Hearing stimulation system and method for operating a hearing stimulation system

Abstract

A hearing stimulation system for a tympanic membrane (16) comprising a signal generator (17) and an optomechanical transducer (18) for exciting a vibration of the tympanic membrane (16). The signal generator (17) is designed to emit a light signal (20) such that the light signal (20) strikes the optomechanical transducer (18) and triggers a thermal deformation in the optomechanical transducer (18). The optomechanical transducer (18) is designed such that the thermal deformation causes a change in the curvature of the optomechanical transducer (18), thereby deflecting a surface section (30, 31) of the optomechanical transducer (18). The invention also relates to a method for operating a hearing stimulation system.

Description

[0001] The invention relates to an auditory stimulation system and a method for operating an auditory stimulation system.

[0002] Hearing aids are devices worn on or in the ear, designed to compensate for hearing loss as effectively as possible. They work by stimulating a sound transducer, which then transmits an ambient sound signal to the eardrum in a suitable form, thus sending it into the auditory pathway. The success of using a hearing aid also depends on the quality of the processed sound being reproduced. Due to physical limitations of the reproduction technology, the performance of current hearing aids, despite significant advances in signal processing, is often still unsatisfactory. For optimal hearing care, it is desirable that the entire audible frequency range (20 Hz to 20 kHz) be amplified without having to block the ear canal.

[0003] Traditional hearing aids use miniature electromagnetic loudspeakers as sound transducers. Due to their design, the reproduction range of these transducers is limited to a maximum of approximately 8 kHz, although often only values ​​up to 5 kHz are achieved when high amplification is required. Furthermore, in the frequency range below 1 kHz, it is necessary to seal the ear canal to reproduce sound at a sufficient level. This significantly reduces the wearing comfort of the hearing aid and increases the risk of ear canal infections.

[0004] As an alternative to miniature loudspeakers, active eardrum contact transducers are known (EP 3 794 843 A1, US 2023 / 0080201 A1). These are electromechanically driven transducers that are in contact with the eardrum and directly set the auditory pathway into mechanical vibration. This allows for a higher playback bandwidth compared to conventional hearing aids, covering almost the entire audible frequency range. This requires an electromechanical component on the eardrum, which, depending on the design, is controlled inductively, optically, or via a cable. This limits the practicality and long-term stability of this approach.

[0005] Optical stimulation of the auditory pathway at various points is also state of the art. For example, direct neuronal stimulation of the hair cells or the auditory nerve with laser light has been demonstrated (M. Jeschke and T. Moser, "Considering optogenetic stimulation for cochlear implants", Hear. Res., Vol. 322, pp. 224-234, Apr. 2015, doi: 10.1016 / j.hea-res.2015.01.005). However, such stimulation is only conceivable in conjunction with cochlear implants.

[0006] The possibility of optoacoustic stimulation of the ear was also described, i.e., the generation of acoustic or mechanical vibrations by applying laser light to various points in the auditory pathway (US 8,545,383 B2). This type of stimulation was demonstrated both at positions accessible to implants, such as within the cochlea or at the round window of the cochlea in the middle ear, and by irradiating the tympanic membrane with laser light of different colors. It was also shown that the efficiency of optoacoustic stimulation when irradiating the tympanic membrane can be increased by placing a three-layered element on the membrane (US 2022 / 0395695 A1, K. Sorg et al., "Optoacoustically induced auditory brainstem responses in the mouse model enhanced through an absorbing film," J. Biomed. Opt., Vol. 26, No. 09, Sep. 1990). 2021, doi: 10.1117 / 1.JBO.26.9.09800.

[0007] The invention is based on the objective of presenting an auditory stimulation system and a method for operating an auditory stimulation system, with which the aforementioned disadvantages are reduced. Starting from the aforementioned prior art, the objective is achieved by the features of the independent claims. Advantageous embodiments are specified in the dependent claims.

[0008] An auditory stimulation system for a tympanic membrane according to the invention comprises a signal transmitter and an optomechanical transducer. The optomechanical transducer is designed to excite vibrations of the tympanic membrane. The signal transmitter is designed to emit a light signal such that the light signal strikes the optomechanical transducer and triggers thermal deformation in the optomechanical transducer. The optomechanical transducer is designed such that the thermal deformation causes a change in the curvature of the optomechanical transducer, thereby deflecting a surface section of the optomechanical transducer.

[0009] The term "light signal" is not limited to the wavelength range of visible light. It encompasses electromagnetic waves with wavelengths in the ultraviolet spectral range and electromagnetic waves with wavelengths in the infrared spectral range. In particular, it includes electromagnetic waves with wavelengths between 200 nm and 20 pm, preferably between 700 nm and 12 µm.

[0010] The optomechanical transducer is a passive element in which the thermal deformation according to the invention is triggered by the incident light signal. The optomechanical transducer thus differs from the electromechanically actuated contact transducers of the prior art. When the curvature of the optomechanical transducer according to the invention changes, the radius of curvature changes on the front and / or back side of the optomechanical transducer. An optomechanical transducer that is flat in its initial state can be transformed into a curved state by thermal deformation. In an optomechanical transducer that has a curved shape in its initial state, the curvature after thermal deformation can be more or less pronounced.

[0011] An auditory stimulation system according to the invention can be used as a hearing aid or for the reproduction of other types of sound signals, such as sound signals from audio devices.

[0012] The invention is based on the premise that vibrations of the eardrum can be stimulated particularly effectively when the stimulation is achieved via an optomechanical transducer. Compared to conventional hearing aids, in which the eardrum is stimulated by air vibrations propagating between a loudspeaker and the eardrum, stimulation by an optomechanical transducer allows access to a wider frequency range within which the eardrum can be stimulated in an open ear canal. Therefore, in the hearing stimulation system according to the invention, the eardrum is stimulated not by a loudspeaker, but by an optomechanical transducer.

[0013] The optomechanical transducer positioned at the eardrum can be mechanically coupled to the eardrum of the supported ear when the hearing stimulation system is used. This coupling can be area-based or point-like, e.g., at the Umbo (Sunil Puria, Peter Luke Santa Maria, Rodney Perkins Otology & Neurotology, "Temporal-Bone Measurements of the Maximum Equivalent Pressure Output and Maximum Stable Gain of a Light-Driven Hearing System that Mechanically Stimulates the Umbo", Issue 37, pages 160-166, 2016). Alternatively, it is also possible that the optomechanical transducer positioned at the eardrum is not in direct mechanical contact with the eardrum, but that the stimulation is achieved by a volume of gas enclosed between the optomechanical transducer and the eardrum. This gas volume can, in particular, be a volume of air.

[0014] The optomechanical transducer is excited by light signals. The light signal transfers energy to the optomechanical transducer, leading to a preferably inhomogeneous heating of the transducer and thus to thermal deformation. The optomechanical transducer is designed such that the thermal deformation causes a change in its curvature, and this change in curvature causes a displacement of a surface section of the optomechanical transducer. Due to the coupling of the optomechanical transducer with the eardrum, this displacement is transmitted as a displacement of the eardrum.

[0015] When the light signal is interrupted, the inhomogeneous temperature distribution equalizes, so that the force generated by the inhomogeneous thermal expansion and the resulting change in curvature also decrease, leading to relaxation. Alternating thermal expansion and relaxation of the optomechanical transducer can excite a desired vibration of the eardrum. The amplitude of the displacement can, for example, range from 1 pm to 10 µm, corresponding to the eardrum displacement in the audible range (Cheng et al., J. Acoust. Soc. Am., Vol. 133, Issue 2, pp. 918–937). The heat introduced into the optomechanical transducer during this excitation is continuously dissipated to the surroundings. In the operating state, an equilibrium is established between the heat input and the heat dissipated, which can lead to a slight increase in the average temperature of the optomechanical transducer.

[0016] The optomechanical transducer can be a prefabricated component designed to be positioned on the eardrum of a supported ear. The optomechanical transducer can be positioned in the ear canal in such a way that mechanical coupling to the eardrum is established. This mechanical coupling can result from the optomechanical transducer being in direct contact with the eardrum. Alternatively, a coupling substance can be used between the optomechanical transducer and the eardrum. This coupling substance can form an adhesive layer between the optomechanical transducer and the eardrum. This adhesive layer can then create a connection between the back of the optomechanical transducer and the eardrum. In one embodiment, the coupling substance is an adhesive used to attach the optomechanical transducer to the eardrum.Another possibility is a coupling substance that, in a liquid state, establishes a connection between the optomechanical transducer and the eardrum. For example, the optomechanical transducer can be coupled to the eardrum by a drop of oil. With a suitable oil viscosity, deflections of the optomechanical transducer are transmitted to the eardrum via the oil. Depending on the design of the optomechanical transducer, the coupling layer can also be designed as a thermally conductive or a thermally insulating layer.

[0017] Alternatively, the optomechanical transducer can be positioned in the ear canal such that a volume of gas is enclosed between the optomechanical transducer and the eardrum. This gas volume should be small enough to ensure effective transmission of the optomechanical transducer's movements to the eardrum. The distance between the optomechanical transducer and the eardrum should be small, for example, less than 5 mm, preferably less than 2 mm, and more preferably less than 1 mm. The optomechanical transducer can be formed by a membrane that is air-permeable. This means that, on the one hand, the volume between the optomechanical transducer and the eardrum is sealed so tightly that effective pressure transmission is possible, thus exciting the eardrum's vibrations.On the other hand, the breathable membrane allows air exchange to occur, keeping humidity and thus the risk of bacterial or fungal infections low.

[0018] The optomechanical transducer can be a component of a hearing device, the hearing device comprising a frame that supports the optomechanical transducer and the signal generator. The signal generator is the element from which the light signal is emitted toward the optomechanical transducer. The actual light source, for example, a laser diode or LED, which generates the light signal, can be located separately from the frame. The transmission of the light signal between the light source and the signal generator can be achieved via an optical fiber. The hearing device can include a spacer to maintain a defined distance between the optomechanical transducer and the eardrum. The spacer can be connected to the frame. The spacer can be ring-shaped and designed so that it does not make central contact with the eardrum.The hearing device can be designed so that the user can insert it into their own ear. The hearing device can also be designed to maintain a fixed position within the ear canal when inserted. This fixed position can be achieved, for example, through contact with the wall of the ear canal.

[0019] The invention also encompasses embodiments in which the optomechanical transducer is not a prefabricated part, but rather a structure applied as a coating to the eardrum. For example, the optomechanical transducer can be produced by applying a layer of liquid or paste-like material to the eardrum and allowing the material to harden into a layer with suitable mechanical properties.

[0020] The optomechanical transducer can have a geometric shape with a small thickness compared to its surface area. The thickness can be less than 500 µm, preferably less than 300 µm. Prefabricated components are generally thicker than 20 µm. In particular, an optomechanical transducer in the form of a coating can also be thinner than 20 µm. If the optomechanical transducer has a circular contour line surrounding the surface, the diameter of the circular contour can be at least 10 times, preferably 50 times, and more preferably 200 times larger than the thickness of the optomechanical transducer. If the optomechanical transducer has a variable thickness, the specified thickness refers to the maximum thickness of the optomechanical transducer. If the optomechanical transducer has a non-circular contour, the specified thickness refers to the diameter of the largest circle lying within the contour.A plane within which the optomechanical converter has its largest contour line, or within which a projection of the largest contour line lies, is called the XY plane.

[0021] When used, the optomechanical transducer can be positioned so that its planar extent is aligned with the eardrum. The optomechanical transducer can have a shape that matches the eardrum. In one embodiment, the optomechanical transducer has a convex or conical shape. The convex or conical shape can conform to the topography of the eardrum. For an optomechanical transducer whose largest contour extends in an XY plane, the deflection can occur in the Z direction. If the largest contour does not lie within a plane, the specification refers to a projection of the optomechanical transducer onto a plane.

[0022] The thickness of the optomechanical transducer can extend between a front and a back surface. The back surface can be the side facing the eardrum, and the front surface can be the side facing away from the eardrum. The optomechanical transducer can have a flat surface forming the back surface and / or a flat surface forming the front surface.

[0023] The invention also encompasses embodiments in which neither the front nor the back surface is formed by a flat surface. In particular, the optomechanical transducer can have a curved or conical shape in its initial state. This shape can correspond to the anatomical shape of the eardrum, which is concave towards the middle ear.

[0024] The signal generator can be designed to emit the light signal in the form of modulated electromagnetic radiation directed at the surface of the optomechanical transducer. The wavelength of the electromagnetic radiation can be in particular in the wavelength range between 200 nm and 20 pm, preferably between 700 nm and 12 µm. The wavelength of the light to be used and the absorption of the optomechanical transducer can be matched so that the light is ideally completely absorbed by the optomechanical transducer and the light energy is converted as efficiently as possible into a curvature of the surface.

[0025] When using the auditory stimulation system according to the invention, the signal transmitter can be positioned in the ear canal such that it has a clear view of the optomechanical transducer, allowing the electromagnetic radiation to propagate in a straight line from the signal transmitter to the optomechanical transducer without the path being blocked by tissue of the ear canal. The signal transmitter can be designed so as not to obstruct the ear canal. It can have a passage that allows air exchange through the transmitter, thus providing good acoustic permeability. The signal transmitter, from which the light signal is emitted towards the optomechanical transducer, can form a single structural unit with the light source in which the electromagnetic radiation is generated. Alternatively, the signal transmitter and the light source can be separate units.The transmission of the light signal between the light source and the signal transmitter can be achieved via a fiber optic cable. The light source can be designed to be positioned outside the ear canal, for example, behind the ear.

[0026] The signal generator can be designed such that a planar section of the optomechanical transducer is illuminated by the light signal. The area illuminated by the light signal on the front surface of the optomechanical transducer can comprise at least 20%, preferably at least 40%, and more preferably at least 60% of the area on the front surface of the optomechanical transducer. The light signal can cover the entire surface or a portion thereof; in particular, the light signal can illuminate the optomechanical transducer with a substantially constant intensity. However, it is also possible to heat the surface with a Gaussian or other beam profile, depending particularly on the selected absorber distribution.

[0027] This also includes embodiments in which the illuminated area is not illuminated across its entire surface. For example, a ring-shaped light signal could be directed onto the optomechanical transducer, meaning that the center of the illuminated area is not illuminated by the light signal. In this case, the large area of ​​the optomechanical transducer that is illuminated by the light signal corresponds to the outer circumference of the ring.

[0028] The light signal can be directed to the optomechanical transducer in the form of a sequence of light pulses. The timing of the light pulses can be configured such that the interval between two light pulses is longer than the duration of the light pulse itself, preferably by at least a factor of 10, more preferably by at least a factor of 100, and more preferably by at least a factor of 1000. The duration of the individual light pulses can preferably be shorter than the thermal confinement time in the optomechanical transducer. A pulse duration shorter than the acoustic confinement time in the optomechanical transducer can also be used. If the light pulses do not have the same duration, the specification refers to the longest of the light pulses. The pause between two light pulses can serve as a relaxation time, during which the optomechanical transducer can dissipate the heat absorbed by the preceding light pulse.Blood circulation near the optomechanical transducer can significantly contribute to heat dissipation. An insulating layer may be present between the optomechanical transducer and the eardrum to prevent excessive heating of the eardrum. The surface of the optomechanical transducer facing away from the eardrum may have a high degree of roughness to promote heat dissipation by convection.

[0029] Depending on the shape and design of the optomechanical transducer, a temperature increase of a few tenths of a degree Celsius may be sufficient to produce the desired deflection. However, temperature increases of several degrees Celsius may also be acceptable. A temperature equilibrium, in which the amount of heat supplied by the light signal corresponds to the amount of heat released during the relaxation period, can be reached, for example, if the relaxation period is at least 5 ps, preferably at least 20 µs. Despite such a relaxation period, the frequency of the light pulses can be sufficiently high to enable the encoding of an acoustic signal. Over a large number of light pulses, a temperature equilibrium can be established in which the tissue temperature in the vicinity of the optomechanical transducer is slightly higher than it would be without the supplied light signals.The temperature remains within a range that is physiologically harmless.

[0030] The light signal can consist of a multitude of light pulses of equal length, spaced equidistantly apart. The amplitude of the light pulses can vary. In particular, the amplitude of the light pulses can vary so that the light signal represents an audible sound signal through amplitude modulation. Other types of modulation can also be implemented, such as frequency modulation with unequal pulse intervals, or general pulse modulation with generally different pulse durations and shapes.

[0031] An acoustic signal present in the vicinity of the hearing stimulation system can be encoded into a light signal. When the optomechanical transducer is stimulated with such an encoded light signal, the desired hearing assistance is achieved by deflecting the optomechanical transducer at a frequency corresponding to the acoustic signal. This deflection of the optomechanical transducer is transmitted to the eardrum.

[0032] For the auditory stimulation system to function effectively, it is advantageous if the optomechanical transducer is designed in such a way that the energy of the incoming light signal is converted as efficiently as possible into a strong deflection of the optomechanical transducer perpendicular to the eardrum. A strong deformation of a homogeneous, single-layer transducer can be achieved, in particular, by inducing an inhomogeneous temperature distribution within the optomechanical transducer. This can be accomplished, for example, by heating the front region of the optomechanical transducer more than the rear region, or by heating the central region more than the outer regions. This thermal deformation can cause mechanical stress within the optomechanical transducer, leading to a change in its geometric shape and thus to a deflection of the optomechanical transducer.

[0033] Good deflection of the optomechanical transducer can be achieved if the optomechanical transducer is constructed from several materials, where a first material has a higher coefficient of thermal expansion than a second material. Alternatively, or additionally, it is also possible for the optomechanical transducer to include a first material with a higher optical absorption coefficient or a lower heat capacity than a second material in the optomechanical transducer.

[0034] The optomechanical transducer can comprise a first layer and a second layer, the first layer being made of a material with a higher coefficient of thermal expansion than the material of the second layer. The first layer can be located on or near the front of the optomechanical transducer. The second layer can be located on or near the back of the optomechanical transducer. Each layer can extend across the entire surface of the optomechanical transducer. When the light signal strikes the optomechanical transducer, the first layer expands more than the second layer, and the optomechanical transducer deforms in a bimetallic manner, causing it to deflect. The deflection relaxes before the next light pulse strikes the optomechanical transducer.

[0035] In an alternative embodiment, a central region of the optomechanical transducer is configured differently from a peripheral region. In particular, the optomechanical transducer can be designed such that the peripheral region prevents the central region from expanding radially. For example, if a central region with a high coefficient of thermal expansion is surrounded by a peripheral region with a lower coefficient of thermal expansion, thermal expansion of the central region into the peripheral region is not possible. Instead, the thermal expansion results in a displacement of the central region. The peripheral region can extend in a ring shape around the central region.Additionally or alternatively, the peripheral area can be made of a material with lower thermal conductivity than the material of the central area. This can also contribute to increasing the deflection of the optomechanical transducer. Additionally or alternatively, the local light irradiation can be selected so that the central area heats up more than the peripheral area.

[0036] A high displacement of the optomechanical transducer can also be promoted by appropriately designing its surface, particularly the front face. This can be achieved, for example, by creating a first region on the surface with a high absorption coefficient and a second region with a lower absorption coefficient. The absorption coefficient determines what proportion of the incident light signal is converted into heat. Thermal expansion is more pronounced in regions with a higher absorption coefficient. The distribution of these surface regions can be chosen to maximize the resulting displacement.In one embodiment, the area with a lower absorption coefficient corresponds to a ring-shaped area on the surface of the optomechanical transducer.

[0037] Additionally or alternatively, the local heat input to the optomechanical transducer can also be influenced by appropriately adjusting the profile of the light signal, i.e., the intensity distribution across the cross-section of the beam path. For example, if an aperture or an axicon is positioned in the beam path, blocking a portion of the beam, other areas are defined where the optomechanical transducer receives a particularly high amount of heat. For instance, a central area of ​​the beam path can be blocked or utilized, resulting in the light signal illuminating or not illuminating a ring-shaped area on the surface of the optomechanical transducer. Alternatively, a Gaussian beam profile can be selected, which irradiates the central area of ​​the optomechanical transducer more intensely than the peripheral area.

[0038] The invention further relates to a method for operating an auditory stimulation system in which a light signal is directed onto an optomechanical transducer coupled to a tympanic membrane, such that the light signal triggers thermal deformation in the optomechanical transducer. The optomechanical transducer is designed such that the thermal deformation causes a change in the curvature of the optomechanical transducer. This change in curvature excites a vibration of the tympanic membrane.

[0039] The disclosure includes further developments of the method with features that are described in connection with the auditory stimulation system according to the invention. The invention includes further developments of the auditory stimulation system with features that are described in connection with the method according to the invention.

[0040] The invention is described below by way of example with reference to the accompanying drawings and advantageous embodiments. The drawings show: Fig. 1: A schematic representation of an ear canal with a hearing stimulation system according to the invention; Fig. 2: A schematic representation of the operation of a hearing stimulation system according to the invention; Fig. 3: A schematic representation of a light signal for stimulating an optomechanical transducer of a hearing stimulation system according to the invention; Fig. 4: A schematic representation of an optomechanical transducer inserted into an ear canal; Fig. 5: A view of the front of the optomechanical transducer made of Fig. 4 ; Fig. 6: a sectional view of the optomechanical transducer according to Fig. 5 ; Fig. 7-8: the view according to Fig. 5-6 in an alternative embodiment of the invention; Figs. 9-10: the view according to Fig. 5-6 in a further embodiment of the invention; Figs. 11-12: the view according to Fig. 5-6 in yet another embodiment of the invention; Figs. 13-14: the view according to Fig. 5-6 in yet another embodiment of the invention; Fig. 15: an alternative embodiment of a signal transmitter according to the invention; Fig. 16: the view according to Fig. 4 in a further embodiment of the invention; Figs. 17, 18: a schematic representation of the operating principle of an auditory stimulation system according to the invention; Figs. 19, 20: an experimental setup to illustrate the operating principle according to the invention; Fig. 21: three views A, B, C of the experimental setup Fig. 19, 20 recorded measured values; Fig. 22: a hearing stimulation system according to the invention in the form of a hearing device.

[0041] In Fig. 1 Figure 16 schematically depicts the ear canal 15 of a human ear adjacent to an auricle 14. A tympanic membrane 16 extends over the cross-section of the ear canal 15. An auditory stimulation system according to the invention is inserted into the ear canal 15, comprising a signal transmitter 17 and an optomechanical transducer 18. The optomechanical transducer 18 is arranged adjacent to the tympanic membrane 16 and is mechanically coupled to it. The signal transmitter 17 is located in a section of the ear canal 15 situated between the tympanic membrane 16 and the auricle 14. The signal transmitter 17 has a passage 25, allowing free air exchange between the environment and the section of the ear canal 15 located between the signal transmitter 17 and the optomechanical transducer 18.

[0042] According to Fig. 2 The signal transmitter 17 comprises an electromagnetic radiation source, for example in the form of an infrared light source 22, which emits a light signal 20.

[0043] In Fig. 3 The figure schematically represents a light signal over time T, generated by the infrared light source 22 based on the received control signals. The light signal 20 comprises a sequence of light pulses 24 that follow each other at equidistant intervals. The frequency of the light pulses 24 can, for example, be on the order of 40 kHz, where the length of a light pulse 24 can constitute a significantly smaller part of a period and the subsequent pause a significantly larger part of the period.

[0044] The infrared light source 22 is controlled such that the sound signal is encoded into a sequence of light pulses 24 by means of amplitude modulation. At a light pulse frequency of 40 kHz, encoding of sound signals in the audible range up to 20 kHz is possible. The signal transmitter 17 is arranged in the ear canal 15 such that the light signal 20 emitted by the signal transmitter 17 can propagate through the ear canal 15 and reach the optomechanical transducer 18. The signal transmitter 17 includes an exit optic 23 with which the light emitted by the infrared light source 22 is shaped into a desired beam shape that is directed onto the surface of the optomechanical transducer 18. In the exemplary embodiment according to Fig. 2 The beam path illuminates the surface of the optomechanical transducer 18 over a large area and with uniform brightness.

[0045] Each light pulse 24 that strikes the optomechanical transducer 18 is ideally absorbed to a very large extent within the material of the optomechanical transducer 18, thereby supplying heat energy to the optomechanical transducer 18. The optomechanical transducer 18 is designed such that the supplied amount of heat causes a change in the curvature of the optomechanical transducer 18. In the illustrative example of the Fig. 17, 18 In its initial state, when no light signal 20 strikes the optomechanical transducer 18, it has a planar shape. Under the influence of the heat supplied by the light signal 20, the curvature of the optomechanical transducer 18 changes, causing it to deflect and become curved, see [reference]. Fig. 18 The deflections of the optomechanical transducer 18 are transmitted to the eardrum 16 to stimulate vibrations of the eardrum 16.

[0046] In the embodiment according to Fig. 2 , 17, 18The optomechanical transducer 18 consists of a homogeneous material that ideally has a high coefficient of thermal expansion and low heat capacity. The supplied heat energy causes thermal deformation primarily in the region of the illuminated surface of the optomechanical transducer 18. Since the temperature increase is significantly smaller in the deeper regions of the optomechanical transducer 18, the near-surface thermal deformation causes the optomechanical transducer 18 to deflect in a manner similar to a bimetallic strip. However, the key difference from a bimetallic strip is that the differential thermal expansion is caused by inhomogeneous absorption of the light energy, rather than by the use of two materials with different coefficients of thermal expansion. The deflection is essentially perpendicular to the plane of the optomechanical transducer 18.The plane of the optomechanical transducer 18 is referred to as the XY plane. The direction in which the deflection acts is the Z-direction.

[0047] During the interval between two light pulses 24, the optomechanical transducer 18 dissipates heat into the surroundings. Some of this heat energy is dissipated convectively, and some, in the case of contact application to the eardrum, also via blood circulation. An insulating layer can be formed between the optomechanical transducer 18 and the eardrum 16 to prevent excessive heating of the eardrum. The relaxation time between two light pulses 24 is sufficient for the optomechanical transducer 18 to essentially return to its initial position, allowing for renewed excitation with the subsequent light pulse. High thermal conductivity and heat dissipation of the optomechanical transducer are advantageous for this process. Over the course of numerous light pulses 24, a temperature equilibrium is established, the temperature of which is slightly elevated compared to the temperature that would be present without the operation of the auditory stimulation system.

[0048] The displacement can be small and may, for example, be significantly below 10 µm. A small displacement is sufficient to stimulate the eardrum and provide hearing assistance.

[0049] The optomechanical transducer 18 is mechanically coupled to the eardrum 16, so that the deflection of the optomechanical transducer 18 is directly transmitted as a deflection of the eardrum 16. In the embodiment according to Fig. 4 The mechanical coupling results from the insertion of the optomechanical transducer 18, which is a plate-shaped element that can also be pre-curved or adapted to the topography of the eardrum, into the ear canal 15 and coupled to the eardrum 16 via an adhesion layer 26. The adhesion layer 26 can be, for example, an oil film. Other forms of adhesion layers are possible, such as an adhesive between the optomechanical transducer 18 and the eardrum 16, which cross-links upon contact with the eardrum 16.

[0050] In the Fig. 5, 6 An alternative embodiment of an optomechanical transducer 18 is shown, in which the body of the optomechanical transducer 18 is composed of a front layer 27 and a rear layer 28. The front layer 27 forms the front 30 of the optomechanical transducer 18 and is stimulated by the light signal 20. The mechanical coupling to the tympanic membrane 16 is achieved via the rear layer 28, which forms the back 31 of the optomechanical transducer 18. The front layer 27 is made of a material with high optical absorption coefficients and a high coefficient of thermal expansion. The rear layer 28 can have high thermal conductivity and adhere well to the tympanic membrane if efficient heat dissipation into the tympanic membrane's blood vessels is desired. Various materials are also possible to adjust the mechanical properties of the optomechanical transducer 18 as desired.The materials can have different thermal conductivities, thermal heat capacities, densities, and mechanical stiffnesses. The heat energy absorbed from a light pulse 24 causes a greater thermal expansion in the front layer 27 than in the rear layer 28, which in turn leads to a deflection of the optomechanical transducer 18 in the Z-direction.

[0051] The front face 30 of the optomechanical transducer 18 has a surface structure 29 that promotes the absorption of the light pulses 24 and the transfer of heat energy to the optomechanical transducer 18. The surface structure 29, which is in Fig. 5 A surface indicated by hatching can have high absorption for the wavelength of the light signal and high roughness.

[0052] In the alternative embodiment according to Fig. 7, 8 The front surface 30 of the optomechanical transducer 18 is divided into a first region 32, where the surface has a high absorption coefficient, and a second region 29, where less energy is absorbed. In the first region 32, the material of the optomechanical transducer 18 absorbs a large amount of thermal energy from a light pulse 24, resulting in increased thermal deformation locally. The shape of the first region 32 and the second region 29 is chosen such that the thermal deformation is effectively converted into a deflection of the optomechanical transducer 18.

[0053] In Fig. 9, 10 Another embodiment is shown. According to Fig. 10 The optomechanical converter 18 has a geometric shape which, even in the relaxed state, exhibits a curvature towards the front 30.

[0054] In the further embodiment in the Fig. 11, 12 The front surface 30 of the optomechanical transducer 18 has a first region 29 with a high absorption coefficient and a second region 32 with a low absorption coefficient. The first region 29 forms the center of the front surface 30, and the second region 32 extends in a ring shape around the first region 29. The increased thermal deformation in the center of the optomechanical transducer 18 leads to a deflection in the Z-direction.

[0055] The Fig. 13, 14 Figure 1 shows another embodiment in which the structure of the optomechanical transducer 18 is two-part. The periphery of the optomechanical transducer is formed by a ring 33. The ring 33 is made of a material with a low coefficient of thermal expansion. Inside the ring 33, a disk 34 made of a material with a higher coefficient of thermal expansion is arranged. If the disk 34 heats up after being struck by a light pulse 24, the ring 33 prevents expansion in the radial direction. Instead, the thermal expansion is converted into a deflection in the Z-direction.

[0056] In the embodiment according to Fig. 15 An aperture 35 is arranged in the beam path of the light signal 20, which blocks out an annular region of the beam path. In this way, an annular region on the front of the optomechanical transducer 18 is not exposed to infrared radiation, which is similar to the effect in Fig. 7, 8 which leads to a deflection in the Z-direction.

[0057] In Fig. 16 The optomechanical transducer 18 is applied to the eardrum 16 in the form of a two-layer coating. The first layer 36 is applied or sprayed onto the eardrum 16 in a liquid state and hardens there. After hardening, the second layer 37 is applied or sprayed onto the first layer 36. The second layer 37 has a higher coefficient of thermal expansion than the first layer 36, so that, similar to in Fig. 6 a bimetallic effect is established and that the optomechanical transducer 18 is deflected in the Z direction when a light pulse 24 strikes it.

[0058] In Fig. 19 A sample 38 is shown, which was used to demonstrate the functional principle according to the invention. The sample 38 comprises a membrane 45 made of a silicone material. The membrane 45 simulates the eardrum of an augmented ear. An optomechanical transducer 43 is coupled to the membrane 45 via an oil film 44. The membrane 45 was excited by a light signal in the form of a single light pulse. The displacement caused by the excitation with the light signal was measured at three points 40A, 40B, 40C. Figures 20A, 20B, 20C show the measured values ​​for the measuring points 40A, 40B, 40C. Each curve corresponds to the displacement A over time, with the first curve 41 referring to the front of the sample 38 and the second curve 42 to the back of the sample 48. The first curve 41 therefore corresponds to the oscillation of the optomechanical transducer 43, and the second curve 42 corresponds to the oscillation of the silicon membrane 45.The divisions on the vertical axis are spaced 20 nm apart. It is shown that the sample 38 is set into vibration by the light signal, with the amplitude of the displacement A being slightly larger at the central measuring point 40B than at the more distant measuring points 40A and 40C. The vibration decays within a period of less than 10 ms.

[0059] In Fig. 22An embodiment is shown in which the optomechanical transducer 18 is a component of a hearing device 47. The hearing device 47 comprises a frame 48 inserted into the ear canal 15, which supports the optomechanical transducer 18. The frame 48 includes an annular sleeve 50 at the front, which rests on the eardrum 16 and defines the distance 53 between the eardrum 16 and the optomechanical transducer 18. An air volume is enclosed between the optomechanical transducer 18, the eardrum 16, and the annular sleeve 50, through which the optomechanical transducer 18 and the eardrum 16 are coupled, so that vibrations can be transmitted from the optomechanical transducer 18 to the eardrum 16.

[0060] The frame 48 further supports the signal transmitter 17, from which the light signal 20 propagates towards the optomechanical transducer 18. The signal transmitter 17 is connected to the frame 48 via a plurality of struts 49. Air exchange from the ear canal 15 towards the optomechanical transducer 18 is possible through the space between the struts 49. The light source 51 is a separate structural unit from the signal transmitter 17, which can, for example, be positioned behind the user's ear. The light signal emitted by the light source 51 is transmitted to the signal transmitter 17 via an optical fiber 52. The hearing device 47 can be designed so that it can be inserted into the user's own ear canal.

Claims

1. Hearing stimulation system for a tympanic membrane (16), comprising a signal generator (17) and an optomechanical transducer (18) for exciting vibrations of the tympanic membrane (16), wherein the signal generator (17) is designed to emit a light signal (20) such that the light signal (20) hits the optomechanical transducer (18) and that the light signal (20) causes a thermal deformation in the optomechanical transducer (18) and wherein the optomechanical transducer (18) is designed such that the thermal deformation causes a change in the curvature of the optomechanical transducer (18) by which a surface section (30, 31) of the optomechanical transducer (18) is deflected.

2. Hearing stimulation system according to claim 1, wherein the optomechanical transducer (18) is a prefabricated component designed to be arranged on the eardrum (16) of an assisted ear.

3. Hearing stimulation system according to claim 2, wherein a coupling substance (26) is arranged between the optomechanical transducer (18) and the eardrum (16) of the assisted ear.

4. Hearing stimulation system according to claim 3, wherein the coupling substance (26) forms an adhesive layer.

5. Hearing stimulation system according to claim 1 or 2, wherein the optomechanical transducer (18) is arranged at a distance from the eardrum (16) and is coupled to the eardrum (16) by a volume of air enclosed between the optomechanical transducer (18) and the eardrum (16).

6. Hearing stimulation system according to claim 5, wherein the optomechanical transducer (18) is air-permeable.

7. Hearing stimulation system according to claim 5 or 6, wherein the optomechanical transducer (18) is part of a hearing device comprising the signal generator (17) and the optomechanical transducer (18) which are rigidly connected to each other as a unit.

8. Hearing stimulation system according to claim 1, wherein the optomechanical transducer (18) is a structure applied as a coating to the eardrum (16).

9. Hearing stimulation system according to one of claims 1 to 8, wherein the largest contour of the optomechanical transducer (18) lies in an XY plane and wherein the optomechanical transducer (18) is deflected in a Z direction orthogonal thereto.

10. Hearing stimulation system according to one of claims 1 to 9, wherein the optomechanical transducer (18) has a pre-curved shape in the direction of the deflection.

11. Hearing stimulation system according to one of claims 1 to 10, wherein the optomechanical transducer (18) has a shape adapted to the topography of the eardrum (16).

12. Hearing stimulation system according to one of claims 1 to 11, wherein the signal generator (17) is provided with a through channel (25).

13. Hearing stimulation system according to one of claims 1 to 12, wherein the signal generator (17) is arranged such that a surface area of ​​at least 20% of a front side of the optomechanical transducer (18) is exposed to the light signal (20).

14. Hearing stimulation system according to any one of claims 1 to 13, wherein the optomechanical transducer (18) is constructed from a plurality of materials, wherein a first material has a different coefficient of thermal expansion, and / or a different coefficient of light absorption, and / or a different thermal conductivity, and / or a different thermal capacity, and / or a different mechanical stiffness than a second material.

15. Method for operating an auditory stimulation system in which a light signal (20) is directed onto an optomechanical transducer (18) coupled to a tympanic membrane (16), such that the light signal (20) causes a thermal deformation in the optomechanical transducer (18), wherein the optomechanical transducer (18) is designed such that the thermal deformation causes a change in the curvature of the optomechanical transducer (18), by which a surface section (30, 31) of the optomechanical transducer (18) is deflected, and wherein the deflection excites a vibration of the tympanic membrane (16).

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