Patent Application
20250001175
The present disclosure relates generally to implantable cochlear stimulation (or “ICS”) systems.
ICS systems are used to help the profoundly deaf perceive a sensation of sound by directly exciting the intact auditory nerve with controlled impulses of electrical current. Ambient sound pressure waves are picked up by an externally worn microphone and converted to electrical signals. The electrical signals, in turn, are processed by a sound processor, converted to a pulse sequence having varying pulse widths, rates and/or amplitudes, and transmitted to an implanted receiver circuit of the ICS system. The implanted receiver circuit is connected to an implantable electrode array that has been inserted into the cochlea of the inner ear, and electrical stimulation current is applied to varying electrode combinations to create a perception of sound. The electrode array may, alternatively, be directly inserted into the cochlear nerve without residing in the cochlea. A representative ICS system is disclosed in U.S. Pat. No. 5,824,022, which is entitled “Cochlear Stimulation System Employing Behind-The-Ear Sound processor With Remote Control” and incorporated herein by reference in its entirety. Examples of commercially available ICS sound processors include, but are not limited to, the Harmony™ BTE sound processor, the Naida™ Cl Q Series sound processor and the Neptune™ body worn sound processor, which are available from Advanced Bionics.
As alluded to above, some ICS systems include an implantable cochlear stimulator (or “cochlear implant”), a sound processor unit (e.g., a body worn processor or behind-the-ear processor), and a microphone that is part of, or is in communication with, the sound processor unit. The cochlear implant communicates with the sound processor unit and, some ICS systems include a headpiece that is in communication with both the sound processor unit and the cochlear implant. The headpiece communicates with the cochlear implant by way of a transmitter (e.g., an antenna) on the headpiece and a receiver (e.g., an antenna) on the implant. Optimum communication is achieved when the transmitter and the receiver are aligned with one another. To that end, the headpiece and the cochlear implant may include respective positioning magnets that are attracted to one another, and that maintain the position of the headpiece transmitter over the implant receiver. The implant magnet may, for example, be located within a pocket in the cochlear implant housing. The skin and subcutaneous tissue that separates the headpiece magnet and implant magnet is sometimes referred to as the “skin flap,” which is frequently 3 mm to 11 mm thick.
The present inventors have determined that conventional cochlear implants and stimulation systems are susceptible to improvement. For example, the magnet in some conventional cochlear implant is a disk-shaped axially magnetized magnet that has north and south magnetic dipoles which are aligned in the axial direction of the disk. Such magnets are not compatible with magnetic resonance imaging (“MRI”) systems, and may have to be surgically removed from the cochlear the implant prior to the MRI procedure and then surgically replaced thereafter. Other cochlear implants include a diametrically magnetized disk-shaped magnet that is rotatable relative to the remainder of the implant about its central axis, and that has a N—S orientation which is perpendicular to the central axis. The present inventors have determined that diametrically magnetized disk-shaped magnets are less than optimal because a dominant magnetic field, such as the MRI magnetic field, that is misaligned by at least 30° or more from the N-S direction of the magnet may demagnetize the magnet or generate an amount of torque on the magnet that is sufficient to dislodge or reverse the magnet and/or dislocate the associated cochlear implant and/or cause excessive discomfort to the patient.
More recently, cochlear implants with MRI-compatible magnet assemblies have been introduced. The MRI-compatible magnet assemblies have a metal case defining a central axis, a frame within the case that is rotatable relative to the case about the central axis, and three or more elongate diametrically magnetized magnets that are rotatable about their respective longitudinal axis relative to the frame. This combination allows the magnets to align with three-dimensional (3D) MRI magnetic fields, regardless of field direction, which results in very low amounts of torque on the magnets. The case is hermetically sealed by welding (e.g., laser welding) the case cover to the case base after the frame and magnets are positioned therein. Examples of such MRI-compatible magnet assemblies may be found in U.S. Pat. Nos. 9,919,154, 10,463,849, and 10,532,209. Another proposed magnet assembly, which includes a single elongate magnet, is described in PCT Pat. Pub. No. 2020/092185 A1.
Although such MRI-compatible magnet assemblies have proven to be a significant advance in the art, the present inventors have determined that they are susceptible to improvement. For example, although plastic frames (e.g., injection molded plastic frames) are desirable due to their relatively low cost, as compared to metal frames, plastic frames are susceptible to being damaged by the heat associated with the welding of the case cover to the case base.
A magnet assembly in accordance with at least one of the present inventions may include a case defining a central axis and including first and second end walls and a side wall, with an inner surface, between the first and second end walls, a frame within the case and rotatable about the central axis of the case, a plurality of diametrically magnetized magnets that are located in the frame, that each define a longitudinal axis and a N-S direction, and that are rotatable about the longitudinal axis relative to the frame, and a ring, defining an outer surface, between the frame and the case side wall and offset from the case side wall such that a first air gap is located between the inner surface of the case side wall and the outer surface of the ring. The present inventions also include cochlear implants including such a magnet assembly.
A magnet assembly in accordance with at least one of the present inventions may include a case defining a central axis and including a base and a cover that are secured to one another with weld, a frame within the case and rotatable about the central axis of the case, a plurality of diametrically magnetized magnets that are located in the frame, that each define a longitudinal axis and a N-S direction, and that are rotatable about the longitudinal axis relative to the frame, and means for thermally insulating the frame from heat associated with welding the base and cover to one another. The present inventions also include cochlear implants including such a magnet assembly.
A method in accordance with at least one of the present inventions may includes placing a frame and a plurality of diametrically magnetized magnets into a case that includes a base with a first end wall and a first side wall portion and cover with a second end wall and a second side wall portion, the first and second side wall portions defining respective inner surfaces, creating an air gap between the frame and the inner surfaces of the case side wall portions, and welding the side wall portions to one another after the frame and the plurality of diametrically magnetized magnets have been placed into the case and the air gap has been created.
There are a number of advantages associated with such magnet assemblies and methods. By way of example, but not limitation, the air gap or other thermal insulation protects the frame and magnets from heat associated with the welding of the case.
The above described and many other features of the present inventions will become apparent as the inventions become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.
Detailed descriptions of the exemplary embodiments will be made with reference to the accompanying drawings.
The following is a detailed description of the best presently known modes of carrying out the inventions. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the inventions.
As illustrated for example in
The case 102 in the exemplary magnet assembly 100 is disk-shaped and defines a central axis A1, which is also the central axis of the frame 108. The frame 108 is rotatable relative to the case 102 about the central axis A1 over 360°. The magnets 110 rotate with the frame 108 about the central axis A1. Each magnet 110 is also rotatable relative to the frame 108 about its own longitudinal axis A2 (also referred to as “axis A2”) over 360°. In the exemplary implementation illustrated in
The exemplary case 102 is not limited to any particular configuration, size or shape. In the illustrated implementation, the case 102 is a two-part structure that includes the base 104 and the cover 106 which are secured to one another in such a manner that a hermetic seal is formed between the cover and the base. Suitable techniques for securing the cover 106 to the base 104 include, for example, seam welding with a laser welder. With respect to materials, the case 102 may be formed from biocompatible paramagnetic metals, such as titanium or titanium alloys. In particular, exemplary metals include commercially pure titanium (e.g., Grade 2) and the titanium alloy Ti-6Al-4V (Grade 5), while exemplary metal thicknesses may range from 0.20 mm to 0.25 mm. With respect to size and shape, the case 102 may have an overall size and shape similar to that of conventional cochlear implant magnets so that the magnet assembly 100 can be substituted for a conventional magnet in an otherwise conventional cochlear implant. The case 102 may also have an overall size and shape that is larger than that of conventional cochlear implant magnets in other embodiments. In some implementations, the diameter that may range from about 9 mm to about 16 mm and the thickness may range from about 1.5 mm to about 3.5 mm. The diameter of the case 102 in the illustrated embodiment is about 12.9 mm and the thickness is about 3.1 mm. As used herein, the word “about” means±10%.
Referring more specifically to
The magnets 110 in the exemplary magnet assembly 100 are elongate diametrically magnetized magnets, two of which are relatively long and two of which are relatively short. The exemplary magnets 110 are circular in a cross-section that is perpendicular to the longitudinal axis A2 and, in some instances, may have rounded corners (as shown). Suitable materials for the magnets 110 include, but are not limited to, neodymium-boron-iron and samarium-cobalt. The magnetic attraction force between the spaced magnets 110 is such that the magnets will remain substantially aligned with one another in the N-S direction, as shown in
To that end, and referring to
Turning to
The exemplary case 102, as noted above, consists of a base 104 and a cover 106 that may be secured to one another by a weld 128 that extends around the circumference of the case. The weld 128 may be formed by a laser welding process, or other welding processes, after the frame 108 and magnets 110 have been positioned within the case 102. The frame 108, as well as magnets within the frame, may be protected from the laser beam itself, heat from the laser beam, and/or heat from the portions of the case 102 that have been heated to their melting point during the welding process by the exemplary thermal insulation arrangement 130 illustrated in
To that end, the completed case 102 has end walls 136 and 138, a side wall 140, and first and second curved walls 142 and 144 that respectively connect the first and second end walls to the side wall. The end and side walls 136-140 are planar in planes defined by the axis A1 (
The air gaps 132, 133 and 134 are thermally insulative, and thereby prevent heat associated with the formation of the weld 128 from damaging the frame 108 and magnets 110, because the thermal conductivity of air is significantly less than that of the materials from which the case 102 and ring 112 are formed. For example, the thermal conductivity of titanium is 19.7 W/mK at 500° K, while the thermal conductivity of air is 0.055 W/mK at 500° K. Additional thermal insulation may also be provided by the ring 112 itself. Although the ring 112 is formed from titanium in the exemplary embodiment, other materials with lower thermal conductivity may be employed. By way of example, but not limitation, the ring 112 may be formed other metals such as stainless steel (thermal conductivity of 21.5 W/mK at 500° K), ceramics such as silicon nitride (thermal conductivity of 18 W/mK at 500° K), zirconia (thermal conductivity of 3 W/mK at 500° K) and alumina (thermal conductivity of 9 W/mK at 500° K).
Another exemplary magnet assembly is generally represented by reference numeral 100a in
Referring more specifically to
The case 102a of the five-magnet magnet assembly 100a may, however, be slightly larger than the case 102 of the four-magnet assembly 100 illustrated in
The exemplary magnet assembly 100a also has a thermal insulation arrangement 130a that includes the ring 112a as well as air gaps 132a and 134a that are defined by portions of the case 102a, the frame 108 and the ring 112a. The respective dimensions of the case 102a and ring 112a are also such that the first and second ends 146a and 148a of the ring 112a rest against the curved walls 142a and 144a, thereby creating the air gap 132a between the ring 112a and case side wall 140a that extends around the perimeter of the ring. The air gaps 134a are defined by the ring 112a, the relatively short rectangular portions 114a, and the curved flanges 122a and 124a. There are also air gaps (not shown) associated with the ends of the relatively long rectangular portion 116a, as is described above with reference to
Turning to
One example of a cochlear implant (or “implantable cochlear stimulator”) including the present magnet assembly 100 (or 100a) is the cochlear implant 200 illustrated in
Turning to
The exemplary body worn sound processor 300 in the exemplary ICS system 50 includes a housing 302 in which and/or on which various components are supported. Such components may include, but are not limited to, sound processor circuitry 304, a headpiece port 306, an auxiliary device port 308 for an auxiliary device such as a mobile phone or a music player, a control panel 310, one or more microphones 312, and a power supply receptacle 314 for a removable battery or other removable power supply 316 (e.g., rechargeable and disposable batteries or other electrochemical cells). The sound processor circuitry 304 converts electrical signals from the microphone 312 into stimulation data. The exemplary headpiece 400 includes a housing 402 and various components, e.g., a RF connector 404, a microphone 406, an antenna (or other transmitter) 408 and an axially magnetized disk-shaped positioning magnet 410, that are carried by the housing. The headpiece 400 may be connected to the sound processor headpiece port 306 by a cable 412. The external positioning magnet 410 is attracted to the magnet assembly 100 of the cochlear stimulator 200 (see
In at least some implementations, the cable 412 will be configured for forward telemetry and power signals at 49 MHz and back telemetry signals at 10.7 MHz. It should be noted that, in other implementations, communication between a sound processor and a headpiece and/or auxiliary device may be accomplished through wireless communication techniques. Additionally, given the presence of the microphone(s) 312 on the sound processor 300, the microphone 406 may be also be omitted in some instances.
The functionality of the sound processor 300 and headpiece 400 may also be combined into a single head wearable sound processor that includes all of the external components (e.g., the battery, microphone, sound processor, antenna coil and magnet). Examples of head wearable sound processors are illustrated and described in U.S. Pat. Nos. 8,811,643 and 8,983,102, which are incorporated herein by reference in their entirety. Headpieces and head wearable sound processors are collectively referred to herein as “head wearable external components.”
Although the inventions disclosed herein have been described in terms of the preferred embodiments above, numerous modifications and/or additions to the above-described preferred embodiments would be readily apparent to one skilled in the art. The inventions include any combination of the elements from the various species and embodiments disclosed in the specification that are not already described. It is intended that the scope of the present inventions extend to all such modifications and/or additions and that the scope of the present inventions is limited solely by the claims set forth below.
This application is a continuation-in-part of, and claims priority to, U.S. application Ser. No. 17/499,813, filed Oct. 12, 2021, which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/017784 | 2/24/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17499813 | Oct 2021 | US |
| Child | 18701147 | US |
