Layered sensor apparatus and method of making same
A sensor apparatus includes a first of a plurality of layers having a top layer, a bottom layer, and at least one intermediate layer having an electrical conductor layer, each of the top layer, the bottom layer, and the at least one intermediate layer is disposed in direct contact with a respective adjacent layer. A second of the plurality of layers is disposed in direct contact with the first plurality of layers such that the bottom layer of the second plurality of layers is disposed in direct contact with the top layer of the first plurality of layers. The first and second plurality of layers are productive of a piezoelectric voltage absent of an external current producing device and in response to being deformed, and are productive of a change in capacitance in response to being deformed.
1. A sensor apparatus, comprising:
a first of a plurality of layers comprising a top layer, a bottom layer, and at least one intermediate layer, the at least one intermediate layer comprising an electrical conductor layer, each of the top layer, the bottom layer, and the at least one intermediate layer is disposed in direct intimate contact with a respective adjacent layer, wherein direct intimate contact includes a physical bond at the respective interface;
a second of the plurality of layers disposed in direct intimate contact with the first plurality of layers such that the bottom layer of the second plurality of layers is disposed in direct contact with the top layer of the first plurality of layers;
the first and second plurality of layers configured to produce productive of a piezoelectric voltage absent of an external current producing device and in response to being deformed; and
the first and second plurality of layers configured to produce productive of a change in capacitance in response to being deformed.
2. The sensor apparatus of claim 1 , wherein:
the top layer of the plurality of layers is a single layer of a first elastomer foam layer having a first rating on a triboelectric series; and
the bottom layer of the plurality of layers is a single layer of a second elastomer layer having a second rating on a triboelectric series.
3. The sensor apparatus of claim 1 , wherein:
the top layer of the plurality of layers is a single layer of a first elastomer foam layer having a first rating on a triboelectric series;
the electrical conductor layer of the at least one intermediate layer is a first electrical conductor layer disposed in direct intimate contact with the top layer;
the at least one intermediate layer further comprises a second elastomer layer having a second rating on a triboelectric series, the second elastomer layer disposed in direct intimate contact with the first electrical conductor layer on a side opposite that of the top layer; and
the bottom layer is a single layer of a second electrical conductor layer disposed in direct intimate contact with the second elastomer layer on a side opposite that of the first electrical conductor layer.
4. The sensor apparatus of claim 1 , wherein:
the first and second plurality of layers are configured to produce a first piezoelectric voltage in response to being deformed by a first impact force, a second piezoelectric voltage in response to being deformed by a second impact force, and a third piezoelectric voltage in response to being deformed by a third impact force;
the first, second and third piezoelectric voltages having a linear relationship with the respective first, second and third impact forces.
5. The sensor apparatus of claim 2 , wherein:
the first elastomer foam layer is unfilled polyurethane.
6. The sensor apparatus of claim 5 , wherein:
the unfilled polyurethane is a polyurethane foam having a density of equal to or greater than 9 pounds per cubic foot and equal to or less than 25 pounds per cubic foot.
7. The sensor apparatus of claim 2 , wherein:
the second elastomer layer is a polyethylene terephthalate (PET) film.
8. The sensor apparatus of claim 1 , wherein:
the electrical conductor layer material comprises at least one of: nickel, aluminum or silver.
9. The sensor apparatus of claim 3 , wherein:
the first electrical conductor layer material and the second electrical conductor layer material comprises at least one of: nickel, aluminum or silver.
10. The sensor apparatus of claim 1 , further comprising:
a third or more of the plurality of layers disposed in direct intimate contact with each other to form a repetitive ordered layered construct;
the layered construct configured to produce a first piezoelectric voltage in response to being deformed by a first impact force, a second piezoelectric voltage in response to being deformed by a second impact force, and a third piezoelectric voltage in response to being deformed by a third impact force;
the first, second and third piezoelectric voltages having a linear relationship with the respective first, second and third impact forces.
11. The sensor apparatus of claim 1 , wherein:
the piezoelectric voltage produced in response to the plurality of layers being deformed is a triboelectric effect exhibited by the plurality of layers.
12. The sensor apparatus of claim 1 , wherein the plurality of layers has a flexural modulus equal to or less than 1.1 GPa (Giga Pascal).
13. The sensor apparatus of claim 1 , wherein the plurality of layers has an overall thickness of equal to or greater than 2 mm and equal to or less than 40 mm.
14. The sensor apparatus of claim 1 , wherein:
the first and second of the plurality of layers have identically ordered layers.
15. A method of making the sensor apparatus of claim 1 , comprising:
applying an elastomer foam A-layer atop a metal-coated substrate comprising an elastomer B-layer to form a layered construct with the metal-coated portion of the metal-coated substrate disposed between the elastomer foam A-layer and the elastomer B-layer, the elastomer foam A-layer having a first rating on a triboelectric series, the elastomer B-layer having a second rating on a triboelectric series;
applying a second of the metal-coated substrate atop the layered construct, and applying a second of the elastomer foam A-layer atop the metal-coated portion of the second metal-coated substrate to form a plurality of the layered construct; and
curing the plurality of the layered construct.
16. The method of claim 15 , wherein:
the metal-coated substrate is a double-sided metal-coated substrate having a first metal-coated portion on one side of the elastomer B-layer and a second metal-coated portion on an opposing side of the elastomer B-layer, the first metal-coated portion being the metal-coated portion disposed between the elastomer foam A-layer and the elastomer B-layer;
the applying a second of the metal-coated substrate comprises applying a second of the double-sided metal-coated substrate atop the layered construct; and
the applying a second of the elastomer foam A-layer comprises applying a second of the elastomer foam A-layer atop the first metal-coated portion of the second double-sided metal-coated substrate.
17. The method of claim 15 , wherein the applied elastomer foam A-layer is an uncured polyurethane foam.
18. The method of claim 15 , wherein the elastomer B-layer is a polyethylene terephthalate (PET) film.
19. The method of claim 14 , wherein the applying an elastomer foam A-layer comprises a roll coating process.
20. A method of making the sensor apparatus of claim 1 , comprising:
applying an elastomer foam A-layer atop a metal-coated substrate comprising an elastomer B-layer to form a layered construct with the metal-coated portion of the metal-coated substrate disposed between the elastomer foam A-layer and the elastomer B-layer, the elastomer foam A-layer having a first rating on a triboelectric series, the elastomer B-layer having a second rating on a triboelectric series;
curing the layered construct to form a cured layered construct and to provide a first of the cured layered construct; and
attaching a second of the cured layered construct atop the first cured layered construct, the first and second cured layered constructs having identically ordered layers.
21. The method of claim 20 , wherein:
the metal-coated substrate is a double-sided metal-coated substrate having a first metal-coated portion on one side of the elastomer B-layer and a second metal-coated portion on an opposing side of the elastomer B-layer, the first metal-coated portion being the metal-coated portion disposed between the elastomer foam A-layer and the elastomer B-layer.
22. The method of claim 20 , wherein:
the attaching comprises chemical bonding, mechanical bonding, or vibratory bonding.
23. The sensor apparatus of claim 1 , wherein:
at least one of the top layer or the bottom layer of the plurality of layers is an elastomer layer.
24. The sensor apparatus of claim 1 , wherein:
the piezoelectric voltage is produced by relative movement between a respective one of the electrical conductor layer and an associated adjacent one of the elastomer layer.