WO2025027503A1

WO2025027503A1 - External portion of medical implant with anatomically contoured skin-contacting surface

Info

Publication number: WO2025027503A1
Application number: PCT/IB2024/057324
Authority: WO
Inventors: Stijn EECKHOUDT; Wim Bervoets; Tim Ruytjens; Claus BERTELS
Original assignee: Cochlear Ltd
Current assignee: Cochlear Ltd
Priority date: 2023-08-03
Filing date: 2024-07-29
Publication date: 2025-02-06
Anticipated expiration: 2026-02-03

Abstract

An apparatus includes a housing configured to be positioned on a first skin portion of a recipient's body. The first skin portion has an anatomical first contour, and the housing includes a first outer surface portion having a second contour substantially matching the first contour. The apparatus further includes at least one first circuit on or within the housing. The at least one first circuit is configured to be, upon the housing being positioned on the first skin portion, in wireless communication with at least one second circuit implanted beneath a second skin portion of the recipient's body.

Description

EXTERNAL PORTION OF MEDICAL IMPLANT WITH ANATOMICALLY

CONTOURED SKIN-CONTACTING SURFACE

BACKGROUND

Field

[0001] The present application relates generally to systems and methods for positioning an external portion of a medical device implanted on or within a recipient’s body. Description of the 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/de vices, 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 disclosed herein, an apparatus comprises a housing configured to be positioned on a first skin portion of a recipient’s body. The first skin portion has an anatomical first contour, and the housing comprises a first outer surface portion having a second contour substantially matching the first contour. The apparatus further comprises at least one first circuit on or within the housing. The at least one first circuit is configured to be, upon the housing being positioned on the first skin portion, in wireless communication with at least one second circuit implanted beneath a second skin portion of the recipient’s body.

[0005] In another aspect disclosed herein, a method comprises accessing information indicative of a first shape of at least a rear surface portion of a recipient’s ear. The method further comprises fabricating, using the information, a surface portion of an external device. The surface portion has a second shape that is substantially a mold-like negative impression of the first shape. The surface portion is configured to at least partially support the external device on the ear. The external device comprises a processor and a communication coil in operative communication with the processor. The communication coil is configured to wirelessly communicate with an implanted device beneath a scalp of the recipient upon the external device being positioned behind the ear with the surface portion in contact with the rear surface portion of the recipient’s ear.

[0006] In another aspect disclosed herein, an apparatus comprises at least one recess and/or protrusion configured to engage an external device configured to be operative communication with an implanted device. The apparatus further comprises a first external surface portion having a first shape configured to be placed on and substantially mate with a first skin surface portion of a recipient’s body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Implementations are described herein in conjunction with the accompanying drawings, in which:

[0008] FIG. 1A is a perspective view of an example cochlear implant auditory prosthesis implanted in a recipient in accordance with certain implementations described herein;

[0009] FIG. IB is a perspective view of an example fully implantable middle ear implant auditory prosthesis implanted in a recipient in accordance with certain implementations described herein;

[0010] FIGs. 2 A and 2B schematically illustrate two rear views of an example apparatus in accordance with certain implementations described herein;

[0011] FIGs. 3A and 3B schematically illustrate another example apparatus in accordance with certain implementations described herein; [0012] FIG. 4A schematically illustrates a perspective and exploded view of an example apparatus 300 in accordance with certain implementations described herein;

[0013] FIG. 4B schematically illustrates three views of an example apparatus configured to facilitate controllable adjustment of the position and/or orientation of the first portion relative to the second portion in accordance with certain implementations described herein;

[0014] FIG. 5 schematically illustrates a perspective and exploded view of another example apparatus in accordance with certain implementations described herein; and

[0015] FIG. 6 is a flow diagram of an example method in accordance with certain implementations described herein.

DETAILED DESCRIPTION

[0016] Certain implementations described herein provide an apparatus configured to use a rear surface portion of a recipient’s auricle (e.g., pinna) as an alignment feature to hold an external portion of an auditory prosthesis system on the recipient’s body with an external communication coil of the external portion aligned with an implanted communication coil of an implanted portion of the auditory prosthesis system beneath a scalp portion behind the auricle. The apparatus includes a custom molded surface configured to mate to a corresponding rear surface of the recipient’s auricle such that the external communication coil produces a wireless communication channel with the implanted communication coil. The custom molded surface can be fabricated using a mold or imaging data of the rear surface portion of the recipient’s auricle.

[0017] The teachings detailed herein are applicable, in at least some implementations, to any type of implantable or non-implantable stimulation system or device (e.g., implantable or non-implantable auditory prosthesis device or system). Implementations can include any type of medical device that can utilize the teachings detailed herein and/or variations thereof. Furthermore, while certain implementations are described herein in the context of auditory prosthesis devices, certain other implementations are compatible in the context of other types of devices or systems (e.g., smart phones; smart speakers).

[0018] Merely for ease of description, apparatus and methods disclosed herein are primarily described with reference to an illustrative medical device, namely an implantable transducer assembly including but not limited to: electro-acoustic electrical/acoustic systems, cochlear implant devices, implantable hearing aid devices, middle ear implant devices, bone conduction devices (e.g., active bone conduction devices; passive bone conduction devices, percutaneous bone conduction devices; transcutaneous bone conduction devices), Direct Acoustic Cochlear Implant (DACI), middle ear transducer (MET), electro-acoustic implant devices, other types of auditory prosthesis devices, and/or combinations or variations thereof, or any other suitable hearing prosthesis system with or without one or more external components. Implementations can include any type of auditory prosthesis that can utilize the teachings detailed herein and/or variations thereof. Certain such implementations can be referred to as “partially implantable,” “semi-implantable,” “mostly implantable,” “fully implantable,” or “totally implantable” auditory prostheses. In some implementations, the teachings detailed herein and/or variations thereof can be utilized in other types of prostheses beyond auditory prostheses.

[0019] FIG. 1A is a perspective view of an example cochlear implant auditory prosthesis 100 implanted in a recipient in accordance with certain implementations described herein. The example auditory prosthesis 100 is shown in FIG. 1A as comprising an implanted stimulator unit 120 and a microphone assembly 124 that is external to the recipient (e.g., a partially implantable cochlear implant). An example auditory prosthesis 100 (e.g., a totally implantable cochlear implant; a mostly implantable cochlear implant) in accordance with certain implementations described herein can replace the external microphone assembly 124 shown in FIG. 1 A with a subcutaneously implantable microphone assembly, as described more fully herein. In certain implementations, the example cochlear implant auditory prosthesis 100 of FIG. 1 A can be in conjunction with a reservoir of liquid medicament as described herein.

[0020] As shown in FIG. 1A, the recipient has an outer ear 101, a middle ear 105, and an inner ear 107. In a fully functional ear, the outer ear 101 comprises an auricle 110 (e.g., pinna) and an ear canal 102. An acoustic pressure or sound wave 103 is collected by the auricle 110 and is channeled into and through the ear canal 102. Disposed across the distal end of the ear canal 102 is a tympanic membrane 104 which vibrates in response to the sound wave 103. This vibration is coupled to oval window 112 or fenestra ovalis through three bones of middle ear 105, collectively referred to as the ossicles 106 and comprising the malleus 108, the incus 109, and the stapes 111. The bones 108, 109, and 111 of the middle ear 105 serve to filter and amplify the sound wave 103, causing the oval window 112 to articulate, or vibrate in response to vibration of the tympanic membrane 104. This vibration sets up waves of fluid motion of the perilymph within cochlea 140. Such fluid motion, in turn, activates tiny hair cells (not shown) inside the cochlea 140. Activation of the hair cells causes appropriate nerve impulses to be generated and transferred through the spiral ganglion cells (not shown) and auditory nerve 114 to the brain (also not shown) where they are perceived as sound.

[0021] As shown in FIG. 1A, the example auditory prosthesis 100 comprises one or more components which are temporarily or permanently implanted in the recipient. The example auditory prosthesis 100 is shown in FIG. 1A with an external component 142 which is directly or indirectly attached to the recipient’s body, and an internal component 144 which is temporarily or permanently implanted in the recipient (e.g., positioned in a recess of the temporal bone adjacent auricle 110 of the recipient). The external component 142 typically comprises one or more input elements (e.g., an external microphone 124, a barometer) for detecting environmental signals (e.g., sound, ambient atmospheric pressure), a processing unit 126 (e.g., a sound processor disposed in a Behind-The-Ear unit), a power source (not shown), and an external transmitter unit 128. In the illustrative implementations of FIG. 1A, the external transmitter unit 128 comprises an external coil 130 (e.g., a wire antenna coil comprising multiple turns of electrically insulated single-strand or multi-strand platinum or gold wire) and, preferably, a magnet (not shown) secured directly or indirectly to the external coil 130. The external coil 130 of the external transmitter unit 128 is part of an inductive radio frequency (RF) communication link with the internal component 144. The sound processing unit 126 processes the output of the microphone 124 that is positioned externally to the recipient’s body, in the depicted implementation, by the recipient’s auricle 110. The sound processing unit 126 processes the output of the microphone 124 and generates encoded signals, sometimes referred to herein as encoded data signals, which are provided to the external transmitter unit 128 (e.g., via a cable). As will be appreciated, the sound processing unit 126 can utilize digital processing techniques to provide frequency shaping, amplification, compression, and other signal conditioning, including conditioning based on recipient-specific fitting parameters.

[0022] The power source of the external component 142 is configured to provide power to the auditory prosthesis 100, where the auditory prosthesis 100 includes a battery (e.g., located in the internal component 144, or disposed in a separate implanted location) that is recharged by the power provided from the external component 142 (e.g., via a transcutaneous energy transfer link). The transcutaneous energy transfer link is used to transfer power and/or data to the internal component 144 of the auditory prosthesis 100. Various types of energy transfer, such as infrared (IR), electromagnetic, capacitive, and inductive transfer, may be used to transfer the power and/or data from the external component 142 to the internal component 144. During operation of the auditory prosthesis 100, the power stored by the rechargeable battery is distributed to the various other implanted components as needed.

[0023] The internal component 144 comprises an internal receiver unit 132, a stimulator unit 120, and an elongate electrode assembly 118. In some implementations, the internal receiver unit 132 and the stimulator unit 120 are hermetically sealed within a biocompatible housing. The internal receiver unit 132 comprises an internal coil 136 (e.g., a wire antenna coil comprising multiple turns of electrically insulated single-strand or multistrand platinum or gold wire), and preferably, a magnet (also not shown) fixed relative to the internal coil 136. The internal receiver unit 132 and the stimulator unit 120 are hermetically sealed within a biocompatible housing, sometimes collectively referred to as a stimulator/receiver unit. The internal coil 136 receives power and/or data signals from the external coil 130 via a transcutaneous energy transfer link (e.g., an inductive RF link). The stimulator unit 120 generates electrical stimulation signals based on the data signals, and the stimulation signals are delivered to the recipient via the elongate electrode assembly 118.

[0024] The elongate electrode assembly 118 has a proximal end connected to the stimulator unit 120, and a distal end implanted in the cochlea 140. The electrode assembly 118 extends from the stimulator unit 120 to the cochlea 140 through the mastoid bone 119. In some implementations, the electrode assembly 118 may be implanted at least in the basal region 116, and sometimes further. For example, the electrode assembly 118 may extend towards apical end of cochlea 140, referred to as cochlea apex 134. In certain circumstances, the electrode assembly 118 may be inserted into the cochlea 140 via a cochleostomy 122. In other circumstances, a cochleostomy may be formed through the round window 121, the oval window 112, the promontory 123, or through an apical turn 147 of the cochlea 140.

[0025] The elongate electrode assembly 118 comprises a longitudinally aligned and distally extending array 146 of electrodes or contacts 148, sometimes referred to as electrode or contact array 146 herein, disposed along a length thereof. Although the electrode array 146 can be disposed on the electrode assembly 118, in most practical applications, the electrode array 146 is integrated into the electrode assembly 118 (e.g., the electrode array 146 is disposed in the electrode assembly 118). As noted, the stimulator unit 120 generates stimulation signals which are applied by the electrodes 148 to the cochlea 140, thereby stimulating the auditory nerve 114.

[0026] While FIG. 1 A schematically illustrates an auditory prosthesis 100 utilizing an external component 142 comprising an external microphone 124, an external sound processing unit 126, and an external power source, in certain other implementations, one or more of the microphone 124, sound processing unit 126, and power source are implantable on or within the recipient (e.g., within the internal component 144). For example, the auditory prosthesis 100 can have each of the microphone 124, sound processing unit 126, and power source implantable on or within the recipient (e.g., encapsulated within a biocompatible assembly located subcutaneously), and can be referred to as a totally implantable cochlear implant (“TICI”). For another example, the auditory prosthesis 100 can have most components of the cochlear implant (e.g., excluding the microphone, which can be an in-the-ear-canal microphone) implantable on or within the recipient, and can be referred to as a mostly implantable cochlear implant (“MICI”).

[0027] FIG. IB schematically illustrates a perspective view of an example fully implantable auditory prosthesis 200 (e.g., fully implantable middle ear implant or totally implantable acoustic system), implanted in a recipient, utilizing an acoustic actuator in accordance with certain implementations described herein. The example auditory prosthesis 200 of FIG. IB comprises a biocompatible implantable assembly 202 (e.g., comprising an implantable capsule) located subcutaneously (e.g., beneath the recipient’s skin and on a recipient's skull). While FIG. IB schematically illustrates an example implantable assembly 202 comprising a microphone, in other example auditory prostheses 200, a pendant microphone can be used (e.g., connected to the implantable assembly 202 by a cable). The implantable assembly 202 includes a signal receiver 204 (e.g., comprising a coil element) and an acoustic transducer 206 (e.g., a microphone comprising a diaphragm and an electret or piezoelectric transducer) that is positioned to receive acoustic signals through the recipient’s overlying tissue. The implantable assembly 202 may further be utilized to house a number of components of the fully implantable auditory prosthesis 200. For example, the implantable assembly 202 can include an energy storage device and a signal processor (e.g., a sound processing unit). Various additional processing logic and/or circuitry components can also be included in the implantable assembly 202 as a matter of design choice.

[0028] For the example auditory prosthesis 200 shown in FIG. IB, the signal processor of the implantable assembly 202 is in operative communication (e.g., electrically interconnected via a wire 208) with an actuator 210 (e.g., comprising a transducer configured to generate mechanical vibrations in response to electrical signals from the signal processor). In certain implementations, the example auditory prosthesis 100, 200 shown in FIGs. 1A and IB can comprise an implantable microphone assembly, such as the microphone assembly 206 shown in FIG. IB. For such an example auditory prosthesis 100, the signal processor of the implantable assembly 202 can be in operative communication (e.g., electrically interconnected via a wire) with the microphone assembly 206 and the stimulator unit of the main implantable component 120. In certain implementations, at least one of the microphone assembly 206 and the signal processor (e.g., a sound processing unit) is implanted on or within the recipient.

[0029] The actuator 210 of the example auditory prosthesis 200 shown in FIG. IB is supportably connected to a positioning system 212, which in turn, is connected to a bone anchor 214 mounted within the recipient's mastoid process (e.g., via a hole drilled through the skull). The actuator 210 includes a connection apparatus 216 for connecting the actuator 210 to the ossicles 106 of the recipient. In a connected state, the connection apparatus 216 provides a communication path for acoustic stimulation of the ossicles 106 (e.g., through transmission of vibrations from the actuator 210 to the incus 109).

[0030] During normal operation, ambient acoustic signals (e.g., ambient sound) impinge on the recipient’ s tissue and are received transcutaneously at the microphone assembly 206. Upon receipt of the transcutaneous signals, a signal processor within the implantable assembly 202 processes the signals to provide a processed audio drive signal via wire 208 to the actuator 210. As will be appreciated, the signal processor may utilize digital processing techniques to provide frequency shaping, amplification, compression, and other signal conditioning, including conditioning based on recipient-specific fitting parameters. The audio drive signal causes the actuator 210 to transmit vibrations at acoustic frequencies to the connection apparatus 216 to affect the desired sound sensation via mechanical stimulation of the incus 109 of the recipient. [0031] The subcutaneously implantable microphone assembly 202 is configured to respond to auditory signals (e.g., sound; pressure variations in an audible frequency range) by generating output signals (e.g., electrical signals; optical signals; electromagnetic signals) indicative of the auditory signals received by the microphone assembly 202, and these output signals are used by the auditory prosthesis 100, 200 to generate stimulation signals which are provided to the recipient’s auditory system. To compensate for the decreased acoustic signal strength reaching the microphone assembly 202 by virtue of being implanted, the diaphragm of an implantable microphone assembly 202 can be configured to provide higher sensitivity than are external non-implantable microphone assemblies. For example, the diaphragm of an implantable microphone assembly 202 can be configured to be more robust and/or larger than diaphragms for external non-implantable microphone assemblies.

[0032] The example auditory prostheses 100 shown in FIG. 1 A utilizes an external microphone 124 and the auditory prosthesis 200 shown in FIG. IB utilizes an implantable microphone assembly 206 comprising a subcutaneously implantable acoustic transducer. In certain implementations described herein, the auditory prosthesis 100 utilizes one or more implanted microphone assemblies on or within the recipient. In certain implementations described herein, the auditory prosthesis 200 utilizes one or more microphone assemblies that are positioned external to the recipient and/or that are implanted on or within the recipient, and utilizes one or more acoustic transducers (e.g., actuator 210) that are implanted on or within the recipient. In certain implementations, an external microphone assembly can be used to supplement an implantable microphone assembly of the auditory prosthesis 100, 200. Thus, the teachings detailed herein and/or variations thereof can be utilized with any type of external or implantable microphone arrangement, and the acoustic transducers shown in FIGs. 1A and IB are merely illustrative.

[0033] FIGs. 2 A and 2B schematically illustrate two rear views of an example apparatus 300 in accordance with certain implementations described herein. FIG. 2A shows the apparatus 300 spaced from a recipient’s body 400 and FIG. 2B shows the apparatus 300 worn on the recipient’s body 400. The apparatus 300 comprises a housing 310 configured to be positioned on a first skin portion 410 of the recipient’s body 400. The first skin portion 410 has an anatomical first contour 412. The housing 310 comprises a first outer surface portion 320 having a second contour 322 substantially matching the first contour 412. The apparatus 300 further comprises at least one first circuit 330 on or within the housing 310. The at least one first circuit 330 is configured to be, upon the housing 310 being positioned on the first skin portion 410, in wireless communication with at least one second circuit 420 implanted beneath a second skin portion 430 of the recipient’s body 400.

[0034] In certain implementations, the apparatus 300 comprises an external portion of an implantable system (e.g., auditory prosthesis 100, 200; cochlear implant system; implanted actuator system) and the at least one second circuit 420 comprises an implanted portion of the implantable system, the at least one second circuit 420 configured to generate stimulation signals and to apply the stimulation signals to the recipient’s body (e.g., the stimulation signals configured to evoke a hearing percept by the recipient). For example, the apparatus 300 can comprise an external component 142 comprising a sound processing unit 126 and an external transmitter unit 128 and the at least one first circuit 330 can comprise an external coil 130 of the external transmitter unit 128. The implanted portion can comprise an internal component 144 comprising an internal receiver unit 132 (e.g., the at least one second circuit 420 comprising an internal coil 136, a stimulator unit 120, and an elongate electrode assembly 118). For another example, the implanted portion can comprise an implantable assembly 202 (e.g., the at least one second circuit 420 comprising a signal receiver 204 and an acoustic transducer 206 in mechanical communication with the ossicles 106, the cochlea 140, and/or the oval window 112).

[0035] In certain implementations, the housing 310 has a width (e.g., along a lateral direction substantially parallel to the second skin portion 430) less than or equal to 40 millimeters (e.g., in a range of 15 millimeters to 35 millimeters; in a range of 25 millimeters to 35 millimeters; in a range of less than 30 millimeters; in a range of 15 millimeters to 30 millimeters). In certain implementations, the housing 310 has a thickness (e.g., in a direction substantially perpendicular to the second skin portion 430) less than or equal to 10 millimeters (e.g., in a range of less than or equal to 7 millimeters, in a range of less than or equal to 6 millimeters; in a range of less than or equal to 5 millimeters).

[0036] For example, as schematically illustrated by FIGs. 2A and 2B, the housing 310 can be configured to be worn on and behind the auricle 110. In certain such implementations, a portion of the housing 310, when worn by the recipient on and behind the auricle 110, extends above the auricle 110 (see, e.g., FIG. 2B) and/or in front of the auricle 110. In certain other such implementations, the housing 310 is wholly within a region behind the auricle 110 such that the housing 310, when worn by the recipient on and behind the auricle 110, is not visible to an observer in front of the recipient (e.g., the housing 310 does not extend above or in front of the auricle 110). The housing 310 can extend along a portion of the back surface of the auricle 110 having an angular range from a first angle of zero (e.g., at a position at an apex of the auricle 110) to a second angle less than 210 degrees (e.g., in a range of zero to 110 degrees). The housing 310 can be configured to contact at least a portion of the external back surface of the concha of the auricle 110.

[0037] In certain implementations, the first outer surface portion 320 of the housing 310 comprises at least one biocompatible (e.g., skin-friendly) material configured to contact the first skin portion 410 of the recipient’s body. In certain implementations, the housing 310 comprises a second outer surface portion 340 configured to contact the second skin portion 430 upon the housing 310 being positioned on the first skin portion 410, the second outer surface portion 340 also comprising at least one biocompatible (e.g., skin-friendly) material. Examples of biocompatible materials compatible with certain implementations described herein include but are not limited to: silicone; rubber; polymer; compressible foam; plaster; plasticine. In certain implementations in which the second outer surface portion 340 is positioned between the at least one first circuit 330 and the at least one second circuit 420 implanted beneath the second skin portion 430, the second outer surface portion 340 is substantially transmissive to electromagnetic fields generated by the at least one first circuit 330 and/or the at least one second circuit 420 such that the housing 310 does not substantially interfere with the transmission of data and/or power via magnetic induction between the apparatus 300 and the implanted device. The housing 310 can also comprise at least one rigid material (e.g., metals; plastics; ceramics) configured to provide structural strength to the housing 310. In certain implementations, the housing 310 is configured to hermetically seal the other components of the apparatus 300 (e.g., the at least one first circuit 330) from an environment surrounding the housing 310.

[0038] In certain implementations, the at least one first circuit 330 comprises at least one energy transmission coil (e.g., a substantially planar electrically conductive wire coil with multiple windings of electrically insulated single-strand or multi-strand copper wire; copper traces on epoxy of a printed circuit board; having a substantially circular, rectangular, spiral, or oval shape or other shape). The at least one energy transmission coil can have a diameter, length, and/or width (e.g., along a lateral direction substantially parallel to the second skin portion 430) less than or equal to 40 millimeters (e.g., in a range of 15 millimeters to 35 millimeters; in a range of 25 millimeters to 35 millimeters; in a range of less than 30 millimeters; in a range of 15 millimeters to 30 millimeters). In certain implementations, the at least one energy transmission coil is substantially parallel to the second outer surface portion 340 of the housing 310, the second outer surface portion 340 configured to be positioned substantially parallel to the second skin portion 430 upon the housing 310 being positioned on the first skin portion 410. For example, the second outer surface portion 340 can be configured to contact the second skin portion 430. In certain implementations, the at least one first circuit 330 and the second outer surface portion 340 are sufficiently flexible to flex in response to the housing 310 being placed in contact with the second skin portion 430, while in certain other implementations, the at least one first circuit 330 and the second outer surface portion 340 are substantially rigid so as to not flex in response to the housing 310 being placed in contact with the second skin portion 430.

[0039] In certain implementations, the at least one first circuit 330 is configured to be in wireless electrical communication (e.g., via a radio-frequency or RF link; via a magnetic induction link) with the at least one second circuit 420 when the housing 310 is positioned on the first skin portion 410 (e.g., such that the at least one first circuit 330 is above the at least one second circuit 420). For example, the at least one first circuit 330 can be inductively coupled with the at least one second circuit 420 and configured to wirelessly transmit electrical power to the at least one second circuit 420 and/or configured to wirelessly transmit information (e.g., data signals; control signals) to and/or to wirelessly receive information from the at least one second circuit 420.

[0040] In certain implementations, the apparatus 300 further comprises an input element (e.g., a microphone; microphone assembly 124; a barometer) and a processor within the housing 310 and in operative communication with the input element and the at least one first circuit 330. The input element can be configured to detect environmental signals (e.g., sound; ambient atmospheric pressure). For example, a microphone can be configured to generate sensor signals in response to sounds received by the microphone, and the processor can be configured to receive the sensor signals from the microphone, to generate data signals in response to the sensor signals, and to wirelessly transmit the data signals from the at least one first circuit 330 to the at least one second circuit 420. The processor can be further configured to generate power signals and to wirelessly transmit the power signals from the at least one first circuit 330 to the at least one second circuit 420 to provide power to the implanted device.

[0041] The processor can comprise one or more microprocessors (e.g., applicationspecific integrated circuits; generalized integrated circuits programmed by software with computer executable instructions; microelectronic circuitry; microcontrollers) configured to control operation of the apparatus 300 and/or the implanted device (e.g., set or adjust parameters of the energy transfer in response to user input and/or conditions during operation). The processor can further comprise at least one storage device (e.g., at least one tangible or non-transitory computer readable storage medium; read only memory; random access memory; flash memory) in operative communication with the one or more microprocessors. The at least one storage device can be configured to store information (e.g., data; commands) accessed by the one or more microprocessors during operation. The at least one storage device can be encoded with software (e.g., a computer program downloaded as an application) comprising computer executable instructions for instructing the one or more microprocessors (e.g., executable data access logic, evaluation logic, and/or information outputting logic). In certain implementations, the one or more microprocessors execute the instructions of the software to provide functionality as described herein. In certain implementations, the apparatus 300 further comprises at least one energy storage device (e.g., battery; capacitor) configured to provide energy to the other components of the apparatus 300.

[0042] In certain implementations, the apparatus 300 is configured to be worn on a first skin portion 410 that substantially faces the second skin portion 430. For example, as schematically illustrated by FIGs. 2A and 2B, the apparatus 300 is configured to be worn on and behind an auricle 110 (e.g., pinna) of the recipient’s body, the first skin portion 410 comprises a rear-facing portion of the auricle 110 (e.g., a back surface of the auricle 110), and the second skin portion 430 comprises an outwardly-facing scalp portion of the recipient’s body 400 (e.g., a scalp portion behind the auricle 110). The first skin portion 410 facing towards the back of the recipient is visible in the rear view of FIG. 2A with various contour lines indicative of the first contour 412, as is the second skin portion 430 behind the auricle 110. The first outer surface portion 320 of the housing 310 in FIG. 2A faces towards the front of the recipient and would not be visible in the rear view of FIG. 2A due to the opacity of the housing 310. However, for the sake of clarity, FIGs. 2A and 2B show the housing 310 as transparent such that various contour lines indicative of the second contour 322 can be seen. Similarly, while the at least one first circuit 330 would not be visible in the rear view of FIG. 2 A due to the opacity of the housing 310 and the at least one second circuit 420 would not be visible due to the opacity of the second skin portion 430, for the sake of clarity, the at least one first circuit 330 and the at least one second circuit 420 are shown in dashed lines in FIGs. 2A and 2B.

[0043] In certain implementations, the first skin portion 410 comprises an anatomical first contour 412 (e.g., the first contour 412 can comprise substantially convex and/or substantially concave portions; the first contour 412 does not have a symmetric or simple geometric shape). The second contour 322 can comprise substantially concave portions and/or substantially convex portions that substantially match and are configured to mate with the corresponding substantially convex portions and/or substantially concave portions of the first contour 412. For example, at least one portion of the first contour 412 can be substantially convex, and at least one portion of the second contour 322 can be substantially concave and configured to mate with the at least one portion of the first contour 412. For another example, at least one portion of the first contour 412 can be substantially concave, and at least one portion of the second contour 322 can be substantially convex and configured to mate with the at least one portion of the first contour 412.

[0044] In certain implementations, the first outer surface portion 320 of the housing 310 is resilient (e.g., flexible; elastic) such that the first outer surface portion 320 flexes in response to being pressed against the first skin portion 410 (e.g., a back surface of the auricle 110). For example, the first outer surface portion 320 can be configured to conform to the first contour 412 of the first skin portion 410 such that the second contour 322 substantially matches the first contour 412 to increase (e.g., maximize) the translational friction between the first outer surface portion 320 and the first skin portion 410, thereby reducing (e.g., minimizing) the risk of the apparatus 300 being removed (e.g., dislodged; knocked off) from the recipient’s body unintentionally. The second outer surface portion 340 of the housing 310 can also be resilient (e.g., flexible; elastic) such that the second outer surface portion 340 flexes in response to being pressed against the second skin portion 430 (e.g., a scalp portion behind the auricle 110). For example, the second outer surface portion 340 can be configured to conform to the curvature of the recipient’s body (e.g., head) to increase (e.g., maximize) the translational friction between the second outer surface portion 340 and the second skin portion 430, thereby reducing (e.g., minimizing) the risk of the apparatus 300 being removed (e.g., dislodged; knocked off) from the recipient’s body unintentionally.

[0045] The geometries of the first skin portions 410 differ among different recipients. For example, different individuals have ear geometries (e.g., sizes, shapes, and/or first contours 412 of the back surface of the auricle 110) that differ from one another, and the two ears of the same individual can have geometries that differ from one another. A first apparatus 300 configured to be worn and used by a first recipient differs from a second apparatus 300 configured to be worn and used by a second recipient (e.g., the first and second apparatus 300 have different sizes, shapes, and/or second contours 322 from one another).

[0046] In certain implementations, the second contour 322 of the first outer surface portion 320 is configured to substantially match the first contour 412 of the first skin portion 410 of one single recipient. For example, the second contour 322 can be tailored to substantially match the back surface of a predetermined auricle 110 of a predetermined individual that is to utilize the apparatus 300. The first outer surface portion 320 can be configured to provide one unique position of the apparatus 300 on the first skin portion 410. In certain implementations, a shape and/or curvature of the second outer surface portion 340 are configured to substantially match the shape and/or curvature of the second skin portion 430 (e.g., scalp portion) of one single recipient.

[0047] In certain implementations, the first outer surface portion 320 is configured to, upon the housing 310 being positioned on the first skin portion 410 (e.g., the first outer surface portion 320 press fit onto the first skin portion 410), generate an attachment force with the first skin portion 410. The contact area between the first outer surface portion 320 and the first skin portion 410 can be sufficiently large such that the attachment force is configured to hold the housing 310 on the first skin portion 410 during operation of the apparatus 300 (e.g., while the apparatus 300 is in wireless communication with the implanted device). For example, the attachment force produced by placing the housing 310 on the first skin portion 410 can comprise a friction or adhesion component (e.g., the first outer surface portion 320 sticking to the first skin portion 410) and/or a suction component (e.g., the first outer surface portion 320 pressing air from between the first outer surface portion 320 and the first skin portion 410 such that the ambient atmospheric pressure holds the housing 310 on the first skin portion 410). The adhesion component can be generated, not from an externally applied adhesive material (e.g., glue) between the first outer surface portion 320 and the first skin portion 410, but from the presence of moisture (e.g., humidity; sweat) and/or sebum at the interface between the first outer surface portion 320 and the first skin portion 410 or from an inherent property of the material of the first outer surface portion 320 and its interaction with the first skin portion 410. The first outer surface portion 320 is configured to be repeatedly attached to and detached from the first skin portion 410 (e.g., the recipient placing the housing 310 on the auricle 110 and removing the housing 310 from the auricle 110) without pain or discomfort.

[0048] In certain implementations, the attachment force is sufficiently strong to hold the housing on the first skin portion 410 without an attractive magnetic force between the apparatus 300 and the implanted device (e.g., one or both of the apparatus 300 and the implanted device does not contain a substantial amount of ferromagnetic or ferrimagnetic material or a retention magnet). As compared to an implanted device configured to generate an attractive magnetic force with an external device, an implanted device not containing a substantial amount of ferromagnetic or ferrimagnetic material in accordance with certain implementations described herein can be more compatible with magnetic resonance imaging (e.g., by not producing the safety concerns and/or imaging artifacts in magnetic resonance imaging resulting from such ferromagnetic or ferrimagnetic materials). In certain implementations, upon mating the second contour 322 of the first outer surface portion 320 to the first contour 412 of the first skin portion 410, the apparatus 300 is configured to align the at least one first circuit 330 with the at least one second circuit 420, even in the absence of a magnetic retention force to hold the apparatus 300 on the recipient’s body 400.

[0049] FIGs. 3A and 3B schematically illustrate another example apparatus 300 in accordance with certain implementations described herein. The apparatus 300 comprises a first portion 510 and a second portion 520 configured to be affixed onto the first portion 510. The first portion 510 comprises an external device comprising a first housing portion 530 and the at least one first circuit 330 on or within the first housing portion 530. The second portion 520 comprises a second housing portion 540 comprising a cavity 550 configured to receive the external device (e.g., the first housing portion 530). The second housing portion 540 further comprises the first outer surface portion 320 having a shape (e.g., the second contour 322) configured to be placed on and substantially mate with a first skin surface portion (e.g., the first skin portion 410 having the first contour 412) of the recipient’s body 400. In FIG. 3A, the first portion 510 and the second portion 520 are spaced from one another and the apparatus 300 is spaced from the first skin portion 410 of the recipient’s body 400. In FIG. 3B, the second portion 520 is affixed onto the first portion 510 and the apparatus 300 is placed on the first skin portion 410.

[0050] The first portion 510 can comprise an external device (e.g., external component 142 comprising an external microphone 124, a sound processing unit 126, a power source, and/or an external transmitter unit 128) configured to be in operative communication with an implanted device (e.g., stimulator unit 120; internal component 144; implanted portion of an auditory prosthesis 100, 200). For example, the first portion 510 can comprise at least one first communication coil (e.g., at least one first circuit 330), the implanted device can comprise at least one second communication coil (e.g., at least one second circuit 420 beneath the second skin portion 430 of the recipient’s body 400), and upon the first housing portion 530 being received by the cavity 550 and the first outer surface portion 320 being placed on the first skin portion 410 of the recipient’s body 400, the at least one first communication coil can be in wireless communication with the at least one second communication coil.

[0051] The second portion 520 can comprise a sheath (e.g., sleeve; cover; jacket) configured to receive (e.g., be placed on) the first portion 510 to provide the external device with the first outer surface portion 320 and the second contour 322 that substantially matches (e.g., configured to substantially mate with) the first contour 412 of the first skin portion 410. The cavity 550 of the second portion 520 can have a size and shape configured to contain the first housing portion 530.

[0052] The second portion 520 can be configured to be repeatedly attached to the first portion 510 and detached from the first portion 510 without damage to the first portion 510 or the second portion 520. In certain implementations, the second portion 520 is configured to provide protection to the first portion 510 from exposure to the ambient environment and from contacting the recipient’s body 400. In certain implementations, the second portion 520 is configured to provide an attachment force with the first skin portion 410 that holds the first portion 510 on the first skin portion 410 with the first and second communication coils in wireless communication with one another (e.g., without a magnetic force between the implanted device and either the first portion 510 or the second portion 520), as described herein. In certain implementations, the apparatus 300 further comprises a second outer surface portion 340 having a second shape configured to be placed on and substantially mate with the second skin portion 430.

[0053] In certain implementations, the first portion 510 is an electronic device (e.g., a Behind-the-Ear unit) while the second portion 520 is a customized (e.g., molded) element configured to be secured to the electronic device. For example, the first portion 510 can be configured to be worn and used by the recipient over multiple years, while the second portion 520 is a replaceable and consumable (e.g., disposable; single-use) element configured to be worn and used over shorter time periods (e.g., one or more days or weeks). For another example, multiple second portions 520 with different sizes can be made available for use with the first portion 510. The different second portions 520 can provide adjustability for different recipients to use the same first portion 510 or for a young recipient to use the same first portion 510 as the recipient matures and grows.

[0054] In certain implementations, the first housing portion 530 is substantially rigid (e.g., metals; plastics; ceramics) and the second housing portion 540 is substantially flexible or elastic (e.g., comprising at least one biocompatible material selected from the group consisting of: silicone; rubber; polymer; compressible foam; plaster; plasticine). In certain implementations, the second portion 520 comprises the second outer surface portion 340 configured to be substantially parallel to the second skin portion 430 (e.g., in contact with the second skin portion 430), while in certain other implementations, the first portion 510 comprises the second outer surface portion 340 (e.g., the second housing portion 530 does not cover a surface portion of the first housing portion 530 that is proximal to the at least one first circuit 330).

[0055] In certain implementations, the cavity 550 is larger than the first housing portion 530 such that the position of the first portion 510 within the cavity 550 (e.g., relative to the first outer surface portion 320 of the second portion 520) can be adjusted. For example, the cavity 550 can be configured to receive one or more shims along with the first housing portion 530 to adjust a position of the first portion 510. For another example, the inner surface of the cavity 550 can comprise a plurality of protrusions (e.g., ridges; ribs) and/or recesses (e.g., grooves) configured to mate with corresponding recesses and/or protrusions of the first housing portion 530 to adjust a position the first portion 510.

[0056] FIG. 4A schematically illustrates a perspective and exploded view of an example apparatus 300 in accordance with certain implementations described herein. The apparatus 300 comprises a first portion 510 (e.g., electronic device; a Behind-the-Ear sound processing unit) comprising the at least one first circuit 330 and a second portion 520 (e.g., sheath) configured to be repeatedly attached to the first portion 510 and detached from the first portion 510 without damage to the first portion 510 or the second portion 520. As shown in FIG. 4A, the second portion 520 fits onto the first portion 510 (e.g., denoted by the dashed line in FIG. 4 A) and is configured to mate with the first skin portion 410 to provide an attachment force that holds the apparatus 300 in operating position (e.g., the at least one first circuit 330 in wireless communication with the at least one second circuit 420) on the first skin portion 410.

[0057] FIG. 4B schematically illustrates three views of an example apparatus 300 configured to facilitate controllable adjustment of the position and/or orientation of the first portion 510 relative to the second portion 520 in accordance with certain implementations described herein. The cavity 550 can be configured such that the first portion 510 can be controllably adjusted within the cavity 550 by translating and/or rotating the position and/or orientation of the first portion 510 relative to the second portion 520. The left-most view of FIG. 4B shows the first portion 510 at a first position and orientation. The middle view of FIG. 4B shows the first portion 510 can be at a second position and orientation translated relative to the first position and orientation. The right-most view of FIG. 4B shows the first portion 510 can be at a third position and orientation rotated relative to the first position and orientation. With the first portion 510 at each of these three positions relative to the second portion 520, upon the apparatus 300 being worn on the recipient’s body, the at least one first circuit 330 is at a different position and orientation relative to the at least one second circuit 420, so the multiple positions and orientations of the first portion 510 relative to the second portion 520 can provide adjustability to the apparatus 300. [0058] FIG. 5 schematically illustrates a perspective and exploded view of another example apparatus 300 in accordance with certain implementations described herein. The first portion 510 comprises at least one recess 512 configured to receive (e.g., engage or mate with) at least one protrusion 522 of the second portion 520. In certain other implementations, the first portion 510 comprises at least one protrusion and the second portion 520 comprises at least one recess configured to receive (e.g., engage or mate with) the at least one protrusion of the first portion 510. The relative position of the at least one protrusion 522 within the at least one recess 512 can be controllably adjustable such that the relative position and/or orientation of the at least one first circuit 330 can be adjusted relative to the at least one second circuit 420 to be amongst a plurality of relative positions. For example, a finite number of relative positions of the first and second portions 510, 520 can be provided by the at least one recess 512 and the at least one protrusion 522 comprising a plurality of corresponding structures (e.g., ridges, ribs, slots, grooves) configured to engage (e.g., mate) with one another when the first portion 510 and the second portion 520 are in mechanical communication (e.g., fit together) with one another.

[0059] In certain implementations, the apparatus 300 (e.g., as shown in FIGs. 2A- 2B, 3A-3B, 4A-4B, and 5A-5B) adjusts a relative position and/or orientation of the at least one first circuit 330 in the X-Y plane (e.g., translation and/or rotation within a plane substantially parallel to the second skin portion 430 overlying the at least one second circuit 420) and/or a relative position and/or orientation of the at least one first circuit 330 in a Z-direction substantially perpendicular to the X-Y plane. For example, the apparatus 300 can adjust an offset distance of the at least one first circuit 330 from the second skin portion 430 and/or a relative angle between the at least one first circuit 330 and the at least one second circuit 420 (e.g., a substantially planar first circuit 330 positioned to be substantially parallel to a substantially planar second circuit 420 or positioned to be at a predetermined non-zero angle relative to the second circuity 420).

[0060] FIG. 6 is a flow diagram of an example method 600 in accordance with certain implementations described herein. While the method 600 is described by referring to some of the structures of the example apparatus 300 of FIGs. 2A-2B, 3A-3B, 4A-4B, and 5, other apparatus and systems with other configurations of components can also be used to perform the method 600 in accordance with certain implementations described herein. [0061] In an operational block 610, the method 600 comprises accessing information indicative of a first shape (e.g., first contour 412) of a first portion of a recipient’s body 400 (e.g., at least a first skin portion 410; a rear surface portion of the recipient’s ear). In certain implementations, accessing the information comprises retrieving the information from at least one storage device (e.g., at least one tangible or non-transitory computer readable storage medium; read only memory; random access memory; flash memory).

[0062] In an operational block 620, the method 600 further comprises fabricating, using the information, a surface portion (e.g., first outer surface portion 320) of an external device (e.g., apparatus 300; external portion of an auditory prosthesis system). The surface portion has a second shape (e.g., second contour 322) that is substantially a mold-like negative impression of the first shape (e.g., the second shape and the first shape are configured to fit or mate together), and the surface portion is configured to at least partially support the external device on the first portion. The external device can comprise a processor and a communication coil (e.g., at least one first circuit 330) in operative communication with the processor. The communication coil can be configured to wirelessly communicate with an implanted device (e.g., comprising at least one second circuit 420; an implanted portion of an auditory prosthesis system) beneath a second skin surface portion of the recipient’s body (e.g., second skin portion 430; scalp of the recipient) upon the external device being positioned on the first portion (e.g., behind the ear) with the surface portion in contact with the first portion of the recipient’s body (e.g., the rear surface portion of the recipient’s ear).

[0063] In certain implementations, the method 600 further comprises generating the information that is to be accessed and used in fabricating the surface portion of the external device. For example, the information can be generated by forming a first negative mold of the first portion of the recipient’s body, fabricating a first positive casting (e.g., having the first contour 412), and using the first positive casting to form a second negative mold, and fabricating the surface portion can comprise using the second negative mold to form a second positive casting that comprises the surface portion of the external device (e.g., the second contour 322). For another example, the information can be generated by imaging (e.g., three- dimensional scanning) the first portion of the recipient’s body and fabricating the surface portion can comprise using additive manufacturing (e.g., three-dimensional printing) to form an element comprising the surface portion of the external device. Imaging the first portion of the recipient’s body can comprise using at least one of: computed tomography (CT) imaging, magnetic resonance imaging (MRI), three-dimensional scanning.

[0064] In certain implementations, such information is generated after the implantation process (e.g., a surgical procedure) in which the device is implanted on or in the recipient’s body, while in certain other implementations, such information is generated prior to the implantation process (e.g., to be used by the medical practitioner during the implantation process to position the implanted device at a target position). The information can further include data regarding a target position at which the device is to be implanted and/or a relative position of the first portion of the recipient’s body and an implanted communication coil of the implanted device.

[0065] Although commonly used terms are used to describe the systems and methods of certain implementations for ease of understanding, these terms are used herein to have their broadest reasonable interpretations. Although various aspects of the disclosure are described with regard to illustrative examples and implementations, the disclosed examples and implementations should not be construed as limiting. Conditional language, such as, among others, "can," "could," "might," or "may," unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain implementations include, while other implementations do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more implementations or that one or more implementations necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular implementation. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a nonexclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.

[0066] It is to be appreciated that the implementations disclosed herein are not mutually exclusive and may be combined with one another in various arrangements. In addition, although the disclosed methods and apparatuses have largely been described in the context of various devices, various implementations described herein can be incorporated in a variety of other suitable devices, methods, and contexts. More generally, as can be appreciated, certain implementations described herein can be used in a variety of implantable medical device contexts that can benefit from certain attributes described herein.

[0067] Language of degree, as used herein, such as the terms “approximately,” “about,” “generally,” and “substantially,” represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately,” “about,” “generally,” and “substantially” may refer to an amount that is within ± 10% of, within ± 5% of, within ± 2% of, within ± 1 % of, or within ± 0.1% of the stated amount. As another example, the terms “generally parallel” and “substantially parallel” refer to a value, amount, or characteristic that departs from exactly parallel by ± 10 degrees, by ± 5 degrees, by ± 2 degrees, by ± 1 degree, or by ± 0.1 degree, and the terms “generally perpendicular” and “substantially perpendicular” refer to a value, amount, or characteristic that departs from exactly perpendicular by ± 10 degrees, by ± 5 degrees, by ± 2 degrees, by ± 1 degree, or by ± 0.1 degree. The ranges disclosed herein also encompass any and all overlap, sub-ranges, and combinations thereof. Language such as “up to,” “at least,” “greater than,” less than,” “between,” and the like includes the number recited. As used herein, the meaning of “a,” “an,” and “said” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “into” and “on,” unless the context clearly dictates otherwise.

[0068] While the methods and systems are discussed herein in terms of elements labeled by ordinal adjectives (e.g., first, second, etc.), the ordinal adjective are used merely as labels to distinguish one element from another (e.g., one signal from another or one circuit from one another), and the ordinal adjective is not used to denote an order of these elements or of their use.

[0069] The invention described and claimed herein is not to be limited in scope by the specific example implementations herein disclosed, since these implementations are intended as illustrations, and not limitations, of several aspects of the invention. Any equivalent implementations are intended to be within the scope of this invention. Indeed, various modifications of the invention in form and detail, in addition to those shown and described herein, will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the claims. The breadth and scope of the invention should not be limited by any of the example implementations disclosed herein but should be defined only in accordance with the claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. An apparatus comprising: a housing configured to be positioned on a first skin portion of a recipient’s body, the first skin portion having an anatomical first contour, the housing comprising a first outer surface portion having a second contour substantially matching the first contour; and at least one first circuit on or within the housing, the at least one first circuit configured to be, upon the housing being positioned on the first skin portion, in wireless communication with at least one second circuit implanted beneath a second skin portion of the recipient’ s body.

2. The apparatus of claim 1, wherein, upon the housing being positioned on the first skin portion, the first outer surface portion is configured to generate an attachment force with the first skin portion, the attachment force configured to hold the housing on the first skin portion.

3. The apparatus of claim 1 or claim 2, wherein the first contour comprises a substantially convex portion and a substantially concave portion, and the second contour comprises a substantially concave portion and a substantially convex portion, the substantially concave portion of the second contour configured to mate with the substantially convex portion of the first contour and the substantially convex portion of the second contour configured to mate with the substantially concave portion of the first contour.

4. The apparatus of claim 3, wherein the first skin portion substantially faces the second skin portion.

5. The apparatus of claim 4, wherein the first skin portion comprises a rear-facing portion of an auricle of the recipient and the second skin portion comprises an outwardly-facing scalp portion of the recipient.

6. The apparatus of any preceding claim, wherein the housing further comprises a second outer surface portion configured to contact the second skin portion upon the housing being positioned on the first skin portion.

7. The apparatus of any preceding claim, wherein the first outer surface portion comprises silicon, rubber, compressible foam, polymer, plaster, or plasticine.

8. The apparatus of any preceding claim, further comprising: an input element; and a processor within the housing and in operative communication with the input element and the at least one first circuit, the processor configured to receive data signals from the input element, to generate wireless signals in response to the data signals, and to wirelessly transmit the wireless signals from the at least one first circuit to the at least one second circuit.

9. The apparatus of claim 8, wherein the housing comprises a first housing portion comprising the first outer surface portion and a second housing portion configured to be affixed to the first housing portion, the second housing portion comprising the input element, the processor, and the at least one first circuit.

10. The apparatus of claim 8 or claim 9, wherein the at least one second circuit is configured to generate stimulation signals and to apply the stimulation signals to the recipient’s body.

11. The apparatus of claim 10, wherein the stimulation signals evoke a hearing percept by the recipient.

12. A method comprising: accessing information indicative of a first shape of at least a rear surface portion of a recipient’s ear; and fabricating, using the information, a surface portion of an external device, the surface portion having a second shape that is substantially a mold-like negative impression of the first shape, the surface portion configured to at least partially support the external device on the ear, the external device comprising a processor and a communication coil in operative communication with the processor, the communication coil configured to wirelessly communicate with an implanted device beneath a scalp of the recipient upon the external device being positioned behind the ear with the surface portion in contact with the rear surface portion of the recipient’s ear.

13. The method of claim 12, further comprising generating the information.

14. The method of claim 13, wherein said generating comprises forming a negative mold of the rear surface portion of the recipient’s ear and said fabricating comprises using the negative mold to form a positive casting comprising the surface portion of the external device.

15. The method of claim 13, wherein said generating comprises imaging the rear surface portion of the recipient’s ear and said fabricating comprises using additive manufacturing to form an element comprising the surface portion of the external device.

16. The method of claim 15, wherein said imaging comprises at least one of: computed tomography (CT) imaging, magnetic resonance imaging (MRI), three-dimensional scanning.

17. The method of any of claims 12 to 16, wherein the external device comprises an external portion of an auditory prosthesis system and the implanted device comprises an implanted portion of the auditory prosthesis system.

18. An apparatus comprising: at least one recess and/or protrusion configured to engage an external device configured to be in operative communication with an implanted device; and a first external surface portion having a first shape configured to be placed on and substantially mate with a first skin surface portion of a recipient’s body.

19. The apparatus of claim 18, wherein the apparatus comprises a sheath configured to be affixed onto the external device.

20. The apparatus of claim 18 or claim 19, wherein the at least one recess and/or protrusion comprises a cavity configured to receive a corresponding portion of the external device.

21. The apparatus of claim 18 or claim 19, wherein the at least one recess and/or protrusion comprises at least one protrusion configured to mate with a corresponding portion of the external device.

22. The apparatus of claim 20 or claim 21, wherein the at least one recess and/or protrusion is configured to facilitate controllable adjustment of a relative position of the apparatus with the external device amongst a plurality of relative positions.

23. The apparatus of any of claims 18 to 22, wherein the external device comprises at least one first communication coil, the implanted device comprises at least one second communication coil, and upon the external device being engaged by the at least one recess and/or protrusion and the first external surface portion being placed on the first skin surface portion of the recipient’s body, the at least one first communication coil is in wireless communication with the at least one second communication coil.

24. The apparatus of any of claims 18 to 23, wherein the implanted device is beneath a second skin surface portion of the recipient’s body, the apparatus further comprises a second external surface portion having a second shape configured to be placed on and substantially mate with the second skin surface portion.

25. The apparatus of any of claims 18 to 24, wherein the apparatus is configured to be repeatedly affixed to and detached from the external device without damage to the apparatus or the external device.

26. The apparatus of any of claims 18 to 25, wherein the apparatus is configured to provide an attachment force that holds the external device on the first skin surface portion of the recipient’s body without an attractive magnetic force between the implanted device and either the apparatus or the external device.