Flexible nanostructure electronic devices

• US 20050184641A1
• Filed: 05/14/2004
• Published: 08/25/2005
• Est. Priority Date: 05/16/2003
• Status: Active Grant

• Current Assignee: Nanomix Incorporated (CJY Holdings Ltd.), Regents of the University of California (University of California)
• Original Assignee: Nanomix Incorporated (CJY Holdings Ltd.)
• Inventors: Bradley, Keith, Gruner, George, Gabriel, Jean-Christophe P., Armitage, N. Peter
• Granted Patent: US 7,956,525 B2
• Time in Patent Office: Days
• US Class Current: 313/495
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: H01B 1/24 the conductive material comprising carbon-silicon compounds, carbon or silicon
• CPC Class Codes: H10K 10/701 Organic molecular electronic devices
• CPC Class Codes: H10K 77/111 Flexible substrates
• CPC Class Codes: H10K 85/221 Carbon nanotubes

Abstract

A flexible electronic device is made up of nanostructures. Specifically, the device includes a flexible substrate, a film of nanostructures in contact with the flexible substrate, a first conducting element in contact with the film of nanostructures, and a second conducting element in contact with the film of nanostructures. The nanostructures may comprise nanotubes, such as carbon nanotubes disposed along the flexible substrate, such as an organic or polymer substrate. The first and second conductive elements may serve as electrical terminals, or as a source and drain. In addition, the electronic device may include a gate electrode that is in proximity to the nanotubes and not in electrical contact with the nanotubes. In this configuration, the device can operate as a transistor or a FET. The device may also be operated in a resistive mode as a chemical sensor (e.g., for sensing NH₃).

Claims

1. An electronic device, comprising:

a flexible substrate;

a film of nanostructures supported by the flexible substrate;

a first conducting element in contact with the film of nanostructures; and

a second conducting element in contact with the film of nanostructures.

2. The device of claim 1, further comprising a gate electrode in proximity to the film of nanostructures and not in electrical contact with the film of nanostructures.

3. The device of claim 2, wherein the gate electrode comprises a conductive nanostructure network.

4. The device of claim 2, wherein the electronic device is selected from the group consisting of transistors, chemical sensors, biological sensors, light sensors, pressure sensors, diodes, logic elements, circuits, resistors, and light-emitting diodes.

5. The device of claim 1, wherein the flexible substrate is selected from the group consisting of organic molecules, polymers, porous polymers, metal oxides, porous metal oxides.

6. The device of claim 1, wherein the flexible substrate is transparent to electromagnetic radiation in at least one range of wavelengths.

7. The device of claim 1, wherein the film of nanostructures comprises at least one nanostructure selected from the group consisting of nanotubes, nanospheres, nanocages, nanococoons, nanofibers, nanowires, nanoropes and nanorods.

8. The device of claim 1, wherein the film of nanostructures is uniform.

9. The device of claim 1, wherein the film of nanostructures comprises an essentially two-dimensional, monolayer network of nanotubes.

10. The device of claim 1, wherein the film of nanostructures comprises a three-dimensional, multiple-layer mat of nanostructures.

11. The device of claim 1, further comprising only a single conducting path through the film of nanostructures between the first conducting element and the second conducting element.

12. The device of claim 1, wherein the film of nanostructures has essentially metallic conduction properties.

13. The device of claim 1, wherein the film of nanostructures has essentially semiconducting conduction properties.

14. The device of claim 1, wherein the film of nanostructures is on a surface of the substrate.

15. The device of claim 1, wherein the film of nanostructures is within the substrate.

16. The device of claim 1, wherein the first conducting element and the second conducting element are metal electrodes.

17. The device of claim 16, wherein the metal electrodes comprise at least one metal selected from the group consisting of transition metals and aluminum.

18. The device of claim 1, wherein the first conducting element and the second conducting element comprise conductive nanostructure networks.

19. The device of claim 1, wherein the flexible substrate comprises an organic substrate.

20. The device of claim 1, wherein the flexible substrate comprises a polymer substrate and the film of nanostructures comprises a film of carbon nanotubes.

21. The device of claim 20, further comprising functionalization materials on the film of carbon nanotubes.

22. The device of claim 21, wherein the electronic device is a sensor device.

23. A method of forming an electronic device, comprising:

forming a nanostructure film on a first substrate;

transferring the nanostructure film to a second substrate; and

making electrical contact to the nanostructure film with at least two conducting elements;

wherein the second substrate is flexible.

24. The method of claim 23, further comprising forming a gate electrode in proximity to the nanostructure film on the second substrate and not in electrical contact with the nanostructure film.

25. The method of claim 23, wherein forming the nanostructure film comprises:

forming a plurality of growth promoter particles on a rigid substrate; and

exposing the growth promoter particles on the rigid substrate to a chemical vapor deposition process that forms nanostructures.

26. The method of claim 25, further comprising continuing the exposing step until a predetermined density of nanostructures is formed on the rigid substrate.

27. The method of claim 26, wherein the exposing step is continued until the predetermined density of nanostructures is approximately at a percolation threshold.

28. The method of claim 27, wherein transferring the nanostructure film comprises:

coating the nanostructures and the first substrate with a liquid polymer;

curing the liquid polymer to form the second substrate; and

removing the second substrate.

29. The method of claim 28, wherein the coating step comprises coating with the liquid polymer selected from the group consisting of polyacrylamide, polyacrylonitrile, polyaniline, polypyrrole, polythiophene, polystyrene, polybutadiene, poly(dimethylsiloxane), polyethylene, polycarbonate, poly(ethylene glycol), poly(ethylene oxide), poly(ethylenimine), poly(alkyl methacrylate), poly(propylene), polyoxyethylene, polytetrafluoroethylene, poly(vinyl alcohol), and polyvinylpyrrolidone.

30. The method of claim 28, wherein curing the liquid polymer comprises heating.

31. The method of claim 28, wherein removing the first substrate comprises using a chemical process to dissolve at least a portion of the first substrate.

32. The method of claim 23, wherein making electrical contact to the nanostructure film with at least two conducting elements comprises:

forming conducting elements in contact with the nanostructure film on the rigid substrate before transferring the nanostructure film to the second substrate; and

transferring the conducting elements to the second substrate.

33. The method of claim 32, wherein forming conducting elements comprises forming metal lines.

34. The method of claim 33, wherein forming metal lines comprises depositing at least one layer of metal and patterning the metal using a lithography process.

35. The method of claim 34, wherein depositing at least one layer of metal comprises depositing at least one metal selected from the group consisting of transition metals and aluminum.

36. The method of claim 32, wherein forming conducting elements comprises forming conductive nanostructure networks.

37. The method of claim 23, wherein forming the nanostructure film comprises:

adding a plurality of nanostructures to a first fluid to form a dilute suspension of nanostructures;

depositing the dilute suspension of nanostructures onto a first side of a porous membrane, thus forming a raft of nanostructures on the first side of the porous membrane; and

over-filling a volume on a second side of the porous membrane with a second fluid, thus floating the raft of nanostructures above the porous membrane.

38. The method of claim 37, wherein adding a plurality of nanostructures to a first fluid comprises adding the nanostructures to a fluid selected from the group consisting of DmbDcb (1,2-dimethylbenzene(ortho-xylene) and 1,2-dichlorobenzene), 1,3-dichlorobenzene, chlorobenzene, and carbon disulfide.

39. The method of claim 38, wherein the adding step further comprises adding the nanostructures to the fluid having a ratio of 1,2-dimethylbenzene(orth-oxylene) to 1,2-dicholorbenzene of between about 1:

1 and 100;

1.

40. The method of claim 39, wherein the adding step further comprises adding the nanostructures to the fluid having a ratio of 1,2-dimethylbenzene(ortho-oxylene) to 1,2-dicholorbenzene of between about 5:

1 and 15;

1.

41. The method of claim 37, wherein adding a plurality of nanostructures comprises forming a dilute suspension of nanostructures with a concentration of between about 1 mg/L and 15 mg/L.

42. The method of claim 37, wherein depositing the dilute suspension of nanostructures onto a first side of a porous membrane comprises depositing onto a membrane made of a material selected from the group consisting of cellulose, cellulose ester, silica, borosilicate, alumina, polytetrafluoroethylene, polyethersulfone, polysulfone, and nylon.

43. The method of claim 42, wherein a porous membrane comprises a membrane with a pore size between about 0.05 μ

m and 5.00 μ

m.

44. The method of claim 37, wherein the second fluid has a density larger than the density of the first fluid.

45. The method of claim 44, wherein the second fluid is deionized water.

46. The method of claim 23, wherein transferring the nanostructure film to a second substrate comprises:

providing a second substrate;

slipping the second substrate into the second fluid below a raft of nanostructures so that only the second fluid and any remaining first fluid intervenes between the second substrate and the raft of nanostructures; and

removing the second fluid and any remaining first fluid at least until the raft makes contact with the second substrate.

47. The method of claim 46, wherein making electrical contact to the nanostructure film with at least two conducting elements comprises providing the conductive elements to the second substrate before transferring the nanostructure film.