Accelerometer contact microphones and methods thereof

1. A contact microphone comprising:

a first proof mass;

a second proof mass;

a first sensing electrode;

a second sensing electrode;

a first sensing gap between the first proof mass and the first sensing electrode;

a second sensing gap between the second proof mass and the second sensing electrode;

a torsional tether configured to support the first proof mass and the second proof mass; and

a casing enclosing the first and second proof masses, the first and second sensing electrodes, and the first and second sensing gaps;

wherein the contact microphone has a vibration acceleration sensitivity of better than 100 μg√Hz.

2. The contact microphone of claim 1 , wherein the contact microphone has an operation bandwidth ranging from 0 Hz and 5,000 Hz.

3. The contact microphone of claim 1 , wherein the contact microphone has an operation bandwidth ranging from 0 Hz and 10,000 Hz.

4. The contact microphone of claim 1 , wherein the first proof mass is substantially thicker than the first sensing electrode.

5. The contact microphone of claim 4 further comprising a substrate;

wherein the contact microphone has tri-axial vibration sensitivity including in the normal direction to the plane of the substrate and in the plane of the substrate.

6. The contact microphone of claim 1 further comprising a substrate;

wherein the torsional tether is attached to the substrate; and

wherein the first proof mass is configured to move out-of-plane of the substrate.

7. The contact microphone of claim 1 further comprising a substrate;

wherein the torsional tether is attached to the substrate;

wherein the first proof mass and the second proof mass are configured to move out-of-plane of the substrate; and

wherein the second proof mass is placed mirror symmetric with respect to the first proof mass.

8. A contact microphone comprising:

a first proof mass;

a first sensing electrode;

a first sensing gap between the first proof mass and the first sensing electrode;

a casing enclosing the first proof mass, the first sensing electrode, and the first sensing gap;

a second sensing electrode; and

a second sensing gap between a first sensing plate of the first proof mass and the second sensing electrode;

wherein the casing further encloses the first sensing plate, the second sensing electrode, and the second sensing gap;

wherein the contact microphone has a vibration acceleration sensitivity of better than 100 μg√Hz; and

wherein the casing is configured to maintain a vacuum environment of smaller than or equal to 50 Torr.

9. A contact microphone comprising:

a substrate;

a first proof mass having a first end and a second end;

a second proof mass having a first end and a second end;

a torsional tether attached to the substrate and configured to:

support the first proof mass at the first end of the first proof mass; and

support the second proof mass at the first end of the second proof mass;

a first sensing electrode proximate the second end of the first proof mass;

a second sensing electrode proximate the second end of the second proof mass;

a first sensing gap smaller than 500 nanometers between the first proof mass and the first sensing electrode;

a second sensing gap smaller than 500 nanometers between the second proof mass and the second sensing electrode; and

a casing enclosing:

the first proof mass;

the second proof mass;

the first sensing electrode;

the second sensing electrode;

the first sensing gap; and

the second sensing gap;

wherein the casing is configured to maintain an environment of smaller than or equal to 50 Torr;

wherein the first proof mass and the second proof mass are configured to move out-of-plane of the substrate; and

wherein the second proof mass is placed mirror symmetric with respect to the first proof mass.

10. A MEMS device comprising:

a casing; and

an accelerometer comprising the contact microphone of claim 1 ;

wherein the accelerometer has a frequency response ranging from 0 Hz and 10,000 Hz with relatively constant sensitivity.

11. The MEMS device of claim 10 , wherein the casing comprises a vacuum having a pressure substantially lower than one atmosphere.

12. A MEMS device comprising:

an accelerometer comprising the contact microphone of claim 9 ;

wherein the accelerometer has a frequency response ranging from 0 Hz and at least 5,000 Hz with relatively constant sensitivity.

13. The MEMS device of claim 12 , wherein the accelerometer has a frequency response ranging from 0 Hz and 10,000 Hz with relatively constant sensitivity.

14. The MEMS device of claim 12 , wherein the accelerometer has a sensitivity of better than 10 μg√Hz.

15. The MEMS device of claim 12 , wherein the accelerometer has a sensitivity of better than 100 μg√Hz.

16. A method comprising:

capturing vibrations emanating from a person with the contact microphone of claim 1 ;

wherein the contact microphone has an operation bandwidth ranging from 0 Hz and at least 5,000 Hz with relatively constant sensitivity.

17. The method of claim 16 , wherein the contact microphone has an operation bandwidth ranging from 0 Hz and 10,000 Hz with relatively constant sensitivity.

18. The method of claim 16 , wherein the contact microphone is encased within a casing.

19. A method comprising:

capturing vibrations emanating from a person with the contact microphone of claim 9 ;

wherein the contact microphone has an operation bandwidth ranging from 0 Hz and at least 5,000 Hz with relatively constant sensitivity; and

wherein the contact microphone has a sensitivity of better than 10 μg√Hz.

20. The method of claim 18 , wherein the contact microphone is disposed within at least one of a stethoscope, a wrist watch, a necklace, a wearable strap, a patch, or a sensor.

21. The method of claim 16 further comprising placing the contact microphone upon at least one of skin of the person or a fabric contacting skin of the person.

22. The method of claim 16 further comprising placing the contact microphone upon the person at a location selected from the group consisting of an intercostal space and a joint space.

23. A method comprising:

placing an accelerometer comprising the contact microphone of claim 1 upon a person; and

capturing vibrations, with the accelerometer, emanating from the person;

wherein placing the accelerometer upon the person comprises placing the accelerometer disposed within one or more of a stethoscope, a wrist watch, a necklace, a wearable strap, a patch, and a sensor.

24. A method of localizing sounds in a patient comprising:

placing a plurality of accelerometers upon a patient, wherein each accelerometer comprises the contact microphone of claim 1 ;

capturing vibrations, with each accelerometer, emanating from the patient; and

determining a source of the vibrations by calculating a vibration acceleration level at each of the accelerometers.

25. A method of localizing sounds in a patient comprising:

placing a plurality of accelerometers upon a patient, wherein each accelerometer comprises the contact microphone of claim 9 ;

capturing vibrations, with each accelerometer, emanating from the person; and

determining a source of the vibrations by calculating a vibration acceleration level at each of the accelerometers.

26. The contact microphone of claim 8 further comprising:

a torsional tether configured to support the first proof mass; and

a substrate;

wherein the torsional tether is attached to the substrate;

wherein the first proof mass is configured to move out-of-plane of the substrate; and

wherein one or more:

the contact microphone has an operation bandwidth ranging from 0 Hz and 10,000 Hz;

the first proof mass is substantially thicker than the first sensing electrode; and/or

the contact microphone has tri-axial vibration sensitivity including in the normal direction to the plane of the substrate and in the plane of the substrate.

27. The contact microphone of claim 26 , wherein:

the torsional tether is further configured to support the second proof mass;

the second proof mass is configured to move out-of-plane of the substrate; and

the second proof mass is placed mirror symmetric with respect to the first proof mass.