Piezoelectric-Coated Carbon Nanotube Generators

• US 20090309456A1
• Filed: 03/17/2009
• Published: 12/17/2009
• Est. Priority Date: 03/17/2008
• Status: Active Grant

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Stollberg, David W.
• Granted Patent: US 8,022,601 B2
• Time in Patent Office: Days
• US Class Current: 310/319
• CPC Class Codes: H02N 2/18 producing electrical output from mechanical input, e.g. generators for measurement devices G01
• CPC Class Codes: H10N 30/06 Forming electrodes or interconnections, e.g. leads or terminals
• CPC Class Codes: H10N 30/076 by vapour phase deposition
• CPC Class Codes: H10N 30/306 Cantilevers
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

A generator includes a first conductive layer, a plurality of elongated piezoelectric nanostructures and a conductive electrode. The piezoelectric nanostructures extend upwardly from the first conductive layer and include a carbon nanotube core and a piezoelectric sheath enveloping at least a portion of the carbon nanotube core. Each piezoelectric nanostructure includes a first end disposed adjacent to the first conductive layer and an opposite second end. The conductive electrode is disposed adjacent to the second end of each of the piezoelectric nanostructures. The conductive electrode is configured so that a Schottky barrier is formed between the second end of at least one of the piezoelectric nanostructures and the conductive electrode when a force is applied to the generator that causes the conductive electrode to touch the piezoelectric nanostructures and to induce stress in the piezoelectric nanostructures.

Claims

1. A generator, comprising:

a. a first conductive layer;

b. a plurality of elongated piezoelectric nanostructures extending upwardly from the first conductive layer, the plurality of elongated piezoelectric nanostructures including a carbon nanotube core and a piezoelectric sheath enveloping at least a portion of the carbon nanotube core, each of the plurality of elongated piezoelectric nanostructures including a first end disposed adjacent to the first conductive layer and an opposite second end; and

c. a conductive electrode disposed adjacent to the second end of each of the plurality of elongated piezoelectric nanostructures, the conductive electrode configured so that a Schottky barrier is formed between the second end of at least one of the plurality of elongated piezoelectric nanostructures and the conductive electrode when a force is applied to the generator that causes the conductive electrode to touch the plurality of elongated piezoelectric nanostructures and to induce stress in the plurality of elongated piezoelectric nanostructures.

2. The generator of claim 1, wherein the piezoelectric sheath comprises zinc oxide.

3. The generator of claim 1, wherein the first conductive layer comprises a first metal.

4. The generator of claim 3, wherein the first metal comprises iron.

5. The generator of claim 1, further comprising a substrate disposed against the first conductive layer and opposite from the plurality of elongated piezoelectric nanostructures.

6. The generator of claim 1, further comprising a silicon layer disposed adjacent to the first conductive layer.

7. The generator of claim 1, wherein conductive electrode comprises:

a. a second conductive layer;

b. a plurality of carbon nanotubes extending away from the second conductive layer; and

c. a conductive sheath disposed about at least a portion of each of the plurality of carbon nanotubes.

8. The generator of claim 7, wherein the conductive sheath comprises gold.

9. The generator of claim 1, wherein conductive electrode comprises:

a. a substrate with a corrugated surface; and

b. a conductive layer disposed adjacent to the corrugated surface.

10. The generator of claim 9, wherein the conductive layer comprises gold.

11. The generator of claim 1, wherein the first conductive layer comprises a first woven carbon fiber mesh and wherein the conductive electrode comprises a second woven carbon fiber mesh from which a second plurality of carbon nanotubes extend, a conductive sheath enveloping at least a portion of each of the second plurality of carbon nanotubes.

12. The generator of claim 11, wherein the conductive sheath comprises gold.

13. A mesh generator, comprising:

a. a first woven carbon fiber mesh;

b. a plurality of elongated piezoelectric nanostructures extending upwardly from the first woven carbon fiber mesh, the plurality of elongated piezoelectric nanostructures including a carbon nanotube core and a piezoelectric sheath enveloping at least a portion of the carbon nanotube core, each of the plurality of elongated piezoelectric nanostructures including a first end disposed adjacent to the first conductive layer and an opposite second end; and

c. a conductive electrode disposed adjacent to the second end of each of the plurality of elongated piezoelectric nanostructures, the conductive electrode configured so that a Schottky barrier is formed between the second end of at least one of the plurality of elongated piezoelectric nanostructures and the conductive electrode when a force is applied to the generator that causes the conductive electrode to touch the plurality of elongated piezoelectric nanostructures and to induce stress in the plurality of elongated piezoelectric nanostructures.

14. The mesh generator of claim 13, wherein the conductive electrode comprises:

a. a second woven carbon fiber mesh; and

b. a plurality of conductive elongated nanostructures extending from the second woven carbon fiber mesh, each of the conductive elongated nanostructures including a carbon nanotube and a metal sheath coating at least a portion of the carbon nanotube.

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

a. growing a first plurality of carbon nanotubes from a first conductive layer;

b. growing a piezoelectric sheath about a portion of each of the first plurality of carbon nanotubes; and

c. generating a conductive electrode and disposing the conductive electrode opposite the first plurality of carbon nanotubes so that when the conductive electrode engages the piezoelectric sheath enveloping at least one of the nanotubes, a Schottky barrier is formed therebetween.

16. The method of claim 15, wherein the action of growing a first plurality of carbon nanotubes comprises applying chemical vapor deposition of carbon to the first conductive layer.

17. The method of claim 15, wherein the action of growing a piezoelectric sheath comprises by applying a method to the first plurality of carbon nanotubes, the method selected from a group of methods consisting of:

sputtering, evaporation, molecular beam epitaxy and ion-assisted deposition.

18. The method of claim 15, wherein the action of generating a conductive electrode comprises the actions of:

a. growing a second plurality of carbon nanotubes from a second conductive layer; and

b. coating the second plurality of carbon nanotubes with a conductive metal layer.

19. The method of claim 18, wherein the coating action comprises employing evaporation of a metal.

20. The method of claim 19, wherein the metal comprises gold.

21. The method of claim 15, wherein the first conductive layer and the second conductive layer each comprises a carbon fiber that is part of a woven carbon fiber mesh.