Granted Patent B2

US 12,253,391 · App. 17/058,102 · Granted Mar 18, 2025

Inventor: Ronald N. Miles (Newark Valley, NY)

Assignee: The Research Foundation for The State University of New York

G01D5/2412G01H11/06H03K17/955H04R19/04

Abstract

Claims (48)

1. A capacitive sensor, comprising:

at least two conductors, isolated from each other by at least one spatial gap, each respective conductor having a respective conductor voltage potential; and

a planar displaceable element configured to move along an axis of displacement having a directional component crossing the spatial gap selectively responsive to a sensed condition, the displaceable element having a displaceable element voltage potential;

the at least two conductors and the displaceable element establishing an electrostatic field occupying a region proximate to the at least two conductors, the displaceable element, and the at least one spatial gap, based on the respective conductor voltage potentials and the displaceable element voltage potential,

a charge distribution between the at least two conductors and the displaceable element being electrically responsive to a perturbation of the electrostatic field by a movement of the displaceable element with respect to the at least two conductors,

wherein the at least two conductors and the displaceable element are configured such that over a range of the movement of the displaceable element with respect to the at least two conductors, the electrostatic field produces an electrostatic force in a plane of the displaceable element and does not substantially alter a responsivity of displacement of the displaceable element to the sensed condition due to an electrostatic force variation dependent on a displacement of the displaceable element, and the electrostatic field does not cause pull-in instability due to a diminishing distance between the displaceable element and one of the at least two conductors having an opposite charge.

2. The capacitive sensor according to claim 1 , wherein:

the at least one spatial gap comprises a linear spatial gap;

the at least two conductors comprise a pair of fixed conductors, separated by the linear spatial gap, each of the pair of fixed conductors being maintained at the respective conductor voltage potential, the electrostatic field in a space above the pair of fixed conductors having a major field vector component directed across the linear spatial gap dependent on a difference between the respective conductor voltage potentials of the pair of fixed conductors, and

the displaceable element comprises a charged element configured with the axis of displacement having a vector component directed across the linear spatial gap, such that a force imposed on the displaceable element due to the electrostatic field is insensitive to a state of displacement of the displaceable element in response to the sensed condition.

3. The capacitive sensor according to claim 1 , wherein the displaceable element comprises a cantilever supported diaphragm.

4. The capacitive sensor according to claim 1 , wherein the displaceable element comprises at least one of a perforated diaphragm, a fiber mesh, a fiber mat, metallized electrospun fiber, carbon nanotubes, and graphene.

5. The capacitive sensor according to claim 1 , wherein the respective voltage potential at each of the at least two conductors is maintained at predefined potential by a respective transimpedance amplifier while a change in charge is induced on the respective at least two conductors by a movement of the displaceable element.

6. The capacitive sensor according to claim 1 , wherein the capacitive sensor comprises a microphone, and the displaceable element has an amplitude of movement corresponding to an acoustic wave.

7. A method of sensing a vibration, comprising:

providing at least two separated conductive surfaces each having a respective conductive surface voltage potential, and a deflectable element having a null position and an axis of deflection perpendicular to a force generated by the at least two separated conductive surfaces on the deflectable element based on an induced voltage potential on the deflectable element with respect to the respective conductive surface voltage potential of the at least two conductive surfaces; and

sensing a change in induced charge on the at least two conductive surfaces resulting from deflection of the deflectable element along the axis of deflection due to a vibration,

wherein the at least two separated conductive surfaces and the deflectable element are configured such that the force generated by the at least two separated conductive surfaces on the deflectable element acts normal to the axis of deflection, provides a restoring force for returning the deflectable element to the null position, and does not substantially alter a deflection of the deflectable element.

8. A sensor comprising:

two conductors, each conductor of the two conductors having a planar surface;

a displaceable electrode configured for movement relative to the two conductors in response to an external condition to be sensed;

a voltage source configured to supply a bias voltage, the bias voltage establishing an electrostatic field in a space between the displaceable electrode and the planar surfaces of the two conductors dependent on a voltage potential of each of the two conductors and a voltage potential of the displaceable electrode; and

a circuit configured to determine a change in charge of the two conductors due to a displacement of the displaceable electrode with respect to the two conductors,

wherein:

the displaceable electrode has a thickness along an axis of movement and a length along an axis orthogonal to the axis of movement;

the length and the thickness are chosen such that the displaceable electrode is compliant and deflects in response to a sensed condition force along the axis of movement; and

the two conductors and the displaceable electrode are oriented such that the length of the displaceable electrode is orthogonal to the planar surfaces of the two conductors, to thereby induce an electrostatic force orthogonal to the axis of movement.

9. The sensor of claim 8 , wherein the displaceable electrode is positioned and oriented relative to the two conductors such that the electrostatic force arising from the electrostatic field acts as a restoring force to return the displaceable electrode to an equilibrium position.

10. The sensor of claim 8 , further comprising a further conductor disposed between the two conductors, wherein the voltage source is further configured to supply a bias voltage to the further conductor.

11. The sensor of claim 10 , wherein:

the two conductors are biased via the voltage source at different voltages relative to the displaceable electrode; and

the further conductor is biased via the voltage source at an intermediate potential.

12. The sensor of claim 10 , wherein:

the two conductors are biased via the voltage source such that the electrostatic force is a net attractive force on the displaceable electrode; and

the further conductor is biased to establish a repulsive electrostatic force on the displaceable electrode.

13. The sensor of claim 8 , wherein the displaceable electrode is compliantly supported by a hinge.

14. The sensor of claim 8 , wherein:

the displaceable electrode comprises a planar diaphragm; and

the planar diaphragm comprises a plurality of apertures such that the external condition to be sensed comprises viscous drag of air flowing through the plurality of apertures.

15. The sensor of claim 8 , wherein the planar surfaces of the two conductors are coplanar.

16. The sensor of claim 8 , wherein:

the two conductors are separated by a gap; and

the displaceable electrode has an equilibrium position disposed in the gap.

17. The sensor of claim 8 , wherein the

voltage potential of each of the two conductors differs by at least 50V from a voltage potential of the displaceable electrode.

18. The sensor of claim 8 , wherein the circuit comprises at least one transimpedance amplifier configured to sense a change in charge between the two conductors.

19. The sensor of claim 8 , wherein a potential at each of the two conductors is maintained at ground potential by a respective transimpedance amplifier while a change in charge is induced on the respective conductive surfaces by a movement of the displaceable electrode.

20. The sensor of claim 8 , wherein the displaceable electrode is configured for movement relative to the two conductors selectively responding and corresponding to vibrations of an acoustic wave.

Assignments (1)

Continuity (3)

References Cited (400)

Cited By (1)

US 12,607,582