Layered sensor having multiple laterally adjacent substrates in a single layer

1. A layered sensor for a flexible sleep monitor, comprising:

a first flexible layer;

a second flexible layer that is substantially parallel to the first flexible layer;

a substrate layer positioned between the first flexible layer and the second flexible layer, and comprising:

a first substrate formed of a first material, and configured to generate electric charge in response to a force applied to the flexible sleep monitor; and

a second substrate formed of a second material different from the first material and positioned laterally adjacent to the first substrate;

a first electrode disposed on a first surface of the first substrate; and

a second electrode disposed on a second surface of the second substrate, wherein:

the first surface and the second surface cooperate to define a continuous surface of the substrate layer;

the substrate layer is flexible; and

the first electrode and the second electrode are configured to be electrically coupled to a processing unit configured to determine a sleep characteristic using a signal received from at least one of the first electrode or the second electrode.

2. The layered sensor of claim 1 , wherein:

the continuous surface of the substrate layer is a first continuous surface of the substrate layer;

the first flexible layer comprises a third substrate;

the second flexible layer comprises a fourth substrate;

the first continuous surface of the substrate layer faces a bottom surface of the first flexible layer;

the substrate layer defines a second continuous surface opposite the first continuous surface and facing a top surface of the second flexible layer; and

the layered sensor further comprises:

a third electrode disposed on a third surface of the third substrate and configured to be electrically coupled to the processing unit; and

a fourth electrode disposed on a fourth surface of the fourth substrate and configured to be electrically coupled to the processing unit.

3. The layered sensor of claim 2 , wherein:

the first flexible layer comprises a fifth substrate cooperating with the third substrate to define the bottom surface of the first flexible layer; and

at least one of the first flexible layer or the second flexible layer is a ground layer.

4. The layered sensor of claim 1 , wherein the substrate layer is formed by interdigitating fingers of a first sheet comprising the first substrate with fingers of a second sheet comprising the second substrate.

5. The layered sensor of claim 1 , wherein the first electrode comprises silver.

6. The layered sensor of claim 1 , wherein the first substrate comprises a flexible piezoelectric material.

7. The layered sensor of claim 6 , wherein the second substrate does not comprise the flexible piezoelectric material.

8. The layered sensor of claim 1 , wherein the sleep characteristic is at least one of a heart rate, a breathing rate, a sleep duration, a snoring duration, a temperature, or a humidity level.

9. A flexible sleep monitor, comprising:

an enclosure; and

a layered sensor at least partially surrounded by the enclosure, and comprising:

a substrate layer positioned within the enclosure, and comprising:

a first substrate formed from a first material; and

a second substrate positioned laterally adjacent to the first substrate and formed from a second material different from the first material; and

a flexible layer positioned between the substrate layer and a portion of the enclosure, and comprising a third substrate, wherein:

the substrate layer is formed by interdigitating first members of a first sheet section of a first sheet comprising the first substrate with second members of a second sheet section of a second sheet comprising the second substrate to form a combined sheet.

10. The flexible sleep monitor of claim 9 , wherein forming the layered sensor further comprises:

attaching the combined sheet to a third sheet to form a stack; and

separating the stack into a first portion and one or more additional portions, the first portion including the first substrate, the second substrate, and the third substrate.

11. The flexible sleep monitor of claim 9 , wherein:

the layered sensor further comprises:

a first electrode positioned on the first substrate; and

a second electrode positioned on the second substrate; and

the first electrode and the second electrode are configured to be electrically coupled to a processing unit configured to determine a sleep characteristic using a signal received from at least one of the first electrode or the second electrode.

12. The flexible sleep monitor of claim 9 , wherein:

the first material is a flexible piezoelectric material; and

the second substrate does not comprise the flexible piezoelectric material.

13. A layered sensor, comprising:

a first flexible layer;

a second flexible layer that is substantially parallel to the first flexible layer;

a substrate layer positioned between the first flexible layer and the second flexible layer, and comprising:

a first substrate formed of a first material, and configured to generate electric charge in response to a force applied to the layered sensor; and

a second substrate formed of a second material different from the first material and positioned laterally adjacent to the first substrate;

a first electrode disposed on a first surface of the first substrate; and

a second electrode disposed on a second surface of the first substrate, the second surface opposite the first surface, wherein:

the substrate layer is flexible; and

at least a portion of the first substrate has a curved shape extending parallel to the substrate layer.

14. The layered sensor of claim 13 , wherein at least a portion of the first substrate has a serpentine shape within the substrate layer.

15. The layered sensor of claim 13 , further comprising:

a differential sensor having a first input electrically connected to the first electrode and a second input electrically connected to the second electrode.

16. The layered sensor of claim 13 , wherein the first electrode and the second electrode are configured to provide a differential signal to a processing unit configured to determine a sleep characteristic of a user using the differential signal.

17. The layered sensor of claim 13 , wherein the first substrate is a PVDF substrate.

18. The layered sensor of claim 17 , wherein the second substrate is a polyurethane substrate.

19. The layered sensor of claim 17 , wherein the first electrode and the second electrode comprise silver.

20. The layered sensor of claim 13 , wherein the first substrate comprises a flexible piezoelectric material.

21. The layered sensor of claim 20 , wherein the second substrate does not comprise the flexible piezoelectric material.