Magnetic field cancellation circuitry

An apparatus includes at least one first circuit configured to generate a first time-varying magnetic field for magnetic induction power transfer to a device, at least one second circuit configured to generate and/or receive a second time-varying magnetic field for magnetic induction data transfer to and/or from the device, and at least one third circuit configured to generate a third time-varying magnetic field in response to a time-varying electric current. The third time-varying magnetic field is configured to at least partially inhibit degradation of said data transfer from the first time-varying magnetic field. The apparatus further includes at least one fourth circuit configured to generate the time-varying electric current in response to a received portion of the first time-varying magnetic field.

BACKGROUND

Field

The present application relates generally to systems and methods for facilitating wireless power and data transmission, and more specifically, for facilitating wireless power and data transmission between an external portion and an implanted portion of an implanted medical system.

Description of the Related Art

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.

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

In one aspect disclosed herein, an apparatus comprises at least one first circuit configured to generate a first time-varying magnetic field for magnetic induction power transfer to a device. The apparatus further comprises at least one second circuit configured to generate and/or receive a second time-varying magnetic field for magnetic induction data transfer to and/or from the device. The apparatus further comprises at least one third circuit configured to generate a third time-varying magnetic field in response to a time-varying electric current, the third time-varying magnetic field configured to at least partially inhibit degradation of said data transfer from the first time-varying magnetic field. The apparatus further comprises at least one fourth circuit configured to generate the time-varying electric current in response to a received portion of the first time-varying magnetic field.

In another aspect disclosed herein, a method comprises transferring power via a first magnetic induction link in a first region. The method further comprises transferring data via a second magnetic induction link in a second region, said transferring data simultaneous with said transferring power. The method further comprises generating an electric current indicative of a first magnetic field from said first magnetic induction link. The method further comprises, in response to the electric current, generating a second magnetic field in the second region in opposition to at least a portion of the first magnetic field within the second region.

In another aspect disclosed herein, an apparatus comprises magnetic induction power transfer circuitry configured to generate an induction power transfer magnetic field. The apparatus further comprises at least one circuit that is sensitive to the induction power transfer magnetic field. The apparatus further comprises protection circuitry configured to generate a protection magnetic field in response to an electric current. The protection magnetic field is configured to at least partially protect the at least one circuit from the induction power transfer magnetic field. The apparatus further comprises circuitry configured to generate the electric current in response to the induction power transfer magnetic field or in response to a signal indicative of the induction power transfer magnetic field.

DETAILED DESCRIPTION

In certain systems, magnetic induction power transfer is performed concurrently and in close proximity to other low-power operations which can experience degradation due to the large time-varying magnetic fields involved in the magnetic induction power transfer. For example, an external portion of an auditory prosthesis can utilize magnetic induction to provide power transcutaneously to an implanted portion of the auditory prosthesis while also using magnetic induction to communicate data transcutaneously with the implanted portion. Due to the relatively small size of the external portion (e.g., an over-the-ear or button sound processor), the low-power magnetic induction data transfer link can experience excessive noise and other interference due to the concurrent operation of the nearby high-power magnetic induction power transfer link. For another example, signals from an electromagnetic microphone of the external portion of the auditory prosthesis can be disrupted by the concurrent operation of the nearby high-power magnetic induction power transfer link to the implanted portion.

Certain implementations described herein comprise cancellation circuitry configured to generate a magnetic field configured to destructively interfere with (e.g., counteract; in opposition to) the portion of the large time-varying magnetic field in the region of the circuitry performing the low-power operation, thereby at least partially inhibiting the degradation of the low-power operation. In certain implementations, the cancellation circuitry is powered by magnetic induction from at least one pick-up coil receiving a portion of the large time-varying magnetic field (e.g., passively powered). In certain other implementations, the cancellation circuitry is powered by a separate power supply in response to a sensor signal indicative of the large time-varying magnetic field (e.g., actively powered).

The teachings detailed herein are applicable, in at least some implementations, to any type of implantable medical device (e.g., implantable sensory prostheses) comprising a first portion (e.g., external to a recipient) and a second portion (e.g., implanted on or within the recipient), the first portion configured to wirelessly transmit power to the second portion and to wirelessly communicate with the second portion. For example, the implantable medical device can comprise an auditory prosthesis system utilizing an external sound processor configured to transcutaneously provide power and data (e.g., control signals) to an implanted assembly (e.g., comprising an actuator) that generates stimulation signals that are perceived by the recipient as sounds. Examples of auditory prosthesis systems compatible with certain implementations described herein include but are not limited to: electro-acoustic electrical/acoustic systems, cochlear implant devices, implantable hearing aid devices, middle ear implant 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 medical device that can utilize the teachings detailed herein and/or variations thereof.

Merely for ease of description, apparatus and methods disclosed herein are primarily described with reference to an illustrative medical device, namely a cochlear implant. However, the teachings detailed herein and/or variations thereof may also be used with a variety of other medical devices that provide a wide range of therapeutic benefits to recipients, patients, or other users. In some implementations, the teachings detailed herein and/or variations thereof can be utilized in other types of implantable medical devices beyond auditory prostheses. For example, apparatus and methods disclosed herein and/or variations thereof may also be used with one or more of the following: vestibular devices (e.g., vestibular implants); visual devices (e.g., bionic eyes); visual prostheses (e.g., retinal implants); sensors; cardiac pacemakers; drug delivery systems; defibrillators; functional electrical stimulation devices; catheters; brain implants; seizure devices (e.g., devices for monitoring and/or treating epileptic events); sleep apnea devices; electroporation; etc. The concepts described herein and/or variations thereof can be applied to any of a variety of implantable medical devices comprising an implanted component configured to use magnetic induction to communicate transcutaneously with an external component (e.g., receive control signals from the external component and/or transmit sensor signals to the external component) while using magnetic induction to receive power from the external component. In still other implementations, the teachings detailed herein and/or variations thereof can be utilized in other types of systems beyond medical devices utilizing magnetic induction for both wireless power transfer and data communication. For example, such other systems can include one or more of the following: consumer products (e.g., smartphones; IoT devices) and electric vehicles (e.g., automobiles).

FIG.1is a perspective view of an example cochlear implant auditory prosthesis100implanted in a recipient in accordance with certain implementations described herein. The example auditory prosthesis100is shown inFIG.1as comprising an implanted stimulator unit120(e.g., an actuator) and an external microphone assembly124(e.g., a partially implantable cochlear implant). An example auditory prosthesis100(e.g., a totally implantable cochlear implant) in accordance with certain implementations described herein can replace the external microphone assembly124shown inFIG.1with a subcutaneously implantable assembly comprising an acoustic transducer (e.g., microphone), as described more fully herein.

As shown inFIG.1, the recipient normally has an outer ear101, a middle ear105, and an inner ear107. In a fully functional ear, the outer ear101comprises an auricle110and an ear canal102. An acoustic pressure or sound wave103is collected by the auricle110and is channeled into and through the ear canal102. Disposed across the distal end of the ear canal102is a tympanic membrane104which vibrates in response to the sound wave103. This vibration is coupled to oval window or fenestra ovalis112through three bones of middle ear105, collectively referred to as the ossicles106and comprising the malleus108, the incus109, and the stapes111. The bones108,109, and111of the middle ear105serve to filter and amplify the sound wave103, causing the oval window112to articulate, or vibrate in response to vibration of the tympanic membrane104. This vibration sets up waves of fluid motion of the perilymph within the cochlea140. Such fluid motion, in turn, activates tiny hair cells (not shown) inside the cochlea140. Activation of the hair cells causes appropriate nerve impulses to be generated and transferred through the spiral ganglion cells (not shown) and auditory nerve114to the brain (also not shown) where they are perceived as sound.

As shown inFIG.1, the example auditory prosthesis100comprises one or more components which are temporarily or permanently implanted in the recipient. The example auditory prosthesis100is shown inFIG.1with an external component142which is directly or indirectly attached to the recipient's body, and an internal component144which is temporarily or permanently implanted in the recipient (e.g., positioned in a recess of the temporal bone adjacent auricle110of the recipient). The external component142typically comprises one or more input elements/devices for receiving input signals at a sound processing unit126. The one or more input elements/devices can include one or more sound input elements (e.g., one or more external microphones124) for detecting sound and/or one or more auxiliary input devices (not shown inFIG.1) (e.g., audio ports, such as a Direct Audio Input (DAI); data ports, such as a Universal Serial Bus (USB) port; cable ports, etc.). In the example ofFIG.1, the sound processing unit126is a behind-the-ear (BTE) sound processing unit configured to be attached to, and worn adjacent to, the recipient's ear. However, in certain other implementations, the sound processing unit126has other arrangements, such as by an OTE processing unit (e.g., a component having a generally cylindrical shape and which is configured to be magnetically coupled to the recipient's head), 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.

The sound processing unit126of certain implementations includes a power source (not shown inFIG.1) (e.g., battery), a processing module (not shown inFIG.1) (e.g., comprising one or more digital signal processors (DSPs), one or more microcontroller cores, one or more application-specific integrated circuits (ASICs), firmware, software, etc. arranged to perform signal processing operations), and an external transmitter unit128. In the illustrative implementation ofFIG.1, the external transmitter unit128comprises circuitry that includes at least one external inductive communication coil130(e.g., a wire antenna coil comprising multiple turns of electrically insulated single-strand or multi-strand platinum or gold wire). The external transmitter unit128also generally comprises a magnet (not shown inFIG.1) secured directly or indirectly to the at least one external inductive communication coil130. The at least one external inductive communication coil130of the external transmitter unit128is part of an inductive radio frequency (RF) communication link with the internal component144. The sound processing unit126processes the signals from the input elements/devices (e.g., microphone124that is positioned externally to the recipient's body, in the depicted implementation ofFIG.1, by the recipient's auricle110). The sound processing unit126generates encoded signals, sometimes referred to herein as encoded data signals, which are provided to the external transmitter unit128(e.g., via a cable). As will be appreciated, the sound processing unit126can utilize digital processing techniques to provide frequency shaping, amplification, compression, and other signal conditioning, including conditioning based on recipient-specific fitting parameters.

The power source of the external component142is configured to provide power to the auditory prosthesis100, where the auditory prosthesis100includes a battery (e.g., located in the internal component144, or disposed in a separate implanted location) that is recharged by the power provided from the external component142(e.g., via a transcutaneous energy transfer link). The transcutaneous energy transfer link is used to transfer power and/or data to the internal component144of the auditory prosthesis100. 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 component142to the internal component144. During operation of the auditory prosthesis100, the power stored by the rechargeable battery is distributed to the various other implanted components as needed.

The internal component144comprises an internal receiver unit132, a stimulator unit120, and an elongate stimulation assembly118. In some implementations, the internal receiver unit132and the stimulator unit120are hermetically sealed within a biocompatible housing, sometimes collectively referred to as a stimulator/receiver unit. The internal receiver unit132comprises at least one internal inductive communication coil136(e.g., a wire antenna coil comprising multiple turns of electrically insulated single-strand or multi-strand platinum or gold wire), and generally, a magnet (not shown inFIG.1) fixed relative to the at least one internal inductive communication coil136. The at least one internal inductive communication coil136receives power and/or data signals from the at least one external inductive communication coil130via a transcutaneous energy transfer link (e.g., an inductive RF link). The stimulator unit120generates stimulation signals (e.g., electrical stimulation signals; optical stimulation signals) based on the data signals, and the stimulation signals are delivered to the recipient via the elongate stimulation assembly118.

The elongate stimulation assembly118has a proximal end connected to the stimulator unit120, and a distal end implanted in the cochlea140. The stimulation assembly118extends from the stimulator unit120to the cochlea140through the mastoid bone119. In some embodiments, the stimulation assembly118can be implanted at least in the basal region116, and sometimes further. For example, the stimulation assembly118can extend towards an apical end of the cochlea140, referred to as the cochlea apex134. In certain circumstances, the stimulation assembly118can be inserted into the cochlea140via a cochleostomy122. In other circumstances, a cochleostomy can be formed through the round window121, the oval window112, the promontory123, or through an apical turn147of the cochlea140.

The elongate stimulation assembly118comprises a longitudinally aligned and distally extending array146(e.g., electrode array; contact array) of stimulation elements148(e.g., electrical electrodes; electrical contacts; optical emitters; optical contacts). The stimulation elements148are longitudinally spaced from one another along a length of the elongate body of the stimulation assembly118. For example, the stimulation assembly118can comprise an array146comprising twenty-two (22) stimulation elements148that are configured to deliver stimulation to the cochlea140. Although the array146of stimulation elements148can be disposed on the stimulation assembly118, in most practical applications, the array146is integrated into the stimulation assembly118(e.g., the stimulation elements148of the array146are disposed in the stimulation assembly118). As noted, the stimulator unit120generates stimulation signals (e.g., electrical signals; optical signals) which are applied by the stimulation elements148to the cochlea140, thereby stimulating the auditory nerve114.

WhileFIG.1schematically illustrates an auditory prosthesis100utilizing an external component142comprising an external microphone124, an external sound processing unit126, and an external power source, in certain other implementations, one or more of the microphone124, sound processing unit126, and power source are implantable on or within the recipient (e.g., within the internal component144). For example, the auditory prosthesis100can have each of the microphone124, sound processing unit126, 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 prosthesis100can 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”).

FIGS.2A-2Gschematically illustrate planar projection views of various example apparatus200in accordance with certain implementations described herein. The apparatus200comprises at least one first circuit210configured to generate a first time-varying magnetic field212for magnetic induction power transfer to a device. The apparatus200further comprises at least one second circuit220configured to generate and/or receive a second time-varying magnetic field (not shown) for magnetic induction data transfer to and/or from the device. The apparatus200further comprises at least one third circuit230configured to generate a third time-varying magnetic field232in response to a time-varying electric current242. The third time-varying magnetic field232is configured to at least partially inhibit degradation of said data transfer from the first time-varying magnetic field212. The apparatus200further comprises at least one fourth circuit240configured to generate the time-varying electric current242in response to a received portion of the first time-varying magnetic field212or in response to a signal indicative of the first time-varying magnetic field212.

In certain implementations, the apparatus200is an external portion of a medical system (e.g., a portion of the medical system that is not implanted on or within the recipient) and the device comprises an implanted portion of the medical system (e.g., a portion implanted on or within a recipient). For example, the apparatus200can comprise an external portion (e.g., a sound processing unit126) of an auditory prosthesis100(e.g., a cochlear implant system). As schematically illustrated byFIGS.2A-2G, the apparatus200of certain implementations comprises a housing250(e.g., polymer; plastic) configured to be worn externally by the recipient and containing the at least one first circuit210, the at least one second circuit220, the at least one third circuit230, and the at least one fourth circuit240. The housing250of certain implementations is configured to further contain at least one power source (e.g., battery) and processing circuitry configured to receive and process data signals to be communicated to the implanted portion of the medical device via the at least one second circuit220. For example, for an auditory prosthesis100, the processing circuitry can be configured to process data signals received from a microphone124and to generate encoded data signals (e.g., utilizing digital processing techniques for frequency shaping, amplification, compression, and/or other signal conditioning, including conditioning based on recipient-specific fitting parameters) which are provided to the implanted portion of the auditory prosthesis100via the at least one second circuit220.

The housing250of certain implementations is configured to be held in place externally to the recipient during power transfer (e.g., using the at least one first circuit210) and data transfer (e.g., using the at least one second circuit220). For example, as schematically illustrated byFIG.2A, the apparatus200can further comprise at least one magnet260(e.g., within the housing250). The at least one magnet260can be configured to create an attractive magnetic force with a corresponding magnetic material (e.g., a magnet) of the implanted portion of the medical system, the attractive magnetic force configured to hold the apparatus200in an operative position relative to the implanted portion. When the apparatus200is in the operative position, the at least one first circuit210forms a magnetic inductive RF power transfer link (e.g., for transcutaneous power transfer) with corresponding circuitry of the implanted portion, and the at least one second circuit220forms a magnetic inductive RF data transfer link (e.g., for transcutaneous data transfer) with corresponding circuitry of the implanted portion.

In certain implementations, the at least one first circuit210comprises at least one electrically conductive power transfer coil214configured to be operationally coupled by magnetic induction to the corresponding circuitry (e.g., at least one electrically conductive power transfer coil) of the implanted portion. For example, the power transfer coil214can comprise an electrically conductive conduit (e.g., wire; conductive trace on a printed circuit board). The at least one power transfer coil214is configured to receive a time-varying electric current (e.g., from controller circuitry of the apparatus200) and to generate the first time-varying magnetic field212(e.g., an inductive power transfer magnetic field) that transfers power via magnetic induction to the corresponding circuitry of the implanted portion. In certain implementations, the first time-varying (e.g., alternating) magnetic field212has a frequency in a range of 100 kHz to 100 MHz (e.g., 5 MHz; 6.78 MHz; 12 MHz; 49 MHz). In certain implementations in which the apparatus200comprises an external portion of a medical system, the power transfer is in a range of 1 mW to 500 mW. In certain other implementations, the power transfer in a range of 1 W to 1 kW (e.g., for consumer devices; for IoT devices) or in a range of 1 kW to 100 kW (e.g., for vehicles).

In certain implementations, the power transfer coil214of the at least one first circuit210has one or more (e.g., 2, 3, 4, 5, or more) windings, a generally planar, generally circular shape (e.g., having an inner diameter in a range of 10 mm to 50 mm), and bounds a region having an area in a range of 70 mm2to 850 mm2. Other shapes (e.g., non-planar; elliptical; square; rectangular; polygonal; geometric; irregular; symmetric; non-symmetric) and sizes of the power transfer coil214are also compatible with certain implementations described herein.FIG.2Ashows the power transfer coil214encircling the magnet260(e.g., the magnet260and the power transfer coil214are substantially concentric and/or substantially planar with one another; the magnet260having a projection in a projection plane that is within a projection of the power transfer coil214in the projection plane). In certain other implementations, the power transfer coil214is positioned at other positions (e.g., alongside; non-concentric) relative to the magnet260.

In certain implementations, the at least one second circuit220comprises at least one antenna224configured to be operationally coupled by magnetic induction to the corresponding circuitry (e.g., at least one antenna) of the implanted portion. The at least one antenna224is configured to transmit data to the corresponding circuitry via the second time-varying magnetic field (e.g., by generating a data-encoded time-varying magnetic field in response to a data-encoded time-varying electric signal from controller circuitry of the apparatus200) and/or to receive data from the corresponding circuitry via the second time-varying magnetic field (e.g., by receiving a data-encoded time-varying magnetic field from the corresponding circuitry and generating a data-encoded time-varying electric signal that is provided to the controller circuitry of the apparatus200). For example, the at least one antenna224can comprise an electrically conductive conduit (e.g., a conductive coil having an axis and wound around a ferrite rod having a length that is in a range of 4 mm to 10 mm and a diameter in a range of 1.5 mm to 3 mm; a conductive coil having an axis and wound around an air-filled region). In certain implementations, the data-encoded time-varying (e.g., alternating) magnetic field generated or received by the at least one second circuit220has a frequency (e.g., in a range of 10 MHz to 20 MHz) and the power of the data transfer is orders of magnitude less than the power transferred by the at least one first circuit210(e.g., the power of the data transfer is on the order of nW or μW).

In certain implementations, the at least one third circuit230comprises at least one cancellation coil234in proximity to the at least one antenna224of the at least one second circuit220(e.g., the cancellation coil234bounds a region containing the antenna224). For example, the cancellation coil234can comprise an electrically conductive conduit (e.g., wire; conductive trace on a printed circuit board). As schematically illustrated byFIG.2A, the cancellation coil234can encircle the antenna224(e.g., the antenna224and the cancellation coil234are substantially concentric and/or substantially planar with one another; the antenna224has a projection in a projection plane that is within a projection of the cancellation coil234in the projection plane) and each of the antenna224and the cancellation coil234are outside a region bounded by the power transfer coil214(e.g., each of the antenna224and the cancellation coil234has a projection in a projection plane that is outside a projection of the power transfer coil214in the projection plane). In certain implementations, the cancellation coil234has one or more (e.g., 2, 3, 4, 5, or more) windings, a generally planar, generally circular shape (e.g., having an inner diameter in a range of 2 mm to 20 mm), and bounds a region having an area in a range of 3 mm2to 300 mm2. Other shapes (e.g., non-planar; elliptical; square; rectangular; polygonal; geometric; irregular; symmetric; non-symmetric) and sizes of the cancellation coil234are also compatible with certain implementations described herein. In certain implementations in which the antenna224comprises a conductive coil having an axis and wound around either a ferrite rod or an air-filled region, the antenna224can be positioned with the axis of the antenna224perpendicular to an axis of the cancellation coil234(e.g., the axis of the antenna224parallel to a printed circuit board on which the cancellation coil234is formed).

In certain implementations, the at least one cancellation coil234is configured to generate the third time-varying magnetic field232(e.g., a protection magnetic field) in response to a time-varying electric current242received by the at least one cancellation circuit234from the at least one fourth circuit240. The third time-varying magnetic field232is configured to at least partially inhibit (e.g., reduce; cancel; prevent; avoid; minimize) degradation of the data transfer between the at least one second circuit220and the corresponding circuitry of the implanted portion, the degradation due to the first time-varying magnetic field212from the at least one first circuit210. For example, the third time-varying magnetic field232is configured to be in opposition to (e.g., to be in opposite phase with) at least a portion of the first time-varying magnetic field212such that the third time-varying magnetic field232destructively interferes with at least the portion of the first time-varying magnetic field212within the region bounded by the at least one cancellation coil234(e.g., at the at least one antenna224of the at least one second circuit220).

In certain implementations, the destructive interference of the first time-varying magnetic field212within the region by the third time-varying magnetic field232at least partially reduces (e.g., counteracts; opposes; cancels; minimizes) a magnitude of the superposition of the first and third time-varying magnetic fields212,232(e.g., net magnetic field) within the region bounded by the at least one cancellation coil234. For example, the third time-varying magnetic field232can have a substantially opposite phase to that of the first time-varying magnetic field212and can have a magnitude at the antenna224that is substantially equal to the magnitude of the first time-varying magnetic field212at the antenna224(e.g., substantially total destructive interference at the antenna224; complete cancellation at the antenna224; substantially zero net magnetic field). In certain implementations, the third time-varying magnetic field232at the antenna224has a magnitude in at least one direction (e.g., substantially perpendicular to the plane of the cancellation coil234) that is substantially equal and opposite to the magnitude of the first time-varying magnetic field212at the antenna224in the at least one direction (e.g., such that the net magnetic field from the superposition of the first and third time-varying magnetic fields212,232in the direction substantially perpendicular to the plane of the cancellation coil234is substantially zero).

In certain implementations, examples of which are schematically illustrated inFIGS.2A-2F, the at least one fourth circuit240comprises at least one pick-up coil244in series electrical communication with the at least one third circuit230. For example, the at least one pick-up coil244can comprise an electrically conductive conduit (e.g., wire; conductive trace on a printed circuit board). As schematically illustrated byFIGS.2A-2F, the at least one pick-up coil244can be in series electrical communication with the cancellation coil234of the at least one third circuit230. The at least one pick-up coil244is configured to generate (e.g., passively) the time-varying electric current242via magnetic induction resulting from the received portion of the first time-varying magnetic field212and to provide the time-varying electric current242to the cancellation coil234. For example, the at least one pick-up coil244can be spaced away from the cancellation coil234and in electrical communication with the cancellation coil234via electrically conductive conduits (e.g., wires; conductive traces on a printed circuit board).

In certain implementations, the pick-up coil244has one or more (e.g., 2, 3, 4, 5, or more) windings, a generally planar, generally circular shape (e.g., having an inner diameter in a range of 2 mm to 50 mm), and bounds a region having an area in a range of 3 mm2to 850 mm2. Other shapes (e.g., non-planar; elliptical; square; rectangular; polygonal; geometric; irregular; symmetric; non-symmetric) and sizes of the pick-up coil244are also compatible with certain implementations described herein.

As described by Lenz's law, a changing magnetic field will induce currents to flow within a conductor exposed to the changing magnetic field, the currents generating secondary magnetic fields that oppose the changing magnetic field. Therefore, a cancellation coil234exposed to the first time-varying magnetic field212will generate magnetic fields that oppose the first time-varying magnetic field212within the cancellation coil234. However, due to the resistance and imperfections of the cancellation coil234, this opposition is only partial and the first time-varying magnetic field212is only partially canceled by the secondary magnetic fields generated by the induced currents in the cancellation coil234.

In certain implementations, the at least one pick-up coil244is configured to generate and provide sufficient electric current to the cancellation coil234such that the cancellation coil234generates the third time-varying magnetic field232with sufficient magnitude to produce a predetermined reduction of a magnitude of the superposition of the first and third time-varying magnetic fields212,232within the region bounded by the cancellation coil234. In certain such implementations, the characteristics of the at least one cancellation coil234and/or the at least one pick-up coil244are selected such that the at least one cancellation coil234generates the third time-varying magnetic field232in response to the electric current from the at least one pick-up coil244(e.g., the electric current magnetically induced in the at least one pick-up coil244by the first time-varying magnetic field212is greater than the electric current magnetically induced in the cancellation coil234by the first time-varying magnetic field212). Examples of such characteristics include but are not limited to one or more of the following: the relative positions of the cancellation coil234and the pick-up coil244relative to the power transfer coil212(e.g., which determine the magnitudes of the time-varying magnetic field212at the cancellation coil234and at the pick-up coil244); the sizes (e.g., areas) of the cancellation coil234and/or the pick-up coil244; and the number of windings of the cancellation coil234and/or the pick-up coil244. Various example implementations are schematically shown inFIGS.2A-2F, which are described below in reference to the equations (e.g., for planar coils) for magnetic flux: Φ(t)=ΦB(t)dA≅NAB(t) and magnetically induced current:

I⁡(t)=1R⁢d⁢Φ⁡(t)dt,
where Φ(t) is the time-varying magnetic flux flowing through the area of the coil, B(t) is the time-varying magnetic field at the coil, R is the resistance of the coil, N is the number of windings of the coil, and A is the area of the coil.

For example, as schematically illustrated byFIG.2A, the pick-up coil244is outside a region encircled by the at least one power transfer coil214(e.g., the pick-up coil244has a projection in a projection plane that is outside a projection of the power transfer coil214in the projection plane), and the pick-up coil244and the cancellation coil234have substantially equal areas (e.g., substantially equal shapes and sizes) and numbers of windings, and the pick-up coil244is positioned closer to the power transfer coil214than is the cancellation coil234(e.g., a distance between the centers of the pick-up coil244and the power transfer coil214is less than a distance between the centers of the cancellation coil234and the power transfer coil214). Because the pick-up coil244is closer to the power transfer coil214, the magnitude of the portion of the first time-varying magnetic field212B(t) flowing through the area A of the pick-up coil244is greater than the magnitude of the portion of the first time-varying magnetic field212B(t) flowing through the area A of the cancellation coil234, such that the cumulative electric current I(t) flowing through the cancellation coil234generates the third time-varying magnetic field232.

For another example, as schematically illustrated byFIG.2B, the pick-up coil244is outside a region encircled by the at least one power transfer coil214(e.g., the pick-up coil244has a projection in a projection plane that is outside a projection of the power transfer coil214in the projection plane), and the pick-up coil244is positioned at a substantially equal distance from the power transfer coil214as is the cancellation coil234(e.g., the distance between the centers of the pick-up coil244and the power transfer coil214is substantially equal to the distance between the centers of the cancellation coil234and the power transfer coil214), but the pick-up coil244has a larger area A and/or a larger number of windings N than does the cancellation coil234.

For another example, as schematically illustrated byFIG.2C, the pick-up coil244is within a region encircled by the at least one power transfer coil214(e.g., the pick-up coil244and the power transfer coil214are substantially concentric and/or substantially planar with one another; the pick-up coil244has a projection in a projection plane that is within a projection of the power transfer coil214in the projection plane). Because the pick-up coil244is within the inner area of the power transfer coil214, the magnitude of the time-varying magnetic flux from the portion of the first time-varying magnetic field212flowing through the area of the pick-up coil244is greater than the magnitude of the time-varying magnetic flux from the portion of the first time-varying magnetic field212flowing through the area of the cancellation coil234, such that the electric current flowing through the cancellation coil234generates the third time-varying magnetic field232.

For another example, as schematically illustrated byFIG.2D, the at least one pick-up coil244comprises a plurality of pick-up coils244in series electrical communication with the cancellation coil234, spaced away from the cancellation coil234and one another, and outside a region encircled by the at least one power transfer coil214(e.g., the pick-up coils244have projections in a projection plane that are outside a projection of the power transfer coil214in the projection plane). Because the cumulative areas A of the pick-up coils244is greater than the area A of the cancellation coil234, the magnitude of the time-varying magnetic flux from the portion of the first time-varying magnetic field212flowing through the cumulative areas of the pick-up coil244is greater than the magnitude of the time-varying magnetic flux from the portion of the first time-varying magnetic field212flowing through the area of the cancellation coil234, such that the electric current flowing through the cancellation coil234generates the third time-varying magnetic field232.

For another example, as schematically illustrated byFIG.2E, the pick-up coil244is outside a region encircled by the at least one power transfer coil214(e.g., the pick-up coil244has a projection in a projection plane that is outside a projection of the power transfer coil214in the projection plane), is closer to the at least one power transfer coil214than is the cancellation coil234, and has a larger area and/or a larger number of windings than does the cancellation coil234.

For another example, as schematically illustrated byFIG.2F, the at least one pick-up coil244comprises a pair of pick-up coils244a,244bin series electrical communication with one another and with the cancellation coil234. A first pick-up coil244ais outside a region encircled by the at least one power transfer coil214(e.g., the first pick-up coil244ahas a projection in a projection plane that is outside a projection of the power transfer coil214in the projection plane) and a second pick-up coil244bis inside the region encircled by the at least one power transfer coil214(e.g., the second pick-up coil244bhas a projection in a projection plane that is inside a projection of the power transfer coil214in the projection plane). In certain implementations, the area of the first pick-up coil244aand the area of the second pick-up coil244bare substantially equal to one another and/or the number of windings of the first pick-up coil244aand the number of windings of the second pick-up coil244bare substantially equal to one another. The direction of the magnetic field within the first pick-up coil244ais substantially opposite to the direction of the magnetic field within the second pick-up coil244bsince the first pick-up coil244ais within the region encircled by the power transfer coil214and the second pick-up coil244bis outside the region encircled by the power transfer coil214. The first pick-up coil244aand the second pick-up coil244bhave a cross-over portion therebetween to compensate for these different directions of the magnetic fields, such that the electrical current induced in one of the first and second pick-up coils244a,244bis in the clockwise direction and the electrical current induced in the other of the first and second pick-up coils244a,244bis in the counterclockwise direction (e.g., the two electrical currents do not oppose one another when provided to the cancellation coil234).

FIG.3schematically illustrates an example apparatus200in accordance with certain implementations described herein. The apparatus200ofFIG.3comprises a first circuit210comprising a power transfer coil214, a second circuit220comprising an antenna224, a third circuit230comprising a cancellation coil234, and a fourth circuit240comprising a pick-up coil244. The power transfer coil214ofFIG.3encircles the magnet260, and the pick-up coil244ofFIG.3comprises multiple windings while the cancellation coil234comprises a single winding. In addition, each of the power transfer coil214, the cancellation coil234, and the pick-up coil244is substantially planar and are substantially planar with one another (e.g., each of the coils214,234,244are substantially in the X-Y plane). In certain other implementations, two or more of the power transfer coil214, the cancellation coil234, and the pick-up coil244are not substantially planar with one another and/or are not substantially planar with one another (e.g., are spaced above or below the X-Y plane).

FIG.4Aschematically illustrates a calculation of the first time-varying magnetic field212generated by the power transfer coil214without either the cancellation coil234or the pick-up coil244. The lines generally encircling the power transfer coil214represent different magnitudes of the first time-varying magnetic field212along the Z direction (perpendicular to the X-Y plane) generated by the power transfer coil214in the X-Y plane.FIG.4Bschematically illustrates a calculation of the superposition of the first time-varying magnetic field212generated by the power transfer coil214and the third time-varying magnetic field232with both the cancellation coil234and the pick-up coil244in accordance with certain implementations described herein. A comparison ofFIGS.4A and4Billustrates that the magnitudes along the Z direction of the superposition of the first time-varying magnetic field212and the third time-varying magnetic field232in the region of the antenna224within the area bounded by the cancellation coil234is reduced by the cancellation coil234and the pick-up coil244.

In certain implementation, an example of which is schematically illustrated inFIG.2E, the at least one fourth circuit240comprises at least one sensor246and control circuitry248(e.g., a microprocessor; an application-specific integrated circuit; an amplifier) in series electrical communication with the at least one third circuit230(e.g., the cancellation coil234). The at least one sensor246can comprise a sensor coil comprising an electrically conductive conduit (e.g., wire; conductive trace on a printed circuit board), the sensor coil configured to generate (e.g., passively) a sensor signal via magnetic induction resulting from the received portion of the first time-varying magnetic field212. The sensor signal is generated in response to the first time-varying magnetic field212at the at least one sensor246, and is indicative of the first time-varying magnetic field212. The control circuitry248is configured to respond to the sensor signal by generating (e.g., actively) the time-varying electric current242, which is indicative of the first time-varying magnetic field212at the at least one second circuit220. In certain implementations, the control circuitry248is configured to receive electrical power from the same power source of the apparatus200that powers the at least one first circuit210, while in certain other implementations, the control circuitry248further comprise a separate power source (e.g., a battery) from which the control circuitry248receives electrical power. For example, the control circuitry248can determine, in response to the sensor signal, an appropriate magnitude and/or phase of the time-varying electric current242to be provided to the cancellation coil234such that the resultant third time-varying magnetic field232at the antenna224destructively interferes with the first time-varying magnetic field212at the antenna224. In certain implementations, the at least one sensor246is positioned at or near the antenna224such that the sensor signal is indicative of the first time-varying magnetic field212at or near the antenna224, and the control circuitry248is configured to use the sensor signal as a feedback signal to optimize (e.g., “zero out”) the first time-varying magnetic field212at or near the antenna224while the first time-varying magnetic field212elsewhere is configured to provide the desired amount of power transfer.

In certain implementations, the at least one fourth circuit240comprises at least a portion of the at least one first circuit210. For example, instead of the at least one sensor246ofFIG.2G, at least a portion of the at least one first circuit210can be configured to generate a signal indicative of the first time-varying magnetic field212and to provide the signal to the control circuitry248of the fourth circuit240. The control circuitry248can be configured to respond to the signal by generating (e.g., actively) the time-varying electric current242. In certain such implementations, the third time-varying magnetic field232and the first time-varying magnetic field212have the same frequency content (e.g., the same phase and the same shape) as one another. The magnitude of the third time-varying magnetic field232can be adjusted (e.g., optimized) by controlling (e.g., limiting) the time-varying electric current242provided to the at least one third circuit230(e.g., by controlling the gain of an amplifier; by using a series resistance; etc.).

FIG.5is a flow diagram of an example method500in accordance with certain implementations described herein. In an operational block510, the method500comprises transferring power via a first magnetic induction link in a first region. For example, the first magnetic induction link can utilize the at least one first circuit210(e.g., energizing the first magnetic induction link by transmitting electric current along the power transfer coil214to transfer power via magnetic induction to a corresponding circuit).

In an operational block520, the method500further comprises transferring data via a second magnetic induction link in a second region, the data transfer simultaneous with the power transfer. For example, the second magnetic induction link can energize the at least one second circuit220(e.g., transmitting electric current along the antenna224) at the same time that the first magnetic induction link is energized. In certain implementations, the second region is within the first region (e.g., the power transfer coil214encircles the antenna224), while in certain other implementations, the second region is separate from the first region (e.g., the power transfer coil214does not encircle the antenna224; the antenna224is alongside the power transfer coil214).

In an operational block530, the method500further comprises generating an electric current indicative of a first magnetic field from the first magnetic induction link. In certain implementations, the electric current is generated by the at least one fourth circuit240. For example, the electric current can be magnetically induced in the pick-up coil244(e.g., using the first magnetic field to magnetically induce the electric current in the pick-up coil244). For another example, the electric current can be generated by magnetically inducing a sensor signal (e.g., using a sensor coil246) indicative of the first magnetic field and using circuitry (e.g., control circuitry248) to generate the electric current in response to the sensor signal.

In an operational block540, the method500further comprises generating, in response to the electric current, a second magnetic field in the second region in opposition to at least a portion of the first magnetic field within the second region. In certain implementations, the second magnetic field is generated via magnetic induction by causing the electric current (e.g., generated by the at least one fourth circuit240) to flow in a path bounding the second region. For example, the electric current can flow along the at least one third circuit230(e.g., cancellation coil236), with the second magnetic field within the second region (e.g., bounded by the cancellation coil236) in opposition to the first magnetic field along a direction substantially perpendicular to the cancellation coil236. In certain implementations, the second magnetic field is configured to destructively interfere with at least a portion of the first magnetic field within the second region. For example, the second magnetic field can substantially totally destructively interfere with the first magnetic field substantially perpendicular to a plane of the cancellation coil236in the second region (e.g., substantially complete cancellation of the Z component of the net magnetic field).

FIGS.6A-6Bschematically illustrate two example apparatus600configured to reduce degradation of various types of low-power systems that are sensitive to magnetic fields in accordance with certain implementations described herein. For example, certain implementations of the apparatus200ofFIGS.2A-2Gas described herein can reduce degradation of a low-power magnetic induction data transfer link due to a nearby high-power magnetic induction power transfer link.

The apparatus600comprises magnetic induction power transfer circuitry610(e.g., at least one first circuit210) configured to generate an induction power transfer magnetic field612(e.g., the first time-varying magnetic field212). The apparatus600further comprises at least one circuit620(e.g., at least one second circuit220) that is sensitive to the induction power transfer magnetic field612. The apparatus600further comprises protection circuitry630(e.g., at least one third circuit230) configured to generate a protection magnetic field632(e.g., the third time-varying magnetic field232) in response to an electric current642(e.g., the time-varying electric current242). The protection magnetic field632is configured to at least partially protect the at least one circuit620from the induction power transfer magnetic field612. The apparatus600further comprises circuitry640(e.g., the at least one fourth circuit240) configured to generate the electric current642in response to the induction power transfer magnetic field612or in response to a signal indicative of the induction power transfer magnetic field612. In certain implementations, the at least one circuit620comprises at least one antenna224of a data transfer link (e.g., as described above with regard toFIGS.2A-2G). As schematically illustrated inFIG.6A, the circuitry640can be separate from the magnetic induction power transfer circuitry610. As schematically illustrated inFIG.6B, the circuitry640can comprise at least a portion of the magnetic induction power transfer circuitry610.

In certain implementations, the at least one circuit620comprises a sensor in various contexts (e.g., medical devices; consumer devices; IoT devices; vehicles) that is sensitive to interference from the induction power transfer magnetic field612of the magnetic induction power transfer circuitry610of the device. For example, the sensor can be a microphone of an auditory prosthesis device or of any other device (e.g., consumer device; IoT device) in which the microphone is vulnerable to magnetic interference from the magnetic induction power transfer circuitry610of the device.

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 conventional cochlear implants, 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 a signal pathway between the stimulation assembly and the recipient during implantation (e.g., insertion) of the stimulation assembly.

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 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.