EP2587841A1 - Membrane for covering an opening in a hearing aid - Google Patents

Abstract

The membrane (10) has a membrane main structure comprising a non-woven structure that is formed by electro-spinning of fibers in the form of nanofibers with diameter of 200nm and 500nm or in the form of microfibers with a diameter of 1mu m-3mu m. The membrane main structure is made of polylactic acid or flupropolymer. The membrane main structure is held by plastic made holding frame (11). The holding frame is fixed in front of opening in hearing aid by a fastening unit (12). Independent claims are included for the following: (1) cover; (2) hearing aid; and (3) method for manufacturing hearing aid.

Description

This invention relates to a membrane for covering an opening in a hearing aid, a cover of an opening in a hearing aid, and a method of manufacturing a membrane for covering an opening in a hearing aid.

Hearing aids typically have a multiplicity of openings that are prone to water penetration and contamination. Examples of such openings are a microphone opening, a receiver opening, an opening for a switch element or an opening for ventilating a battery.

Various types of hearing aids are known in which parts of the hearing aid are arranged behind the ear, in the ear or in the ear canal. By this close-fitting use hearing aids are e.g. Sweat or - especially in the ear canal - cerumen, ie earwax exposed. If moisture penetrates into the hearing aid, this can lead to corrosion and thus to malfunctions and defects. By cerumen in particular the acoustic openings for the microphone and the handset - also called receiver - be blocked. In the hearing aid penetrating cerumen can also lead to defects.

Due to the miniaturization of the hearing aids, the openings become smaller and can therefore be blocked by relatively small amounts of external contamination and cerumen. The dirt and cerumen accumulate over the course of the use, so that the blocking of the openings is initially easily overlooked by the user.

From the European patent EP0310866B1 Microporous membrane is known, which is attached to protect against cerumen and moisture in front of a sound outlet opening of a hearing aid, wherein the membrane, for example made of polytetrafluoroethylene (PTFE). Screeched polytetrafluoroethylene, also called expanded PTFE (ePTFE), is known under the Gore-Tex® brand.

It is an object of the present invention to improve the protection against ingress of moisture and dirt into an opening of a hearing aid.

The object is achieved in each case by a membrane according to patent claim 1 and by a method according to patent claim 15.

By electrostatic spinning, electrospinning for short, it is possible to produce a membrane with a structure of non-interwoven micro- or nanofibers, which is water and dirt repellent. The use of such a membrane to cover an opening in a hearing aid asks for protection against ingress of moisture and dirt into the hearing aid.

In one embodiment of the invention, the membrane is made of a polylactic acid, also known as polyactides or PLA for the common English term "polyactic acid" produced. Such a polymer as a starting material allows easy electrospinning. Preferably, the levorotatory L-form of polyactides, also called PLLA, is used for the common English term "poly (L-lactide) acid".

Alternatively, the fiber is made from a fluoropolymer which is hydrophobic and oleophobic and thus offers particularly good protection against water or cerumen. Examples of a suitable fluoropolymer are polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), also known under the trademark Teflon®.

By electrospinning fibers with an average diameter of 50nm up to 10μm can be produced. Fibers in the form of microfibers with a diameter of 1μm and 3μm can be easily manufactured, are sturdy and yet allow the production of a membrane that provides protection against water and dirt. Nanofibers with a diameter between 200nm and 500nm are particularly suitable for a very dense structure with very small pores, which are particularly water and dirt repellent.

In particular, for the use of the membrane for covering an acoustic interface of the hearing aid, e.g. a sound outlet opening on the listener or sound inlet opening on the microphone, the use of a very thin - and thus sound-permeable - membrane with a thickness of less than 50 microns is particularly advantageous. On the other hand, as the thicknesses increase, water impermeability increases. A good balance of the various requirements is possible in the range between 20μm and 80μm.

Depending on the type of opening to be covered on the hearing aid a membrane diameter between 2mm and 10mm is preferred.

A separate from the hearing aid cover with a membrane described above allows easy replacement of the membrane in the event of damage. In addition, such a cover for a hearing aid offers the possibility to equip a hearing aid model with different membranes or to change the type of cover. For this purpose, it is provided that the cover next to the membrane itself still has a holding frame which partially surrounds the membrane, and a fastening means for attaching the cover to the hearing aid.

A cover with a holding frame made of plastic, in which the membrane is cast, is particularly easy to produce. By a fastener with a click closure, a simple attachment of the cover to the hearing aid is possible despite the small size of a hearing aid. A hearing aid with an embodiment of the aforementioned membrane is protected against ingress of water and protection in the hearing aid.

The method for producing the membrane is based on the known method for electrospinning, wherein the non-woven structure resulting from the electrospinning is shaped in adaptation to the opening of the hearing device. This shaping can e.g. done by punching or cutting. In further method steps, the membrane can either be inserted into the holding frame of the cover which can be fastened to the hearing device or fastened directly to the opening of the hearing device.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the embodiments, which will be described in detail in conjunction with the drawings.

FIG 1

eine Anordnung zum Elektrospinnen von Fasern mit einer Zielplatte,

FIG 2

eine Anordnung zum Elektrospinnen von Fasern mit einer Zieltrommel,

FIG 3

eine Draufsicht auf eine Membran aus PLLA-Mikrofasern mit einem Durchmesser von 2µm,

FIG 4

einen Querschnitt der Membran gemäß Figur 3,

FIG 5

eine Draufsicht einer Membran aus PLLA-Nanofasern mit einem Durchmesser von 400nm,

FIG 6

einen Querschnitt der Membran gemäß Figur 5,

FIG 7

eine Draufsicht auf eine Abdeckung mit einer Membran und einen Halterahmen.

FIG 8

einen Querschnitt der Abdeckung gemäß Figur 7,

FIG 9

ein Hörergehäuse mit einer Membran-Abdeckung gemäß den Figuren 7 und 8,

FIG 10

eine gitterartige Anordnung einer Vielzahl von Membranen,

FIG 11

ein Hörgerät mit Membranabdeckungen, und

FIG 12

ein Verfahren zur Herstellung einer Membran für ein Hörgerät mittels Elektrospinnen.

Show it:

FIG. 1

an arrangement for electrospinning fibers with a target plate,

FIG. 2

an arrangement for electrospinning fibers with a target drum,

FIG. 3

a plan view of a membrane of PLLA microfibers with a diameter of 2 microns,

FIG. 4

a cross-section of the membrane according to FIG. 3 .

FIG. 5

a plan view of a membrane of PLLA nanofibers with a diameter of 400nm,

FIG. 6

a cross-section of the membrane according to FIG. 5 .

FIG. 7

a plan view of a cover with a membrane and a support frame.

FIG. 8

a cross-section of the cover according to FIG. 7 .

FIG. 9

a receiver housing with a membrane cover according to the FIGS. 7 and 8 .

FIG. 10

a lattice-like arrangement of a plurality of membranes,

FIG. 11

a hearing aid with membrane covers, and

FIG. 12

a method for producing a membrane for a hearing aid by means of electrospinning.

FIG. 1 shows the principle of an arrangement for the electrospinning of fibers. In a syringe 1 is a molten or dissolved polymer 2, which is pushed out of the syringe 1 through the cannula 3. The cannula 3 is aligned with a target plate 4. Both the cannula 3 and the target plate 4 are metallic. By a voltage source 5, a voltage between the cannula 3 and the target plate 4 is generated, wherein the voltage is typically between 5kV and 35kV. The distance between the cannula 3 de target plate 4 may for example be 5cm to 30cm.

Through an interaction of the surface tension of the liquid polymer 2 and the electrostatic attraction of the polymer 2 through the target plate 4, the polymer at the tip of the cannula 3 forms a so-called Taylor cone, from the tip of a thin, initially still liquid polymer thread 6 emerges. The polymer thread 6 accelerates on the way to the target plate 4 and hardens increasingly, until it finally accumulates on the target plate 4 as a thin, stiffened fiber. Due to the stress gradient from the tip of the cannula 3 and the target plate 4, the polymer thread 6 accelerates its Movement and assumes an irregularly swirling shape during the solidification process.

As a result of this process, a mat of non-interwoven structure of thin fibers is formed on the target plate 4. The fibers can have a diameter between 50nm and 10μm. Among other things, this depends on the distance between the cannula 3 and the target plate 4, the type of polymer, the form of the liquefaction of the polymer and the applied voltage. This method and the relationships between these production parameters and the resulting thread are basically known per se.

FIG. 2 shows another arrangement for electrospinning, which differs from the in FIG. 1 illustrated arrangement differs by the type of the target electrode. In FIG. 2 is instead of the target plate 4, a metallic target drum 7 is arranged, which rotates about its longitudinal axis and is displaceable in the longitudinal direction. Such movement during the manufacturing process affects the properties of the fiber itself and the fiber structure. These movement parameters can thus be taken into account when adapting the tissue to the requirements in the context of an iterative optimization process.

By adjusting the movement parameters, the fibers can be given a particular orientation in particular. It is also possible, after passing through the roll in one direction, to repeat the process of electrospinning on the same roll with a changed orientation of movement to superimpose fiber layers with different orientations into a total structure.

The FIGS. 3 to 6 show in each case in a plan view and a cross section two examples of non-interwoven structures of fibers 8 as a result of electrospinning. These fiber structures are designed to meet certain requirements for a membrane to cover an opening in a Hearing aid meet. Such membranes should be water, grease and / or dirt repellent. In addition, they must be mechanically durable enough and easy to handle. To cover sound openings, the membrane must also be sound permeable.

Suitable polymers are PET, PLA, PLLA and fluoropolymers such as PTFE, ePTFE and PVDF. The fibers 8 may have an average diameter between 400 nm and 2 μm and be arranged to a membrane thickness between 20 μm and 70 μm. The density of the structure may be, for example, 10% or less, i. the polymer volume corresponds to 10% or less of the total volume of the membrane. With increasing density and increasing membrane thickness, the structure becomes increasingly impermeable to water, but at the same time less permeable to sound. This shows by way of example that the individual manufacturing and material parameters have to be weighed in terms of requirements and coordinated in the context. This is done in the context of the expert trade by a systematic, iterative adaptation process.

Figures 3 and 4 show in plan view and a cross section of a membrane with a structure of non-interwoven fibers 8 made of PLLA with an average diameter of 2 microns and a thickness of 70 .mu.m. Even thinner membranes of this type with a thickness of 20 microns are conceivable.

With a membrane thickness of 60μm to 70μm, the membrane withstands a water pressure of 20mbar for more than 12 hours without water penetrating the membrane. A reduction in the membrane thickness increased to 40μm significantly increases your water permeability.

Figures 5 and 6 also show in plan view and in cross-section, respectively, an acoustically improved membrane having an average fiber diameter of 400 nm and an increased fiber density. The fibers 8 are as in the in the Figures 3 and 4 illustrated embodiment of the polymer PLLA.

With a membrane thickness of 20μm, this membrane withstands a pressure of about 10mbar for 60 seconds before water slowly permeates through the membrane.

It is possible to use polymer blends to combine their properties. In addition, the membrane can be produced by stacking fiber structures of different polymers and different fiber properties. The individual fiber layers may also differ with regard to their fiber density, the respective thickness and the fiber structure. Thus, e.g. a coarse layer strengthen the stability of the membrane and a thin and dense layer increase the waterproofness.

• wasserabweisende Eigenschaften,
• fettabweisende Eigenschaften,
• Faserdurchmesser,
• Mischung von Fasern 8 aus unterschiedlichem Materialien,
• Mischung von Fasern 8 mit unterschiedlichem Faserdurchmesser,
• Verwendung von ausgerichteten, bzw. nicht-ausgerichteten Fasern 8,
• mehrere Schichten aus ausgerichteten Faser 8 mit unterschiedlichen Orientierungen, z.B. zueinander zwei Schichten mit zueinander orthogonal ausgerichteten Fasern 8,
• Größe der Poren zwischen den Fasern 8,
• Nachträgliche Härtung der Membran, z.B. durch Tempern,
• Laser-Strukturieren der Membran,
• Einschluss von bioaktiven Materialien in die Fasern 8, z.B. antibakterielle Wirkstoffe,
• Konzentrische Anordnung von Fasern 8 aus zwei Materialien, z.B. sogenannte core sheet-Fasern.
• Benutzung von Materialien, die zur medizinischen Nutzung freigegeben sind.

The following parameters can be adapted to adapt the membrane to cover different openings:

• water-repellent properties,
• fat-repellent properties,
• Fiber diameter,
• Mixture of fibers 8 of different materials,
• Mixture of fibers 8 with different fiber diameter,
• Use of aligned or non-oriented fibers 8,
• a plurality of layers of aligned fiber 8 with different orientations, for example two layers with mutually orthogonally oriented fibers 8,
• Size of the pores between the fibers 8,
• Subsequent hardening of the membrane, eg by tempering,
• Laser structuring of the membrane,
• Inclusion of bioactive materials in the fibers 8, eg antibacterial agents,
• Concentric arrangement of fibers 8 of two materials, for example so-called core-sheet fibers.
• Use of materials approved for medical use.

In principle, the membrane should be as thin as possible, e.g. less than 50μm thick yet durable. For grease and water repellent properties, fluoropolymers can be used. In addition, the membrane should be easily connected to the hearing aid.

FIG. 7 shows in a plan view a cover 9 for an opening in a hearing aid. The cover 9 comprises a round membrane 10 and a holding frame 11 which encloses the membrane 10 in its full extent. The membrane 10 has a diameter of 5mm in this embodiment. To cover openings in a hearing aid typically membrane diameters between 2mm and 10mm are useful. The holding frame 11 has a radial width of 1mm.

The membrane 10 is round in this embodiment. Alternative also elliptical, rectangular and any other shapes are conceivable.

The membrane 10 is made flat here, but may also be curved in one direction, spherically curved or bulged locally. The shape of the membrane 10 may be determined by the enclosure in the support frame 11 or may already be predetermined by a shape of electrospinning, e.g. by a corresponding shape of the target electrode.

FIG. 8 shows a cross section of the cover 9 after FIG. 7 , In this view, it can be seen that the membrane 10 is cast radially into the holding frame 11. The holding frame 11 comprises a fastening means in the form of a click fastener 12, whose operation in FIG. 9 is explained.

FIG. 9 shows schematically a listener housing 13, on which the cover 9 after the FIGS. 7 and 8 by means of the click fastener 12 is attached. The click closure 12 has a radially inwardly directed formation, which engages positively in a corresponding counterpart in the receiver housing 13. The molding rotates in this embodiment, the full extent of the support frame 11. Alternatively, the formation may also have individual punctiform nubs.

The receiver housing 12 is designed for insertion into an auditory canal. Accordingly, the shape of the receiver housing 12 is anatomically adapted, which is not apparent from this schematic drawing. In the receiver housing 12 there is a receiver 14, which is connected by means of an electric line 15 via a cable 16 leading out of the receiver housing 12 to the remaining part of the hearing device, which is e.g. is designed for an arrangement behind the auricle. Depending on an electrical signal via the electrical line 15, the receiver 14 generates an acoustic signal that emerges through the membrane 10 from the receiver housing 12.

The cover 9 is mounted in front of an opening of the receiver housing 12 so that the membrane 10 seals the opening against ingress of water and foreign particles, e.g. Cerumen and dust, closes. In this embodiment, the membrane 10 is acoustically transparent, so that the sound generated by the receiver 14 can emerge from the receiver housing 12.

FIG. 10 shows a grid-like arrangement of a plurality of membranes 10. The membranes 10 are each connected via six radially arranged around the respective membranes 10 plastic webs 17 with a plastic mesh 18. This shape is suitable for transporting the membranes 10 in a simple manner and for incorporating them in an automatic further processing process.

The shape of the membranes 10 is determined after electrospinning by laser ablation or by simple blanking or punching. Then the individual membranes 10 are received in the grid-like arrangement and connected to the plastic webs 17. Arranged in this form, further details of the shape of the membranes 10 can be determined by further laser ablation.

FIG. 10 merely shows a section of the grid-like arrangement which widens in all directions by repeating the pattern shown.

Instead of a lattice-shaped arrangement of membranes, a linear arrangement of the membranes 10 in a chain one behind the other also permits simple further processing.

FIG. 11 schematically shows a behind the ear portable hearing aid 19 with two microphones 20, a signal processing unit 21, a battery compartment 22, a control element 23 and a receiver 14. For the microphones 20, the battery compartment 22, the control element 23 and the handset 14 is in the housing the hearing aid 19 each provided an opening.

These openings are covered with various membranes 10, which are not shown in this schematic drawing. The membranes 10 are each made by electrospinning, wherein the production parameters are adapted to the respective requirements of the membrane 10.

In the battery compartment, an opening is provided which serves to ventilate the battery, which is usually dependent on an air supply for operation. The membrane 10 mounted in front of this opening must be particularly watertight.

The control element may be a switch element for selecting a hearing program or a volume control. The associated opening in the housing of the hearing aid 19 must in this case with a mechanically stable and waterproof membrane 10th be covered. However, the membrane 10 does not have to be acoustically permeable.

FIG. 12 shows a method of manufacturing the membrane 10 to cover an opening of a hearing aid 19. In a first step 24, a non-interwoven structure is created by electrospinning fibers 8. The process of electrospinning has already been linked to the FIGS. 1 and 2 described in more detail. In the description to the FIGS. 3 to 6 It was described how the production parameters are systematically adapted to the requirements for covering openings on a hearing aid 19. In a second step 25, from the non-woven structure of fibers 8, the membrane 10 is shaped to conform to the opening. This shaping is done by laser ablation, cutting or punching.

In a further optional process step, a plurality of the membranes 10 are arranged in a regular grid, as shown in FIG FIG. 10 is shown.

Finally, the membrane 10 is attached to the hearing aid 19 to cover the opening. This is done, for example, in two sub-steps, so that the membrane 10 first - as in the context of FIGS. 7, 8 and 9 described - is poured into a holding frame 11 and then the resulting cover 9 by means of the click mechanism 12 is attached to the hearing aid 19.

Although the invention has been further illustrated and described in detail by the embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims (15)

A membrane (10) for covering an opening in a hearing aid (19), wherein the membrane (10) is made by electrospinning fibers (8) into a non-woven structure. A membrane (10) according to claim 1, wherein the membrane (10) is made of a polylactic acid. The membrane (10) of claim 1, wherein the membrane (10) is made of a fluoropolymer. Membrane (10) according to one of claims 1 to 3 with fibers in the form of nanofibers with a diameter of 200 nm and 500 nm. Membrane (10) according to one of Claims 1 to 3, having fibers (8) in the form of microfibers with a diameter of 1 μm and 3 μm. Membrane (10) according to one of claims 1 to 5 with a membrane thickness of between 20μm and 80μm. A membrane (10) according to any one of claims 1 to 5 having a membrane thickness of less than 50μm. Membrane (10) according to one of claims 1 to 7 with a membrane diameter between 2mm and 10mm. Cover (9) for an opening in a hearing aid (19) comprising: a membrane (10) according to one of claims 1 to 8, - A support frame (11) which surrounds the membrane (10) at least partially and - A fastening means (12) for attaching the cover (9) to the hearing aid (19). Cover (9) according to claim 9, wherein the holding frame (11) comprises plastic, in which the membrane (10) is cast. Cover (9) according to one of claims 1 to 10, wherein the fastening means comprises a click closure (12). Hearing aid (19) having an opening which is covered with a membrane (10) according to one of claims 1 to 8. Hearing aid (19) according to claim 12, wherein the opening is a microphone opening, a listener opening, an opening for a switch element (23) or an opening for venting a battery compartment (22). Method for producing a membrane (10) for covering an opening of a hearing device (19), comprising the following steps: Electrospinning fibers (8) into a non-interwoven structure, - Forming the membrane (10) of the non-woven structure in adaptation to the opening. A method according to claim 14 for producing a membrane (10) according to any one of claims 1 to 8.

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