Wire impact protection

Abstract

An implantable medical device includes an at least semi-constrained volume of substantially incompressible insulative material with embedded wires. The at least semi-constrained volume of substantially incompressible insulative material is configured to have a preferential direction of movement in response to an external force.

Description

WIRE IMPACT PROTECTIONBACKGROUNDTechnical Field[oooi] The present disclosure relates generally to protection of embedded wires from impact stress.Related Art

[0002] Medical devices have provided a wide range of therapeutic benefits to recipients over recent decades. Medical devices can include internal or implantable components / devices, external or wearable components / devices, or combinations thereof (e.g., a device having an external component communicating 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 in performing lifesaving and / or lifestyle enhancement functions and / or recipient monitoring for a number of years.

[0003] The types of medical devices and the ranges of functions performed thereby have increased over the years. For example, many medical devices, sometimes referred to as “implantable medical devices,” now often include one or more instruments, apparatus, sensors, processors, controllers or other functional mechanical or electrical components that are permanently or temporarily implanted in a recipient. These functional devices are typically used to diagnose, prevent, monitor, treat, or manage a disease / injury or symptom thereof, or to investigate, replace or modify the anatomy or a physiological process. Many of these functional devices utilize power and / or data received from external devices that are part of, or operate in conjunction with, implantable components.SUMMARY

[0004] In one aspect, a method is provided. The method comprises: providing one or more wires within an at least semi -constrained volume of silicone; and configuring the at least semiconstrained volume of silicone such that a direction of movement of the at least semiconstrained volume of silicone under impact is controlled to inhibit breakage of the one or more wires.

[0005] In another aspect, an apparatus is provided. The apparatus comprises: an at least semiconstrained silicone body; a plurality of wire sections disposed in the silicone body; and at least one compression relief region disposed in the silicone body.

[0006] In another aspect, a method is provided. The method comprises: forming an at least partially constrained volume of substantially incompressible insulative material with embedded wires; and configuring the at least partially constrained volume of substantially incompressible insulative material to have a preferential direction of movement in response to an impact from a first direction.

[0007] In another aspect, an apparatus is provided. The apparatus comprises: a volume of silicone comprising a first surface and a second surface, wherein the volume of silicone is constrained adjacent the second surface; and at least one wire disposed in the volume of silicone, wherein the volume of silicone is configured to have a preferential extrusion direction in response to an impact delivered proximate to the first surface, wherein extrusion of the volume of silicone in the preferential extrusion direction results in application of an axial force on the at least one wire while minimizing shear forces applied to the at least one wire.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Embodiments of the present disclosure are described herein in conjunction with the accompanying drawings, in which:

[0009] FIG. 1 is a perspective view of a cochlear implant system with which aspects of the techniques presented herein can be implemented;[ooio] FIG. 2 is a top view of an embodiment of a portion of an implantable device;[ooii] FIG. 3 is a side view of the implantable device of FIG. 2 during an impact;

[0012] FIG. 4 illustrates a pattern of the deflection of the implantable device of FIG. 2 after a central impact,

[0013] FIG. 5A is an example Finite Element Analysis (FEA) plot illustrating the pattern of extrusion of the silicone in the implantable device of FIG. 2 in response to a central impact;

[0014] FIG. 5B is an FEA plot illustrating the effect of the extrusion of the silicone on an electrode wire in the implantable device of FIG. 2 in response to a central impact;

[0015] FIG. 6 illustrates a top view of a portion of an implantable device in which a direction of extrusion of silicone under impact is controlled, according to embodiments described herein;

[0016] FIG. 7 is an example FEA plot illustrating controlled movement of silicone, according to embodiments described herein;

[0017] FIG. 8 is a side view of an example in which a void and strain relief are placed around a section of a wire, according to embodiments described herein;

[0018] FIGs. 9A, 9B, and 9C illustrate example side views of an implantable device located between a recipient's skin and skull in which silicone is constrained, with which aspects of the techniques can be implemented;

[0019] FIG. 10A illustrates a high-density surface electrode, with which aspects of the techniques can be implemented;

[0020] FIG. 10B is a simplified cross-section illustrating a side view of a single pad and wire in a silicone encapsulant, with which aspects of the techniques can be implemented;

[0021] FIG. 10C is a simplified cross-section illustrating a side view of single pad and wire under a localized force, with which aspects of the techniques can be implemented;

[0022] FIG. 10D is a top view illustrating the localized force applied to the silicone encapsulant, with which aspects of the techniques can be implemented;

[0023] FIG. 10E illustrates a simplified cross-section illustrating a side view of a single pad and wire in the silicone encapsulant with a compression relief region, with which aspects of the techniques can be implemented;

[0024] FIG. 1 OF is a top view illustrating a localized force applied to the silicone encapsulant with the embedded compression relief region, with which aspects of the techniques can be implemented;

[0025] FIG. 11 is a flowchart of an embodiment of a method for manufacturing a device according to embodiments described herein; and

[0026] FIG. 12 illustrates an embodiment of another method for manufacturing a device according to embodiments described herein.DETAILED DESCRIPTION

[0027] Presented herein are techniques for protecting embedded wires from impact stresses through controlled extrusion of a substantially incompressible insulative material. Morespecifically, wires in an implantable medical device, such as an implantable auditory prosthesis, can be surrounded by (e.g., embedded in) an at least semi-constrained volume of substantially incompressible insulative material (e.g., an electrically non-conductive material whose volume or density does not change with pressure, such as silicone). In accordance with embodiments presented herein, an at least semi-constrained volume of substantially incompressible insulative material is configured such that a direction of movement or extrusion of the semi-constrained volume under impact is controlled to inhibit breakage of the one or more wires embedded therein. A semi-constrained volume of material refers to a volume of material that has one or more limits / constraints on the movement of the material (e.g., the material is at least partially bounded by one or more structures). The constraints can be, for example, biological structures (e.g., bone, skin, etc.), device structures / components, etc.

[0028] There are a number of different types of devices in / with which embodiments of the present disclosure can be implemented. Merely for ease of description, the techniques presented herein are primarily described with reference to a specific device in the form of a cochlear implant system. However, it is to be appreciated that the techniques presented herein can also be partially or fully implemented by any of a number of different types of devices, including consumer electronic device (e.g., mobile phones), wearable devices (e.g., smartwatches), hearing devices, implantable medical devices, wearable devices, etc. As used herein, the term “hearing device” is to be broadly construed as any device that delivers sound signals to a recipient in any form, including in the form of acoustical stimulation, mechanical stimulation, electrical stimulation, etc. As such, a hearing device can be a device for use by a hearing-impaired person (e.g., hearing aids, middle ear auditory prostheses, bone conduction devices, direct acoustic stimulators, electro-acoustic hearing prostheses, auditory brainstem stimulators, bimodal hearing prostheses, bilateral hearing prostheses, dedicated tinnitus therapy devices, tinnitus therapy device systems, combinations or variations thereof, etc.) or a device for use by a person with normal hearing (e.g., consumer devices that provide audio streaming, consumer headphones, earphones, and other listening devices). In other examples, the techniques presented herein can be implemented by, or used in conjunction with, various implantable medical devices, such as vestibular devices (e.g., vestibular implants), visual devices (i.e., bionic eyes), sensors, pacemakers, drug delivery systems, defibrillators, functional electrical stimulation devices, catheters, seizure devices (e.g., devices for monitoring and / or treating epileptic events), sleep apnea devices, electroporation devices, etc.

[0029] In addition, the techniques presented herein can be implemented with various different types of substantially incompressible insulative materials. However, again merely for ease of illustration, the techniques are described herein with reference to a specific at least semiconstrained volume of substantially incompressible insulative material, namely silicone. As such, it is to be appreciated that reference to silicone is non-limiting and that the techniques presented herein can be used with other electrically non-conductive material whose volume or density does not change with pressure.

[0030] FIG. 1 is a schematic diagram of an exemplary cochlear implant system 100 configured to implement aspects of the techniques presented herein. The cochlear implant system 100 comprises an external component 102 and an intemal / implantable component 104. The external component 102 is directly or indirectly attached to the body of the recipient and typically comprises an external coil 106 and, generally, a magnet (not shown in FIG. 1) fixed relative to the external coil 106. The external component 102 also comprises one or more input elements / devices for receiving input signals at a sound processing unit 112. In this example, the one or more input devices include sound input devices 108 (e.g., microphones positioned by an auricle 110 of the recipient, telecoils, etc.) configured to capture / receive input signals. The one or more input devices could also include, for example, one or more auxiliary input devices (e.g., audio ports, such as a Direct Audio Input (DAI), data ports, such as a Universal Serial Bus (USB) port, cable port, etc.), and a wireless transmitter / receiver (transceiver), each located in, on, or near the sound processing unit 112.

[0031] The sound processing unit 112 also includes, for example, at least one power source (e.g., a battery), a radio-frequency (RF) transceiver, and a processing module. The processing module can comprise, for example, one or more processors and a memory device (memory) that includes sound processing logic. The memory device can comprise any one or more of: Non-Volatile Memory (NVM), Ferroelectric Random Access Memory (FRAM), read only memory (ROM), random access memory (RAM), magnetic disk storage media devices, optical storage media devices, flash memory devices, electrical, optical, or other physical / tangible memory storage devices. The one or more processors are, for example, microprocessors or microcontrollers that execute instructions for the sound processing logic stored in memory device.

[0032] In the examples of FIG. 1, the sound processing unit 112 is a behind-the-ear (BTE) sound processing unit configured to be attached to, and worn adjacent to, the recipient’s ear. In general, the sound processing unit 112 comprises a housing that is shaped to be worn on theouter ear of the recipient and is connected to the separate external coil 106 via a cable, where the external coil 106 is configured to be magnetically and inductively coupled to the implantable component 104. It is to be appreciated that alternative external components could be located in the recipient’s ear canal, worn on the body, etc. It is also to be appreciated that embodiments of the present disclosure can be implemented by sound processing units having other arrangements. For instance, the sound processing unit 112 is an off-the-ear (OTE) sound processing unit, sometimes referred to herein as an OTE component, that is configured to send data and power to the implantable component 104. The OTE sound processing unit can have a generally cylindrical shape that is configured to be magnetically coupled to the recipient’s head (e.g., includes an integrated external magnet configured to be magnetically coupled to an intemal / implantable magnet in the implantable component 104). The OTE sound processing unit can also include an integrated external (headpiece) coil that is configured to be inductively coupled to the implantable component 104. In further embodiments, the sound processing unit can include a mini or micro-BTE unit, an in-the-canal unit that is configured to be located in the recipient’s ear canal, a body-worn sound processing unit, etc.

[0033] Returning to the example embodiment of FIG. 1, the implantable component 104 comprises an implant body (main module) 114, a lead region 116, and an intra-cochlear stimulating assembly 118, all configured to be implanted under the skin / tissue (tissue) of the recipient. The implant body 114 generally comprises a hermetically-sealed housing 115 in which RF interface circuitry and a stimulator unit are disposed. The hermetically-sealed housing 115 can include, in certain examples, at least one power source (e.g., one or more batteries, one or more capacitors, etc.) to enable operation of the implantable component 104. The implant body 114 also includes an intemal / implantable coil 122 that is generally external to the hermetically-sealed housing 115, but which is connected to the RF interface circuitry 124 via a hermetic feedthrough.

[0034] As noted, the stimulating assembly 118 is configured to be at least partially implanted in the recipient’s cochlea 137. The stimulating assembly 118 includes a carrier member and a plurality of longitudinally spaced intra-cochlear electrical stimulating electrodes or contacts 126 that collectively form a contact or electrode array 128 for delivery of electrical stimulation (current) to the recipient’s cochlea. The stimulating assembly 118 extends through an opening in the recipient’s cochlea (e.g., cochleostomy, the round window, etc.) and has a proximal end connected to the stimulator unit via a lead region 116 and a hermetic feedthrough. The lead region 116 includes a plurality of conductors (wires) that electrically couple the electrodes 126to the stimulator unit. The implantable component 104 can also include an electrode outside of the cochlea, such as an extra-cochlear electrode (ECE). As described further below, the stimulating assembly 118 includes a longitudinally-elastic inlay (not shown in FIG. 1) that disposed in the carrier member.

[0035] As noted, the cochlear implant system 100 includes the external coil 106 and the implantable coil 122. The coils 106, 122 are typically wire antenna coils each comprised of multiple turns of electrically insulated single-strand or multi-strand platinum or gold wire. Generally, a magnet is fixed relative to each of the external coil 106 and the implantable coil 122. The magnets fixed relative to the external coil 106 and the implantable coil 122 facilitate the operational alignment of the external coil with the implantable coil. This operational alignment of the coils 106, 122 enables the external component 102 to transmit data, as well as possibly power, to the implantable component 104 via a closely-coupled wireless link formed between the external coil 106 with the implantable coil 122. In certain examples, the closely- coupled wireless link is a radio frequency (RF) link. However, various other types of energy transfer, such as infrared (IR), electromagnetic, capacitive, and inductive transfer, can be used to transfer the power and / or data from an external component to an implantable component and, as such, FIG. 1 illustrates one example arrangement.

[0036] As noted above, the sound processing unit 112 includes the processing module. The processing module is configured to process received input audio signals (received at one or more of the input devices, such as the sound input devices 108 and / or the auxiliary input devices), and convert the input audio signals into stimulation control signals for use in stimulating a first ear of a recipient (i.e., the processing module is configured to perform sound processing on input audio signals received at the sound processing unit 112).

[0037] It is to be appreciated that the use of an external component is merely illustrative and that the techniques presented herein can be used in cochlear implant arrangements and, indeed, other types of implantable medical devices. For example, in certain embodiments, the techniques presented herein can be implemented in a totally implantable cochlear implant (TICI) system where all components of the cochlear implant system are configured to be implanted under the skin / tissue of a recipient. Because all components are implantable, a TICI system operates, for at least a finite period of time, without the need of an external device. However, an external device can be used to, for example, charge an implantable power source of the TICI system, to receive signal data (obtained via the magnetic coils), etc. A TICI system can include an implantable battery and implantable electronic assembly.

[0038] FIG. 2 is a top view of a portion 200 of a conventional implantable component / device 201, while FIG. 3 is a side view of the implantable device 201, and portion 200, during an impact, such as being struck by an object 251. The implantable device 201 can comprise, for example, an implantable portion of a cochlear implant system, a portion of a TICI system, or a portion of another medical device that can be implanted under a recipient’s skin or in another area of a recipient’s body (e.g., a retina, etc.). For ease of descriptions, FIGs. 2 and 3 will generally be described together.

[0039] Portion 200 includes a central feedthrough 214 that comprises 32 pins, such as feedthrough pin 204, each with slots cut into it, to which wires, such as electrode wire 206, are crimped, welded, or otherwise attached. The wires can provide connections to components of the hearing device, such as electrodes, a coil, a microphone, vibration sensor, etc. In an example in which the implantable device is an auditory prosthesis implanted in a head of a recipient, the connections between the feedthrough 214 and the wires from the various function components, such as the stimulation electrodes, return electrodes, radio-frequency (RF) coil, can be located within an enclosed rectangular channel called the non-hermetic area 202.

[0040] The portion 200 illustrated in FIG. 2 can be positioned against or adjacent the skull of a recipient and a portion of the implantable device opposite the portion 200 can be positioned against or adjacent the skin / tissue of the recipient. Components 208 and 210 of portion 200 can include additional components of the implantable device, such a battery, electronic assembly, etc. Although not illustrated in FIG. 2, the portion 200 can be enclosed in a top shell and a bottom shell, such as a set of titanium shells, that are welded together to protect the components of the device. The portion 200 can be at least semi-constrained by the top and bottom shells and by the recipient’s skin and skull. In addition, the non-hermetic area 202 can be at least partially or semi-constrained. That is, the non-hermetic area 202 can be constrained on two sides by components 208 and 210 and further partially or semi -constrained by a top shell, a bottom shell, skin / tissue of a recipient of the device, a skull of the recipient of the medical device, or additional / different means.

[0041] In the example portion 200 shown in FIG. 2, an electrode wire bundle enters the non- hermetic area 202 from the inferior side of the non-hermetic area 202 and the electrode wires run up a channel 212 on the first (shown as left side in FIG. 2) of the non-hermetic area 202. The electrode wires are routed through a 90-degree bend to meet the feedthrough pins corresponding to the electrode channel number. That is, in this example, each electrode wire 206 runs up the channel 212 and is routed through the 90-degree bend to meet a correspondingfeedthrough pin 204. Only one electrode wire 206 and one feedthrough pin 204 are labeled in FIG. 2 for simplicity. The feedthrough pin 204 is very large (e.g., 0.30-0.40 mm diameter) compared to the electrode wire 206 (e.g., 0.020-0.030 mm). As such, under impact, the electrode wire 206 will break before the feedthrough pin 204 deforms.

[0042] After the wires 206 have been welded and / or crimped to the pins, the non-hermetic area 202 is potted with silicone, shown in FIG. 2 by shaded region 255, before a cover shell (not shown in FIG. 2) is welded to protect the components in the non-hermetic area 202. The cover shell is welded to a bottom shell to protect the connections and to increase the impact strength of the components by creating a closed rectangular cross-section that supports the feedthrough 214 and limits its deflection. In this arrangement, the wires 206 are embedded in silicone and the silicone is referred to as being a semi-constrained volume of silicone.

[0043] As noted, FIG. 3 is a side view of the implantable device 201 during an impact from an expected direction, such as being struck by an object 251 (e.g., an external impact applied from the direction of the skin of the recipient). During impact, such as an impact to the head of the recipient (when the device is an implantable device implanted between the skin and skull of the recipient), the feedthrough 214 deflects toward the skull side of the device and into the non- hermetic area 202 which, in turn, places pressure on the semi-constrained volume of silicone 2.

[0044] As noted above, silicone is a largely incompressible material and maintains the same volume under pressure. However, because silicone is relatively soft, the silicone reduces in thickness where pressured or impacted and extrudes outward in a direction perpendicular to the direction of the applied pressure / impact (the applied force). FIG. 4 illustrates a pattern of the deflection / extrusion of deflection of the feedthrough 214 (and the corresponding deflection of the semi-constrained volume of silicone 255) in a conventional arrangement (e.g., without the benefits of the techniques presented) in response to the central impact by object 251 of FIG. 3. As illustrated in FIG. 4, when the impact is a central impact, area 402 in the center of feedthrough 214 has the greatest amount of deflection into the non-hermetic area 202. The amount of deflection decreases as the distance from the center increases. As illustrated in FIG. 4, area 404 has the second greatest amount of deflection, followed by area 406 and area 408. Area 410 has zero deflection due to the walls surrounding the feedthrough 214. The corresponding deflection, which is deflection in the direction parallel to the impact direction, of the silicone in the non-hermetic area 202 follows a similar pattern.

[0045] Since the silicone is constrained on two horizontal surfaces by components 208 and 210, the deflection of the feedthrough 214 into the non-hermetic area 202 causes, in this conventional arrangement, the silicone to extrude out the ends of non-hermetic area 202. More specifically, referring back to FIG. 2, since the silicone is constrained on side A by component 208 and on side C by component 210, the silicone will extrude out of sides B and D when portion 200 is impacted.

[0046] FIG. 5A is a Finite Element Analysis (FEA) plot illustrating the pattern of extrusion of the silicone in various directions based on the deflection of feedthrough 214 into the non- hermetic area 202 in response to a central impact. Area 502 illustrates a higher extrusion in the direction of side D and area 504 illustrates a higher extrusion in the direction of side B. As illustrated, since the silicone is constrained on side A and side C by components 208 and 210, when the impact is a central impact, the highest level of extrusion of the silicone occurs at side B and side D.

[0047] FIG. 5B is another illustration of FEA plot illustrating the impact of the extrusion of the silicone on an electrode wire. More specifically, FIG. 5B illustrates the shape of an unstressed electrode wire 206 and a stressed electrode wire 506 overlayed on top of the FEA plot. As discussed with respect to FIG. 1, an unstressed electrode wire 206 runs through a channel parallel to side A, is routed through a 90-degree bend toward side C, and is welded, crimped, or otherwise affixed to a pin, such as feedthrough pin 204. Also as discussed above, under compression, the silicone in the non-hermetic area 202 extrudes toward side D and toward side B from the center. The unstressed electrode wire 206 is a straight wire that runs in a direction perpendicular to the direction of extrusion of the compressed silicone and is constrained by the silicone and the adjacent electrode wires in the main bundle that runs in the channel. Because the channel is close to and adhered to the side wall, there is little movement when the main bulk of silicone is extruded. Upon impact, when the silicone extrudes toward side D, unstressed electrode wire 206 is stressed and bends, as illustrated by stressed electrode wire 506. In particular, the electrode wire experiences shear stress and tension at the joint to the feedthrough and tension in other areas of the electrode wire. The joint to the feedthrough may act as a stress raiser, which increases the likelihood of damage to or breakage of the electrode wire. As such, it has been discovered by the inventors that the impact of the silicone extrusion causes a large number of electrode wires to break. That is, the inventors have determined that the shear stress placed on the electrode wires by the silicone extruding in adirection perpendicular to the electrode wires frequently cause the electrode wires to break at the feedthrough pins.

[0048] FIG. 6 illustrates a top view of a portion 600 of an implantable device 601 in accordance with embodiments presented herein. In this example, the direction of extrusion of the silicone is preferentially controlled so that the silicone extrudes in a direction parallel to the wires.

[0049] More specifically, the portion 600 is substantially similar to portion 200, and includes the central feedthrough 214, electrode wires 206, the non-hermetic area 202, etc. As noted above, the non-hermetic area 202 is constrained on two sides by components 208 and 210 and further at least partially or semi-constrained by a top shell, a bottom shell, skin / tissue of a recipient of the device, a skull of the recipient of the medical device, or additional / different means.

[0050] Similar to FIG. 2, in the example portion 600, an electrode wire bundle enters the non- hermetic area 202 from the inferior side of the non-hermetic area 202 and the electrode wires run up a channel 212 on the first (shown as left side in FIG. 6) of the non-hermetic area 202. The electrode wires are routed through a 90-degree bend to meet the feedthrough pins corresponding to the electrode channel number. That is, in this example, each electrode wire 206 runs up the channel 212 and is routed through the 90-degree bend to meet a corresponding feedthrough pin 204. Only one electrode wire 206 and one feedthrough pin 204 are labeled in FIG. 6 for simplicity.

[0051] In the example of FIG. 6, after the wires 206 have been attached to the feedthrough 214, the non-hermetic area is potted with a body / volume of silicone 655 (e.g., includes an at least semi-constrained silicone body or volume of silicone). In this example, the volume of silicone 655 includes at least one compression relief region 660 adjacent to the feedthrough pins / electrode wires (i.e., between the feedthrough and side C or side A). As described further below, the at least one compression relief region 66 is configured to provide the semiconstrained volume of silicone 655 with a preferential direction of movement in response to an impact from a first direction, such as impact at the feedthrough 214.

[0052] As described further below, a compression relief region can take different forms in accordance with different embodiments presented herein. In certain embodiments, the compression relief region comprises a void space (void), while in other embodiments the compression relief region comprises a compression relief member, such as relatively more compressible material.

[0053] For example, in the example of FIG. 6, the compression relief region 660 comprises, for example, a void space, a volume of compressible foam and / or another volume of another material that compresses more readily than silicone, a different and more readily compressible grade of silicone, etc. As a result, presence of the compression relief region 660 at the illustrated location (adjacent to the feedthrough) causes the volume of silicone 655 to preferentially extrude into the area of the compression relief region 660, instead of out the ends of the non- hermetic channel.

[0054] Stated differently, with the compression relief region 660 embedded in the silicone 655 of the non-hermetic area 202, application of a force from an expected direction at the feedthrough causes the silicone to extrude in a direction parallel to the electrode wires 206 (into the compression relief region 660), instead of extruding in a direction perpendicular to the electrode wires. Movement or extrusion of the silicone in a direction parallel to the electrode wires applies axial force to the electrode wires, which inhibits breakage of the electrode wires. The extrusion of the silicone in the direction parallel to the electrode wires puts the electrode wires into axial compression (i.e., buckling) instead of shearing stress, which is much less likely to cause a mechanical break (resulting in an open circuit). Although the axial compression can cause the electrode wires to bunch or buckle, this movement of the electrode wire is less likely to cause breakage than the shear stress caused by the silicone moving in a direction perpendicular to the electrode wires. As such, embedding compression relief region 660 in the silicone of non-hermetic area 202 decreases the likelihood of the electrode wires breaking when the feedthrough deflects into the non-hermetic area when impacted.

[0055] When compression relief region 660 comprises a void, the silicone under compression can extrude into the void, unlike conventional arrangements in which the non-hermetic area 202 is completely filled with silicone and results in shear stresses on the electrode wires. Therefore, in the embodiment in which compression relief region 660 comprises a void, the void should be large enough that the silicone does not completely fill the void when the silicone is subject to a force. That is, the void should be sufficiently large so as to accommodate the deflection of the silicone in response to the applied pressure.

[0056] When compression relief region 660 comprises a compression relief member, such as a compressible foam or another material that is more readily compressed when the silicone is subject to a force, the compressibility of the foam or other material is changed so that the silicone has a preferential direction of movement (i.e., in a direction parallel to the electrode wires). In other words, the compressible foam or other material will compress more readilythan the silicone, which causes the silicone to extrude toward (into) the area that was previously filled with the compressible foam or other compressible material in a direction parallel to the wires.

[0057] The compression relief region 660 can be long enough to span the length of all of the pins / wires of feedthrough 214. In some embodiments, the compression relief region 660 may not be a single area and can, instead, include two or more areas (e.g., two or more compression relief regions). In these embodiments, the separate areas can span the length of all of the pins / wires and each pin / wire is adjacent an area so that direction of silicone extrusion is changed to be parallel to each wire. For example, compression relief region 660 can comprise a first area that spans the length of the 18 pins closest to side D and a second area that spans the length of the 18 pins closest to side B.

[0058] In some embodiments, a central reinforcing pillar 617 can additionally be added underneath the feedthrough to limit the maximum deflection of the feedthrough. As described above, in some embodiments, compression relief region 660 can comprise a void. Creating voids in the silicone makes it easier for the feedthrough to deflect and, therefore, less support is provided to the feedthrough when a voided is added to the silicone. In other words, in the example illustrated in FIG. 2, the silicone supports a substantial amount of load due to the incompressibility of the silicone. In the example illustrated in FIG. 6, the support provided by the stiffness of the silicone is lower due to the void in the silicone. The central reinforcing pillar 617 can add stability to the feedthrough and limit the deflection of the feedthrough under compression. According to embodiments described herein, incorporating compression relief region 660 into the silicone in the non-hermetic area 202 allows for larger amounts of deflection to be applied to the silicone before wires start to break, which maximizes the utility and allowability tolerances for any support structures.

[0059] Although a central reinforcing pillar 617 is illustrated in FIG. 6, other types of reinforcement structures can be added to limit the deflection of the feedthrough under compression. For example, potting compounds of different hardness may be added as a reinforcement structure instead of using a separate component. Such reinforcement structures can be useful to limit feedthrough deflection and, in turn, protect the electrode wires from breaking. However, manufacturing tolerances become very critical when adding a reinforcement structure. If a gap around any reinforcement structure is similar, then the structure won’t take any load until the gap is closed through deformation of the surrounding components, which can limit the effectiveness.

[0060] FIG. 7 is an FEA plot 700 illustrating the left-right movement of the silicone in the non- hermetic area 202 when compression relief region 660 and pillar 617 are added to the non- hermetic area 202. As shown in plot 700, the lateral movement of the silicone in the direction of sides B and D is greatly reduced when compression relief region 660 and pillar 617 are added to the non-hermetic area 202. Therefore, as illustrated by plot 700, embedding compression relief region 660 into the non-hermetic area 202 preferentially changes the direction of extrusion of the compressed silicone from a direction perpendicular to the wires to a direction parallel to the wires, which decreases the instances of the breakage of the wires when the device is impacted.

[0061] Although the above embodiments have been described with respect to electrode wires, embodiments described herein can be useful for protecting other type of wires (e.g., coil wires, , microphone wires, etc.). In addition, although FIGS. 2-4, 5 A, 5B, 6, and 7 illustrate changing the direction of the extrusion of the compressed silicone from a direction perpendicular to the electrode wires to a direction parallel to the electrode wires, other embodiments provide for changing the direction of the extrusion of the compressed silicone in other directions. That is, more broadly, embodiments described herein provide for allowing the movement of silicone due to external forces to be redirected from a non-desirable direction to a more preferred direction to protect structures encapsulated within the silicone. For example, embodiments described herein can be applied to protect coil wires from damage, such as wires located in an elongate lead.

[0062] For example, in some situations, a tubular-shaped or elongate component can include a wire surrounded by silicone (e.g., to protect the wire). If the elongate component is impacted / subjectto an external force, the silicone can extrude in the right directions parallel to the wire. The extrusion of the silicone in his direction can place a stress on the wire, causing the wire to break. However, FIG. 8 illustrates an embodiment of the present invention in which a wire can be protected from such an elongate stress.

[0063] More specifically, FIG. 8 illustrates an embodiment in which an elongate wire 804 includes a strain relief 808 and, additionally, a void 806 disposed around the strain relief 808 (e.g., between the strain relief and the silicone 802). When a tensile force is applied to the wire 804 (as shown by the arrows in FIG. 8, potentially as a result of an external force or impact), the strain relief 808 allows the wire 804 to straighten as the silicone 802 is extruded in the directions shown by arrows, which prevents or inhibits breakage of the wire 804. Placing the void 806 around the wire 804 at the strain relief 808 allows more relative movement betweenthe wire 804 and the silicone 802. In this embodiment, the wire 804 survives impact forces better than a wire with a strain relief and no void because the unfdled tube (i.e., a tube with a gap or void between the strain relief and the silicone) allows for more relative movement between the wire and the silicone. In order for the wire 804 to survive impact forces better than a wire with a strain relief and no void, the void should be larger than what is generally provided by a wire inside of a tube.

[0064] Although a void 806 is illustrated in FIG. 8, a compressible foam or other compressible material can additionally be placed between the strain relief and the silicone to allow for more relative movement between the wire and the silicone to prevent or inhibit breakage of the wire. Therefore, more broadly speaking, FIG. 8 illustrates that a compression relief region could be disposed around a wire strain relief. In addition to the configuration illustrated in FIG. 8, in some embodiments, the wire may be routed in a 90-degree bend at the strain relief or may be in a non-planar configuration. In some embodiments, the configuration may include a helixed wire in a non-backfilled tube.

[0065] As noted above, the techniques presented herein are used with at least semi-constrained volumes of material, such as silicone. Also as noted above, an at least semi-constrained volume of material refers to a volume of material that has one or more limits / constraints on the size and movement of the material (e.g., the material is at least partially bounded by one or more structures). The constraints can be, of example, biological structures (e.g., due to bone, skin, etc.), due to device structures / components, etc.

[0066] FIGs. 9A-9C illustrate example side views of a device implanted between a recipient’s skin and skull in which silicone is constrained therebetween (e.g., the recipient’s skin and skull form at least part of the boundary of the at least semi-constrained volume of silicone). FIG. 9A illustrates an example in accordance with the embodiments discussed with respect to FIGs. 6 and 7 in which an implantable device 906 is placed between tissue 902 (such as skin) and a recipient’s skull 904 with the silicone 910 facing or adjacent the skull 904. In FIG. 9A, implantable device 906 includes a cover shell 908 that constrains the silicone 910. During impact, the silicone 910 is constrained by a top shell of implantable device 906 and cover shell 908 and the silicone 910 extrudes as discussed above with respect to FIGs. 6, and 7.

[0067] FIG. 9B illustrates an example in which cover shell 908 is removed from implantable device 906. As illustrated in FIG. 9B, silicone 910 is facing or adjacent the skull 904 and is constrained by the skull 904. During impact, the skull 904 constrains the silicone in a mannersimilar to the manner in which the cover shell 908 constrains the silicone 910 in the example illustrated in FIG. 9A. As such, the silicone 910 extrudes in a similar manner and direction under impact as in the example illustrated in FIG. 9A.

[0068] FIG. 9C illustrates an example in which the cover shell 908 is removed and implantable device 906 is flipped so that the silicone 910 is facing or adjacent the tissue 902. In this example, the silicone 910 is constrained by the overlying skin / tissue 902. When implantable device 906 is impacted by an object 912, the impact is “blunted” by the tissue 902, which spreads the loading over a large area. In this example, the tissue 902 provides a constraint similar to the constraint provided by the skull 904 in the example illustrated in FIG. 9B and the cover shell 908 in the example illustrated in FIG. 9A. Under impact, the silicone 910 extrudes in a similar manner and direction as the examples illustrated in FIGs. 9A and 9B.

[0069] As illustrated in FIGs. 9A-9C the embodiments discussed herein to control a direction of the extrusion of the silicone under impact / compression can be applied to multiple configurations of implantable device 906.

[0070] FIGs. 10A-10F illustrate examples in which the direction of extrusion of compressed silicone is controlled in a high-density “patch’Vsurface electrode (e.g., for a retinal implant / device). FIG. 10A illustrates a high-density surface electrode 1000 that includes a silicone encapsulant 1002 surrounding multiple wires 1004 connected to pads 1006. In the example illustrated in FIG. 10A, due to the high density of the wires 1004, there is no space for conventional strain relief.

[0071] FIG. 10B is a simplified cross-section illustrating a side view of a single pad 1006 and wire 1004 in the silicone encapsulant 1002. In the example illustrated in FIG. 10B, stress is highest in area 1008 and if the wire 1004 is mechanically strained, area 1008 is generally the point of failure.

[0072] FIG. 10C is a simplified cross-section illustrating a side view of single pad 1006 and wire 1004 under a localized force applied to the outside of the high-density surface electrode 1000. As illustrated by arrows 1010, the localized force applied to the silicone encapsulant 1002 causes tension on the wire 1004 in opposing directions, which can result in breakage of the wire 1004. FIG. 10D is a top view illustrating the localized force applied to the silicone encapsulant 1002. Arrows 1012 indicate the direction of silicone displacement when the localized force in applied. As illustrated, the localized force causes the silicone to extrude away from the area of impact equally in all directions. Since the silicone extrudes in oppositedirections from the area of impact equally along the wire 1004, the extrusion of the silicone caused by the impact can cause breakage of the wire 1004.

[0073] FIG. 10E illustrates a simplified cross-section illustrating a side view of a single pad 1006 and wire 1004 in the silicone encapsulant 1002 in which a compression relief region is disposed in the silicone. In the example illustrated in FIG. 10E, the compression relief region includes a void 1014. When an impact is applied to the silicone encapsulant 1002, inclusion of the void 1014 controls a direction of extrusion of the compressed silicone to relieve the stress applied to wire 1004. In the example illustrated in FIG. 10E, the void 1014 is added along a wall of the silicone encapsulant 1002 above the wire 1004 and the pad 1006. The location of the void 1014 is exemplary and the void 1014 can be located in one or more different areas. In addition, instead of including the void 1014, an area of compressible foam or another readily compressible material can be included.

[0074] FIG. 1 OF is a top view illustrating the localized force applied to the silicone encapsulant 1002 when the void 1014 is included. As illustrated by arrows 1016, when the void 1014 (or readily compressible material) is embedded in the silicone, the silicone moves inward (i.e., toward the center of the void 1014), which limits the force applied to the wire 1004. By including the void 1014, the direction of extrusion of the compressed silicone can be changed to a preferential direction to provide compression relief on the wire 1004 and limit or prevent breakage of the wire 1004.

[0075] Each of FIGs. 11 and 12 discussed below illustrates a respective method related to a device, such as any of the devices described herein. It should be noted that each method can be performed by the same or a different entity. Additionally, any of the methods can be performed differently than depicted. For example, an additional operation can be performed, or any of the depicted operations can be performed differently, performed in a different order, or not performed.

[0076] FIG. 11 is a flowchart of an embodiment of a method 1100 for manufacturing a device. At block 1102, one or more wires are provided within an at least semi-constrained volume of silicone. At block 1104, the at least semi-constrained volume of silicone is configured such that a direction of movement of the at least semi-constrained silicone under impact is controlled to inhibit breakage of the one or more wires.

[0077] In some embodiments, a void can be embedded in the at least semi-constrained volume of silicone. In some embodiments, a compressible foam or another material that is more readilycompressed than the at least semi-constrained volume of silicone is embedded in the partially constrained volume of silicone. When the at least semi -constrained volume of silicone is under impact, the direction of movement or extrusion of the at least semi-constrained volume of silicone is controlled to inhibit breakage of the one or more wires. For example, the at least semi -constrained volume of silicone can move to at least partially fdl the void or compress the compressible material. Movement in the direction to fill the void or compress the compressible material can prevent the at least semi-constrained volume of silicone from moving in a direction perpendicular to the wires, which places a shear force on the one or more wires and can cause breakage of the one or more wires.

[0078] In contrast, the movement of the at least semi-constrained volume of silicone in the direction to fill the void or compress the compressible material can inhibit the risk of breakage of the one or more wires. For example, the movement to fill the void or compress the compressible material can be in a direction parallel to the wires instead of perpendicular to the wires. The movement of the at least semi-constrained volume of silicone in a direction parallel to the one or more wires can place an axial force on the one or more wires, which inhibits breakage of the wires compared to the shear force.

[0079] In some embodiments, the at least semi-constrained volume of silicone is configured with a void around a strain relief to allow more relative movement between the one or more wires and the semi-constrained volume of silicone. In other embodiments, the at least semiconstrained volume of silicone is configured with a void such that a direction of movement of the at least semi-constrained silicone under impact is inward to fill the void to limit force on the one or more wires.

[0080] FIG. 12 illustrates an embodiment of another method 1200 for manufacturing a device, such as an implantable medical device. At block 1202, an at least partially constrained volume of silicone with embedded wires is formed. At block 1204, the at least partially constrained volume of silicone is configured to have a preferential direction of movement in response to an impact from a first direction.

[0081] In some embodiments, the preferential direction is a direction parallel to the embedded wires to limit shear force on the embedded wires. In other embodiments, the preferential direction is a direction to fill a void or compress a compressible material to limit force on the embedded wires. In yet other embodiments, the preferential direction allows movement between the embedded wires and the at least semi -constrained volume of silicone.

[0082] As should be appreciated, while particular uses of the technology have been illustrated and discussed above, the disclosed technology can be used with a variety of devices in accordance with many examples of the technology. The above discussion is not meant to suggest that the disclosed technology is only suitable for implementation within systems akin to that illustrated in the figures. In general, additional configurations can be used to practice the processes and systems herein and / or some aspects described can be excluded without departing from the processes and systems disclosed herein.

[0083] This disclosure described some aspects of the present technology with reference to the accompanying drawings, in which only some of the possible aspects were shown. Other aspects can, however, be embodied in many different forms and should not be construed as limited to the aspects set forth herein. Rather, these aspects were provided so that this disclosure was thorough and complete and fully conveyed the scope of the possible aspects to those skilled in the art.

[0084] As should be appreciated, the various aspects (e.g., portions, components, etc.) described with respect to the figures herein are not intended to limit the systems and processes to the particular aspects described. Accordingly, additional configurations can be used to practice the methods and systems herein and / or some aspects described can be excluded without departing from the methods and systems disclosed herein.

[0085] According to certain aspects, systems and non-transitory computer readable storage media are provided. The systems are configured with hardware configured to execute operations analogous to the methods of the present disclosure. The one or more non-transitory computer readable storage media comprise instructions that, when executed by one or more processors, cause the one or more processors to execute operations analogous to the methods of the present disclosure.

[0086] Similarly, where steps of a process are disclosed, those steps are described for purposes of illustrating the present methods and systems and are not intended to limit the disclosure to a particular sequence of steps. For example, the steps can be performed in differing order, two or more steps can be performed concurrently, additional steps can be performed, and disclosed steps can be excluded without departing from the present disclosure. Further, the disclosed processes can be repeated.

[0087] Although specific aspects were described herein, the scope of the technology is not limited to those specific aspects. One skilled in the art will recognize other aspects orimprovements that are within the scope of the present technology. Therefore, the specific structure, acts, or media are disclosed only as illustrative aspects. The scope of the technology is defined by the following claims and any equivalents therein.

[0088] It is also to be appreciated that the embodiments presented herein are not mutually exclusive and that the various embodiments can be combined with another in any of a number of different manners.

Claims

CLAIMSWhat is claimed is:

1. A method comprising : providing one or more wires within an at least semi -constrained volume of silicone; and configuring the at least semi-constrained volume of silicone such that a direction of movement of the at least semi-constrained volume of silicone under impact is controlled to inhibit breakage of the one or more wires.

2. The method of claim 1, wherein configuring the at least semi-constrained volume of silicone includes embedding a void in the at least semi-constrained volume of silicone.

3. The method of claim 1, wherein configuring the at least semi-constrained volume of silicone includes embedding a compressible material in the at least semi-constrained volume of silicone.

4. The method of claim 1, 2, or 3, wherein the one or more wires and the at least semiconstrained volume of silicone are embedded in an implantable medical device.

5. The method of claim 4, wherein the implantable medical device is implanted between tissue and a skull of a recipient of the implantable medical device.

6. The method of claim 1, 2, or 3, wherein the at least semi -constrained volume of silicone is constrained by components of a medical device.

7. The method of claim 6, wherein the at least semi -constrained volume of silicone is constrained by a skull of a recipient of the medical device.

8. The method of claim 6, wherein the at least semi -constrained volume of silicone is constrained by tissue of a recipient of the medical device.

9. The method of claim 1, 2, or 3, wherein configuring the at least semi-constrained volume of silicone includes configuring the at least semi-constrained volume of silicone to move in a direction under impact that places an axial force on the one or more wires.

10. The method of claim 1, 2, or 3, wherein the one or more wires include electrode wires in an implantable auditory prosthesis.

11. An apparatus comprising: an at least semi-constrained silicone body; a plurality of wire sections disposed in the silicone body; and at least one compression relief region disposed in the silicone body.

12. The apparatus of claim 11, wherein the at least one compression relief region is configured to provide a preferential direction of extrusion for the silicone body in response to a force applied from a first expected direction.

13. The apparatus of claim 11, wherein the at least one compression relief region is configured such that a force applied from a first expected direction places the plurality of wire sections under at least one of axial tension or compression.

14. The apparatus of claim 11, 12, or 13, wherein the at least one compression relief region is configured to limit shear forces applied to the plurality of wire sections in response to the force applied from the first expected direction.

15. The apparatus of claim 11, 12, or 13, wherein the apparatus is configured to be implanted under skin of recipient, and wherein the first expected direction is from the direction of the skin of the recipient.

16. The apparatus of claim 11, 12, or 13, wherein the at least one compression relief region comprises a void in the silicone body.

17. The apparatus of claim 11, 12, or 13, wherein the silicone body comprises a first grade of silicone, and wherein the at least one compression relief region comprises a second grade of silicone that is relatively softer than the first grade of silicone.

18. The apparatus of claim 11, 12, or 13, wherein the at least one compression relief region comprises a component that is relatively more compressible that the silicone body.

19. The apparatus of claim 18, wherein the at least one compression relief region comprises a compressible foam.

20. The apparatus of claim 11, 12, or 13, wherein the at least one compression relief region comprises a plurality of compression relief regions.

21. A method comprising : forming an at least partially constrained volume of substantially incompressible insulative material with embedded wires; and configuring the at least partially constrained volume of substantially incompressible insulative material to have a preferential direction of movement in response to an impact from a first direction.

22. The method of claim 21, wherein configuring the at least partially constrained volume of substantially incompressible insulative material to have a preferential direction of movement in response to an impact from a first direction comprises: embedding a compression relief region in the at least partially constrained volume of substantially incompressible insulative material to modulate an extrusion direction of the at least partially constrained volume of substantially incompressible insulative material in response to the impact from the first direction.

23. The method of claim 22, wherein the compression relief region comprises a void in the at least partially constrained volume of substantially incompressible insulative material.

24. The method of claim 22, wherein the compression relief region comprises a volume of material that is more readily compressed than the at least partially constrained volume of substantially incompressible insulative material.

25. The method of claim 21, 22, 23, or 24, wherein the at least partially constrained volume of substantially incompressible insulative material is constrained by components of an implantable device.

26. The method of claim 25, wherein the at least partially constrained volume of substantially incompressible insulative material is constrained by a skull of a recipient of the implantable device.

27. The method of claim 25, wherein the at least partially constrained volume of substantially incompressible insulative material is constrained by tissue of a recipient of the implantable device.

28. The method of claim 25, wherein the substantially incompressible insulative material is silicone.

29. An apparatus comprising: a volume of silicone comprising a first surface and a second surface, wherein the volume of silicone is constrained adjacent the second surface; and at least one wire disposed in the volume of silicone; wherein the volume of silicone is configured to have a preferential extrusion direction in response to an impact delivered proximate to the first surface, wherein extrusion of the volume of silicone in the preferential extrusion direction results in application of an axial force on the at least one wire while minimizing shear forces applied to the at least one wire.

30. The apparatus of claim 29, wherein the preferential extrusion direction is parallel to the at least one wire.

31. The apparatus of claim 29 or 30, wherein the apparatus is an implantable medical device.

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