WO2025169439A1 - Cochlear implant device - Google Patents

Abstract

The present disclosure relates to a cochlear implant device comprising: a plurality of optical waveguides having different lengths; and an optical transmitter that makes light incident on an optical waveguide according to a sound frequency. The light emission positions of the plurality of optical waveguides correspond to the sensitivity of the sound frequency in a cochlea.

Description

cochlear implant device

This disclosure relates to a cochlear implant device worn on the human body, and in particular to a cochlear implant device that uses light.

It is said that if children with congenital hearing loss are diagnosed early and given appropriate support, it can have a positive impact on their overall development. For this reason, newborn hearing screening tests are becoming more common, and it is expected that the number of newborns with early-stage hearing loss will increase in the future. Furthermore, as the population ages, it is expected that the number of people developing age-related hearing loss will also increase. For these reasons, it is extremely important to restore hearing lost due to hearing loss.

Hearing aids and cochlear implants are used to restore hearing. Hearing aids cannot be used if even some of the hair cells are not functioning. On the other hand, cochlear implants can be used even if the hair cells are severely damaged. For this reason, electrically stimulating cochlear implants, which transmit sound by electrically stimulating the cochlear cells, are currently in widespread use.

Cochlear implants are said to be one of the most successful artificial organs, with approximately 10,000 to 30,000 people in Japan wearing them. Electrical stimulation-type cochlear implants still have difficulty extracting a speaker's words from noise, such as in a crowded street, compared to people with normal hearing. To solve these problems, optical cochlear implant devices, which use light to stimulate cochlear cells, are being investigated (see, for example, Non-Patent Document 1). Infrared light has low toxicity to biological cells and penetrates deep into cochlear cells, making it a promising option.

However, when considering safety for the human body and ease of maintenance, a passive type (where the light source is worn outside the body and light is delivered to the inside via fiber) is considered preferable (see, for example, Non-Patent Document 2). On the other hand, it has been demonstrated that stimulating cochlear cells with multiple lights can result in clearer hearing. What has been demonstrated here is an active type, that is, a technology in which a light source is embedded inside the body to emit multiple lights (see, for example, Non-Patent Document 3).

Dieter, Alexander, Daniel Keppeler, and Tobias Moser. “Towards the optical cochlear implant: optogenetic approaches for Hearing restoration.” EMBO molecular medicine 12.4 (2020): e11618. Gundelach, Lili A. , et al. “Towards the clinical translation of optogenetic skeletal muscle stimulation on.” Pfluegers Archiv-European Journal of Physiology 472.5 (2020): 527-545. Keppeler, Daniel, et al. “Multichannel optogenetic stimulation of the auditory pathway using microfabricated LE D cochlear implants in rodents.” Science Translational Medicine 12.553 (2020): eabb8086.

Non-Patent Document 2 indicates that a passive type internally mounted unit is desirable, but in order to stimulate cochlear cells with multiple light beams, it was necessary to use an active type internally mounted unit, as in Non-Patent Document 3. Therefore, the purpose of this disclosure is to provide a cochlear implant device that is passive yet can stimulate cochlear cells in multiple locations.

In order to achieve the above objective, the cochlear implant device disclosed herein comprises multiple optical waveguides of different lengths and an optical transmitter that directs light into the optical waveguides according to sound frequencies, with the light emission positions of the multiple optical waveguides corresponding to the sensitivity of sound frequencies within the cochlea.

The cochlear implant device of the present disclosure may include an external attachment unit that includes the optical transmitter and is attached to the outside of the human body, and an internal attachment unit that includes the multiple optical waveguides and is attached to the inside of the human body.

The externally worn unit may include a microphone that converts sound into an electrical signal, and a sound processor that outputs sound intensity for each sound frequency by analyzing the frequency components of the electrical signal from the microphone. The optical transmitter outputs light having a light intensity corresponding to the sound intensity to one of the multiple optical waveguides that corresponds to the sound frequency from the sound processor.

The internally mounted unit includes an output unit that extracts light at a different location for each of the multiple optical waveguides. For example, the multiple optical waveguides may be configured to be cut at an angle. Alternatively, an oblique diffraction grating may be provided in one of the multiple optical waveguides. Alternatively, a Y-shaped waveguide may be provided in one of the multiple optical waveguides. Alternatively, one of the multiple optical waveguides may be configured to be cut at an angle. Alternatively, a reflection filter may be provided in one of the multiple optical waveguides.

The above disclosures may be combined to the greatest extent possible.

This disclosure makes it possible to provide a passive cochlear implant device that can stimulate cochlear cells in different locations with multiple light sources.

1 illustrates an example embodiment of a cochlear implant device of the present disclosure. 10 is a diagram illustrating an example of the configuration of the externally worn unit. 2 shows an example of the configuration of an optical transmitter 30. 10 shows an example of the configuration of a plurality of optical waveguides 60. 10 shows an example of the configuration of a plurality of optical waveguides 60. 10 shows an example of the configuration of a plurality of optical waveguides 60. 10 shows an example of the configuration of a plurality of optical waveguides 60. 10 shows an example of the configuration of a plurality of optical waveguides 60. 10 shows an example of the configuration of a plurality of optical waveguides 60.

Embodiments of the present disclosure will be described in detail below with reference to the drawings. However, the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Furthermore, components with the same reference numerals in this specification and drawings are considered to be identical to each other.

The configuration of the cochlear implant device of this embodiment is shown in Figure 1. In Figure 1, A represents the ear, B represents the skull, C represents the inner ear, and D represents the cochlea. The cochlear implant device comprises an externally mounted unit 100 that is mounted outside the human body, and an internally mounted unit 200 that is mounted inside the human body. Figure 1 shows an example in which the internally mounted unit 200 is mounted near ear A, and the internally mounted unit 200 is mounted outside the skull.

The internally worn unit 200 includes multiple optical waveguides 60 of different lengths. The light emission positions in the multiple optical waveguides 60 correspond to the sensitivity of sound frequencies within the cochlea D. The externally worn unit 100 includes an optical transmitter 30 that inputs light into the optical waveguide 60 according to the sound frequency. This allows the present disclosure to irradiate cochlear cells with light according to the sound frequency. Note that some of the multiple optical waveguides 60 may be the same length.

It is desirable that the internally mounted unit 200 does not contain any conductors. The optical waveguide 60 and its connecting members can all be made of synthetic resin such as plastic or glass. This is because the absence of conductors does not interfere with the use of MRI (Magnetic Resonance Imaging).

The configuration of the externally worn unit 100 is shown in Figure 2. In Figure 2, the externally worn unit 100 comprises a microphone 10, a sound processor 20, and an optical transmitter 30. The microphone 10 converts collected sound into an electrical signal. The sound processor 20 analyzes the frequency components of the electrical signal from the microphone 10 and outputs the sound intensity for each sound frequency. The optical transmitter 30 directs light of an intensity corresponding to the sound intensity into an optical waveguide 60 corresponding to the sound frequency.

The configuration of the optical transmitter 30 is shown in Figure 3. The optical transmitter 30 acquires frequency information from the sound processor 20. The frequency information includes sound intensity information for each sound frequency. The signal processing unit 31 processes the frequency information from the sound processor 20 and instructs the optical emitting unit 32 corresponding to the sound frequency to emit light. The optical emitting unit 32 emits light in accordance with the instruction from the signal processing unit 31.

This disclosure illustrates an example having n optical transmitters 32. Each of the optical transmitters 32-1 to 32-n outputs light corresponding to the sound intensity to one of the optical waveguides 60 corresponding to the sound frequency. In FIG. 1, the optical waveguides 60 propagate signal light, extract the signal light at the output corresponding to the optical waveguide 60, and irradiate the cochlear cells. The signal light is output from the optical transmitter 32 corresponding to the sound frequency collected by the microphone 10, and has a light intensity corresponding to the sound intensity of that frequency. Therefore, this embodiment can irradiate cochlear cells corresponding to the sound frequency with light of a light intensity corresponding to the sound intensity. The light intensity of the optical transmitter 32 may be controlled by controlling the current value applied to the light source or by a variable attenuator.

Here, it is preferable that the light transmitter 32 intensity-modulates the signal light before outputting it. This is because cochlear cells are more sensitive to intensity-modulated light than to light of a constant intensity. It is desirable that the intensity modulation frequency of the light transmitter 32 be variable so that the intensity modulation frequency at which sensitivity is high can be adjusted. It is also desirable that the light transmitter 32 be able to vary the conversion coefficient from sound intensity to light intensity according to the sensitivity of the cochlear cells. The light transmitter 32 may use a light source with a fixed wavelength or a light source with a tunable wavelength. The intensity modulation of the signal light may be performed by the voltage applied to the light source, or by an optical switch.

The following explains the distribution of sound frequency sensitivity within the cochlea D. High frequency sensitivity is high near the entrance of the cochlea D, while low frequency sensitivity is high in the center. While this varies from person to person, for example, 20 kHz is the highest sensitivity near the entrance of the cochlea D, while 200 Hz is the highest sensitivity in the center. If the emission section is compatible with these sound frequencies, cochlear cells can be stimulated efficiently.

An example configuration of multiple optical waveguides 60 is shown in Figure 4. The multiple optical waveguides 60 can be made using any means capable of propagating each signal light individually, such as multi-core optical fiber, bundled optical fiber, tape optical fiber, or silica-based planar lightwave circuit. Multiple signal lights (34-1 to 34-n) are input from the light input section of the optical waveguide 60 and output from the output section 61. Sensitivity to sound frequencies varies depending on the location within the cochlea D. Furthermore, the light transmitter 32 and the optical waveguides 60 connected to it correspond to sound frequencies. Therefore, the lengths of the optical waveguides 60 are different, and the positions of the output sections 61 are different.

The emission position of the signal light from the emission unit 61 corresponds to the sensitivity of the sound frequency within the cochlea D. For example, the correspondence mapping between sound frequencies and the light emitter 32 can be such that signal light 34-1 has a sound frequency of 200 Hz, signal light 34-2 has a sound frequency of 400 Hz, and signal light 34-n has a sound frequency of 20 kHz. The emission unit 61 of signal light 34-n is positioned near the entrance of the cochlea D. The emission unit 61 of signal light 34-1 is positioned near the center of the cochlea D. In this way, the signal lights emitted from the multiple emission units 61 each stimulate cochlear cells located at positions in the cochlea D corresponding to the emission units 61. Note that optical waveguides 60 of equal length may be present, in which case the emission units 61 may be positioned at the same position in the cochlea D.

Because the position of the emission unit 61 is determined for each optical waveguide 60, it is possible to accurately stimulate cochlear cells corresponding to the sound frequency with signal light. Here, with the present disclosure, the wavelength of the signal light irradiated onto the cochlear cells can be set arbitrarily. As a result, the present disclosure makes it possible to comprehensively stimulate various wavelengths to address the sensitivity distribution of cochlear cells, which varies greatly from person to person. For example, it is possible to test in advance what sounds a cochlear implant device user can hear when signal light of a certain wavelength is emitted from a certain optical waveguide 60, and then assign sound frequencies and wavelengths to the light emission unit 32 based on the test results.

The wavelength of the signal light can be changed by changing the type of light source in the light emitting unit 32 or by changing the temperature of the light source in the light emitting unit 32. However, some output units 61 have wavelength dependency, such as diffraction gratings, so the wavelength of the signal light is selected from a wavelength range suitable for the output unit 61.

The emission section 61 can employ any one of the following configurations or a combination thereof.
(i) A configuration in which a plurality of optical waveguides 60 are cut obliquely.
(ii) A configuration in which an oblique diffraction grating is provided in any of the plurality of optical waveguides 60.
(iii) A configuration in which a reflection filter is provided in any of the plurality of optical waveguides 60.
(iv) A configuration in which any of the plurality of optical waveguides 60 is cut obliquely.
(v) A configuration in which a Y-shaped waveguide is provided in any of the plurality of optical waveguides 60.
(vi) A configuration in which any of the plurality of optical waveguides 60 is bent.

Figure 5 shows an example configuration of multiple optical waveguides 60. The emission section 61 can be realized, for example, by cutting multiple optical waveguides 60 at an angle. By cutting the optical waveguides 60 at an angle, each optical waveguide 60 can emit signal light at a different location. Because the optical waveguides 60 are cut at an angle, the signal light emitted from the optical waveguide 60 is refracted due to the difference in refractive index between the optical waveguide 60 and air.

A configuration in which multiple optical waveguides 60 are cut at an angle can be created by polishing or etching the multiple optical waveguides 60. Depending on the angle at which the optical waveguides 60 are cut at an angle, it is possible to adjust the location of the signal light that can be extracted from each optical waveguide 60. Therefore, the angle at which the multiple optical waveguides 60 are cut at an angle may differ depending on the optical waveguide 60.

Figure 6 shows an example configuration of multiple optical waveguides 60. The output section 61 may be created by adding a diffraction grating 62 to the location of the multiple optical waveguides 60 from which the signal light is to be extracted. By adding a reflective diffraction grating 62 at an angle, the signal light is reflected at an angle, making it possible to extract the signal light from the optical waveguide 60.

The diffraction grating 62 can be fabricated by periodically irradiating it with a femtosecond laser. By using a photosensitive optical fiber for the optical waveguide 60, the diffraction grating 62 can also be fabricated by photolithography using ultraviolet light.

The diffraction grating 62 can be placed at any position on the optical waveguide 60, and the direction in which the signal light is extracted can also be adjusted. This means that the emission unit 61 can be placed at a position suitable for the user of the cochlear implant device, and the signal light can be emitted in a direction suitable for the user of the cochlear implant device. The diffraction grating 62 can also widen the range of wavelengths of the usable signal light.

An example configuration of multiple optical waveguides 60 is shown in Figure 7. The output section 61 may be created by installing a reflective filter 63 at a location among the multiple optical waveguides 60 where it is desired to extract the signal light. The reflective filter 63 can reflect the signal light, and by installing it at an angle, it is possible to extract the signal light from the optical waveguide 60. The reflective filter 63 can be made from a dielectric multilayer film filter, etc.

When the output of the light emitting unit 32 is strong, a low reflectivity of the reflection filter 63 does not pose a problem, so the optical waveguide 60 can also be manufactured by cutting it at an angle. For example, a multi-core optical fiber, bundled optical fiber, or tape optical fiber can be used, and each optical fiber can be cut at an angle to the desired length. By adopting such a configuration, it becomes possible to manufacture multiple optical waveguides 60 and emission units 61 at low cost.

Figure 8 shows an example configuration of multiple optical waveguides 60. The output section 61 can be created by installing a Y-shaped waveguide 64 that branches the signal light at the location among the multiple optical waveguides 60 where the signal light is to be extracted. By using the Y-shaped waveguide 64, it is possible to extract the signal light accurately to the desired position in the optical waveguide 60. The Y-shaped waveguide 64 can be created by drawing with a femtosecond laser or using a silica-based planar lightwave circuit.

The Y-shaped waveguide 64 can be installed at any position on the optical waveguide 60, and the direction in which the signal light is extracted can also be adjusted. This allows the emission unit 61 to be installed at a position suitable for the user of the cochlear implant device, and the signal light to be emitted in a direction suitable for the user of the cochlear implant device.

Incidentally, since light leaks when the optical waveguide is bent sharply, a bent optical waveguide 65 may be used, as shown in Figure 9. In this case, too, it is possible to create it using femtosecond laser imaging or a silica-based planar lightwave circuit. Furthermore, since even a small amount of signal light leakage can stimulate cochlear cells, the bent optical waveguide 65 may be constructed by bending an optical fiber at the position of the emission section 61.

10: microphone 20: sound processor 30: optical transmitter 31: signal processing unit 32: optical transmitter 60: optical waveguide 61: emitter 62: diffraction grating 63: reflection filter 64: Y-shaped waveguide 100: externally worn unit 200: internally worn unit

Claims (8)

A plurality of optical waveguides having different lengths;
an optical transmitter that inputs light into an optical waveguide according to the sound frequency;
Equipped with
The light emission positions of the plurality of optical waveguides correspond to the sensitivity of sound frequencies in the cochlea.
Cochlear implant device. an external attachment unit that includes the optical transmitter and is attached to the outside of a human body;
an internally attached unit that includes the plurality of optical waveguides and is attached to a human body;
Equipped with
the internally mounted unit includes an output unit that extracts light at different positions for each of the plurality of optical waveguides;
10. The cochlear implant device of claim 1. The externally worn unit is
A microphone that converts sound into an electrical signal,
a sound processor that analyzes frequency components of the electrical signal from the microphone and outputs sound intensity for each sound frequency;
Equipped with
the optical transmitter outputs light having a light intensity corresponding to a sound intensity to an optical waveguide corresponding to a sound frequency from the sound processor among the plurality of optical waveguides;
3. The cochlear implant device of claim 2. The cochlear implant device described in claim 2, characterized in that the output section includes a configuration in which the multiple optical waveguides are cut at an angle. The cochlear implant device described in claim 2, characterized in that the output section includes an oblique diffraction grating provided in one of the multiple optical waveguides. The cochlear implant device described in claim 2, characterized in that the output section includes a Y-shaped waveguide provided in one of the plurality of optical waveguides. The cochlear implant device described in claim 2, characterized in that the output section includes a configuration in which one of the multiple optical waveguides is cut obliquely. The cochlear implant device described in claim 2, characterized in that the output section includes a reflection filter provided in one of the multiple optical waveguides.