Microphones for an implantable hearing aid

• US 5,881,158 A
• Filed: 05/23/1997
• Issued: 03/09/1999
• Est. Priority Date: 05/24/1996
• Status: Expired due to Term

• Current Assignee: OtoKinetics Inc.
• Original Assignee: United States Surgical Corporation (Medtronic Plc)
• Inventors: Lesinski, S. George, Neukermans, Armand P.
• Primary Examiner(s): LE, HUYEN D
• Application Number:
  US08/862,874
• Time in Patent Office: 655 Days
• Field of Search: 381/113, 381/116, 381/173, 381/174, 381/190, 381/191, 381/328, 381/326, 381/322, 600/25, 607/56, 607/57
• US Class Current: 381/174
• CPC Class Codes: H04R 19/016 for microphones
• CPC Class Codes: H04R 2225/61 Aspects relating to mechanical or electronic switches or control elements, e.g. functioning
• CPC Class Codes: H04R 2225/67 Implantable hearing aids or parts thereof not covered by H04R25/606
• CPC Class Codes: H04R 25/402 using contructional means
• CPC Class Codes: H04R 25/405 by combining a plurality of transducers
• CPC Class Codes: H04R 25/603 of mechanical or electronic switches or control elements
• CPC Class Codes: H04R 25/606 acting directly on the eardrum, the ossicles or the skull, e.g. mastoid, tooth, maxillary or mandibular bone, or mechanically stimulating the cochlea, e.g. at the oval window

Abstract

A implantable sealed microphone (50) includes a diaphragm (52) having a thin central region (54) surrounded by a thicker rim (56). One side of sheet electret material (72) is bonded to the diaphragm (52) while the other side contacts a roughened plate (82). The rim (56) is bonded to a housing (112) thereby hermetically enclosing the electret (72) and the plate (82). The microphone (50) also includes an electrical connector (94) that couples both the plate (82) and the electret (72) to an input of an amplifier (30) included in an implantable hearing aid system (10). Preferably, the microphone (50) is incorporated into a sealed electronics module (100) together with the amplifier (30) and an energy storage device such as a battery that energizes operation of the implantable hearing aid system (10). In such a configuration, the microphone'"'"'s diaphragm (52) forms a surface of the electronics module'"'"'s housing (112). An electrical connector (134) couples an output signal from the amplifier (30) to a microactuator (32) of the implantable hearing aid system (10).

Claims

1. A sealed microphone adapted for inclusion in an implantable hearing aid system to provide an input signal to an amplifier included in the implantable hearing aid system, the microphone comprising:

a diaphragm having a thin central region surrounded by a thicker rim;

an electret bonded to said diaphragm;

a roughened plate contacted by said electret;

a housing for receiving said plate and said electret, said housing being electrically insulated from said plate, the rim of said diaphragm being bonded to a surface of said housing thereby hermetically sealing the microphone; and

an electrical connector coupled both to said plate and said electret for providing the input signal to the amplifier of the implantable hearing aid system.

2. The microphone of claim 1 wherein said diaphragm is formed by a metallic sheet that is lithographically etched to form the thin central region thereof.

3. The microphone of claim 2 wherein the metallic sheet is formed from titanium.

4. The microphone of claim 2 wherein the metallic sheet is coated with a sealing layer of material.

5. The microphone of claim 4 wherein the sealing layer is formed from gold.

6. The microphone of claim 1 wherein the thin central region of said diaphragm includes a plurality of reinforcing ribs that subdivide the central region into a plurality of individual membranes.

7. The microphone of claim 1 wherein the electret includes an electrically conductive layer that contacts said diaphragm.

8. The microphone of claim 7 wherein the electrically conductive layer is formed by a layer of metallic material.

9. The microphone of claim 1 further comprising electrical leads for coupling the microphone to the amplifier.

10. The microphone of claim 1 wherein said plate is roughened by a plurality of posts formed thereon.