Piezoelectric actuator with damping

Abstract

An apparatus includes at least one actuator configured to generate vibrations within a range of vibration frequencies. The at least one actuator includes a housing configured to be positioned on or within a body of a recipient. The actuator also includes a support portion configured to be in operative communication with a fixation device implanted within a body of the recipient. The actuator also includes an oscillator within the housing, the oscillator including a piezoelectric material and having a first portion in mechanical communication with the support portion and a second portion spaced apart from the support portion. The piezoelectric material is configured to undergo a bending oscillation in which the second portion moves relative to the first portion in response to the received voltage signal. The actuator also includes at least one damper configured to attenuate at least one vibration resonance of the at least one actuator within at least a portion of the vibration frequency range and independent of elastic damping of the piezoelectric material.

Description

background Technical Field

[0001] The present application relates generally to implantable actuators for generating vibrations, and more particularly to implantable hearing prostheses for generating auditory vibrations. Background Art

[0002] Medical devices have provided a wide range of therapeutic benefits to recipients over the last several decades. Medical devices may include internal or implantable components / devices, external or wearable components / devices, or combinations thereof (e.g., a device having an external component that communicates with an implantable component). Medical devices, such as traditional hearing aids, partially or fully implantable hearing prostheses (e.g., bone conduction devices, mechanical stimulators, cochlear implants, etc.), pacemakers, defibrillators, functional electrical stimulation devices, and other medical devices, have been successful over the years in performing life-saving and / or lifestyle-improving functions and / or recipient monitoring.

[0003] Over the years, the types of medical devices and the range of functions performed by them have increased. For example, many medical devices, sometimes referred to as "implantable medical devices," now typically include one or more instruments, devices, sensors, processors, controllers, or other functional mechanical or electrical components that are permanently or temporarily implanted in the body of a recipient. These functional devices are typically used to diagnose, prevent, monitor, treat, or manage disease / injury or its symptoms, or to study, replace, or modify anatomical structures or physiological processes. Many of these functional devices utilize power and / or data received from an external device that is part of or operates in conjunction with the implantable component. Summary of the invention

[0004] In one aspect disclosed herein, a device includes at least one actuator configured to generate vibrations within a range of vibration frequencies. The at least one actuator includes a housing configured to be positioned on or within a body of a recipient. The actuator also includes a support portion configured to be in operable communication with a fixation device implanted within the body of the recipient. The actuator also includes an oscillator within the housing. The oscillator includes a piezoelectric material and has a first portion mechanically connected to the support portion and a second portion spaced apart from the support portion. The piezoelectric material is configured to undergo a bending oscillation in response to a received voltage signal, in which the second portion moves relative to the first portion. The actuator also includes at least one mass within the housing and in mechanical communication with the second portion. The at least one mass is configured to move with the second portion in response to the bending oscillation of the piezoelectric material. The actuator also includes at least one damper configured to damp at least one vibration resonance of the at least one actuator within at least a portion of the vibration frequency range and independently of elastic damping of the piezoelectric material.

[0005] In another aspect disclosed herein, a method includes applying an oscillating voltage signal to a piezoelectric element mechanically coupled to a rigid portion and at least one mass. The piezoelectric element responds to the voltage signal by transmitting an oscillating motion relative to the rigid portion to the at least one mass. The method also includes attenuating the oscillating motion using viscoelastic damping, electromagnetic damping, and / or pneumatic damping.

[0006] In another aspect disclosed herein, a device includes a piezoelectric actuator configured to generate a vibration signal in response to an oscillating voltage signal. The piezoelectric actuator is configured to be implanted on or in a recipient's body and transmit the vibration signal to the recipient's body. The piezoelectric actuator includes at least one damper configured to dampen at least one vibration resonance of the piezoelectric actuator using inelastic damping.

[0007] In another aspect disclosed herein, a device includes an actuator configured to be implanted on or in a recipient's body and transmit a vibration signal to the recipient's body. The actuator includes at least one piezoelectric material and at least one surface layer covering a surface of the at least one piezoelectric material. The at least one piezoelectric material is configured to generate a vibration signal in response to an oscillating voltage signal. The at least one surface layer extends into surface gaps, voids, and / or cracks of the at least one piezoelectric material. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Embodiments are described herein with reference to the accompanying drawings, in which:

[0009] Figure 1A schematically illustrates a portion of an exemplary transcutaneous bone conduction device implanted in a recipient according to certain embodiments described herein;

[0010] Figure 1B schematically illustrates a portion of another exemplary transcutaneous bone conduction device implanted in a recipient according to certain embodiments described herein;

[0011] Figure 1C depicts a side view of a portion of an exemplary transcutaneous bone conduction device according to certain embodiments described herein;

[0012] Figure 2 schematically illustrates a cross-sectional view of an exemplary device having at least one mechanical damper positioned between an oscillator and at least one mass according to certain embodiments described herein;

[0013] Figures 3A-3D schematically illustrates a cross-sectional view of an exemplary apparatus having at least one mechanical damper between a support portion and at least one mass according to certain embodiments described herein;

[0014] Figure 3E schematically illustrates a cross-sectional view of an exemplary apparatus having at least one mechanical damper between a housing and at least one mass according to certain embodiments described herein;

[0015] Figures 4A-4C Schematically illustrates cross-sectional views of three exemplary devices according to certain embodiments described herein, wherein at least one electromagnetic damper includes at least one permanent magnet;

[0016] Figures 5A-5C schematically illustrates cross-sectional views of three exemplary devices including at least one pneumatic damper according to certain embodiments described herein;

[0017] Fig. 6A schematically illustrates exemplary damping of vibration resonance according to certain embodiments described herein;

[0018] Figure 6B schematically illustrates exemplary damping of vibration anti-resonance according to certain embodiments described herein; and

[0019] Figure 7 is a flow chart of an exemplary method according to certain embodiments described herein. DETAILED DESCRIPTION

[0020] Certain embodiments described herein provide a piezoelectric actuator having at least one damping element configured to attenuate at least one vibration resonance independently of elastic damping of the piezoelectric material over at least a portion of the vibration frequency range of the piezoelectric actuator (e.g., the damping properties of the damping element can be tuned independently of the vibration properties of the actuator). Examples of damping elements include, but are not limited to: a mechanical damper comprising at least one viscoelastic material configured to experience shear forces; an electromagnetic damper comprising at least one permanent magnet configured to generate eddy currents; and / or a pneumatic damper comprising a gas or liquid configured to compress / expand and / or flow through at least one orifice. The at least one damping element can facilitate mechanical coupling with the piezoelectric material to provide a more uniform and / or more reliable force transfer from the piezoelectric material.

[0021] In at least some embodiments, the teachings detailed herein are applicable to any type of implantable medical device (e.g., an implantable vibration stimulation system or device; a bone conduction hearing prosthesis) that includes a first portion that is implanted on or in a recipient's body and configured to provide vibrations to a portion of the recipient's body. Embodiments may include any type of medical device that may utilize the teachings detailed herein and / or variations thereof. Furthermore, while certain embodiments are described herein in the context of an implantable hearing prosthesis device, certain other embodiments are compatible in the context of other implantable or non-implantable devices or systems (e.g., bone conduction headphones; bone conduction speakers; bone conduction microphones; ultrasound imaging).

[0022] For ease of description only, the apparatus and methods disclosed herein are described primarily with reference to an exemplary medical device, namely an active transdermal or percutaneous bone conduction hearing prosthesis system. However, the teachings and / or variations thereof detailed herein may also be used with a variety of other medical systems or non-medical systems that provide a wide range of therapeutic benefits to recipients, patients, or other users. In some embodiments, the teachings and / or variations thereof detailed herein may be used in other types of devices beyond hearing prostheses that may benefit from vibration generating actuators that can fit within areas with confined spaces and / or improve control of piezoelectric vibrations (e.g., the direction of vibration motion). Embodiments may include any type of hearing prosthesis capable of utilizing the teachings and / or variations thereof detailed herein. Certain such embodiments may be referred to as "partially implantable," "semi-implantable," "mostly implantable," "fully implantable," or "fully implantable" hearing prostheses. In some embodiments, the teachings and / or variations thereof detailed herein may be utilized in other types of prostheses than hearing prostheses.

[0023] Figure 1AA portion of an exemplary transcutaneous bone conduction device 100 is schematically shown implanted in a recipient according to certain embodiments described herein. Figure 1B A portion of another exemplary transcutaneous bone conduction device 200 is schematically shown implanted in a recipient according to certain embodiments described herein. Figure 1C Schematically illustrated is a side view of a portion of an exemplary transcutaneous bone conduction device 300 according to certain embodiments described herein.

[0024] Figure 1A The exemplary transcutaneous bone conduction device 100 includes an external device 104 and an implantable component 106 . Figure 1A The transcutaneous bone conduction device 100 is a passive transcutaneous bone conduction device in which a vibration actuator 108 is located in the external device 104 and delivers vibration stimulation to the skull 136 through the skin 132. The vibration actuator 108 is located in the housing 110 of the external component 104 and is coupled to a plate 112. The plate 112 can be in the form of a permanent magnet and / or another form that generates and / or reacts to a magnetic field, or otherwise allows for the establishment of a magnetic attraction between the external device 104 and the implantable component 106 sufficient to hold the external device 104 against the skin 132 of the recipient.

[0025] In some embodiments, the vibration actuator 108 is a device that converts electrical signals into vibrations. In operation, the sound input element 126 can convert sound into electrical signals. Specifically, the transcutaneous bone conduction device 100 can provide these electrical signals to the vibration actuator 108, or to a sound processor (not shown) that processes the electrical signals, and then provide those processed signals to the vibration actuator 108. The vibration actuator 108 can convert (processed or unprocessed) electrical signals into vibrations. Since the vibration actuator 108 is mechanically coupled to the plate 112, the vibration is transmitted from the vibration actuator 108 to the plate 112. The implanted plate assembly 114 is part of the implantable component 106 and is made of a ferromagnetic material, which can be in the form of a permanent magnet that generates a magnetic field and / or reacts to a magnetic field, or otherwise allows the establishment of a magnetic attraction sufficient to keep the external device 104 against the skin 132 of the recipient between the external device 104 and the implantable component 106. Thus, vibrations generated by the vibration actuator 108 of the external device 104 are transmitted from the plate 112 through the skin 132 to the plate 116 of the plate assembly 114. This can be achieved due to mechanical conduction of vibrations caused by the external device 104 in direct contact with the skin 132 and / or by the magnetic field between the two plates 112, 116 through the skin 132. These vibrations are transmitted without components penetrating the skin 132, fat 128, or muscle 134 layers on the head.

[0026] In some embodiments, the implanted plate assembly 114 is substantially rigidly attached to the bone fixation device 118. The implantable plate assembly 114 can include a through hole 120, the contour of which conforms to the outer contour of the bone fixation device 118. This through hole 120 thus forms a bone fixation device interface section that conforms to the contour of the exposed section of the bone fixation device 118. In some embodiments, the size and dimensions of the section are designed so that there is at least a sliding fit or an interference fit relative to the section. Screws 122 can be used to secure the plate assembly 114 to the bone fixation device 118. In some embodiments, a silicone layer 124 is located between the plate 116 and the bone 136 of the skull.

[0027] like Figure 1A 14, the head of the screw 122 is larger than the hole through the implantable plate assembly 114, and thus the screw 122 securely holds the implantable plate assembly 114 to the bone fixation device 118. The portion of the screw 122 that interfaces with the bone fixation device 118 substantially corresponds to an abutment screw, thus allowing the screw 122 to be easily fitted into existing bone fixation devices used in percutaneous bone conduction devices. In certain embodiments, the screw 122 is configured so that the same tools and procedures used to install the abutment screw and / or remove the abutment screw from the bone fixation device 118 can be used to install the screw 122 and / or remove the screw from the bone fixation device 118.

[0028] like Figure 1B Schematically shown, an exemplary transcutaneous bone conduction device 200 includes an external device 204 and an implantable component 206. Device 200 is an active transcutaneous bone conduction device in that a vibration actuator 208 is located in the implantable component 206. For example, a vibration element in the form of a vibration actuator 208 is located in a housing 210 of the implantable component 206. In certain embodiments, the vibration actuator 208 is a device that converts an electrical signal into vibrations, much like the vibration actuator 108 described herein with respect to the transcutaneous bone conduction device 100. The vibration actuator 208 can be in direct contact with the outer surface of the recipient's skull 136 (e.g., the vibration actuator 208 is in substantial contact with the recipient's bone 136 such that a vibration force from the vibration actuator 208 is transmitted from the vibration actuator 208 to the recipient's bone 136). In some embodiments, one or more thin non-bone tissue layers (e.g., silicone layer 224) may be present between the vibration actuator 208 and the recipient's bone 136 (e.g., bone tissue) while still allowing sufficient support to allow the vibration force generated by the vibration actuator 208 to be effectively transferred to the recipient's bone 136.

[0029] In some embodiments, the external component 204 includes a sound input element 226 that converts sound into electrical signals. Specifically, the device 200 provides these electrical signals to the vibration actuator 208, or to a sound processor (not shown) that processes the electrical signals, and then provides those processed signals to the implantable component 206 via a magnetic inductive link through the skin of the recipient. For example, the communication coil 232 of the external component 204 can transmit these signals to the implanted communication coil 234 located in the housing 236 of the implantable component 206. The components (not shown) in the housing 236, such as a signal generator or an implanted sound processor, then generate electrical signals that will be transmitted to the vibration actuator 208 via an electrical lead assembly 238. The vibration actuator 208 converts the electrical signals into vibrations. In some embodiments, the vibration actuator 208 can be positioned so close to the housing 236 that there is no electrical lead 238 (for example, the housing 210 and the housing 236 are the same single housing containing the vibration actuator 208, the communication coil 234 and other components such as a signal generator or a sound processor).

[0030] In some embodiments, the vibration actuator 208 is mechanically coupled to the housing 210. The housing 210 and the vibration actuator 208 together form a vibration element. The housing 210 can be substantially rigidly attached to the bone fixation device 218. In this regard, the housing 210 can include a through hole 220, the contour of which conforms to the outer contour of the bone fixation device 218. Screws 222 can be used to secure the housing 210 to the bone fixation device 218. Figure 1B 2, the head of the screw 222 is larger than the through hole 220 of the housing 210, and thus the screw 222 securely holds the housing 210 to the bone fixing device 218. The portion of the screw 222 that interfaces with the bone fixing device 218 substantially corresponds to the abutment screw described in detail below, thus allowing the screw 222 to be easily fitted into an existing bone fixing device used in a percutaneous bone conduction device (or an existing passive bone conduction device). In some embodiments, the screw 222 is configured so that the same tools and procedures used to install the abutment screw and / or remove the abutment screw from the bone fixing device 218 can be used to install the screw 222 and / or remove the screw from the bone fixing device 218.

[0031] Figure 1A The exemplary transcutaneous bone conduction hearing device 100 includes an external sound input element 126 (eg, an external microphone), and Figure 1B The exemplary transcutaneous bone conduction hearing device 200 includes an external sound input element 226 (e.g., an external microphone). Other exemplary hearing devices according to certain embodiments described herein (e.g., a fully implantable transcutaneous bone conduction device) may replace the external sound input elements 126, 226 with a subcutaneous implantable sound input component (e.g., an implanted microphone).

[0032] In certain embodiments, the exemplary transcutaneous bone conduction device 300 includes an operable removal member 304 and a bone conduction implant 310, such as Figure 1C Schematically shown. The operably removable component 304 includes a housing 305 and is operably releasably coupled to the bone conduction implant 310. Operably releasably coupled means that it is releasable in such a manner that the recipient can relatively easily attach and remove the operably removable component 304 during normal use of the transcutaneous bone conduction device 300 (repeatedly if necessary). This releasable coupling is achieved via a coupling device 302 of the operably removable component 304 and a corresponding mating device (e.g., abutment 312) of the bone conduction implant 310, as will be described in detail below. This operably releasable coupling is in contrast to how the bone conduction implant 310 is attached to the skull, as will also be described in detail below.

[0033] The operable removable component 304 of certain embodiments includes a sound input element (e.g., a microphone; a cable or wireless connection configured to receive a signal indicating sound from an audiovisual device); a sound processor (e.g., a sound processing circuit system, a control electronic device, an actuator drive component, a power module), the sound processor configured to generate a control signal in response to an electrical signal from the sound input element; and at least one vibration actuator 308, the at least one vibration actuator configured to generate an acoustic vibration in response to the control signal. The at least one vibration actuator 308 may include a vibrating electromagnetic actuator, a vibrating piezoelectric actuator, and / or another type of vibration actuator, and the operable removable component 304 is sometimes referred to herein as a vibrator unit. The control signal is configured to vibrate the at least one vibration actuator 308, thereby generating a mechanical output force in the form of an acoustic vibration, which is delivered to the recipient's skull via the bone conduction implant 310. In other words, the operatively removable component 304 uses at least one vibration actuator 308 to convert the received sound signal into mechanical motion to transmit vibrations to the recipient's skull, which are detected by the recipient's auditory ossicles and / or cochlea. In some embodiments, the operatively removable component 304 includes a single housing 305 (e.g., Figure 1C Schematically shown), while in certain other embodiments, the operable removal member 304 includes multiple housings (e.g., separate housings or different housings that may have wired and / or wireless connections therebetween).

[0034] like Figure 1CAs schematically shown in FIG. 1 , the operably removable component 304 further includes a coupling device 302 configured to operably removably attach the operably removable component 304 to a bone conduction implant 310 (also referred to as an anchoring system and / or fixation system) implanted in a recipient. The coupling device 302 can be configured to be repeatedly coupled to and detached from the bone conduction implant 310. The coupling device 302 includes a longitudinal axis 306 (e.g., an axis along the length of the coupling device 302; an axis about which the coupling device 302 is at least partially symmetrical). At least one vibration actuator 308 of the operably removable component 304 is in vibration communication with the coupling device 302 such that vibrations generated by the at least one vibration actuator 308 are transmitted to the coupling device 302 and then to the bone conduction implant 310 in a manner at least effective to evoke auditory perception.

[0035] Figure 1C The exemplary bone conduction implant 310 includes a percutaneous abutment 312, a bone fixing device 318 (hereinafter sometimes referred to as the fixing device 318), and an abutment screw 320. Figure 1C An exemplary bone conduction implant 310 is shown in accordance with certain embodiments described herein, but other bone conduction implants 310 (e.g., including abutments 312, fixtures 318, and / or abutment screws 320 of any type, size / geometry) are also compatible with certain embodiments described herein.

[0036] In some embodiments, coupling device 302 can be configured to be removably attached to bone conduction implant 310 by pressing coupling device 302 against abutment 312 in a direction along (e.g., substantially parallel to) longitudinal axis 306 of coupling device 302 and / or along (e.g., substantially parallel to) longitudinal axis 313 of abutment 312. In some such embodiments, coupling device 302 can be configured to snap-couple to abutment 312. In some embodiments, such as Figure 1C As depicted, coupling device 302 includes a male component, and base 312 includes a female component configured to mate with the male component of coupling device 302. In certain embodiments, this configuration can be reversed, wherein coupling device 302 includes a female component, and base 312 includes a male component configured to mate with the female component of coupling device 302.

[0037] Certain embodiments of the base 312 are symmetrical with respect to at least those portions of the base 312 above the top portion of the fixture 318. For example, the outer surface of the base 312 can form a concentric outer contour around a longitudinal axis 313 of the base 312 (e.g., an axis along the length of the base 312; an axis about which the base 312 is at least partially symmetrical). Figure 1CAs shown in , the outer surface of the base 312 establishes a diameter lying on a plane perpendicular to the longitudinal axis 313, which varies along the length of the longitudinal axis 313. For example, the base 312 may include an outer diameter that gradually increases as the distance from the fixture 318 increases. In certain other embodiments, the outer diameter may have other outer profiles.

[0038] In certain embodiments, the abutment 312 is configured for integration between the skin and the abutment 312. Integration between the skin and the abutment 312 can be considered to occur when the soft tissue of the skin 132 encapsulates the abutment 312 in fibrous tissue and does not readily separate itself from the abutment 312, which can inhibit microbial embedment and / or growth adjacent to the osteoconductive implant 310. For example, the abutment 312 can have a surface having features configured to reduce certain adverse skin reactions. In certain embodiments, the abutment 312 is coated to reduce the shear modulus, which can also promote integration of the skin with the abutment 313. For example, at least a portion of the abutment 312 can be coated with or otherwise include a hydroxyapatite layer that enhances integration of the skin with the abutment 312.

[0039] In some embodiments, the abutment 312 is configured to be attached to the fixture 318 via an abutment screw 320, and the fixture 318 is configured to be fixed to (e.g., screwed into) the recipient's skull 136. The abutment 312 extends from the fixture 318, through the muscle 134, the fat 128, and the skin 132, so that the coupling device 140 can be attached thereto. The abutment screw 320 (e.g., including a screw head 322 and an elongated coupling shaft 324 connected to the screw head 322) connects and holds the abutment 312 to the fixture 318, thereby rigidly attaching the abutment 312 to the fixture 318. The rigid attachment is such that the base 312 is vibrationally connected to the fixture 318 so that at least some of the vibration energy transmitted to the base 312 is transmitted to the fixture 318 in a sufficient manner to effectively evoke auditory perception (e.g., to mechanically vibrate the recipient's skull, vibrations received by the recipient's cochlea to compensate for conductive hearing loss, mixed hearing loss, or single-sided deafness). The transcutaneous base 312 provides an attachment location for the coupling device 302 that facilitates effective transmission of mechanical forces.

[0040] The fixture 318 can be made of any material with a known ability to integrate into the surrounding bone tissue (e.g., including materials that exhibit acceptable bone integration properties). In some embodiments, the fixture 318 is formed of a single piece of material (e.g., titanium) and includes an external thread 326 and a flange 328, the external thread forming a male screw configured to be installed in the skull 136, and the flange configured to act as a stopper when the fixture 318 is implanted in the skull 136. The thread 326 can have a maximum diameter of about 3.5 mm to about 5.0 mm, and the flange 328 can have a diameter that exceeds the maximum diameter of the thread 326 (e.g., more than about 10%-20%). The flange 328 can have a planar bottom surface for abutting against the outer bone surface when the fixture 318 has been screwed down into the skull 136. The flange 328 prevents the fixture 318 (e.g., the thread 326) from potentially penetrating the bone 136 completely.

[0041] The body of the fixture 318 can have a length sufficient to firmly anchor the fixture 318 to the skull 136 without completely penetrating the skull 136. The length of the body can therefore depend on the thickness of the skull 136 at the implantation site. For example, the fixture 318 can have a length of no more than 5 mm or between about 3.0 mm and about 5.0 mm measured from the planar bottom surface of the flange 328 to the end of the distal region (e.g., the portion farthest from the flange 328), which limits and / or prevents the possibility that the fixture 318 may completely penetrate the skull 136.

[0042] The interior of the fixture 318 may also include an inner lower hole 330 having a female thread configured to cooperate with the male thread of the elongated coupling shaft 324 to secure the abutment screw 320 and the abutment 312 to the fixture 318. The fixture 318 may also include an inner upper hole 332 that receives the bottom portion of the abutment 312. Figure 1C The coupling device 302 is shown directly engaging (eg, directly contacting) the abutment screw 320 (eg, the screw head 322 ), but in certain other embodiments, the coupling device 302 engages the abutment 312 without directly engaging (eg, not directly contacting) the abutment screw 320 .

[0043] In certain embodiments, the bottom of the abutment 312 includes a fixture connection section that extends below a reference plane that extends across the top of the fixture 318 and interfaces with the fixture 318. When the abutment screw 320 is sufficiently tensioned, the abutment 312 is sufficiently elastically and / or plastically pressed against the fixture 318, and / or vice versa, to form a tight seal at the interface of the surfaces of the abutment 312 and the fixture 318. Certain such embodiments can reduce (e.g., eliminate) the chance of microbial microleakage into the gap between the abutment 312, the fixture 318, and the abutment screw 320.

[0044] Figure 2 , 3A -3E, 4A-4C, 5A-5C, and 6 schematically illustrate side cross-sectional views of various exemplary devices 400 according to certain embodiments described herein. Figure 2 , 3A The exemplary device 400 of -3E, 4A-4C, 5A-5C and 6 may be as Figure 1A The external component 104 of the passive transcutaneous bone conduction device 100 is schematically shown. Figure 1B The implantable component 206 of the active transcutaneous bone conduction device 200 schematically shown in FIG. Figure 1C An operable removal component 304 of a transcutaneous bone conduction device 300 is schematically shown in FIG.

[0045] like Figure 2 , 3AThe exemplary device 400 schematically shown in Figures 3E, 4A-4C, 5A-5C and 6 includes at least one actuator 410 configured to generate vibrations within a range of vibration frequencies. At least one actuator 410 includes a housing 420 configured to be positioned on or within a recipient's body. At least one actuator 410 also includes a support portion 430 configured to communicate with a fixation device (e.g., a bone fixation device 118, 218, 318) implanted within the recipient's body. At least one actuator 410 also includes an oscillator 440 within the housing 420. The oscillator 440 includes a piezoelectric material 442 and has a first portion 444 in mechanical communication with the support portion 430 and a second portion 446 spaced apart from the support portion 430. The piezoelectric material 442 is configured to undergo a bending oscillation in response to a received voltage signal, in which the second portion 446 moves relative to the first portion 444. The at least one actuator 410 also includes at least one mass 450 within the housing 410 and in mechanical communication with the second portion 446. The at least one mass 450 is configured to move with the second portion 446 in response to the bending oscillations of the piezoelectric material 442. The at least one actuator 410 also includes at least one damper 460 configured to dampen a vibration resonance of the at least one actuator 410 over at least a portion of the vibration frequency range and independent of elastic damping of the piezoelectric material 442.

[0046] In some embodiments, at least one actuator 410 includes a vibration actuator 108 within a housing 420 (e.g., housing 110) that is external to the recipient's body (e.g., on the recipient's skin 132), and the support portion 430 includes at least one slender structure (e.g., a cylindrical element; a post; a screw) and a plate 112 (e.g., a permanent magnet and / or a ferromagnetic or ferrimagnetic element) that is secured to the slender structure and magnetically attracted to a corresponding implanted plate assembly 114 that is substantially rigidly attached to a bone fixation device 118 (e.g., plate 112, plate assembly 114, and a magnetic attraction force that operably couples the support portion 430 to the fixation device). In certain other embodiments, at least one actuator 410 includes a vibration actuator 208 within a housing 420 (e.g., housing 210) implanted within a recipient's body (e.g., beneath a recipient's tissue; beneath skin 132, fat 128, and / or muscle 134 layers; on bone 136), and a support portion 430 includes at least one elongated structure 220 (e.g., a columnar element; a column; a screw 222) rigidly secured to a bone fixation device 218 (e.g., via a clamp, screw, adhesive, epoxy, or other coupling). In certain other embodiments, at least one actuator 410 includes a vibration actuator 308 within a housing 420 (e.g., outer housing 305), the vibration actuator having a coupling device 302 configured to mate with an abutment 312 of a bone conduction implant 310, and a support portion 420 includes at least one elongated structure (e.g., a columnar element; a column; a screw) in mechanical communication with the bone fixation device 318 via the coupling device 302 and the abutment 312.

[0047] In some embodiments, the actuator 410 is configured to generate vibration energy (e.g., vibration) within a vibration frequency range (e.g., a range of 20 Hz to 20 kHz) that a recipient can perceive as sound, which is referred to herein as auditory vibration. The support portion 430 is a portion that transmits the auditory vibration to a fixture (e.g., a bone fixture 118, 218, 318) and propagates from the fixture via bone conduction to the inner ear region (e.g., within the temporal bone and including the vestibule, cochlea, and semicircular canals) and / or the middle ear region (e.g., within the recipient's head, partially defined by the tympanic membrane and including the ossicles, round window, oval window, and Eustachian tube) to be detected as a propagation path for sound.

[0048] In some embodiments, the housing 420 (e.g., housing 110, 210, 305) is configured to hermetically seal the oscillator 440 and the at least one mass 450 from the environment surrounding the actuator 410. The housing 420 can have a length and / or width of less than or equal to 40 mm (e.g., in the range of 15 mm to 35 mm; in the range of 25 mm to 35 mm; in the range of less than 30 mm; in the range of 15 mm to 30 mm), and / or a thickness of less than or equal to 7 mm (e.g., in the range of less than or equal to 6 mm; in the range of less than or equal to 5 mm; in the range of less than or equal to 4 mm). The housing 420 of some embodiments includes at least one biocompatible material (e.g., plastic; PEEK; silicone; ceramic; zirconia).

[0049] In some embodiments, the support portion 430 is configured to be rigidly fixed to the oscillator 440 to support the oscillator 440 within the housing 420 and transmit vibrations from the oscillator 440 to a fixation device (e.g., a bone fixation device 118, 218, 318) implanted in the body of a recipient. The support portion 430 of some embodiments includes a substantially rigid material (e.g., metal) and can be substantially cylindrically symmetrical about a longitudinal axis 432 of the support portion 430.

[0050] In some embodiments, the piezoelectric material 442 of the oscillator 440 comprises an integral (e.g., single; monolithic) component. The oscillator 440 of some embodiments comprises two or more layers that are mechanically connected (e.g., bonded together) to each other as an integral component (e.g., stacked), at least one of the layers comprising the piezoelectric material 442 (e.g., a unimorph having one piezoelectric layer and a non-piezoelectric layer; a bimorph having two or more piezoelectric layers). The integral component may include other non-piezoelectric materials, such as bonding materials between the piezoelectric layers (e.g., adhesive; epoxy; metal), conductive materials (e.g., metal) configured to apply a voltage signal to the piezoelectric material 442, and / or a non-piezoelectric layer secured to the piezoelectric material 442 (e.g., a metal backing plate). In some embodiments, the number of layers of the oscillator 440 is selected to provide a predetermined power, size (e.g., area, thickness), stiffness, and / or resonant frequency. Examples of piezoelectric materials compatible with certain embodiments described herein include, but are not limited to: quartz; gallium orthophosphate; lanthanum gallium silicate; barium titanate; lead titanate; lead zirconate titanate (PZT); potassium niobate; lithium niobate; lithium tantalate; sodium tungstate; potassium sodium niobate; bismuth ferrite; sodium niobate; polyvinylidene fluoride; macrofiber composites (MFC); other piezoelectric crystals, ceramics, or polymers.

[0051] In some embodiments, the oscillator 440 is substantially planar (e.g., a plate; a sheet; a slab; a disk). For example, the piezoelectric material 442 may include a substantially rectangular plate, a substantially circular disk, or another planar shape (e.g., an ellipse; a polygon with 5, 6, 7, 8, or more sides; a geometric figure; a non-geometric figure; a regular shape; an irregular shape). In some embodiments, the oscillator 440 has a length (e.g., in the range of 2 mm to 20 mm), a width substantially perpendicular to the length (e.g., in the range of 2 mm to 20 mm), and a thickness substantially perpendicular to the length and width (e.g., in the range of less than 2 mm; in the range of less than 1 mm; in the range of greater than 300 microns). Various configurations and geometries of the oscillator 440 are compatible with certain embodiments described herein (see, e.g., “Piezoelectric Ceramic Products: Fundamentals, Characteristics and Applications,” Physik Instruments (PI) GmbH & Co., Lederhose, Germany, www.piceramic.com, (2016)).

[0052] In some embodiments, the first portion 444 of the oscillator 440 is rigidly secured to the support portion 430 by a coupling 448 (e.g., a clamp, screw, adhesive, epoxy) and does not substantially move relative to the support portion 430 during bending oscillations of the oscillator 440. For example, the first portion 444 can include a hole (e.g., the hole has an inner periphery that is part of the first portion 444), wherein the support portion 430 extends through the hole along the longitudinal axis 432 and is rigidly secured to the first portion 444, and the piezoelectric material 442 extends along a plane that is substantially perpendicular to the longitudinal axis 432.

[0053] In certain embodiments, the second portion 446 of the oscillator 440 is configured to move substantially relative to the support portion 430 during bending oscillations of the oscillator 440 (e.g., in response to a time-varying voltage signal applied to portions of the oscillator 440). For example, the second portion 446 can include at least a portion of a perimeter of the piezoelectric material 442 and can be in mechanical communication with the at least one mass 450 via at least one connector 452 (e.g., a clamp, screw, adhesive, epoxy) such that the bending oscillation moves (e.g., vibrates) the second portion 446 and the at least one mass 450 along a direction substantially parallel to the longitudinal axis 432 of the support portion 430 (e.g., substantially perpendicular to the oscillator 440).

[0054] In some embodiments, at least one mass 450 includes one or more materials having a sufficiently large mass density and dimensions (e.g., length; width; thickness; volume) such that at least one mass 450 has a mass (e.g., a weight) configured to achieve a predetermined resonant frequency (e.g., in the range of 250 Hz to 3 kHz; approximately 750 Hz) of a bending oscillation (e.g., a vibration generated). Examples of such materials for at least one mass 450 include, but are not limited to: tungsten; tungsten alloy; osmium; osmium alloy. At least one mass 450 can include an integral (e.g., single; monolithic) component, multiple components (e.g., two or more sub-masses) fixed to each other, and / or multiple components separated from each other. In some embodiments, at least one mass 450 includes a separate mass 450 positioned at a separate location at the second portion 446 of the oscillator 440. For example, the at least one mass 450 may include two or more separate masses 450 positioned at the perimeter of the piezoelectric material 442 (e.g., two masses 450 at opposite ends of the substantially rectangular piezoelectric material 442) such that the at least one mass 450 is spaced apart from the support portion 430. As another example, the at least one mass 450 may include a single mass 450 extending at least partially around the perimeter of the piezoelectric material 442. The at least one mass 450 of some embodiments extends from the second portion 446 of the oscillator 400 toward the support portion 430 (e.g., as shown in FIG. 1 ). Figure 2 , 3A -3E, 4A-4C, 5A-5C and 6).

[0055] The piezoelectric material 442 of the oscillator 440 typically has very low intrinsic damping, resulting in sharp vibration resonances (e.g., high Q values, where the Q value is the resonant frequency divided by the -3 dB bandwidth), poor sound quality, and / or mechanical failure. In certain embodiments, the at least one damper 460 can be configured to dampen at least one vibration resonance of the at least one actuator 410 to improve sound quality and / or provide more durability to mechanical failure compared to the at least one actuator 410 without the at least one damper 460. In addition, the piezoelectric material 442 is typically brittle, where material fracture occurs at the microscopic bending level and mechanical failure occurs when the at least one actuator 410 is shaken or impacted. Moreover, the piezoelectric material 442 typically has a rough surface, such that the piezoelectric material 442 does not fully contact when pressed against a hard, flat surface, resulting in uneven and / or unreliable force transmission and large localized stresses. In some embodiments, at least one damper 460 can also be configured to coat at least one surface of the piezoelectric element 442 (e.g., a surface that is mechanically connected to the support portion 430 and / or at least one mass 450) to provide more uniform and / or more reliable force transfer compared to at least one actuator 410 without the at least one damper 460.

[0056] In certain embodiments, the at least one damper 460 includes at least one damping material configured to deform in response to movement of the oscillator 400 and dissipate at least a portion of the mechanical energy of the oscillator 400. For example, the at least one damping material can be elastic (e.g., elastically compressible; flexible) and / or viscoelastic. In certain embodiments, the at least one damper 460 can provide viscoelastic damping (e.g., energy dissipation through internal friction within the at least one material) and / or structural damping (e.g., energy dissipation through friction between the at least one material and other portions of the at least one actuator 410). Examples of the at least one damping material of the at least one damper 460 that may be compatible with certain embodiments described herein include, but are not limited to: rubber, elastomer, Viton; TM Fluoroelastomers or silicones (e.g., gaskets); viscoelastic elements (e.g., layers); adhesives (e.g., double-sided tape); foams (e.g., open-cell or closed-cell); and surface coatings and / or varnishes (e.g., having a thickness of less than 1 micron). Examples of elastomers that may be compatible with certain embodiments described herein include, but are not limited to, silicone rubber (VMQ), silicone gel, silicone foam, fluorosilicone rubber (FVMQ), Viton (FKM), Kalrez (FFKM), ethylene propylene diene monomer (EPDM), nitrile rubber (NBR), polyurethane rubber, and polyurethane foam. Examples of tacky adhesives having a carrier (e.g., tape) that may be compatible with certain embodiments described herein include, but are not limited to, viscoelastic damping polymer 110 and VHB available from 3M Company, St. Paul, Minnesota. TM Adhesive transfer tapes 9460, 9469, 9473. The shape, size, and material of the at least one damper 460 can be selected to tune the resonant vibration frequency of the at least one actuator 410.

[0057] In some embodiments, the at least one damper 460 is positioned such that the vibratory movement (e.g., vibration) of the oscillator 400 generates compressive and / or shear forces on and / or within the at least one damper 460. In some embodiments, the at least one damper 460 includes a relatively small thickness (e.g., less than 1 micron) and a relatively large surface area (e.g., about tens of square millimeters), and is configured to dampen the vibration of the oscillator 400 by shear forces rather than compressive forces.

[0058] Figure 2Schematically illustrates a cross-sectional view of an exemplary device 400 having at least one damper 460 positioned between a piezoelectric material 442 of an oscillator 440 and at least one mass 450 in accordance with certain embodiments described herein. For example, the at least one damper 460 may include at least one viscoelastic element (e.g., layer; gasket) between the oscillator 440 and the at least one mass 450. Figure 2 The at least one damper 460 is shown to include at least a portion of the at least one coupler 452, but the at least one damper 460 may be separate from the at least one coupler 452. The at least one viscoelastic element may be adhered (e.g., fixed) to both the oscillator 440 and the at least one mass 450 (see, e.g., Figure 2 ), or at least one viscoelastic element may be clamped between the oscillator 440 and the at least one mass 450 (eg, by a screw or a retaining ring of the at least one mass 450).

[0059] In certain embodiments, at least one damper 460 includes at least one layer that coats at least a portion of the piezoelectric material 442 (e.g., coated onto the piezoelectric material 442 by dipping the piezoelectric material 442 in polyurethane; or depositing a nanocoating, parylene, or gold onto the piezoelectric material 442) and substantially fills surface gaps of the piezoelectric material 442. The at least one layer can be compressed (e.g., squeezed) between the piezoelectric material 442 and another solid surface such that the at least one layer extends into (e.g., fills) surface gaps, voids, and / or cracks of the piezoelectric material 442 (e.g., smoothing the surface; providing more uniform and / or more reliable force transmission). In some embodiments, at least one damper 460 is adhered to the piezoelectric material 442 (e.g., by glue or epoxy), while in some embodiments, at least one damper 460 is held in place without being adhered to the piezoelectric material 442 (e.g., is clamped without glue or epoxy, thereby avoiding the manufacturing step of applying glue or epoxy and avoiding potential degradation of the glue or epoxy over time).

[0060] The vibratory movement of the oscillator 400 may generate a compressive force (e.g., in a direction substantially parallel to the direction of movement of the second portion 446) and / or a shear force (e.g., in a direction substantially perpendicular to the direction of movement of the second portion 446) on and / or within the at least one damper 460. In certain embodiments, the at least one coupler 452 is configured to allow relative movement between the second portion 446 and the at least one mass 450 in a direction substantially perpendicular to the direction of movement of the second portion 446 (e.g., allow shear forces on and / or within the at least one damper 460), while inhibiting relative movement of the second portion 446 and the at least one mass 450 in a direction substantially parallel to the direction of movement of the second portion 446 (e.g., inhibiting compressive forces on the at least one damper 460).

[0061] In certain embodiments, at least one dampener 460 is mechanically secured to both a substantially non-moving portion of the actuator 410 and a moving portion of the actuator 410. For example, Figures 3A-3D Schematically illustrates a cross-sectional view of an exemplary apparatus 400 having at least one damper 460 between a support portion 430 and at least one mass 450 according to certain embodiments described herein. As another example, Figure 3E Schematically depicts a cross-sectional view of an exemplary device 400 having at least one damper 460 between a housing 420 and at least one mass 450 according to certain embodiments described herein. In certain embodiments, the at least one damper 460 substantially surrounds the support portion 430, while in certain other embodiments, the at least one damper 460 only partially extends around the support portion 430. Figures 3A-3D In each of the figures, at least one damper 460 is sufficiently soft (e.g., pliable) to shear forces to allow at least one mass 450 to move relative to the support portion 430 in a direction substantially parallel to the longitudinal axis 432 in response to the bending oscillations of the oscillator 440 while providing a damping force that dissipates at least some of the mechanical energy of the at least one actuator 410. Figure 3E In the embodiment, at least one damper 460 is soft enough (e.g., flexible) to compressive forces to allow at least one mass 450 to move relative to the support portion 430 in a direction substantially parallel to the longitudinal axis 432 in response to bending oscillations of the oscillator 440 while providing a damping force that dissipates at least some of the mechanical energy of at least one actuator 410.

[0062] like Figure 3A and 3B As shown in FIG. 1 , at least one damper 460 includes a gasket 462 (eg, an O-ring) comprising a viscoelastic material (eg, rubber; elastomer; Viton TMFluoroelastomer; silicone). Although Figure 3A and 3B The gasket 462 is shown as being retained within the first channel 434 (e.g., slot; groove) of the support portion 430 and the second channel 454 (e.g., slot; groove) of the at least one mass 450, but in certain other embodiments, the gasket 462 is retained within only a single channel (e.g., a single slot or groove of the support portion 430 or a single slot or groove of the at least one mass 450). In certain embodiments, the gasket 462 has a substantially rectangular cross-section (see, e.g., Figure 3A ), a substantially circular cross-section (see e.g. Figure 3B ) or another cross-sectional shape (e.g., elliptical; polygonal; geometric; non-geometric; regular; irregular).

[0063] In some embodiments, at least one damper 460 includes a viscoelastic layer 463 (e.g., silicone and / or foam cured in place; double-sided tape) between a surface 435 of the support portion 430 and a surface 455 of the at least one mass 450, and secured to the surface of the support portion and the surface of the at least one mass (see, e.g., Figure 3C ) or between the surface 427 of the housing 420 and the surface 457 of the at least one mass 450 and fixed to the surface of the housing and the surface of the at least one mass (see, e.g. Figure 3E ). In certain other embodiments, at least one damper 460 includes a viscoelastic element (e.g., a layer) between and secured to a surface of the housing 420 and the second portion 446 of the oscillator 440.

[0064] Figure 3D A cross-sectional view of an exemplary device 400 is schematically shown, wherein at least one damper 460 includes at least one first permanent magnet 436 in mechanical communication with a support portion 430, at least one second permanent magnet 456 in mechanical communication with at least one mass 450, and at least one viscoelastic material including a ferrofluid 464 between the at least one first permanent magnet 436 and the at least one second permanent magnet 456. The ferrofluid 464 includes a plurality of ferromagnetic or ferrimagnetic particles loosely bound together such that the particles can move relative to each other, thereby generating friction that dampens the mechanical energy of the at least one actuator 410. In certain other embodiments, the at least one damper 460 includes other types of multiple elements (e.g., elastic fiber bundles, such as strings, or multiple microparticles) configured to move relative to each other in response to movement of the oscillator 400, the moving elements being loosely bound together, and dissipating at least some of the mechanical energy through friction between the elements.

[0065] In certain other embodiments, at least one damper 460 may include a viscoelastic material (e.g., soft polyurethane; silicone; foam) that substantially surrounds and contacts the entire components (e.g., support portion 430, oscillator 440, and at least one mass 450) within housing 420. For example, the viscoelastic material may be injected into substantially the entire interior volume of housing 420.

[0066] Figures 4A-4C Schematically illustrates a cross-sectional view of an exemplary device 400 according to certain embodiments described herein, wherein at least one damper 460 includes at least one permanent magnet 465 configured to generate eddy currents within a conductive portion 466 of at least one actuator 410 in response to bending oscillations of an oscillator 440. The eddy currents can be configured to dissipate energy in the conductive portion 466. In certain embodiments, the at least one permanent magnet 465 is fixed to a moving portion of the actuator 410, and the conductive portion 466 includes a portion of a substantially non-moving portion of the actuator 410 or is fixed to a substantially non-moving portion of the actuator (see, e.g., Figure 4A and 4B In some embodiments, at least one permanent magnet 465 is fixed to a substantially non-moving portion of the actuator 410, and the conductive portion 466 is part of or fixed to a moving portion of the actuator 410 (see, e.g. Figure 4C ).

[0067] If Figure 4A As shown schematically, at least one permanent magnet 465 is fixed to at least one mass 450, and the conductive portion 466 includes a short-circuited wire coil attached to the housing 420. Figure 4B As schematically shown, at least one permanent magnet 465 is fixed to at least one mass 450, and the conductive portion 466 includes a short-circuited wire coil (e.g., gold; copper) attached to the support portion 430. The at least one permanent magnet 465 and the wire coil of the conductive portion 466 can be configured to be tuned to provide a predetermined eddy current damping of the oscillations of the at least one actuator 410. For example, the wire coil can include at least one capacitor or other circuitry selected to constrain eddy currents generated within the wire coil.

[0068] In certain other embodiments, the conductive portion 466 includes a portion of the housing 420 and / or a portion of the support portion 430 and / or a portion of at least one mass 450. Figure 4C As shown schematically, at least one mass 450 (e.g., comprising a resistivity of 5.6 x 10 -8Ohm-meter of tungsten) includes a conductive portion 466, and the at least one permanent magnet 465 includes a plurality of permanent magnets 465 fixed to the housing 420 and / or the support portion 430. In some embodiments, the housing 420 and / or the support portion 430 and / or the at least one mass 450 includes a material having a high resistivity (e.g., a resistivity of 1.7 x 10 -6 Ohm-meter grade 5 titanium), and the conductive portion 466 includes a conductive layer (e.g., having a conductivity of 2.8 x 10 -8 Ohm-meter resistivity of gold).

[0069] Figures 5A-5C Schematically illustrated are cross-sectional views of three exemplary apparatuses 400 that utilize viscous materials according to certain embodiments described herein. Figure 5A A cross-sectional view of an exemplary device 400 is schematically shown, wherein at least one damper 460 includes a coiled piston damper 470 that is fixed to a substantially non-moving portion of the actuator 410 (e.g., the support portion 430) and is in mechanical communication with a moving portion of the actuator 410 (e.g., the at least one mass 450). In certain other embodiments, the coiled piston damper 470 is fixed to a moving portion of the actuator 410 and is in mechanical communication with a substantially non-moving portion of the actuator 410. As shown by Figure 5A As shown schematically, the coiled piston damper 470 may include a coiled tube 472 containing a viscous material (e.g., gas; liquid; gel) and having a first end 474, a second end 476 spaced from the first end 474, and a movable piston 478 in mechanical communication with the at least one mass 450 at the second end 476. The piston 478 may be configured to move relative to the tube 472 in response to movement of the at least one mass 450 to exert a force on the viscous material within the tube 472.

[0070] For example, first end 474 can be open to the environment within housing 420, and the viscous material within tube 472 can be the same gas (e.g., helium) that fills the environment surrounding oscillator 440 and at least one mass 450 within housing 420. First end 474 can include a mesh (e.g., an acoustically resistive mesh, examples of which are available from Knowles Electronics, Inc. of Itasca, IL) and / or an open-cell foam (e.g., Foam, which is available from Flexolan Foam GmbH, Bayern, Germany; As another example, first end 474 can be closed to the environment within housing 420, and the viscous material within tube 472 can include a material (e.g., a fluid; gel) that is different from the gas that fills the environment surrounding oscillator 440 and at least one mass 450 within housing 420. Coiled piston damper 470 can be configured to dampen vibration resonance of at least one actuator 410 by moving piston 478 in response to vibrations of oscillator 440 and exerting a force on the viscous material within tube 476.

[0071] Figure 5B A cross-sectional view of an exemplary device 400 is schematically shown, wherein at least one damper 460 comprises a film damper 480 fixed to a substantially non-moving portion of the actuator 410 (e.g., the housing 420 and / or the support portion 430) and in mechanical communication with a moving portion of the actuator 410 (e.g., the at least one mass 450). Figure 5B As shown schematically, the membrane damper 480 may include a reservoir 482 containing a fluid (e.g., a gas; helium; nitrogen; air), a movable membrane 484 (e.g., rubber; flexible thin metal) that at least partially defines a volume within the reservoir 482 and is in mechanical communication with the at least one mass 450; and at least one orifice 486 configured to allow gas to flow out of and into the reservoir 482 (e.g., to and from the environment surrounding the oscillator 440 and the at least one mass 450 within the housing 420). In response to movement of the at least one mass 450, the membrane 484 moves, thereby changing the volume of the reservoir 482 and forcing the gas to flow through the at least one orifice 486. By moving the membrane 484 in response to vibrations of the oscillator 440 and exerting a force on the gas within the reservoir 482, the membrane damper 480 may be configured to dampen vibration resonances of the at least one actuator 410.

[0072] Figure 5C A cross-sectional view of an exemplary device 400 is schematically shown, wherein at least one damper 460 comprises a filmless damper 490 that is fixed to a substantially non-moving portion of the actuator 410 (e.g., the housing 420 and / or the support portion 430) and is in mechanical communication with a moving portion of the actuator 410 (e.g., the at least one mass 450). Figure 5CAs shown schematically, the filmless damper 490 can include a reservoir 492 containing a gas (e.g., helium; nitrogen; air), one or more walls 494 at least partially defining the volume of the reservoir 492, and at least one orifice 496 configured to allow gas to flow out of and into the reservoir 492 (e.g., to and from the environment within the housing 420 surrounding the oscillator 440 and the at least one mass 450). At least one surface of the at least one mass 450 at least partially defines the volume within the reservoir 492. In certain embodiments, the filmless damper 490 includes a seal (e.g., an O-ring) between the at least one mass 450 and the one or more walls 494. In response to movement of the at least one mass 450, the volume of the reservoir 492 changes, thereby forcing the gas to flow through the at least one orifice 496. The filmless damper 490 may be configured to dampen vibrational resonances of the at least one actuator 410 by exerting a force on the gas within the reservoir 492 in response to vibrations of the oscillator 440 .

[0073] In certain embodiments, one or more of the moving parts of the actuator 410 (e.g., oscillator 440; at least one mass 450) include at least one through-hole extending from a first surface to a second surface (e.g., the first surface and the second surface are substantially parallel to each other and substantially perpendicular to the direction of motion of the at least one mass 450). The at least one through-hole can be configured to allow gas (e.g., helium; nitrogen; air) within the housing 420 and in the environment surrounding the oscillator 440 and the at least one mass 450 to flow through the at least one through-hole in response to movement of the moving part during vibration of the at least one actuator 410. The at least one through-hole can be configured to dampen vibration resonance of the at least one actuator 410.

[0074] In certain embodiments, at least one aperture of at least one actuator 410 (e.g., at least one aperture 486 of a membrane damper 480; at least one aperture 496 of a membraneless damper 490; at least one perforation of a moving portion) comprises a mesh (e.g., an acoustically resistive mesh, examples of which are available from Knowles Electronics, Inc., Itasca, IL) and / or an open-cell foam (e.g., Foam, which is available from Flexolan Foam GmbH, Bayern, Germany; Foam, which is available from BASF, Ludwigshafen, Germany). The mesh and / or open cell foam is configured to increase the flow resistance of gas into and out of the reservoir 482, 492 or the flow resistance of gas flowing through the at least one perforation.

[0075] Fig. 6A Schematically illustrates exemplary damping of vibration resonances according to certain embodiments described herein. The vibration resonance spectrum of an undamped actuator is given by Fig. 6A The vibration resonance spectrum of the actuator with various non-zero damping values ​​is shown in Fig. 6A The two other lines in are shown. To increase the amount of damping, the vibration resonance of the undamped actuator (eg, at about 1 kHz) is reduced in magnitude and shifted towards higher frequencies. Figure 6B Schematically illustrates exemplary damping of vibration anti-resonance according to certain embodiments described herein. Figure 6B The dashed line in the figure shows the vibration resonance spectrum of the actuator with damping. Figure 6B The solid line in is shown. For the damped actuator, the notch of the vibration anti-resonance of the undamped actuator is shallower and the response is smoothed.

[0076] Figure 7 7 is a flow chart of an exemplary method 700 according to certain embodiments described herein. In operation block 710, method 700 includes applying an oscillating voltage signal to a piezoelectric element (e.g., oscillator 440) mechanically coupled to a rigid portion (e.g., support portion 430) and at least one mass (e.g., at least one mass 450). The piezoelectric element responds to the voltage signal by transmitting an oscillating motion relative to the rigid portion to the at least one mass. For example, the rigid portion can be rigidly fixed to a fixture implanted in a recipient's body, and the rigid portion and fixture can be configured to transmit vibrational energy from the piezoelectric element to the recipient's body.

[0077] In operation block 720, method 700 also includes attenuating the oscillatory motion using viscoelastic damping, electromagnetic damping, and / or pneumatic damping. For example, this attenuation includes reducing the magnitude of at least one vibration resonance of the piezoelectric element independently of the elastic damping of the piezoelectric element. In some embodiments, the attenuation using viscoelastic damping includes applying a shear force to the viscoelastic material. For example, the viscoelastic material can be between the surface of at least one mass and the substantially non-oscillating surface, or between the surface of at least one mass and the surface of the piezoelectric element. In some such embodiments, the viscoelastic material includes a coating on the surface of the piezoelectric element.

[0078] Although for ease of understanding, common terms are used to describe the systems and methods of certain embodiments, these terms are used herein to have their broadest reasonable interpretation. Although various aspects of the present disclosure are described with respect to illustrative examples and embodiments, the disclosed examples and embodiments should not be interpreted as restrictive. Unless otherwise specifically stated, or otherwise understood in the context as used, conditional language such as "can", "could", "might" or "may" is generally intended to convey that a particular embodiment includes specific features, elements and / or steps, while other embodiments do not include specific features, elements and / or steps. Therefore, such conditional language is generally not intended to imply that features, elements and / or steps are required in any way for one or more embodiments, or is not intended to imply that one or more embodiments must include logic for determining whether these features, elements and / or steps are included in any particular embodiment or will be executed in any particular embodiment with or without user input or prompts. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components or steps in a non-exclusive manner, indicating that the referenced elements, components or steps may exist or utilize or be combined with other elements, components or steps that are not explicitly referenced.

[0079] It should be appreciated that the embodiments disclosed herein are not mutually exclusive and may be combined with one another in various arrangements. In addition, although the disclosed methods and apparatus are described largely in the context of conventional cochlear implants, the various specific implementations described herein may be incorporated into a variety of other suitable devices, methods, and contexts. More generally, as can be appreciated, the specific embodiments described herein may be used in a variety of implantable medical device environments that may benefit from making received power available for use by the implanted device during a time period when at least one power storage device of the implanted device is unable to provide electrical power for operation of the implantable medical device.

[0080] As used herein, degree language such as the terms "approximately," "about," "substantially," and "substantially" represent values, quantities, or features that are close to the stated value, quantity, or feature that still performs the desired function or achieves the desired result. For example, the terms "approximately," "about," "substantially," and "substantially" may refer to an amount within ±10% of the stated amount, within ±5% of the stated amount, within ±2% of the stated amount, within ±1% of the stated amount, or within ±0.1% of the stated amount. As another example, the terms "substantially parallel" and "substantially parallel" refer to a value, quantity, or feature that deviates from exact parallelism by ±10 degrees, ±5 degrees, ±2 degrees, ±1 degrees, or ±0.1 degrees, and the terms "substantially perpendicular" and "substantially perpendicular" refer to a value, quantity, or feature that deviates from exact perpendicularity by ±10 degrees, ±5 degrees, ±2 degrees, ±1 degrees, or ±0.1 degrees. The ranges disclosed herein also encompass any and all overlaps, subranges, and combinations thereof. Language such as "up to," "at least," "greater than," "less than," "between," and the like include the recited numbers. As used herein, the meanings of "a," "an," and "the" include the plural unless the context clearly dictates otherwise. Additionally, as used in the description herein, the meaning of "in" includes "into" and "on," unless the context clearly dictates otherwise.

[0081] Although methods and systems are discussed herein in terms of elements labeled by ordinal adjectives (e.g., first, second, etc.), the ordinal adjectives are merely used as labels to distinguish one element from another (e.g., one signal from another signal, or one circuit from another circuit), and the ordinal adjectives are not used to indicate the order of these elements or their order of use.

[0082] The invention described and claimed herein is not limited in scope by the specific example embodiments disclosed herein, because these embodiments are intended to be illustrative of several aspects of the present invention, rather than limiting. Any equivalent embodiments are intended to be within the scope of the present invention. In fact, various modifications of the present invention in form and detail will become apparent to those skilled in the art from the foregoing description, in addition to those shown and described herein. Such modifications are also intended to fall within the scope of the claims. The breadth and scope of the present invention should not be limited by any of the example embodiments disclosed herein, but should only be defined according to the claims and their equivalents.

Claims

1. A device comprising: At least one actuator, the at least one actuator configured to generate vibrations within a range of vibration frequencies, the at least one actuator comprising: a housing configured to be positioned on or within a body of a recipient; a support portion configured to be in operable communication with a fixation device implanted within a body of the recipient; an oscillator within the housing, the oscillator comprising a piezoelectric material and having a first portion in mechanical communication with the support portion and a second portion spaced apart from the support portion, the piezoelectric material being configured to undergo a bending oscillation in response to a received voltage signal in which the second portion moves relative to the first portion; at least one mass within the housing and in mechanical communication with the second portion, the at least one mass configured to move with the second portion in response to the bending oscillations of the piezoelectric material; and At least one damper is configured to damp at least one vibration resonance of the at least one actuator within at least a portion of the vibration frequency range and independent of elastic damping of the piezoelectric material.

2. An apparatus according to claim 1, wherein the at least one damper comprises at least one viscoelastic element between the oscillator and the at least one mass, between the oscillator and the housing, between the at least one mass and the support part and / or between the at least one mass and the housing.

3. An apparatus according to claim 2, wherein the at least one viscoelastic element comprises a viscoelastic layer between the piezoelectric material and the at least one mass, between the support portion and the at least one mass, and / or between the at least one mass and the shell.

4. The apparatus of claim 2, wherein the at least one viscoelastic element comprises an O-ring or a gasket between the support portion and the at least one mass.

5. The device according to claim 2 further includes at least one first permanent magnet mechanically connected to the support part and at least one second permanent magnet mechanically connected to the at least one mass, and at least one viscoelastic material, wherein the at least one viscoelastic material includes a ferromagnetic fluid between the at least one first permanent magnet and the at least one second permanent magnet.

6. Apparatus according to any preceding claim, wherein the at least one damper comprises at least one permanent magnet configured to generate eddy currents within a conductive portion of the at least one actuator in response to the bending oscillations of the oscillator.

7. The device according to claim 6, wherein the at least one permanent magnet is fixed to the at least one mass, and the conductive portion comprises a part of the housing and / or a part of the support portion.

8. The apparatus of claim 6, wherein the at least one permanent magnet is in mechanical communication with the at least one mass, and the conductive portion comprises a wire coil attached to the housing and / or the support portion.

9. The apparatus of claim 6, wherein the at least one permanent magnet is in mechanical communication with the housing and / or the support portion, and the conductive portion comprises a portion of the at least one mass.

10. An apparatus according to any preceding claim, wherein the at least one damper comprises a reservoir containing a fluid and a movable portion mechanically connected to the reservoir and the at least one mass, the movable portion being configured to move and change the volume within the reservoir in response to movement of the at least one mass.

11. The apparatus of claim 10, wherein the movable portion comprises a membrane that at least partially defines the volume within the reservoir.

12. The apparatus of claim 10, wherein the movable portion comprises at least one surface of the at least one mass, the at least one surface at least partially defining the volume within the reservoir.

13. The apparatus of any one of claims 10 to 12, wherein the at least one dampener comprises at least one orifice configured to allow gas to flow therethrough into and out of the volume within the reservoir.

14. The apparatus of claim 13, wherein the at least one aperture comprises a plurality of apertures through an open cell foam material and / or a mesh.

15. An apparatus according to any preceding claim, wherein the at least one damper comprises at least one perforation extending from a first surface of the at least one mass to a second surface of the at least one mass, the at least one perforation being configured to allow gas to flow therethrough in response to movement of the at least one mass.

16. The apparatus of claim 15, wherein the first surface and the second surface are substantially parallel to each other and substantially perpendicular to a direction of motion of the at least one mass.

17. Apparatus according to claim 15 or claim 16, wherein the at least one perforation comprises a plurality of perforations through the open cell foam material and / or mesh.

18. A method comprising: applying an oscillating voltage signal to a piezoelectric element mechanically coupled to the rigid portion and the at least one mass, the piezoelectric element responding to the voltage signal by imparting an oscillating motion relative to the rigid portion to the at least one mass; as well as The oscillatory motion is damped using viscoelastic damping, electromagnetic damping and / or pneumatic damping.

19. The method of claim 18, wherein the rigid portion is rigidly secured to a fixture implanted within a recipient's body, the rigid portion and the fixture configured to transmit vibrational energy from the piezoelectric element to the recipient's body.

20. A method according to claim 18 or claim 19, wherein the attenuating comprises reducing the magnitude of at least one vibration resonance of the piezoelectric element independently of elastic damping of the piezoelectric element.

21. A method according to any one of claims 18 to 20, wherein the attenuating comprises applying a shear force to the viscoelastic material.

22. The method of claim 21, wherein the viscoelastic material is between a surface of the at least one mass and a substantially non-oscillating surface, or between a surface of the at least one mass and a surface of the piezoelectric element.

23. A method according to claim 21 or claim 22, wherein the viscoelastic material comprises a coating on the surface of the piezoelectric element.

24. An apparatus comprising: A piezoelectric actuator configured to generate a vibration signal in response to an oscillating voltage signal, the piezoelectric actuator being configured to be implanted on or within a recipient's body and to transmit the vibration signal to the recipient's body, the piezoelectric actuator comprising at least one damper configured to attenuate at least one vibration resonance of the piezoelectric actuator using inelastic damping.

25. The apparatus of claim 24, wherein the inelastic damping comprises viscoelastic damping, electromagnetic damping and / or pneumatic damping.

26. The apparatus of any one of claims 24 to 25, wherein the piezoelectric actuator further comprises: an abutment configured to be in mechanical communication with a fixation device secured to a bone surface of the recipient's body; as well as A substantially planar piezoelectric material is in mechanical communication with the base and extends substantially perpendicular to a longitudinal axis of the base, the piezoelectric material being configured to generate the vibration signal by bending in a direction along the longitudinal axis in response to the oscillating voltage signal.

27. The apparatus of claim 26, wherein the base station is configured to transmit the vibration signal to the recipient's body via the fixture such that the vibration signal evokes the recipient's hearing perception.

28. The apparatus of any one of claims 24 to 27, wherein the piezoelectric actuator further comprises a housing configured to hermetically seal the at least one damper from an environment surrounding the piezoelectric actuator.

29. An apparatus comprising: An actuator configured to be implanted on or in a recipient's body and transmit a vibration signal to the recipient's body, the actuator comprising at least one piezoelectric material and at least one surface layer covering a surface of the at least one piezoelectric material, the at least one piezoelectric material being configured to generate a vibration signal in response to an oscillating voltage signal, the at least one surface layer extending into surface gaps, voids and / or cracks of the at least one piezoelectric material.

30. The apparatus of claim 29, wherein at least one layer comprises at least one of polyurethane, nanocoating, parylene, and gold.

31. An apparatus according to claim 29 or claim 30, wherein the at least one piezoelectric material is substantially planar.

32. An apparatus according to any one of claims 29 to 31, wherein the actuator further comprises at least one mass, wherein the at least one mass is mechanically connected to the at least one piezoelectric material and is configured to move in response to vibrations of the at least one piezoelectric material, wherein at least a portion of at least one layer is between the at least one piezoelectric material and the at least one mass.

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