the device 100.

[0032] Although FIG. 1 illustrates a single device 100, the present technology is also applicable to implantable systems including multiple devices 100 implanted at different locations in the heart H. For example, an 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.

[0033] 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 to be implanted within a chamber of a heart of the patient to monitor activity of the heart and/or provide electrical therapy (e.g., pacing therapy) to the heart. The device 200 includes a housing 202 having a size and form factor that allows the device 200 to be entirely implanted within a single chamber of the patient’s heart. In the illustrated embodiment, the housing 202 has an elongate shape (e.g., a generally cylindrical shape, a generally prismatic shape) extending between a distal end 204 and proximal end 206. The housing 202 can define a hermetically sealed internal 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 to temporarily engage with a delivery tool during implantation and/or extraction of the device 200.

[0034] The housing 202 can be formed partially or entirely from a conductive material, such as titanium or titanium alloy, stainless steel, MP35N (a non-magnetic nickel- cobalt-chromium-molybdenum alloy), a platinum alloy, or other biocompatible metal or metal alloy, or other suitable conductive material. Alternatively or in combination, the housing 202 can be formed partially or entirely from a nonconductive (e.g., insulative) material, such as ceramic, glass, sapphire, silicone, polyurethane, epoxy, acetyl co-polymer plastics, polyether ether ketone (PEEK), a liquid crystal polymer, other biocompatible polymer, or other suitable nonconductive material.

[0035] The device 200 can include a plurality of electrodes 210a-210c configured to sense electrical activity of the heart and/or deliver electrical stimulation to the heart. In the illustrated embodiment, for example, the device 200 includes a first electrode 210a and a second electrode 210b at or proximate to the distal end 204 of the housing 202, and a third electrode 210c on the housing 202. The first and second electrodes 210a, 210b can be configured as cathode electrodes that directly contact cardiac tissue, e.g., a distal end of the first electrode 210a can be configured to rest within a ventricular myocardium of the patient, and the second electrode 210b can be configured to contact an atrial endocardium of the patient. The third electrode 210c can be configured as an anode and/or return electrode that does not directly contact cardiac tissue.

[0036] As shown in FIG. 2, the first electrode 210a can be an elongate structure that extends from the distal end 204 of the housing 202 to penetrate through the wall tissue of a first heart chamber (e.g., the chamber in which the device 200 is implanted) into wall tissue of a second, different heart chamber. For example, in some embodiments, the device 200 is implanted in the RA with the distal end 204 oriented toward the LV (e.g., similar to the arrangement of the device 100 in FIG. 1), and the first electrode 210a extends through the wall tissue of the RA and into the wall tissue of the EV. In the illustrated embodiment, the first electrode 210a is configured as a coil (e.g., a helical and/or spiral coil), while in other embodiments, the first electrode 210a can have a different form factor (e.g., an elongate dart, barb, tine, or other tissue penetrating element). The first electrode 210a can include a proximal end that is coupled to the distal end 204 of the housing 202, and a free distal end that is not attached to the housing 202. The distal end of the first electrode 210a can have a conical, hemi-spherical, or slanted 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 sharpened or angular tip, and/or sharpened or beveled edges, but the degree of sharpness can be constrained to avoid a cutting action that could lead to lateral displacement of the distal end of the first electrode 210a and undesired tissue trauma.

[0037| The second electrode 210b can be a structure that extends 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 proximal to 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 full turn), loop, button, pad, or any other suitable form factor. The second electrode 210b can include a proximal end that is coupled to the distal end 204 of the housing 202, and a distal end that may or may not be coupled to the housing 202. In some embodiments, the second electrode 210b is configured to flexibly maintain contact with wall tissue of the heart chamber in which the device 200 is implanted, (e.g., the RA endocardium), despite variations in the tissue surface and/or in the distance between the distal end 204 of the housing 202 and the tissue surface, which may occur as the wall tissue moves during the cardiac cycle. Accordingly, 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.

[0038] The first and second electrodes 210a, 210b can each be formed of an electrically conductive material, such as titanium, platinum, iridium, tantalum, or alloys thereof. The first electrode 210a can include one or more insulative coatings (e.g., parylene, polyurethane, silicone, epoxy) that reduce the electrically conductive surface area of the first electrode 210a to define a first electrically active 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 electrically conductive surface area of the second electrode 210b to define a second electrically active 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 and second electrodes 210a, 210b, and thereby reduce the current delivered during a pacing pulse, which can conserve the power used by the device 200. In some embodiments, the first and second electrodes 210a, 210b include an electrically conductive material coating (e.g., TiN) on the first and second electrically active regions 212, 214, respectively, to define the active regions. The first and second electrodes 210a, 210b can be made of the same materials, or can be made of different materials. 0039| All, substantially all, or a portion of the housing 202 can serve as a third electrode 210c (e.g., an anode and/or return electrode) during pacing and/or sensing. In some embodiments, the third electrode 210c partially or fully circumscribes a portion of the housing 202 at or near the proximal end 206. Although FIG. 2 illustrates the third electrode 210c as a singular band, in other embodiments, the third electrode 210c can include multiple segments spaced a distance apart along a longitudinal axis 216 of the housing 202 and/or around a perimeter of the housing 202. Additionally, the third electrode 210c can also be located at other positions along the housing 202, e.g., located at or near the distal end 204 or at other positions along the longitudinal axis 216.

(0040] In embodiments where the housing 202 is formed from a conductive material, one or more portions of the housing 202 can be electrically insulated by a nonconductive material, such as a coating of parylene, polyurethane, silicone, epoxy or other biocompatible polymer, or other suitable material. For the portions of the housing 202 without the nonconductive material, one or more discrete areas of the housing 202 with conductive material can be exposed to define the third electrode 210c. In embodiments where the housing 202 is formed from a nonconductive material, a conductive material can be applied to one or more discrete areas 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) that is coupled to the housing 202.

|0041 | The electrodes 210a-210c can be used to sense electrical activity of one or more heart chambers and/or to deliver electrical stimulation to one or more heart chambers. For example, the first electrode 210a can be paired with the second electrode 210b or the third electrode 210c to 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 the atrial myocardium. In a further example, the third electrode 210c can be paired at different times with both the first electrode 210a and the second electrode 210b for either ventricular or atrial functionality, respectively. As yet another example, the first electrode 210a and the second electrode 210b can be paired with each other with different polarities for atrial and ventricular functionality.

[004 1 In some embodiments, the second electrode 210b is configured as an atrial cathode electrode for delivering pacing pulses to the atrial tissue at a target implant region in combination with the third electrode 210c. The second electrode 210b and the third electrode 210c can also be used to sense atrial P-waves for use in controlling atrial pacing pulses (e.g., delivered in the absence of a sensed P-wave) and for controlling atrial- synchronized ventricular pacing pulses delivered using the first electrode 210a as a cathode and the third electrode 210c as the return anode. The configuration of the electrodes 210a- 210c illustrated in FIG. 2 allows the device 200 to sense cardiac signals from 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 heart chamber (e.g., the RA).

[0043] The device 200 can include a fixation mechanism 218 configured to fix the device 200 to cardiac tissue at a target implant region (e.g., the triangle of Koch). In the illustrated embodiment, the first electrode 210a and/or second electrode 210b at the distal end 204 of the housing 202 can serve as the fixation mechanism 218. In other embodiments, the fixation mechanism 218 can be a different component than the first electrode 210a and/or the second electrode 210b, such one or more separate barbs, tines, coils, darts, etc.

[0044] FIG. 3 is a side view of another pacing device 300 configured in accordance with embodiments of the present technology. The device 300 is configured to be implanted within a chamber of a heart of a patient to monitor activity of the heart and/or to provide electrical therapy to the heart. In the embodiment shown in FIG. 3, the device 300 includes a housing 302, a plurality of fixation tines 304, a first electrode 306a, and a second electrode 306b.

[0045| The housing 302 can have a size and form factor that allows the device 300 to be entirely implanted within a chamber of a heart of a patient. For example, as shown in FIG. 3, the housing 302 has a generally cylindrical (e.g., pill-shaped or capsule-shaped), elongate form factor extending between a distal end 308 and a proximal end 310. The housing 302 contains electronic components of the device 300, and can be hermetically or near-hermetically sealed to prevent fluid ingress into the housing 302. The materials used to form the housing 302 can include any of the conductive and nonconductive materials described above with respect to FIG. 2.

[0046] The device 300 can include a fixation mechanism configured to fix the device 300 to cardiac tissue at a target implant region (e.g., the endocardial wall near the apex of the RV). In the illustrated embodiment, the device 300 includes a plurality of fixation tines 304 extending from the distal end 308 of the housing 302 and configured to engage with cardiac tissue to secure the housing 302 at a fixed position within the chamber of the heart. The fixation tines 304 can be configured to anchor the housing 302 to the cardiac tissue such that the device 300 moves along with the cardiac tissue during cardiac contractions. The device 300 can include any suitable number of fixation tines 304, such as one, two, three, four, five, or more fixation tines 304. The fixation tines 304 can be fabricated from any suitable material, such as a shape memory material (e.g., Nitinol). Alternatively or in combination, the device 300 can be fixed to cardiac tissue using other types of fixation mechanisms, such as, but not limited to, barbs, coils, darts, and the like.

[0047] Optionally, the device 300 can include an attachment mechanism configured to temporarily couple the device 300 to a delivery tool, e.g., for delivery and/or extraction of the device 300. In the illustrated embodiment, for example, the proximal end 310 includes a flange 318 that defines an opening. The flange 318 can be attached to a tether (e.g., by threading the tether through the opening) that extends through an elongate shaft (e.g., a catheter) to implant or extract the device 300.

[0048] In some embodiments, the device 300 is configured to sense electrical activity of the heart and/or deliver electrical stimulation to the heart via the first electrode 306a and second electrode 306b (collectively, “electrodes 306”). The first electrode 306a can serve as a cathode configured to electrically contact cardiac tissue and deliver pacing pulses thereto, and the second electrode 306b can serve as an anode and/or a return electrode. Optionally, the device 300 can be equipped with multiple cathode electrodes. Such multiple cathode electrodes can be configured to electrically contact and deliver pacing pulses to cardiac tissue of a single heart chamber, or cardiac tissue of multiple heart chambers. In some such embodiments, the multiple cathode electrodes are configured to electrically contact and deliver pacing pulses to cardiac tissue of different heart chambers. For example, one cathode electrode can be configured to electrically contact and deliver pacing pulses to atrial tissue, and another cathode electrode may be configured to electrically contact and deliver pacing pulses to ventricular tissue. 0049 The electrodes 306 can be configured in many different ways. For example, one or both of the electrodes 306 can be discrete components that are mechanically coupled to the housing 302. As another example, one or both of the electrodes 306 can be defined by an outer portion of the housing 302 that is electrically conductive. The electrodes 306 can be electrically isolated from each other. In some embodiments, a portion of the housing 302 is covered by or formed from an insulative material to isolate the electrodes 306 from each other 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).

(00501 In the illustrated embodiment, the first electrode 306a is located at the distal end 308 of the housing 302. The first electrode 306a may be referred to as a tip electrode, and the fixation tines 304 can be configured to anchor the device 300 to cardiac tissue such that the first electrode 306a maintains contact with the cardiac tissue. In some examples, the housing 302 includes an end cap 312 at the distal end 308, and the end cap 312 includes a feedthrough assembly to electrically couple the first electrode 306a to the electronics within the housing 302, while electrically isolating the first electrode 306a from the remaining portions of the housing 302, e.g., including the second electrode 306b and/or other conductive portions of the housing 302

(00511 The second electrode 306b can be located on the housing 302 away from (e.g., proximal to) the first electrode 306a. As shown in FIG. 3, the housing 302 includes a first portion 314 and a second portion 316, with the first portion 314 being located proximal to the end cap 312, and the second portion 316 being located proximal to the first portion 314. The second portion 316 can optionally define at least part of a power source case 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.

[0052| In some embodiments, the second electrode 306b is a conductive portion of the housing 302 (e.g., an annular portion of the housing 302 that is made partially or entirely from a conductive material). Additionally or alternatively, the second electrode 306b can be a conductive material that is coated onto the material of the housing 302, or a discrete component (e.g., a ring electrode) that is coupled to the housing 302. The remaining portions of the housing 302 can include or be coated with an insulative material so that the second electrode 306b is electrically isolated from the rest of the housing 302 and/or from the first electrodes 306a.

[0053| FIG. 4 is a schematic block diagram illustrating electronic components of a pacing device 400 configured in accordance with embodiments of the present technology. Any of the electronic components shown in FIG. 4 can be incorporated into any of the embodiments of implantable devices described herein, such as the device 100 of FIG. 1, the device 200 of FIG. 2, or the device 300 of FIG. 3.

[0054| As shown in FIG. 4, the device 400 includes a plurality of electrodes 402a- 402c that are electrically coupled to components within a housing 404 of the device 400. Although the device 400 is illustrated 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. 0055 J 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 and deliver electrical signals to tissue of a first heart chamber (e.g., ventricular tissue), and the second electrode 402b can be configured to electrically contact and deliver electrical signals to tissue of a second, different heart chamber (e.g., atrial tissue). The third electrode 402c can be an anode and/or return electrode that does not electrically contact heart tissue. Optionally, either the first electrode 402a or the second electrode 402b can be omitted, or the device 400 can include additional electrodes that electrically contact and deliver electrical signals to tissue of a heart chamber (e.g., the first heart chamber, the second heart chamber, or another heart chamber).

[0 561 The device 400 includes a plurality of electronic components within the housing 404, such as switch circuitry 406, sensing circuitry 408, therapy generation circuitry 410, one or more sensors 412, processing circuitry 414, communication circuitry 416, memory 418, and/or a power source 420. The various circuitry can be or include programmable or fixed function circuitry configured to perform the operations described herein. One or more of the components of the device 400 shown in FIG. 4 can be part of an electronics assembly. For example, one or more of the switch circuitry 406, sensing circuitry 408, therapy generation circuitry 410, sensor(s) 412, processing circuitry 414, communication circuitry 416, and/or memory 418 can be mounted on a circuit board of an electronics assembly of the device 400.

[0057] The switch circuitry 406 can include one or more switches (e.g., a switch matrix, switch arrays, or other collection of switches), multiplexers, transistors, and/or other electrical circuitry. The switch circuitry 406 can selectively couple one or more of the electrodes 402a-402c to other components of the device 400 (e.g., the sensing circuitry 408 and/or the therapy generation circuitry 410). The subset of the electrodes 402a-402c to be used can depend on the particular operation of the device 400 that is being performed, such as whether the device 400 is sensing or delivering therapy, the locations of the heart being monitored or treated, etc. In some embodiments, the processing circuitry 414 determines which subset of the electrodes 402a-402c should be used for a particular operation, and controls the switch circuitry 406 to selectively couple those electrodes to the appropriate components of the device 400.

[0058] The sensing circuitry 408 can monitor signals from at least one of electrodes 402a-402c to monitor electrical activity of the heart, impedance, and/or other electrical phenomena. Sensing can be performed to determine heart rates and/or heart rate variability, and/or to detect ventricular dyssynchrony, arrhythmias (e.g., tachyarrhythmias), and/or other electrical signals. The sensing circuitry 408 can include filters, amplifiers, analog-to- digital converters, and/or other circuitry configured to sense cardiac electrical signals via one or more of the electrodes 402a-402c.

(0059] In some embodiments, the switch circuitry 406 as controlled by the processing circuitry 414 selectively couples the sensing circuitry 408 to selected combinations of the electrodes 402a-402c, e.g., to selectively sense the electrical activity of one or more chambers of the heart. For example, the switch circuitry 406 can couple each of the first electrode 402a and the second electrode 402b (in combination with the third electrode 402c) to respective sensing channels provided by the sensing circuitry 408 to sense electrical signals from the cardiac tissues in electrical contact with the first electrode 402a (e.g., ventricular tissue) and the second electrodes 402b (e.g., atrial tissue), respectively. In some embodiments, the sensing circuitry 408 is configured to detect events, (e.g., depolarizations) within the cardiac electrical signals, and to provide indications thereof to the processing circuitry 414. In this manner, the processing circuitry 414 can determine the timing of atrial and/or ventricular depolarizations, and can control the delivery of cardiac pacing (e.g., AV synchronized cardiac pacing) based thereon.

(0060] The therapy generation circuitry 410 can generate electrical stimulation signals, such as cardiac pacing pulses. The therapy generation circuitry 410 can be electrically coupled to one or more of the electrodes 402a-402c to deliver pulses to a portion of cardiac muscle within the heart via one or more of the electrodes 402a-402c. In some embodiments, the therapy generation circuitry 410 delivers pacing stimulation in the form of electrical pulses. The therapy generation circuitry 410 can include charging circuitry, and one or more charge storage devices (e.g., capacitors). Optionally, the therapy generation circuitry 410 can include switches and/or other circuitry to control when the charge storage devices are discharged to the electrodes 402a-402c.

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

[0062] The processing circuitry 414 can include one or more processors, such as a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or equivalent discrete or analog logic circuitry. In some embodiments, the processing circuitry 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 the processing circuitry 414 herein may be embodied as software, firmware, hardware, or any combination thereof.

[0063] The processing circuitry 414 can control the therapy generation circuitry 410 to deliver stimulation therapy to a patient’s heart according to therapy parameters, which can be stored in the memory 418. For example, the processing circuitry 414 can control the therapy generation circuitry 410 to deliver electrical pulses with the amplitudes, pulse widths, rates, frequencies, and/or electrode polarities specified by the therapy parameters. In this manner, the therapy generation circuitry 410 can deliver pacing pulses to the heart via one or more of the electrodes 402a-402c. The device 400 can use any combination of the electrodes 402a-402cto deliver therapy and/or detect electrical signals from the patient.

[0064] The memory 418 (e.g., a data storage device or other non-transitory medium) can store computer-readable instructions that, when executed by the processing circuitry 414, cause the device 400 to perform the various operations described herein. The memory 418 can include any volatile, non-volatile, magnetic, optical, or electrical media, such as a 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 media.

[0065] The sensor(s) 412 can include one or more sensing elements that transduce patient physiological activity to an electrical signal to sense values of a respective patient parameter. Sensor(s) 412 can include one or more motion sensors, optical sensors, chemical sensors, temperature sensors, pressure sensors, and/or any other types of sensors. The sensor(s) 412 can output patient parameter values to the processing circuitry 414 that can be used as feedback to control sensing and/or delivery of therapy by the device 400.

[0066] For example, the sensor(s) 412 can include at least one motion sensor, such as one or more inertial measurement units (IMUs), accelerometers, gyroscopes, electrical or magnetic field sensors, and/or other devices capable of detecting motion and/or the position of the device 400. The motion of the device 400 detected by the motion sensor may be indicative of cardiac events (e.g., paced activation of the ventricles), blood flow through the heart, patient posture, patient activity, and/or noise. The processing circuitry 414 can control and/or monitor the motion data produced by the motion sensor to identify one or more features of the cardiac contraction within the signal (e.g., on a beat-by-beat basis or otherwise) to facilitate delivery of therapy (e.g., delivery of ventricular pacing pulses in an atrial- synchronized manner). Optionally, the processing circuitry 414 can use the motion data to detect a current activity level of the patient, which can be used for rate-responsive pacing of the patient’s heart.

[0067] The communication circuitry 416 is configured to allow the device 400 to wirelessly communicate with another device, such as a device external to the patient’s body (e.g., the external device 110 of FIG. 1) and/or another device under the control of the processing circuitry 414. For instance, the processing circuitry 414 can receive updates to operational parameters from the other device, and/or can provide collected data, (e.g., sensed heart activity and/or other patient parameters) to the other device via the communication circuitry 416. The communication circuitry 416 can use radiofrequency (RF) communication techniques (e.g., via an antenna) and/or any other suitable communication modality.

[0068] The power source 420 delivers operating power to various components of the device 400. The power source 420 can include one or more batteries, each of which can independently be rechargeable or non-rechargeable. Recharging of the power source 420 can be accomplished through proximal inductive interaction between an external charger and an inductive charging coil within the device 400. Alternatively or in combination, recharging of the power source 420 can be accomplished using an energy harvesting mechanism 422 of the device 400. Additional details of energy harvesting mechanisms and associated methods are provided in Section II below.

[00691 The components of the device 400 illustrated in FIG. 4 can be modified in many different ways. For example, any of the components shown in FIG. 4 can be combined with each other, e.g., the switch circuitry 406 can be incorporated into the sensing circuitry 408 and/or the therapy generation circuitry 410. Any of the components shown in FIG. 4 can be divided into smaller subcomponents. Some of the components in FIG. 4 are optional and may be omitted (e.g., the switch circuitry 406 and/or sensor(s) 412). The device 400 can also include additional components not shown in FIG. 4. For example, the device 400 can include power management circuitry coupled to the power source 420 to allow the processing circuitry 414 to monitor the status of the power source 420 (e.g., charge level, charging rate, net power into and/or out of the power source 420, remaining battery life).

[0070] The components of the device 400 shown in FIG. 4 represent functionality that can be included in any of the devices of the present technology. The components illustrated in FIG. 4 can include any discrete and/or integrated electronic circuit components that implement analog and/or digital circuits capable of producing the functions attributed to the components herein. For example, the components can include analog circuits, such as amplification circuits, filtering circuits, and/or other signal conditioning circuits. The components can also include digital circuits, such as combinational or sequential logic circuits, memory devices, and the like. The functions attributed to the components of FIG. 4 may be embodied as one or more processors, hardware, firmware, software, or any combination thereof. The depiction of different features as separate blocks in 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 may 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 FIG. 4, some or all of the functionality attributed to the switch circuitry 406, sensing circuitry 408, therapy generation circuitry 410, sensor(s) 412, and/or communication circuitry 416 can alternatively or additionally be implemented by the processing circuitry 414, or vice-versa. II. Energy Harvesting Technology

{00711 In some embodiments, the present technology provides implantable devices that include an energy harvesting mechanism (also known as an “energy harvester” or “harvester”). The power capacity of a power source of an implantable device may be limited due to size constraints, such as if the device is implanted within a small space within the patient’s body (e.g., within a single heart chamber) and/or to reduce the risk of the device interfering with normal physiological function, as well as safety considerations. To prolong the usable life of such implantable devices, an energy harvesting mechanism can be used to generate energy in situ to recharge the power source.

[00721 FIG. 5 is a side cross-sectional view of a device 500 including an energy harvesting mechanism 502, in accordance with embodiments of the present technology. 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 (e.g., electrodes, fixation mechanism, circuitry, and/or other electronic components). In other embodiments, however, the device 500 can be a different type of implantable medical device.

[0073] The device 500 includes a housing 504 having an elongate shape extending between distal end 508 and a proximal end 510. The housing 504 defines an interior cavity 506 containing the energy harvesting mechanism 502 and other components of the device 500, such as a power source 512, power conditioning circuitry 514, and an electronics assembly 516. When the device 500 is implanted in a patient’s body, the energy harvesting mechanism 502 generates energy from physiological motion. For example, in some embodiments, the device 500 is configured to be implanted within a heart chamber of the patient and generates energy from cardiac motion (e.g., motion of the heart wall to which the device 500 is affixed) and/or blood flow through the heart chamber. The energy produced by the energy harvesting mechanism 502 can be used to charge the power source 512, which in turn powers the operation of the device 500.

[0074] In some embodiments, the energy harvesting mechanism 502 includes a piezoelectric element 518 that converts mechanical energy into electrical energy via the piezoelectric effect. The piezoelectric element 518 can be or include a flexible elongate member (e.g., beam, plate, shaft, rod, fiber) made partially or entirely out 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 difluoride (PVDF)), or a piezoelectric composite (e.g., a piezoelectric ceramic embedded in a polymer matrix, such as a macro fiber composite). The piezoelectric element 518 can be in a cantilever configuration in which a first end 522 of the piezoelectric element 518 is fixed relative to the housing 504, and a second end 524 of the piezoelectric element 518 opposite the first end 522 is movable relative to the housing 504. In the illustrated embodiment, the first end 522 of the piezoelectric element 518 is located near the distal end 508 of the housing 504, the second end 524 of the piezoelectric element 518 is located near the proximal end 510 of the housing 504, and the longitudinal axis of the piezoelectric element 518 is aligned with (e.g., parallel to) the longitudinal axis of the housing 504. In other embodiments, however, the piezoelectric element 518 can be oriented differently with respect to the housing 504. Additionally, the energy harvesting mechanism 502 can optionally include multiple piezoelectric elements 518.

[0075] In some embodiments, the second end 524 of the piezoelectric element 518 is coupled to a harvester mass 520 (also known as a “proof mass” or “inertial mass”). Due to the inertia of the harvester mass 520, when the device 500 is subjected to external forces from physiological motion, the harvester mass 520 can cause displacement of the second end 524 of the piezoelectric element 518 relative to the housing 504 and the fixed first end 522 of the piezoelectric element 518, and thus cause elastic deformation of the piezoelectric element 518. For instance, the piezoelectric element 518 can be deformed from a resting, straightened configuration (shown in FIG. 5) to a bent configuration (e.g., an upwardly bent configuration or a downwardly bent configuration). The resulting mechanical strain in the piezoelectric element 518 can produce an electrical current that can be used to charge the power source 512.

[0076] The power source 512 can include one or more rechargeable batteries that are electrically coupled to the energy harvesting mechanism 502 to store the energy produced by the energy harvesting mechanism 502. In the illustrated embodiment, the power source 512 is configured as a tubular structure that surrounds at least a portion of the energy harvesting mechanism 502 (e.g., an intermediate portion of the piezoelectric element 518 between the distal end 508 and the proximal end 510). This configuration can be advantageous for reducing the overall size of the device 500 while maintaining sufficient space within the interior cavity 506 to allow for movement of the harvester mass 520 and piezoelectric element 518. In other embodiments, however, the power source 512 can have a different shape and/or can be located at a different portion within the housing 504.

[0077] In some embodiments, the device 500 includes power conditioning circuitry 514 electrically coupled to and interposed between the energy harvesting mechanism 502 and the power source 512. The power conditioning circuitry 514 can be configured to perform operations such as rectification, filtering, voltage regulation, etc., of the electrical signal produced by the energy harvesting mechanism 502, before transmission to the power source 512.

(0078J The power source 512 is electrically coupled to the electronics assembly 516 to power the operation thereof. The electronics assembly 516 can include the electronic components of the device 500, such as any of the components described above with respect to FIG. 4 (e.g., switch circuitry 406, sensing circuitry 408, therapy generation circuitry 410, sensors 412 processing circuitry 414, communication circuitry 416, and/or memory 418). Optionally, the electronics assembly 516 can include components (e.g., processing circuitry 414 and/or other circuitry) that perform power management functions, such as monitoring the status 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., amount of current and/or power produced by the energy harvesting mechanism 502), power consumption of the electronics assembly 516, etc.

[0079] In some embodiments, an implantable device can include an energy harvesting mechanism that is self-adjustable to increase the amount of energy that can be harvested by the energy harvesting mechanism from motion of the device. A related principle can be described with reference to the energy harvesting mechanism 502 shown in FIG. 5. As described with reference to the energy harvesting mechanism 502, a piezoelectric element 518 can have a preferred motional axis (which also may be referred to as a “principal bending direction” or “preferential flexing direction”), which is the axis along which the piezoelectric element 518 primarily deflects to achieve its bent configuration. For example, in some embodiments, the piezoelectric element 518 can include a member having a flattened body with a transverse axis and a longitudinal axis defining a plane, where the preferred motional axis is orthogonal to the plane. The energy harvesting mechanism 502 generally will generate maximum energy when the acceleration of the device 500 is aligned with the preferred motional axis of the piezoelectric element 518. When this alignment occurs, the piezoelectric element 518 can achieve maximum beam deflection in response to the external forces applied to the device 500 (e.g., from physiological motion, such as cardiac motion when the device 500 is implanted in a heart). In general, such maximum beam deflection may enable the energy harvesting mechanism to operate at high efficiency (e.g., producing an increased amount of energy for a given amount or magnitude of cardiac motion). Accordingly, in some embodiments of an implantable device that is implanted in a heart, the implantable device can include an energy harvesting mechanism that is capable of self-aligning the piezoelectric element to the maximum acceleration direction regardless of implant position of the heart.

[0080] However, in many circumstances the piezoelectric element may be poorly oriented relative to the direction of cardiac motion for the purpose of energy harvesting. For example, it can be challenging to radially position the energy harvesting mechanism in a cardiac pacemaker during an implant procedure for the cardiac pacemaker, as such radial positioning is at least in part dependent on understanding the primary direction of cardiac motion and/or dependent on the precision of anchoring the cardiac pacemaker in a cardiac tissue wall (which may require, for example, rotating a helical or spiral electrode to penetrate tissue). Additionally, once the cardiac pacemaker is implanted in a patient, the primary direction of cardiac tissue motion may change acutely and/or chronically with patient posture, patient activity, and/or cardiac disease state of the patient, etc.

[0081 ] Accordingly, in some embodiments, a cardiac pacemaker or other implantable device can include an energy harvesting mechanism that is rotatable to orient the piezoelectric element to achieve maximum, near-maximum, or increased beam deflection in various circumstances (e.g., different patient postures, different patient activities, different patient cardiac health, etc.). For example, FIG. 6A is an illustrative schematic of an example energy harvesting arrangement 600 including an energy harvesting mechanism 620 configured to perform rotational self-alignment. The energy harvesting mechanism 620 can be similar to the energy harvesting mechanism 502, except as described herein. For example, the energy harvesting mechanism 620 can include a member 624 having a first end 624a and a second end 624b movable along a flexing axis (e.g., preferred motional axis) relative to the first end 624a, and a longitudinal axis (A) extending between the first end 624a and the second end 624b. In some embodiments, the longitudinal axis (A) is aligned with the geometric center of the cross-section of the member 624. The member 624 can further include a harvester mass 628 (e.g., similar to harvester mass 520) coupled to the second end 624b of the member. As shown in FIGS. 6B and 6C, the member 624 can be arranged at least partially in a housing 604 (e.g., similar to housing 504). In some embodiments, the member 624 can include a piezoelectric material, similar to the piezoelectric element 518 described with reference to FIG. 5. Furthermore, in some embodiments an energy harvesting arrangement can include multiple members 624, such as in a radially distributed manner similar to that shown and/or described in U.S. Patent Application No. 63/496,471, filed as attorney docket no. A0009983US01, which is incorporated in its entirety by this reference.

[0 82| The energy harvesting mechanism 620 with rotational alignment can be configured to passively rotate (e.g., freely rotate, such as without active assistance from a powered actuator or other active guidance for rotational adjustments) around the longitudinal axis. For example, the housing 604 may, in some circumstances, move in a direction along a motion axis (C). The motion axis (C) may, for example, be the dominant direction of cardiac motion when the housing is implanted in cardiac tissue. In response to motion of the housing along a motion axis (C) that is misaligned with the flexing axis (B) (FIG. 6B), the member 624 can be configured to passively rotate around the longitudinal axis until the flexing axis (B) is substantially aligned (or more closely aligned) with the motion axis (C) as shown in FIG. 6C. For example, in response to an angular offset of angle (a) between the flexing axis (B) and the motion axis (C), the member can be configured to passively rotate approximately a degrees in a first direction (e.g., counter-clockwise as illustrated in FIG. 6B) until the flexing axis (B) and the motion axis (C) are approximately aligned (or more closely aligned). Additionally or alternatively, the member can be configured to passively rotate in a second direction opposite the first direction by an angle that is explementary with a degrees (i.e., 360-a degrees) until the flexing axis (B) and the motion axis (C) are approximately aligned. In this manner, the member can be configured to self-align the flexing axis (B) with the motion axis (C) along which the housing is moving. [0083| Without being bound by any particular theory, it is believed that the flexing or deflection of the member 624 (and/or motion of the harvester mass 628) may help induce alignment of the flexing axis (B) and the motion axis (C) as the result of a tendency for the energy harvesting arrangement 600 to maximize resonance within the energy harvesting mechanism. When the flexing axis (B) and the motion axis (C) are not aligned well, the energy harvesting mechanism exhibits low resonance. In contrast, when the flexing axis (B) and the motion axis (C) are substantially aligned, the energy harvesting mechanism exhibits high resonance. Accordingly, the deformation of the member 624 in response to motion of the housing may encourage passive self-alignment of the flexing axis (B) and the motion axis (C) through a natural tendency to increase resonance.

(0084| In some instances, passive rotation of the energy harvesting mechanism can be advantageous compared to actively-powered rotation at least because a passively rotating energy harvesting mechanism eliminates additional power draw that would otherwise be required by the actuator (thereby increasing the amount of power that can be dedicated for the cardiac pacemaker or other device power needs). Additionally, because it does not require a separate actuator for actively assisting rotation, a passively rotating energy harvesting mechanism may be simpler to build and may have lower space requirements. However, in some embodiments, the energy harvesting mechanism can additionally or alternatively be rotatable with active assistance from an associated actuator.

[0 85| In some embodiments, the energy harvesting arrangement 600 can further include a bearing 610 that facilitates passive rotation of the energy harvesting mechanism 620 (including member 624) around the longitudinal axis (A) relative to the housing 604. For example, as shown in FIGS . 6B and 6C, the bearing 610 can be arranged at least partially in the housing 604 of the device. The bearing 610 can include an inner bearing surface 612 that is fixed relative to the first end 624a of the member 624, and an outer bearing surface 614 that is fixed relative to the housing 604, where the inner bearing surface 612 is configured to freely move relative to the outer bearing surface 614. For example, the inner bearing surface 612 can be telescopically engaged with the outer bearing surface 614 in a manner that enables rotational motion of the inner bearing surface 612 relative to the outer bearing surface 614. The friction of the bearing 610 can be tuned such that the member 624 is configured to self-align with the primary direction of motion of the housing 604, rather than with the direction of gravity. [0086[ The first end 624a of the member 624 can be fixed relative to the inner bearing surface 612 in various suitable manners. In some embodiments, the first end 624a of the member can be coupled to a shaft 622 that includes the inner bearing surface 612. As shown in FIGS. 6B and 6C, for example, the shaft 622 can have an outer surface that functions as the inner bearing surface 612. At least a portion of the outer surface or circumference of the shaft 622 can have a curved or arcuate shape (e.g., can be circular or elliptical, or can have an arc segment) configured to rotate relative to the outer bearing surface 614. In some embodiments, the member 624 can be coupled generally to the center of the shaft 622, such that the axis of the rotation of the shaft 622 (and inner bearing surface 612) is aligned with the longitudinal axis (A) of the member 624. However, in some embodiments, the member 624 can be radially offset from the center of the shaft 622. The first end 624a can be coupled to the shaft 622 through a suitable mechanical interfit (e.g., press-fit, mating features, etc.), epoxy, and/or one or more suitable fasteners. Alternatively, the first end 624a can be integrally formed with the shaft 622. For example, the first end 624a of the member 624 can have a cross-section that is enlarged relative to the rest of the member 624, is circular or elliptical, and/or otherwise includes an arcuate portion.

[0087] The outer bearing surface 614 can be part of a separate component within the housing 604 (e.g., liner of the housing 604) or integrally formed as an internal surface or other suitable feature of the housing 604. Like the inner bearing surface 612, at least a portion of the outer bearing surface 614 can have a curved or arcuate shape (e.g., can be circular or elliptical, or can have an arc segment).

[0088] In some embodiments, the inner bearing surface 612 and/or the outer bearing surface 614 can include a lubricious or low-friction material (e.g., Delrin®, Teflon®, etc.) that helps facilitate relative sliding rotation between the inner and outer bearing surfaces. Additionally or alternatively, a lubricant can be applied to and/or between the inner and outer bearing surfaces to help facilitate relative sliding rotation between these surfaces.

[0089] Although the bearing 610 can, in some embodiments, be at least partially incorporated into the member 624, the shaft 622, and/or the housing 604, it should be understood that in some embodiments, the bearing 610 can be a discrete component formed separately from the member 624, the shaft 622, and/or the housing 604. For example, the bearing 610 can be a ball bearing, with an inner race engaged with the member 624 and/or shaft 622, and an outer race engaged with the housing 604 (or other component coupled to the housing 604).

{0090] Different example embodiments of a bearing for an energy harvesting arrangement are illustrated in FIGS. 7A-7C. FIG. 7A illustrates an example energy harvesting arrangement 700a including a member 724 (with harvester mass 728) that is coupled to a shaft 722. The shaft 722 can be engaged in a slip fit manner with an outer bearing feature 710 that enables rotation of the shaft 722 within the outer bearing feature 710. The outer bearing feature 710 can, for example, be at least partially incorporated into the housing (not shown) or a component coupled to the housing. Similar to that described above with respect to bearing 610, the shaft 722 can have a cylindrical surface (or other curved or arcuate surface) functioning as an inner bearing surface that is engaged with the outer bearing feature 710.

[0091] FIG. 7B illustrates an example energy harvesting arrangement 700b that is similar to the energy harvesting arrangement 700a, except that the energy harvesting arrangement 700b includes a shaft having a narrowed neck region 722b between a front flange 722a and a rear flange 722c that are axially spaced apart. The neck region 722b can be engaged in a slip fit manner with the outer bearing feature 710, while the front flange 722a and the rear flange 722c can limit axial motion of the shaft (and member 724) relative to the outer bearing feature 710. As shown in FIG. 7B , the rear flange 722c can be a separate backing component coupled to the neck region 722b (e.g., via threads, epoxy, etc.). In some embodiments, the front flange 722a can additionally or alternatively be a separate component coupled to the neck region 722b in a similar manner. However, in some embodiments, one or both of the front flange 722a and the rear flange 722c can be integrally formed with the neck region 722b. Furthermore, similar to that described above, at least a portion of the shaft can be integrally formed with the member 724. While the front flange 722a and the rear flange 722c are shown in FIG. 7B as generally having square faces, it should be understood that other general shapes can be suitable in some embodiments of the shaft. For example, the shaft can be coupled to or include one or more outwardly flared (e.g., tapered) or bulbous features that limit axial motion of the shaft relative to the outer bearing feature 710. [00921 FIG. 7C illustrates an example energy harvesting arrangement 700c that is similar to the energy harvesting arrangement 700b, except that the energy harvesting arrangement 700c has a shaft (e.g., front flange portion 722d and rear flange portion 722f) that is closer in size or equal to the diameter of the outer bearing feature 710 compared to the corresponding features of the energy harvesting arrangement 700b, and the neck region 722e has a shorter axial length compared to the neck region of the energy harvesting arrangement 700b.

[0093] In some embodiments, a self-aligning energy harvesting arrangement can include a preferential rotational bias configured to help initiate rotation of the member around its longitudinal axis (e.g., to help overcome static friction). The rotational bias can, in some embodiments, be imparted at least in part by asymmetry across the longitudinal axis or rotational axis of the member (e.g., a bilaterally asymmetric distribution of mass) in the energy harvesting mechanism, where the asymmetry can employ gravity to urge or encourage rotation of the member. The asymmetric characteristic of the energy harvesting mechanism can be due to asymmetry in the harvester mass, the member, the shaft coupling the member to the bearing, or any combination thereof. For example, as shown in FIG. 8A, in some embodiments an energy harvesting arrangement 800 can have an energy harvesting mechanism (including member 824 and the harvester mass 828) with a center of mass Cmass radially offset from the longitudinal axis (A) of the member 824 by a distance (r), where the longitudinal axis (A) is a geometric center of the cross-section of the member 824. In general, gravity acting upon Cmass can cause a rotational torque to be applied to the member 824 in accordance with Equation 1 below:

T = m*g*r (1) where r is a torque produced as a function of the mass m of the energy harvesting mechanism (including the member 824 and the harvester mass 828), the gravitational acceleration g, and the distance (r) between Cmass and the longitudinal axis around which the energy harvesting mechanism is configured to rotate.

[0094] FIGS. 8B-8D illustrate an example operation of a self-aligning energy harvesting arrangement 800 including an energy harvesting mechanism (including a member 824 and harvester mass 828) with preferential rotational bias, and a bearing 810 coupled to the energy harvesting mechanism. FIG. 8B illustrates a circumstance where the flexing axis (B) of the member 824 is misaligned with the motion axis (C) of the applied motion or acceleration (e.g., applied to the housing or device in which the energy harvesting mechanism is arranged). Specifically, the flexing axis (B) is approximately orthogonal to the motion axis (C) with no vector component of the applied motion that is aligned with the flexing axis (B) of the member 824. In this orientation of the member 824, the member 824 experiences low (e.g., minimum) radial acceleration or oscillatory motion along its preferential flexing direction, thereby resulting in low (e.g., minimum) energy production for the energy harvesting mechanism. If the energy harvesting mechanism had a radially symmetrically distributed mass (e.g., such that Cmassis coincident with the longitudinal axis (A)), then it may be difficult for the energy harvesting mechanism to passively rotate around the longitudinal axis (A) when the member 824 is in the orientation relative to the applied motion axis (C) as shown in FIG. 8B. However, the offset center of mass Cmass provides a rotational bias or torque r that can help initiate the rotation of the energy harvesting mechanism around the longitudinal axis (A) (as shown in FIG. 8C). The torque r and/or oscillating acceleration of the member 824 can further help the energy harvesting mechanism passively rotate until the flexing axis (B) is substantially aligned with the motion axis (C) (FIG. 8D).

[0095] Although FIGS. 8B-8D illustrate an advantage of the radially offset Cmass for a starting position where the flexing axis (B) is substantially orthogonal to the motion axis (C), the rotational bias provided by the offset center of mass Cmass may also advantageously assist the self-alignment of the energy harvesting mechanism by helping the energy harvesting mechanism overcome static friction (e.g., in the bearing 810) from any particular starting rotational orientation.

[0096] In some embodiments, an energy harvester mechanism can be asymmetric across or about the longitudinal axis of the member at least in part due to a harvester mass having an asymmetric distribution of mass. For example, in some embodiments, a first longitudinal side of the harvester mass can have a greater mass than a second longitudinal side of the member (e.g., a side opposite the first longitudinal side). For example, the harvester mass can have an asymmetric geometric shape where one longitudinal side of the member has a greater mass than another longitudinal side of the member. As shown in FIG. 9A, for example, an energy harvesting arrangement 900a can include an energy harvesting mechanism with a member 924 and a harvester mass 928a coupled to the member 924, where the harvester mass 928a can have a geometrically asymmetrical shape (e.g., generally circular cross-section but having a portion faced off along a chord of the cross-section). The energy harvesting mechanism can be coupled to a bearing 910 and configured to passively rotate, as described elsewhere herein. It should be understood that in some embodiments, the harvester mass 928a can have any suitable geometric cross-section that is asymmetric relative to the longitudinal axis (A) (e.g., bilaterally asymmetric), other than that shown in FIG. 9A, that achieves a bilaterally asymmetric distribution of mass in the harvester mass. For example, the harvester mass 928a can be faced off (e.g., shaped so as to form a flat surface in place of a portion of a cylinder) at multiple circumferential points on one side of the longitudinal axis.

|0097| As another example, the harvester mass can additionally or alternatively include at least one void of negative space that reduces the mass of the harvester mass on one longitudinal side of the harvester mass. For example, as shown in FIG. 9B, a harvester mass 928b can include a void 927 that is radially offset from the longitudinal axis (A) (e.g., at least part of the void is radially offset from the longitudinal axis). The void can, for example, include a cavity, recess, cutout, or other suitable shape. In some embodiments, the harvester mass 928b can include multiple voids to create asymmetry in the mass distribution of the harvester mass 928b.

[0098| As another example, the harvester mass can additionally or alternatively include at least one region having a higher density material than other region(s) of the harvester mass. For example, as shown in FIG. 9C, a harvester mass 928c can include a first region 925 having a first density, and a second region 929 having a second density higher than the first density. The second region 929 can be radially offset from the longitudinal axis (A) (e.g., at least part of the region 929 can be radially offset from the longitudinal axis). The higher density region 929 can, for example, be spherical, ellipsoid, or have any suitable shape. In some embodiments, the harvester mass 928c can include multiple higher density regions (e.g., two, three, four, five or more) to create asymmetry in the mass distribution of the harvester mass.

[0099| In some embodiments, an energy harvester mechanism can additionally or alternatively be asymmetric across the longitudinal axis of the member 924 due to the member 924 having an asymmetric distribution of mass. Furthermore, in some embodiments, an energy harvester mechanism can additionally or alternatively be asymmetric across the longitudinal axis of the member due to the shaft 922 (coupling the member 924 to the bearing 910) having an asymmetric distribution of mass. For example, the member 924 and/or the shaft 922 can be asymmetric due to an asymmetric geometric shape, a void, and/or one or more regions of higher density material, similar to that described herein for the harvester mass with respect to FIGS. 9A-9C. 01001 Furthermore, in some embodiments, preferential rotational bias in an energy harvesting arrangement can additionally or alternatively be imparted by one or more characteristics of the bearing coupled to the energy harvesting mechanism. For example, as shown in FIG. 10A, in some embodiments an energy harvesting arrangement 1000 can include an energy harvesting mechanism with a member 1024 and a harvester mass 1028, where the member 1024 is coupled to a shaft 1022 that engages with a bearing surface 1014. As shown in FIG. 10, the shaft 1022 and/or the bearing surface 1014 can be slightly elliptical, such that at least in some orientations, the shaft 1022 (and the member 1024) has a tendency to passively rotate around the longitudinal axis (A) of the member 1024 to reduce mechanical interference between the shaft 1022 and the bearing surface 1014. This tendency can, in at least some circumstances, provide a preferential rotational bias for the energy harvesting mechanism. In a similar manner, in some embodiments the shaft 1022 and/or the bearing surface 1014 can additionally or alternatively have arcuate regions of different friction and/or different degrees of deformability, which in at least some circumstances can provide a preferential rotational bias for the energy harvesting mechanism.

[0101] In some embodiments, the rotation of the energy harvesting mechanism (e.g., rotation of the member) can be limited to a certain rotational range of motion. The limited rotational range of motion can be predetermined. The limited range of motion can help reduce interference with or caused by electrical components (e.g., leads, wires, other connections, etc.) in the energy harvesting mechanism as the member in the energy harvesting mechanism rotates. As another example, the limited range of motion can additionally or alternatively help avoid tension on the electrical connections (e.g., leads or wires) as the member in the energy harvesting mechanism rotates. In some embodiments the rotation of the member can be limited to a rotational range of less than about 360 degrees, or less than about 270 degrees, or less than about 180 degrees around the longitudinal axis of the member. In some embodiments, a range of rotational motion of N degrees can include N/2 degrees of mobility in a first direction (e.g., clockwise), and N/2 degrees of mobility in a second direction (e.g., counter-clockwise).

[0102] In some embodiments, the energy harvesting arrangement can include one or more stops configured to limit the rotation of the member to a rotational range of motion. For example, as shown in FIG. 10B, an energy harvesting arrangement 1000b can include one or more stops 1030 arranged on the bearing surface 1014b. Each stop 1030 can be configured to abut a cutout or other abutment feature of the shaft 1022b once the shaft (and the attached member 1024b) rotates to a certain rotational orientation. This mechanical abutment functions to substantially prevent further rotation of the shaft 1022b and the member 1024b. Accordingly, the angular placement of the stop(s) 1030 and/or angular placement of the abutment feature(s) of the shaft 1022b can at least in part define the limited rotational range of motion of the member 1024b. It should be understood that the energy harvesting arrangement can include other mechanical abutment interactions different from that shown in FIG. 10B. For example, in some embodiments, the shaft 1022b can additionally or alternatively include one or more stops configured to mechanically abut a cutout in the bearing surface 1014b. As another example, in some embodiments, the shaft 1022b can have a varying radius and be engaged with a bearing surface not corresponding to or matching the shaft’s cross-section, such that mechanical interference between the shaft surface and the bearing surface increases when the shaft is at certain rotational orientations. For example, as shown in FIG. 10A, the shaft 1022 can have an elliptical cross-section with a minor axis and a major axis, and the shaft 1022 can be engaged with a circular bearing surface 1014. In this example, mechanical interference can substantially prevent contact between a point on the shaft surface along the major axis and the bearing surface, thereby substantially limiting rotation of the shaft 1022 and attached member 1024.

(0103] Additionally or alternatively, in some embodiments, the energy harvesting arrangement can include one or more stops incorporating a frictional interference that limits the rotation of the member to a rotational range of motion. For example, in some embodiments the shaft and/or the bearing surface engaged with the shaft can include different arcuate segments with varying amounts of friction, such that the shaft can more freely rotate in regions of lower friction between the shaft and the bearing surface, and less freely rotate in regions of higher friction between the shaft and the bearing surface. Friction in certain regions can be increased, for example, by selecting high friction materials for the shaft and/or the bearing surface (e.g., Delrin®, Teflon®) and/or adding textural features (e.g., detents, ribs, bumps, etc.) to the shaft and/or the bearing surface.

{0104] Furthermore, in some embodiments an energy harvesting arrangement can include one or more electrical connections coupled to the member, for carrying energy (e.g., current) produced by the energy harvesting mechanism to a power source. For example, as shown in FIG. 11 and similar to other energy harvesting arrangements described herein, an energy harvesting arrangement 1100 can include an energy harvesting mechanism including a member 1124 and a harvester mass 1128, with electrical contacts 1140a and 1140b (e.g., positive and negative electrical contacts) coupled to the member 1124. The member 1124 can be coupled to a shaft 1122 that is engaged with an outer bearing feature 1110 to facilitate passive rotation of the member 1124. The shaft 1122 can include one or more channels configured to carry electrical leads extending from the electrical contacts 1140a and 1140b to a power source 1130. For example, the shaft 1122 can include two channels 1124a and 1124b for carrying an electrical lead from electrical contacts 1140a and 1140b, respectively. The channels 1124a and 1124b can be elongated and extend axially along the shaft 1124a, and then merge to form a channel 1124c configured to carry a bundle of combined leads from the electrical contacts 1140a and 1140b. Alternatively in some embodiments, the shaft 1122 can include an annular channel that can carry leads from multiple electrical contacts. In some embodiments, the electrical leads from the electrical contacts (e.g., electrical contacts 1140a and 1140b) can include strain relief (e.g., excess length) to help avoid loading the electrical leads in tension when the shaft 1122 rotates relative to the outer bearing feature 1110. In some embodiments, the shaft 1122 can additionally or alternatively be configured to have a limited range of rotational motion (e.g., with one or more stops, as described herein, such as with respect to FIGS. 10A and 10B), to help avoid loading the electrical leads in tension when the shaft 1122 rotates relative to the outer bearing feature 1110.

[0105] Additionally or alternatively, in some embodiments an energy harvesting arrangement can include one or more wiper contacts that help maintain electrical communication between the member and a power source, regardless of rotational orientation of the shaft. For example, as shown in FIGS. 12A and 12B and similar to other energy harvesting arrangements described herein, an energy harvesting arrangement 1200 can include an energy harvesting mechanism including a member 1124 and a harvester mass 1228, with electrical leads 1240a and 1240b (e.g., positive and negative wires) coupled to the member 1224. The member 1224 can be coupled to a shaft 1222 that is engaged with an outer bearing feature 1210 to facilitate passive rotation of the member 1224. Electrical leads 1240a and 1240b can extend to conductive rings 1242a and 1242b, respectively, that are located on the shaft 1222. Spring contacts 1244a and 1244b can be in electrical contact with the conductive rings 1242a and 1242b, respectively, and further carry power signals to a power source (not shown). The spring contacts 1244a and 1244b can be touching the conductive rings 1242a and 1242b with low friction surface contact that can be tuned to generate a rotational drag force that creates desirable system dampening for the rotational motion of the shaft 1222. For example, spring force of the spring contacts 1244a and 1244b and/or outer diameter of the shaft 1222 can be selected or otherwise tuned to result in a desired rotational drag while maintaining electrical communication in the pathways from the member 1224 to the electrical leads 1240a and 1240b, conductive rings 1242a and 1242b, and spring contacts 1244a and 1244b.

As described herein, various embodiments of passively rotating, selfaligning energy harvesting mechanisms can be enabled to produce more energy when the flexing motion of the energy harvesting mechanism is substantially aligned with motion of the housing or device containing the energy harvesting mechanism (for maximum radial acceleration or oscillatory motion of the energy harvesting mechanism). FIGS. 13 A and 13B are plots illustrating simulated probability distributions of power generated by a passively rotating, self-aligning energy harvesting mechanism (such as that described herein) in an implant, for different implant orientations. These plots are based on animal data with a cardiac pacemaker implanted in atrial sites other than the Triangle of Koch (FIG. 13 A) and animal data with a cardiac pacemaker implanted in a Triangle of Koch implant site (FIG. 13B). As shown in FIGS. 13A and 13B, when the implant is oriented along the direction of maximum radial acceleration of the energy harvesting mechanism (AR radial max, VfA radial max) such as aligned with the flexing direction of the energy harvesting mechanism, in general it is more likely that implants will produce greater amounts of power (e.g., line is shifted more to the right along the X-axis of FIGS. 13A and 13B). When the implant is oriented along the direction of minimum radial acceleration of the energy harvesting mechanism (AR radial min, VfA radial min), such as orthogonal to the flexing direction of the energy harvesting mechanism, in general it is less likely that implants will produce greater amounts of power (e.g., line is shifted more to the left along the X-axis of FIGS. 13A and 13B). FIGS. 13A and 13B also indicate probability distribution functions (AR radial avg, VfA radial avg) for an implant position that is between the orientations for maximum and minimum radial acceleration.

Examples

(01O7| The following examples are included to further describe some aspects of the present technology, and should not be used to limit the scope of the technology.

Example 1. A device comprising: a housing configured for being implanted in the human body; and an energy harvester arranged at least partially in the housing and configured to produce energy from motion of the housing, wherein the energy harvester comprises a member having a first end, a second end movable along a flexing axis relative to the first end, and a longitudinal axis extending between the first and second ends, wherein in response to motion of the housing along a motion axis that is different than the flexing axis, the member is configured to passively rotate around the longitudinal axis until the flexing axis is more closely aligned with the motion axis.

Example 2. The device of Example 1, wherein in response to motion of the housing along a motion axis that is different than the flexing axis, the member is configured to passively rotate around the longitudinal axis until the flexing axis is substantially aligned with the motion axis.

Example 3. The device of Example 1 or 2, wherein the member comprises a piezoelectric material.

Example 4. The device of any one of Examples 1-3, further comprising a bearing arranged at least partially in the housing.

Example 5. The device of Example 4, wherein the bearing comprises a first bearing surface fixed relative to the first end of the member and a second bearing surface fixed relative to the housing, and wherein the first bearing surface is configured to freely move relative to the second bearing surface.

Example 6. The device of any one of Examples 1-5, wherein the energy harvester is asymmetric about the longitudinal axis.

Example 7. The device of any one of Examples 1-6, wherein the energy harvester has a center of mass that is radially offset from the longitudinal axis.

Example 8. The device of any one of Examples 1-7, wherein the energy harvester comprises a harvester mass coupled to the second end of the member.

Example 9. The device of Example 8, wherein the harvester mass has a center of mass that is radially offset from the longitudinal axis.

Example 10. The device of Example 8 or 9, wherein the harvester mass comprises a void radially offset from the longitudinal axis.

Example 11. The device of any one of Examples 8-10, wherein the harvester mass comprises a first region having a first density and a second region having a second density higher than the first density, wherein the second region is radially offset from the longitudinal axis.

Example 12. The device of any one of Examples 1-11, wherein rotation of the member around the longitudinal axis is limited to a rotational range of less than 360 degrees.

Example 13. The device of Example 12, wherein the rotational range is about 180 degrees or less.

Example 14. The device of Example 12 or 13, further comprising a stop configured to limit the rotation of the member to the rotational range.

Example 15. The device of any one of Examples 1-14, further comprising a power source configured to be charged by the energy harvester. Example 16. The device of any one of Examples 1-15, further comprising one or more electrodes configured to perform at least one of the group consisting of electrical stimulation and sensing.

Example 17. The device of any one of Examples 1-16, wherein the device is a pacemaker.

Example 18. The device of Example 17, wherein the device is a leadless pacemaker.

Example 19. The device of any one of Examples 1-18, wherein the device further comprises circuitry configured to generate cardiac pacing pulses.

Example 20. A device comprising: a housing configured for implantation in a human body; an energy harvester arranged at least partially in the housing and configured to produce energy from motion of the housing, wherein the energy harvester comprises a member having a first end, a second end movable along a flexing axis relative to the first end, and a longitudinal axis extending between the first and second ends, wherein the member is configured to passively rotate around the longitudinal axis to self-align the flexing axis with motion of the housing.

Example 21. The device of Example 20, wherein the member comprises a piezoelectric material.

Example 22. The device of Example 20 or 21, further comprising a bearing arranged at least partially in the housing.

Example 23. The device of Example 22, wherein the bearing comprises a first bearing surface fixed relative to the first end of the member and a second bearing surface fixed relative to the housing, and wherein the first bearing surface is configured to freely move relative to the second bearing surface.

Example 24. The device of any one of Examples 20-23, wherein the energy harvester is asymmetric about the longitudinal axis.

Example 25. The device of any one of Examples 20-24, wherein the energy harvester has a center of mass that is radially offset from the longitudinal axis.

Example 26. The device of any one of Examples 20-25, wherein the energy harvester comprises a harvester mass coupled to the second end of the member.

Example 27. The device of Example 26, wherein the harvester mass has a center of mass that is radially offset from the longitudinal axis.

Example 28. The device of Example 26 or 27, wherein the harvester mass comprises a void radially offset from the longitudinal axis.

Example 29. The device of any one of Examples 26-28, wherein the harvester mass comprises a first region having a first density and a second region having a second density higher than the first density, wherein the second region is radially offset from the longitudinal axis.

Example 30. The device of any one of Examples 20-29, wherein rotation of the member around the longitudinal axis is limited to a rotational range of less than 360 degrees.

Example 31. The device of Example 30, wherein the rotational range is about 180 degrees or less.

Example 32. The device of Example 30 or 31, further comprising a stop configured to limit the rotation of the member to the rotational range. Example 33. The device of any one of Examples 20-32, further comprising a power source configured to be charged by the energy harvester.

Example 34. The device of any one of Examples 20-33, further comprising one or more electrodes configured to perform at least one of the group consisting of electrical stimulation and sensing.

Example 35. The device of any one of Examples 20-34, wherein the device is a pacemaker.

Example 36. The device of Example 35, wherein the device is a leadless pacemaker.

Example 37. The device of any one of Examples 20-36, wherein the device further comprises circuitry configured to generate cardiac pacing pulses.

Example 38. An implantable medical device comprising: an energy harvester comprising a deflecting member having a first end, a second end movable relative to the first end, and a longitudinal axis extending between the first and second ends, wherein the energy harvester is configured to produce energy from deflection of the member; and a bearing coupled to the energy harvester such that the member is configured to passively rotate around the longitudinal axis, wherein the rotation of the member around the longitudinal axis is limited to a rotational range of motion.

Example 39. The device of Example 38, wherein the member comprises a piezoelectric material.

Example 40. The device of Example 38 or 39, wherein the energy harvester is asymmetric about the longitudinal axis. Example 41. The device of any one of Examples 38-40, wherein the energy harvester has a center of mass that is radially offset from the longitudinal axis.

Example 42. The device of any one of Examples 38-41, further comprising a stop configured to limit the rotation of the member around the longitudinal axis.

Example 43. The device of Example 42, wherein the stop comprises a mechanical abutment.

Example 44. The device of Example 42 or 43, wherein the stop comprises a frictional interference.

Example 45. The device of any one of Examples 38-44, further comprising one or more electrodes configured to perform at least one of the group consisting of electrical stimulation and sensing.

Example 46. The device of any one of Examples 38-45, wherein the device is a pacemaker.

Example 47. The device of Example 46, wherein the device is a leadless pacemaker.

Example 48. The device of any one of Examples 38-47, wherein the device further comprises circuitry configured to generate cardiac pacing pulses.

Conclusion

[0108J Although many of the embodiments are described above with respect to systems, devices, and methods for cardiac pacing, the technology is applicable to other applications and/or other approaches, such as other therapies involving implantable devices. Moreover, other embodiments in addition to those described herein are within the scope of the technology. Additionally, several other embodiments of the technology can have different configurations, components, or procedures than those described herein. A person of ordinary skill in the art, therefore, will accordingly understand that the technology can have other embodiments with additional elements, or the technology can have other embodiments without several of the features shown and described above.

[0109] The 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 (e.g., physician or patient programmers), stimulators, or other devices. The terms “processor” or “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry.

10110] The various processes described herein can be partially or fully implemented using program code including instructions executable by one or more processors of a computing system for implementing specific logical functions or steps 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. Computer-readable media containing code, or portions of code, can include any appropriate media known in the art, such as non-transitory computer-readable storage media. Computer-readable media can include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage and/or transmission of information, including, but not limited to, random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or other memory technology; compact disc read-only memory (CD-ROM), digital video disc (DVD), or other optical storage; magnetic cassettes, magnetic tape, magnetic disk storage, or other magnetic storage devices; solid state drives (SSD) or other solid state storage devices; or any other medium which can be used to store the desired information and which can be accessed by a system device.

[0111] The descriptions of embodiments of the technology are not intended to be exhaustive or to limit the technology to the precise form disclosed above. Where the context permits, singular or plural terms may also include the plural or singular term, respectively. Although specific embodiments of, and examples for, the technology are described above for illustrative purposes, various equivalent modifications are possible within the scope of the technology, as those skilled in the relevant art will recognize. For example, while steps are presented in a given order, alternative embodiments may perform steps in a different order. The various embodiments described herein may also be combined to provide further embodiments.

[0112] As used herein, the terms “generally,” “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by those of ordinary skill in the art.

[0113] Moreover, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in reference to a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of the items in the list. As used herein, the phrase “and/or” as in “A and/or B” refers to A alone, B alone, and A and B. Additionally, the term “comprising” is used throughout to mean including at least the recited feature(s) such that any greater number of the same feature and/or additional types of other features are not precluded.

I0114J To the extent any materials incorporated herein by reference conflict with the present disclosure, the present disclosure controls.

[0115] It will also be appreciated that specific embodiments have been described herein for purposes of illustration, but that various modifications may be made without deviating from the technology. Further, while advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein.

Claims

CLAIMS I/Wc claim:

1. A device comprising: a housing configured for being implanted in the human body; and an energy harvester arranged at least partially in the housing and configured to produce energy from motion of the housing, wherein the energy harvester comprises a member having a first end, a second end movable along a flexing axis relative to the first end, and a longitudinal axis extending between the first and second ends, wherein in response to motion of the housing along a motion axis that is different than the flexing axis, the member is configured to passively rotate around the longitudinal axis until the flexing axis is more closely aligned with the motion axis.

2. The device of claim 1, wherein in response to motion of the housing along a motion axis that is different than the flexing axis, the member is configured to passively rotate around the longitudinal axis until the flexing axis is substantially aligned with the motion axis.

3. The device of claim 1 or 2, wherein the member comprises a piezoelectric material.

4. The device of any one of claims 1-3, further comprising a bearing having a first bearing surface fixed relative to the first end of the member and a second bearing surface fixed relative to the housing, and wherein the first bearing surface is configured to freely move relative to the second bearing surface.

5. The device of any one of claims 1-4, wherein the energy harvester is asymmetric about the longitudinal axis.

6. The device of any one of claims 1-5, wherein the energy harvester has a center of mass that is radially offset from the longitudinal axis.

7. The device of any one of claims 1-6, wherein the energy harvester comprises a harvester mass coupled to the second end of the member.

8. The device of claim 7, wherein the harvester mass has a center of mass that is radially offset from the longitudinal axis.

9. The device of claim 7 or 8, wherein the harvester mass comprises a void radially offset from the longitudinal axis.

10. The device of any one of claims 7-9, wherein the harvester mass comprises a first region having a first density and a second region having a second density higher than the first density, wherein the second region is radially offset from the longitudinal axis.

11. The device of any one of claims 1-10, wherein rotation of the member around the longitudinal axis is limited to a rotational range of less than 360 degrees.

12. The device of claim 11, further comprising a stop configured to limit the rotation of the member to the rotational range.

13. The device of any one of claims 1-12, further comprising a power source configured to be charged by the energy harvester.

14. The device of any one of claims 1-13, further comprising one or more electrodes configured to perform at least one of the group consisting of electrical stimulation and sensing.

15. The device of any one of claims 1-14, wherein the device is a pacemaker.