Methods and apparatus for a capacitive pressure sensor

1. A capacitive sensor, comprising:

a first substrate, having a first surface; and

a second substrate, having a first surface directly adjacent to the first surface of the first substrate, comprising:

a capacitor comprising:

a first electrode; and

a second electrode positioned substantially coplanar with the first electrode;

wherein the first electrode and the second electrode form a capacitance;

wherein at least one of the first substrate and the second substrate is capable of deforming in response to an applied first pressure to produce a first change in the capacitance and the first and second substrates deform under the applied first pressure to create a gap between at least a portion of the first and second substrates.

2. The capacitive sensor according to claim 1 , wherein the first and second substrates are configured to deform when the first pressure is applied to a second surface of the first substrate.

3. The capacitive sensor according to claim 1 , wherein the first and second substrates are configured to deform when the first pressure is applied to a second surface of the second substrate.

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

the first substrate maintains its shape under an applied second pressure;

the second substrate maintain its shape under the applied second pressure; and

the applied second pressure produces a second change in the capacitance.

5. The capacitive sensor according to claim 1 , wherein the first and second substrates are arranged in a vertically-stacked orientation.

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

the second electrode is nested within an interior region formed by the first electrode; and

the first and second electrodes are separated by a gap.

7. The capacitive sensor according to claim 1 , wherein the first substrate, comprises:

a flexible portion disposed along an outer edge of the capacitive sensor; and

a rigid portion within an interior region formed by the flexible portion; and

wherein the rigid and flexible portions are coplanar with each other.

8. A method for detecting an applied pressure, comprising:

providing a capacitive sensor comprising:

a first substrate; and

a second substrate abutting the first substrate;

wherein:

the second substrate comprises a first electrode coplanar with a second electrode;

the first and second electrodes form a capacitance; and

at least one of the first substrate and second substrate is capable of deforming in response to the applied pressure;

generating an electric field between the first and second electrodes;

measuring a change in the capacitance of the capacitive sensor; and

utilizing the measured change in the capacitance to determine:

an applied first pressure; and

an applied second pressure.

9. The method according to claim 8 , wherein the second electrode is nested within a region defined by the first electrode.

10. The method according to claim 8 , wherein utilizing the measured change in capacitance to determine the first and second applied pressures comprises:

converting the change in capacitance to a digital value;

comparing the digital value to a first threshold;

generating a first signal based on the comparison of the digital value to the first threshold, wherein the first signal indicates the first applied pressure;

comparing the digital value to a second threshold; and

generating a second signal based on the comparison of the digital value to the second threshold, wherein the second signal indicates the second applied pressure.

11. The method according to claim 8 , wherein:

the applied first pressure corresponds to zero change in distance between the first and second substrates; and

the applied second pressure corresponds to a change in distance between the first and second substrates that is greater than zero.

12. The method according to claim 8 , wherein the second pressure is greater than 861 Pascals.

13. The method according to claim 8 , wherein the first and second substrates are arranged in a vertically-stacked orientation.

14. A capacitive sensor, comprising:

a first substrate, having a first surface; and

a second substrate, having a first surface adjacent to the first surface of the first substrate, comprising:

a capacitor comprising:

a first electrode; and

a second electrode positioned substantially coplanar with the first electrode;

wherein the first electrode and the second electrode form an intentional capacitance, at most, with each other;

wherein:

a first gap is disposed between the first and second substrates;

the second substrate deforms under a first applied pressure to a second surface of the second substrate and reduces at least a portion of the first gap between the first and second substrates; and

the first substrate maintains its shape under the applied pressure.

15. The capacitive sensor according to claim 14 , wherein the first and second substrates are arranged in a vertically-stacked orientation.

16. The capacitive sensor according to claim 14 , wherein:

the second electrode is nested within an interior region formed by the first electrode; and

the first and second electrodes are separated by a second gap.

17. The capacitive sensor according to claim 14 , wherein the first gap is filled with air.

18. The capacitive sensor according to claim 14 , wherein the first gap is filled with one of: a liquid, a gel, and a foam.

19. The capacitive sensor according to claim 14 , wherein the first substrate comprises:

a flexible portion disposed along an outer edge of the capacitive sensor; and

a rigid portion within an interior region formed by the flexible portion; and

wherein the rigid and flexible portions are coplanar with each other.