Stacked Mechanical Nanogenerators

• US 20090115293A1
• Filed: 12/18/2008
• Published: 05/07/2009
• Est. Priority Date: 12/20/2005
• Status: Active Grant

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: WANG, Zhong L., XU, Sheng
• Granted Patent: US 8,003,982 B2
• Time in Patent Office: Days
• US Class Current: 310/364
• CPC Class Codes: H02N 2/18 producing electrical output from mechanical input, e.g. generators for measurement devices G01
• CPC Class Codes: H10N 30/01 Manufacture or treatment
• CPC Class Codes: H10N 30/30 with mechanical input and electrical output, e.g. functioning as generators or sensors
• CPC Class Codes: H10N 30/306 Cantilevers
• CPC Class Codes: Y10S 977/724 Devices having flexible or movable element
• CPC Class Codes: Y10S 977/73 for electrical purposes
• CPC Class Codes: Y10S 977/811 Of specified metal oxide composition, e.g. conducting or semiconducting compositions such as ITO, ZnOx
• CPC Class Codes: Y10S 977/948 Energy storage/generating using nanostructure, e.g. fuel cell, battery
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

An electric power generator includes a first conductive layer, a plurality of semiconducting piezoelectric nanostructures, a second conductive layer and a plurality of conductive nanostructures. The first conductive layer has a first surface from which the semiconducting piezoelectric nanostructures extend. The second conductive layer has a second surface and is parallel to the first conductive layer so that the second surface faces the first surface of the first conductive layer. The conductive nanostructures depend downwardly therefrom. The second conductive layer is spaced apart from the first conductive layer at a distance so that when a force is applied, the semiconducting piezoelectric nanostructures engage the conductive nanostructures so that the piezoelectric nanostructures bend, thereby generating a potential difference across the at semiconducting piezoelectric nanostructures and also thereby forming a Schottky barrier between the semiconducting piezoelectric nanostructures and the conductive nanostructures.

Claims

1. An electric power generator, comprising:

a. a first conductive layer having a first surface;

b. a plurality of semiconducting piezoelectric nanostructures extending upwardly from the first surface;

c. a second conductive layer having a second surface and disposed parallel to the first conductive layer so that the second surface faces the first surface of the first conductive layer;

d. a plurality of conductive nanostructures depending downwardly from the second surface,

the second conductive layer spaced apart from the first conductive layer at a distance so that when a force is applied to at least one of the first conductive layer and the second conductive layer, at least one of the semiconducting piezoelectric nanostructures engages at least one of the plurality of conductive nanostructures so that the at least one of the semiconducting piezoelectric nanostructures bends, thereby generating a potential difference across the at least one of the semiconducting piezoelectric nanostructures and also thereby forming a Schottky barrier between the at least one of the semiconducting piezoelectric nanostructures and the at least one of the conductive nanostructures.

2. The electric power generator of claim 1, wherein the first conductive layer and the second conductive layer each comprise a metal.

3. The electric power generator of claim 2, wherein the metal comprises gold.

4. The electric power generator of claim 1, wherein the semiconducting piezoelectric nanostructures comprise zinc oxide nanowires.

5. The electric power generator of claim 1, wherein each of the conductive nanostructures comprises:

a. a zinc oxide core; and

b. a gold outer shell.

6. A stacked electric power generator, comprising:

a. a first conductive layer having a first surface, a plurality of semiconducting piezoelectric nanostructures extending upwardly from the first surface;

b. a second conductive layer having a second surface and disposed parallel to the first conductive layer so that the second surface faces the first surface of the first conductive layer, a plurality of conductive nanostructures depending downwardly from the second surface,

c. a plurality of intermediate conductive layers disposed between the first conductive layer and the second conductive layer, each intermediate conductive layer having an downwardly-facing surface facing the first conductive layer and an upwardly-facing surface facing the second conductive layer, a plurality of semiconducting piezoelectric nanostructures extending upwardly from each upwardly-facing surface and a plurality of conductive nanostructures depending downwardly from the downwardly facing surface,

the first conductive layer, the second conductive layer and each of the plurality of intermediate conductive layers spaced apart so at a distance so that when a force is applied to at least one of the first conductive layer and the second conductive layer, at least one of the semiconducting piezoelectric nanostructures engages at least one of the plurality of conductive nanostructures so that the at least one of the semiconducting piezoelectric nanostructures bends, thereby generating a potential difference across the at least one of the semiconducting piezoelectric nanostructures and also thereby forming a Schottky barrier between the at least one of the semiconducting piezoelectric nanostructures and the at least one of the conductive nanostructures.

7. A method of making an electric power generator, comprising the actions of:

a. creating a plurality of generating units, each generating unit created by;

i. growing a plurality of semiconducting piezoelectric nanostructures extending upwardly from a first surface of a first conductive layer; and

ii. growing a plurality of conductive nanostructures depending downwardly from a second surface of the first conductive layer, thereby creating a generating unit; and

b. stacking a plurality of generating units to form stacked generating units so that each second conductive layer of a first generating unit is spaced apart from the first conductive layer of a second generating unit at a distance so that when a force is applied to at least one of the first conductive layer and the second conductive layer, at least one of the semiconducting piezoelectric nanostructures engages at least one of the plurality of conductive nanostructures so that the at least one of the semiconducting piezoelectric nanostructures bends, thereby generating a potential difference across the at least one of the semiconducting piezoelectric nanostructures and also thereby forming a Schottky barrier between the at least one of the semiconducting piezoelectric nanostructures and the at least one of the conductive nanostructures.

8. The method of claim 7, wherein the first conductive layer comprises a metal.

9. The method of claim 8, wherein the metal comprises gold.

10. The method of claim 7, wherein the semiconducting piezoelectric nanostructures comprise zinc oxide nanowires.

11. The method of claim 7, wherein each of the conductive nanostructures comprises:

a. a zinc oxide core; and

b. a gold outer shell.

12. A generator for harvesting electrical energy from a pulsed source of mechanical energy, comprising:

a. a conductive substrate;

b. a plurality of semiconducting piezoelectric wires extending upwardly from the conductive substrate;

c. an elastic and insulating polymer film infiltrated into the plurality of semiconducting piezoelectric wires, the polymer film having a thickness so that a top portion of the semiconducting piezoelectric wires extend beyond the polymer film; and

d. a metal layer disposed on the polymer film and in electrical contact with the top portion of the semiconducting piezoelectric wires.

13. The generator of claim 12, wherein the semiconducting piezoelectric wires comprise ZnO.

14. The generator of claim 12, wherein the semiconducting piezoelectric wires comprise nanowires.

15. The generator of claim 12, further comprising a plurality of generators of a type as recited in claim 12 stacked on top of the generator.

16. A method of making a generator, comprising the actions of:

a. applying a layer of metal film on a conductive substrate;

b. annealing the metal film at a preselected temperature to form a textured metal film;

c. growing a plurality of aligned piezoelectric semiconducting nanowires from the textured metal film;

d. infiltrating a layer of an insulative and elastic polymer into the piezoelectric semiconducting nanowires;

e. etching the layer of insulative and elastic polymer so as to expose tips of the piezoelectric semiconducting nanowires; and

f. depositing a metal layer onto the layer of insulative and elastic polymer so that the metal layer is in contact with the tips of the piezoelectric semiconducting nanowires.

17. The method of claim 16, wherein the annealing action includes heating the piezoelectric semiconducting film to at least 350°

C.

18. The method of claim 16, wherein the action of growing a plurality of aligned piezoelectric semiconducting nanowires includes ensuring that a [0001] crystal face of the piezoelectric semiconducting nanowires is upwardly disposed.

19. The method of claim 16, wherein the action of growing a plurality of aligned piezoelectric semiconducting nanowires employs wet chemical deposition.

20. The method of claim 16, wherein the action of growing a plurality of aligned piezoelectric semiconducting nanowires employs chemical vapor deposition.

21. The method of claim 16, further comprising the action of applying an insulating layer to a bottom face of the conductive substrate to form a generating unit.

22. The method of claim 21, further comprising the action of stacking a plurality of generating units to form a stacked generator.