EP1422971A1 - Implantable transducer for hearing systems and method for adjusting the frequency response of such a transducer - Google Patents

Abstract

The transducer has a dynamic transducer part with a multifunctional connecting unit forming a connection relative to a static transducer part. The connecting unit has one function of forming a support for the dynamic transducer part and a hermetically sealed transducer housing (11). The unit has mechanical properties selected to achieve a set frequency response for the transducer. A permanent magnet arrangement vibrates in the direction of an axis of a ring coil arrangement. An Independent claim is also included for a method for tuning the frequency response of an implantable, electromagnetic hearing aid transducer.

Description

The invention relates to a working on the electromagnetic transducer principle implantable transducer for hearing systems and a method for tuning the Frequency response of such a converter.

Transducers of the type considered here are basically, for example, from ENT, 1997-45: 792-800, H. Leysieffer et al. "An implantable piezoelectric hearing aid transducer for inner ear deaf people ". This essay deals accordingly his title especially with piezoelectric transducers; it is there, however generally noted that actuator hearing aid converters are also under use of the electromagnetic conversion process that can be realized at an electromagnetic transducer a permanent magnet in a time-varying Field of a fixed coil moves and that this has the advantage of miniaturization of the portable permanent magnet.

An embodiment of a hearing aid for an at least partially implantable hearing aid certain electromagnetic transducers for direct mechanical excitation of the Middle or inner ear is described in US 6,162,169. It dips on the inside a membrane suspended permanent magnet in a housing-fixed electromagnetic Component, in particular a ring coil. The membrane is oscillatable and it closes the open face of a hermetically sealed cup-shaped Converter housing. On the outside of the membrane is a coupling element for Transmitted vibrations attached to the middle and / or inner ear.

The invention is based, an object according to the electromagnetic transducer principle working implantable transducer for hearing aids to create occurring in practice, among other things from the type of converter use as Actuator or sensor, depending on the intended implantation location and the like Conditions can be adapted particularly well. It is also intended to be a procedure be provided for tuning the frequency response of such a converter.

As far as the converter structure is concerned, this object is achieved according to the invention by an implantable, working according to the electromagnetic transducer principle Transducer for hearing systems with a static part, to which a hermetic on all sides tight converter housing and a ring coil arrangement fixedly attached therein, and with a dynamic part that at least with the static converter part a connecting element is in mechanical connection, in the implanted state to a body part of an implant carrier via at least one connecting element is coupled and a permanent magnet arrangement which interacts with the toroidal coil arrangement has, which by means of a bearing in the direction of the axis of Ring coil assembly is mounted to vibrate, with at least one connecting element is designed as a multi-functional element, which is also part of the storage and / or part of the hermetically sealed transducer housing, and wherein the mechanical Properties of the multi-function element to achieve a target frequency response of the converter are selected.

The invention also relates to a method for tuning the frequency response one that works according to the electromagnetic transducer principle, implantable Transducers for hearing aids, with a static part, to which an all-round hermetic tight converter housing and a ring coil arrangement fixedly attached therein, and is provided with a dynamic part that overlaps with the static converter part at least one connecting element is in mechanical connection in the implanted Condition on a body part of an implant carrier via at least one connecting element is coupled and a cooperating with the toroidal arrangement Has permanent magnet arrangement which by means of a bearing in the direction of Axis of the toroidal coil arrangement is mounted so that it can vibrate, the mechanical Properties of at least one connecting element that functions as a multi-function element at the same time part of the storage and / or part of the hermetically sealed converter housing is selected to achieve a target frequency response of the transducer.

The invention assumes that it is for implantable electromechanical actuators it is essential to ensure high efficiency. Especially in the case of Implants are namely problematic in terms of energy supply, so it is on it arrives, a certain amount of energy in the highest possible amount of mechanical Implement energy. The invention is based on the knowledge that the efficiency, with which an actuator transfers energy to the body in a significant way from the adaptation of the frequency response of the actuator to the load impedance and therefore depends the matching of the frequency response characteristics with respect to the impedance of the the actuator effective load has a significant impact on the efficiency of the Can have energy transfer from the transducer to the body. With electromechanical It is essential for sensors to be as sensitive as possible and achieve linearity. The frequency response of the converter is also decisive for this.

A common requirement for implantable actuator and sensory transducers for Hearing aids is also miniaturization since it is available for implantation Space is usually extremely limited. With the concepts currently available for implantable transducers, however, no mechanisms are provided that allow the frequency response of one and the same actuator in adaptation to that at the implantation site to systematically coordinate the anticipated circumstances. This shortage will remedied according to the invention in a surprisingly simple and effective manner. Through the multiple use of individual components of the converter, the Space requirement for the converter kept particularly small. The number of necessary Individual parts and the assembly effort are minimized.

Further refinements of the invention result from the subclaims.

Preferably, at least one multiple function element is one of setting the Target frequency response of the transducer bendable membrane, which serves as a connecting element for a mutual elastic connection of static and dynamic Transformer part provides and which also forms a wall part of the converter housing.

The converter housing can in particular be a rigid tubular peripheral wall and with these have tightly connected end walls, at least one of the end walls from a bendable serving to set the target frequency response of the transducer Membrane is formed over which the static and dynamic part of the transducer are elastically connected to each other and at the same time part of the storage of the permanent magnet arrangement is. In this case, the membrane takes over four at the same time Functions: By appropriate choice of their mechanical properties, for For example, the choice of its wall thickness, it serves as a tuning element for the frequency response of the converter. It provides, or at least supports, the connection of static and dynamic converter part. It forms part of the hermetically sealed Converter housing, and it also serves to store the dynamic Transducer part permanent magnet assembly.

At least one of the connecting elements can also be used as a damping element Damping the vibratory movements of the permanent magnet arrangement can be designed, the mechanical properties of the damping element also with regard are selected to achieve the target frequency response.

At least one membrane can be provided as the damping element, which at the same time May be part of the bearing arrangement of the permanent magnet arrangement. The the Frequency response of the transducer influencing damping properties of such Membrane can not only be selected by choosing the membrane wall thickness, but also other also by choosing an appropriate perforation or slitting the Adjust the membrane.

However, as a damping element influencing the frequency response of the converter among other things, at least one plug made of viscous material may also be provided, that compared to both the static converter part and the dynamic one Converter part can be supported.

According to a preferred embodiment of the invention, the permanent magnet arrangement mounted on a pole, which by means of storage at least two axially spaced locations with respect to the converter housing is axially adjustable, this rod being an actuator element from the Converter housing can protrude.

The permanent magnet arrangement is preferably in its own, hermetically sealed and biocompatible housing.

The converter housing is expediently cylindrical, in particular circular cylindrical, designed.

Fig. 1

eine Prinzipskizze eines implantierbaren, elektromechanischen Hörsystemwandlers,

Fig. 2

eine Prinzipskizze ähnlich Fig.1 für eine abgewandelte Ausführungsform des Wandlers,

Fig. 3

eine aufgebrochene perspektivische Darstellung eines erfindungsgemäß aufgebauten Hörsystemwandlers,

Fig. 4

eine Draufsicht auf eine bei dem Wandler nach Fig. 3 vorgesehene zweite Membran mit Lagerfunktion,

Fig. 5

den Einfluss der Dicke der einen Teil des hermetisch dichten Gehäuses bildenden Membran des Wandlers gemäß Fig. 3 auf den Frequenzgang des Wandlers,

Fig. 6

eine Seitenansicht einer abgewandelten zweiten Membran, die als Dämpfungselement mit Lagerfunktion ausgebildet ist,

Fig. 7

den Einfluss einer Membran der in Fig. 6 dargestellten Art auf die Transferfunktion des akustischen Wandlers,

Fig. 8

eine Seitenansicht einer weiter abgewandelten Ausbildung eines Verbindungselementes mit Dämpfungsfunktion und

Fig. 9

einen Querschnitt einer in einem eigenen Gehäuse untergebrachten Permanentmagnetanordnung.

Preferred embodiments of the invention are explained below with reference to the accompanying drawings. It shows:

Fig. 1

a schematic diagram of an implantable, electromechanical hearing system transducer,

Fig. 2

1 shows a schematic diagram similar to FIG. 1 for a modified embodiment of the converter,

Fig. 3

2 shows a broken perspective view of a hearing system transducer constructed according to the invention,

Fig. 4

3 shows a plan view of a second membrane with a bearing function provided in the converter according to FIG. 3,

Fig. 5

3 the influence of the thickness of the membrane of the transducer according to FIG. 3 forming part of the hermetically sealed housing on the frequency response of the transducer,

Fig. 6

2 shows a side view of a modified second membrane, which is designed as a damping element with a bearing function,

Fig. 7

the influence of a membrane of the type shown in FIG. 6 on the transfer function of the acoustic transducer,

Fig. 8

a side view of a further modified embodiment of a connecting element with damping function and

Fig. 9

a cross section of a permanent magnet assembly housed in its own housing.

In the basic representations of FIGS. 1 and 2, a converter, which can be used either as a vibration-stimulating actuator or as a vibration-sensing sensor, is shown in a block framed by broken lines. M ₁ denotes the static part of the converter. The static transducer part M ₁ represents an element which, in the implanted state, is in substantially rigid contact with a body part B _{1 of} the implant carrier, for example a muscle or bone, which has a large mass compared to the mass of the transducer. M ₂ represents the dynamic part of the transducer in FIGS. 1 and 2. It is in contact with a body part B _{2 of} the implant carrier, the mass or impedance of which is preferably comparable to the mass or impedance of the transducer. The body part B ₂ can be, in particular in the case of an actuator, the eardrum, a middle ear cross-section, the perilymph or the basilar membrane in the inner ear.

In the arrangement according to FIG. 1, the static converter part M ₁ and the dynamic converter part M _{2 are} mechanically connected to one another via a connecting element E ₁ , which is indicated as a spring. Another connecting element E ₂ , illustrated as an attenuator, provides the mechanical connection between the dynamic converter part M ₂ and the body part B ₂ .

In the arrangement according to FIG. 2, the static converter part M ₁ and the dynamic converter part M _{2 are} connected to one another via two connecting elements E ₁ and E ₂ , of which the connecting element E _{1 is} again designed as a spring and the connecting element E ₂ as an attenuator , A connecting element E ₃ designed as a spring is provided for coupling the dynamic converter part M ₂ to the body part B ₂ .

It is understood that further combinations of connecting elements are used can be. For example, instead of one spring element, several such Elements with different suspension properties and / or instead of an attenuator several such links with differing damping characteristics be provided to influence the frequency response in the desired manner. In any case, it is ensured that at least one of these connecting elements is designed as a multi-functional element, which is also part of the storage of dynamic converter part and / or part of a hermetically sealed converter housing.

An embodiment of an actuator constructed in the manner previously discussed Hearing aid transducer is shown in Fig. 3. The functionality of the converter is based on the inductive principle. The transducer, designated overall by 10, has a hermetic seal gas and liquid-tight housing 11 of, for example, circular cylindrical Mold made of biocompatible, gas and liquid-tight material, for example titanium, Gold or platinum. The converter housing 10 includes a rigid, tubular one Circumferential wall 12 and two substantially circular end walls, of which in Fig. 3rd only one can be seen. The latter is formed by a flexible membrane 13, whose outer edge with the peripheral wall 12 in a tight and hermetically sealed connection stands. Through a central opening of the membrane 13, a rod 14 extends with the membrane 13 is firmly and hermetically sealed and from the converter housing 11 protrudes as an actuator element. The longitudinal axis of the rod 14 coincides with the Longitudinal central axis of the housing 11 and with the center of the membrane 13 together. On the rod 14 is a permanent magnet arrangement having two permanent magnets 15 attached. The two permanent magnets are magnetized in the axial direction, which is indicated in Fig. 3 with a double arrow and which is also the direction of vibration of the dynamic part of the converter. The permanent magnet arrangement 15 as such can preferably be packed hermetically sealed and biocompatible his. For example, the permanent magnet arrangement 15 can be in its own housing made of titanium, gold or platinum, of which the concentric outer and Inner walls 32 and 33 are shown. This will make the body of the Implant carrier protected against toxic permanent magnet materials even if which should break part of the transducer housing membrane 13. The inherent The safety of the converter design shown is further improved in this way.

In the housing 11 is seated an overall fixed with respect to the peripheral wall 12 with 16 designated coil arrangement to that in the illustrated embodiment include three axially successive cylindrical ring coils. The permanent magnet arrangement 15 is located within that of the coil arrangement 16 Space. The coil arrangement 16 generates this for driving the permanent magnet arrangement 15 required alternating electromagnetic field. Connections 17 for the Coil assembly 16 are hermetic from the converter housing 11 via not shown sealed bushings led out. An AC signal is applied to the connections 17 applied, the permanent magnet assembly 15 together with the Coupling rod 14 causes axial vibrations.

The coil arrangement and the permanent magnet arrangement interacting with it can in principle also be constructed in a manner other than that shown in FIG. 3 be, for example, in US Pat. No. 5,299,176 for non-implantable transducers known way or similar.

The rod 14 and the permanent magnet assembly 15 are related to the coil assembly 16 axially limited adjustable by means of a bearing. To storage include the membrane 13 and another in the illustrated embodiment bendable, essentially circular membrane 18. The membrane 18 sits on the side of the coil arrangement 16 facing away from the membrane 13 Membrane 18 is also fixed with respect to the peripheral wall 12, and the Rod 14 is in a central opening 19 of the top view illustrated in FIG. 4 Membrane 18 attached. Unlike the membrane 13, however, the membrane 18 does not Part of the hermetically sealed converter housing 11, but it is axially spaced from the front wall of the housing 11, which cannot be seen in FIG. 3. The membrane 18 is provided with a series of concentric openings. The resulting Circular ring sections 20 of the membrane 18 are connected to one another via webs 21. The membrane 18 can be made of the same material as the membrane 13, for example made of titanium, gold or platinum. Such a perforated membrane can Bearing function take over without the frequency response of the converter appreciable influence.

In the embodiment of FIG. 3, the coil arrangement 16 and the converter housing - with the exception of the membrane 13 - form the static part M _{1 of} the converter shown in FIGS. 1 and 2. In the implanted state of the transducer, this static transducer part is essentially rigidly coupled to the cranial bone of the implant carrier. The rod 14 and the permanent magnet arrangement 15 carried by it represent the dynamic transducer part M ₂ of FIGS. 1 and 2. The membrane 13 corresponds to the connecting element E ₁ of FIGS. 1 and 2; however, it also has a housing function and a bearing function at the same time, and it serves to adjust the frequency response of the converter 10. A corresponding attenuator could be integrated in the coupling rod 14 in order to implement the damping connecting element E ₂ in FIG. 1. Correspondingly, the connecting element E ₂ having spring properties in FIG. 2 can be connected by a coupling rod 14 that is resilient in the axial direction and / or by

Realize insertion of a spring element in this rod.

(a) wenn eine einen Teil des hermetisch dichten Gehäuse bildende Membran 13 von 20 µm Dicke und eine Lagermembran 18 von 20 µm Dicke verwendet werden, und

(b) wenn eine einen Teil des hermetisch dichten Gehäuse bildende Membran 13 von 25 µm Dicke und eine Lagermembran 18 von 30 µm Dicke verwendet werden.

To achieve a desired frequency response of the transducer 10, for example, the thickness of the membrane 13 forming part of the hermetically sealed housing 11 can be varied. FIG. 5 clearly shows the influence of the dimensioning of the membrane 13 of the transducer 10 according to FIG. 3 on the transducer frequency response. The transfer function, measured as the deflection in μm as a function of the frequency in Hz of the driver signal of the coil arrangement 16, of a test arrangement in which both membranes 13 and 18 are omitted are compared with the corresponding transfer functions that result from

(a) when a membrane 13 of 20 µm thick forming part of the hermetically sealed housing and a bearing membrane 18 of 20 µm thick are used, and

(b) if a membrane 13 of 25 µm thick forming part of the hermetically sealed housing and a bearing membrane 18 of 30 µm thick are used.

The resonance peak of the frequency response curves according to FIG. 5 shifts at one Significant change in the thickness of the membrane 13 from 20 µm to 25 µm from about 800 Hz to about 1000 Hz. The thickness of the bearing membrane 18, however, has the Frequency response practically no influence.

Instead of the bearing membrane 18, a membrane 25 shown schematically in FIG. 6 can also be provided, which in addition to a bearing function also has a damping function which influences the frequency response of the transducer in the desired manner. For this purpose, an uninterrupted layer 26 made of viscous material, for example silicone, can be selected as the membrane material. In order to ensure the storage function, such a viscous membrane can be covered with a layer 27 of solid and preferably biocompatible elastic material, for example a thermoset or metal, in particular titanium, gold, platinum or a mixture of at least two of these metals. This elastic coating layer 27 is perforated, and preferably analogously to the perforation of the membrane 18 shown in FIG. 4. Such a membrane 25 corresponds functionally to the connecting element E ₂ of FIG. 2.

FIG. 7 shows the measured effect of a silicone membrane according to FIG. 6 on the transfer function an acoustic transducer. The thick solid curve represents the Transfer function without silicone membrane, while the thin curve shows the Transfer function of the converter with silicone membrane 25 is. In the range below about 3000 Hz and above about 8000 Hz, the membrane 25 has a damping effect. In the range of around 4000 up to 8000 Hz, however, the transducer deflection is increased by the membrane 25.

It goes without saying that, in principle, other connecting elements with a damping function can also be considered and can be used to influence the frequency response of the converter. For example, in FIG. 8 an attenuator in the form of a circular cylindrical plug 30 made of viscous material, for example silicone, is shown. The plug sits on the side of the diaphragm 18 facing away from the coil arrangement 16 according to FIG. 3 on the coupling rod 14. The plug 30 can be supported directly or indirectly on a rigid part of the converter housing 11 and can influence the movement of the dynamic converter part M ₂ in the axial direction , A similar plug made of viscous material can, however, also abut against the axial end of the coupling rod 14 on the side of the membrane 18 facing away from the coil arrangement 16 for damping purposes.

The isolated influence of such a plug is that large deflections of the dynamic transducer part M ₂ are damped more than small deflections. This effect corresponds to a relatively strong damping at low frequencies and a relatively weak damping at high frequencies. Such an influence on the frequency response can be useful for an actuator to improve the hearing if, for example, signals below 250 Hz that are not required for speech understanding are to be masked out.

In the embodiment of FIG. 8, the storage function of the membrane 18 in Connected to the membrane 13 shown in FIG. 3. Attenuator 30 itself does not need to have a bearing effect. According to a further modified Embodiment, however, can also be a viscous plug of the type described be designed so that it is essentially only in the axial, but not in the radial direction gives way. Then the grafting itself can be used as a storage and management function for the dynamic Take over converter part, and the membrane 18 may be omitted if necessary.

The use of several attenuators, for example in the form of Membranes and / or plugs of the type described can, depending on the use of the transducer also be useful as a sensor or as a transducer in the ultrasound spectrum. An attenuator alone, analogous to a resonance element, its effect can only be in one achieve a limited range of the frequency spectrum. Several differently designed Attenuators, on the other hand, allow the spectrum to be targeted in several To influence frequency ranges. For example, in the converter according to FIG. 3 in addition to attenuating frequencies below 250 Hz, frequencies above 4000 Hz are damped, that is, signals with higher than required for speech recognition Frequency, this can be achieved in addition to that 6 a viscous plug of the metal-coated viscous membrane according to FIG type described above is provided.

Claims (16)

Implantable transducer (10) which works according to the electromagnetic transducer principle for hearing systems with a static part (M ₁ ; 11, 16), which includes a transducer housing (11) which is hermetically sealed on all sides and a toroidal coil arrangement (16) fixed therein, and with one dynamic part (M ₂ ; 14, 15), which is in mechanical connection with the static converter part via at least one connecting element (E ₁ or E ₁ , E ₂ ; 13, 18, 25), in the implanted state to a part of the body (B ₂ ) an implant carrier is coupled via at least one connecting element (E ₂ or E ₃ ) and has a permanent magnet arrangement (15) which interacts with the toroidal coil arrangement and is mounted so that it can vibrate in the direction of the axis of the toroidal coil arrangement by means of a bearing (13, 18, 25) at least one connecting element (13, 18, 25) is designed as a multiple functional element, which is at the same time part of the bearing and / or part of the hermetic is tight converter housing, and wherein the mechanical properties of the multi-function element are selected to achieve a desired frequency response of the converter. Implantable transducer according to claim 1, characterized in that at least one multiple function element is a flexible membrane (13) which serves to set the desired frequency response of the transducer and forms a wall part of the transducer housing (11). Implantable transducer according to Claim 2, characterized in that the transducer housing (11) has a rigid tubular peripheral wall (12) and end walls which are tightly connected thereto, and that at least one of the end walls is made of a flexible membrane (which serves to set the desired frequency response of the transducer) 13) is formed, via which the static and the dynamic part of the transducer (10) are elastically connected to one another and which is also part of the bearing (13, 18, 25) of the permanent magnet arrangement (15). Implantable transducer according to one of the preceding claims, characterized in that at least one of the connecting elements (25) is at the same time designed as a damping element for damping the oscillating movements of the permanent magnet arrangement (15), and in that the mechanical properties of the damping element are also taken into account in order to achieve the desired Frequency response are selected. Implantable transducer according to claim 4, characterized in that at least one membrane (25) consisting at least partially of viscous material is provided as the damping connecting element. Implantable transducer according to claim 5, characterized in that the membrane (25) serving as a damping element is at the same time part of the bearing (13, 18, 25) of the permanent magnet arrangement (15). Implantable transducer according to claims 5 and 6, characterized in that the membrane serving as a damping element has a layer (26) made of viscous material, which is covered with an openwork layer (27) made of solid, elastic material. Implantable transducer according to claim 7, characterized in that the material of the perforated layer (27) is selected from the group consisting of titanium, gold, platinum and mixtures of at least two of these metals. Implantable transducer according to claim 7, characterized in that the perforated layer (27) consists of a thermoset. Implantable transducer according to one of the preceding claims, characterized in that part of the mounting of the permanent magnet arrangement (15) is a perforated membrane (18) which is between the static part (M ₁ ; 11, 16) and the dynamic part (M ₂ ; 14 , 15) of the converter (10) is seated. Implantable transducer according to one of the preceding claims, characterized by at least one damping element in the form of a plug (30) made of viscous material which interacts with the dynamic part (M ₂ ) of the transducer (10). Implantable transducer according to one of the preceding claims, characterized in that the permanent magnet arrangement (15) is mounted on a rod (14) which is mounted by means of the bearing (13, 18, 25) at at least two axially spaced locations with respect to the The converter housing (11) is axially adjustable. Implantable transducer according to claim 12, characterized in that the rod (14) carrying the permanent magnet arrangement (15) projects as an actuator element from the transducer housing (11). Implantable transducer according to one of the preceding claims, characterized in that the permanent magnet arrangement (15) is accommodated in its own, hermetically sealed and biocompatible housing. Implantable transducer according to one of the preceding claims, characterized in that the transducer housing (11) is cylindrical, in particular circular cylindrical. Method for tuning the frequency response of an electromagnetic Transducer principle working, implantable transducer for hearing systems, the with a static part, to which an all-round hermetically sealed converter housing and include a toroidal coil assembly fixed therein, and with one dynamic part is provided, which with the static converter part over at least a connecting element is in mechanical connection in the implanted Condition on a body part of an implant carrier via at least one connecting element is coupled and a cooperating with the toroidal arrangement Has permanent magnet arrangement, which by means of a storage in Direction of the axis of the toroidal coil arrangement is mounted so that it can vibrate the mechanical properties of at least one connecting element, which as Multiple functional element at the same time part of the storage and / or part of the hermetic is tight converter housing, to achieve a target frequency response of Converter can be selected.

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