US 5,772,575 A · Implantable hearing aid

Abstract

A hearing aid includes an implantable microphone, signal-processing amplifier, battery, and microactuator. An electrical signal from the microphone is amplified and processed by the amplifier before being applied to the microactuator. The microactuator is adapted for implantation in a subject at a location from which it may mechanically create vibrations in the perilymph fluid within a subject's inner ear. A transducer of the microactuator is preferably a thin circular disk, 2 to 8 mils thick, of stress-biased PLZT. Disks of this stress-biased PLZT material can be mounted as drumheads in various different ways, preferably in conjunction with a flexible diaphragm, to small threaded metal tubes, e.g. 1.4 mm in diameter and 2.0 mm long. These tubes may be implanted into a fenestration formed through the promontory adjacent to the oval window of a subject's inner ear. Securing the disk to a tube having a larger diameter than that implanted into the fenestration and filling the tube with fluid provides hydraulic amplification of the transducer's displacement. The implantable microphone is preferably fabricated from a thin sheet of PVDF that is overcoated with inert metal electrodes.

Claims57

Dependent claims

A hearing aid adapted for implantation into a subject having both a fluid-filled inner ear, and a middle ear that has an ear drum located distal from the inner ear, said hearing aid comprising:

a microphone adapted for subcutaneous implantation in the subject and for generating an electric signal in response to impingement of sound waves upon the subject;
signal processing means adapted for receiving the electric signal from the microphone, and for processing and re-transmitting a processed electric signal, said signal processing means also being adapted for implantation in the subject;
a battery for supplying electrical power to said signal processing means, said battery also being adapted for implantation in the subject;
and
a microactuator adapted for implantation in the subject in a location which disposes a transducer included in said microactuator intermediate the fluid filled inner ear and the ear drum, the transducer creating mechanical vibrations in the fluid within the inner ear of the subject in response to receiving the processed electric signal from said signal processing means, the vibrations in the fluid present in the inner ear being proportional to displacing, in response to a sinusoidal processed electric signal at a frequency of 1000 Hz, at least 1.0.times.10.sup.-4 microliters of the fluid for an electrical power input to the microactuator of less than 50 microwatts, whereby upon implantation of the microactuator the hearing aid stimulates auditory nerve fibers which stimulation the subject perceives as sound.

2 more elements

A hearing aid adapted for implantation into a subject having both a middle ear cavity in which is located an ossicular chain that consists of a malleus, an incus, and a stapes which terminates in a stages footplate;

and a fluid-filled inner ear that is enclosed by a bony otic capsule having a promontory, an oval window to which the stapes footplate attaches, and a round window;
said hearing aid comprising:
a microphone adapted for subcutaneous implantation in the subject and for generating an electric signal in response to impingement of sound waves upon the subject;
signal processing means adapted for receiving the electric signal from the microphone, and for processing and re-transmitting a processed electric signal, said signal processing means also being adapted for implantation in the subject;
a battery for supplying electrical power to said signal processing means, said battery also being adapted for implantation in the subject;
and
a microactuator adapted for implantation in the subject in a location from which a transducer included in said microactuator is adapted to mechanically create vibrations in fluid within the inner ear of the subject, the transducer including a first plate of a piezoelectric material, the first plate of the transducer being secured to a tube, the piezoelectric material being electrically coupled to the signal processing means for receiving the processed electric signal from said signal processing means, wherein the transducer includes a first flexible diaphragm sealed across a first end of the tube, the first plate of the transducer being coupled to the first flexible diaphragm for deflecting the first flexible diaphragm to generate the vibrations in the fluid within the inner ear, whereby upon implantation of the microactuator the hearing aid stimulates auditory nerve fibers which stimulation the subject perceives as sound.

4 more elements

and a fluid-filled inner ear that is enclosed by a bony otic capsule having a promontory, an oval window to which the stapes footplate attaches, and a round window;
said hearing aid comprising:
a microphone adapted for subcutaneous implantation in the subject and for generating an electric signal in response to impingement of sound waves upon the subject;
signal processing means adapted for receiving the electric signal from the microphone, and for processing and re-transmitting a processed electric signal, said signal processing means also being adapted for implantation in the subject;
a battery for supplying electrical power to said signal processing means, said battery also being adapted for implantation in the subject;
and
a microactuator adapted for implantation in the subject in a location from which a transducer included in said microactuator is adapted to mechanically create vibrations in fluid within the inner ear of the subject, the transducer including a first plate of a piezoelectric material, the first plate of the transducer being secured to a tube, the piezoelectric material being electrically coupled to the signal processing means for receiving the processed electric signal from said signal processing means, wherein said signal processing means includes a programming circuit adapted for receiving and recognizing as programming commands for establishing signal processing characteristics of said signal processing means a set of tones received by said microphone, and in response thereto the programming circuit appropriately modifies signal processing characteristics of said signal processing means and, whereby upon implantation of the microactuator the hearing aid stimulates auditory nerve fibers which stimulation the subject perceives as sound.

4 more elements

A microactuator adapted for receiving an electric signal and in response thereto generating vibrations in a fluid, the microactuator comprising:

a tube having a first end, and a second end distal from and larger than the first end;
a first flexible diaphragm sealed across the first end of said tube and being adapted for contacting the fluid and for generating vibrations in the fluid upon a deflection of said first flexible diaphragm;
a second flexible diaphragm hermetically sealed across the second end of said tube thereby hermetically sealing said tube;
an incompressible liquid filling said hermetically sealed tube;
and
a first plate of a piezoelectric material that is adapted for receiving the electric signal and is mechanically coupled to said second flexible diaphragm, whereby upon application of an electric signal to said first plate, said first plate indirectly deflects said first flexible diaphragm by directly deflecting said second flexible diaphragm which deflection is coupled by said liquid within the tube from said second flexible diaphragm to said first flexible diaphragm.

3 more elements

Dependencies are inferred from the claim text.

Implantable hearing aid

Life of this patent

Implantable hearing aid

Life of this patent

Abstract

Claims57