Strip electrode with conductive nano tube printing

• US 20050186333A1
• Filed: 02/23/2005
• Published: 08/25/2005
• Est. Priority Date: 02/23/2004
• Status: Active Grant

• Current Assignee: Joel S. Douglas
• Original Assignee: MysticMD Inc. (eGen Partners LLC)
• Inventors: Douglas, Joel S.
• Granted Patent: US 7,285,198 B2
• Time in Patent Office: Days
• US Class Current: 427/97.100
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/002 Electrode membranes
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

A sensor system that detects a current representative of a compound in a liquid mixture features a multi or three electrode strip adapted for releasable attachment to signal readout circuitry. The strip comprises an elongated support which is preferably flat adapted for releasable attachment to the readout circuitry; a first conductor and a second and a third conductor each extend along the support and comprise means for connection to the circuitry. The circuit is formed with single-walled or multi walled nanotubes conductive traces and may be formed from multiple layers or dispersions containing, carbon nanotubes, carbon nanotubes/antimony tin oxide, carbon nanotubes/platinum, or carbon nanotubes/silver or carbon nanotubes/silver-cloride. An active electrode formed from a separate conductive carbon nanotubes layer or suitable dispersion, positioned to contact the liquid mixture and the first conductor, comprises a deposit of an enzyme capable of catalyzing a reaction involving the compound and preferably an electron mediator, capable of transferring electrons between the enzyme-catalyzed reaction and the first conductor. A reference electrode also formed from a conductive carbon nanotube layer or suitable dispersion is positioned to contact the mixture and the second conductor. The system includes circuitry adapted to provide an electrical signal representative of the current which is formed from printing conductive inks made with nano size particles such as conductive carbon or carbon/platinum or carbon/silver, or carbon nanotubes/antimony tin oxide to form a conductive carbon nanotube layers. The multiple-electrode strip is manufactured, by then applying the enzyme and preferably the mediator onto the electrode. Alternatively the electrode can have a carbon nanotubes/antimony tin oxide, carbon nanotubes/platinum, or carbon nanotubes/silver or carbon nanotubes/silver-cloride surface and or a conductive carbon or silver ink surface connecting leg. The carbon nanotube solution is first coated and patterned into electro shapes and the conductive carbon nanotubes, carbon or silver ink can be attached by printing the ink to interface with the carbon nanotube electro surface. A platinum electrode test strip is also disclosed that is formed from either nano platinum distributed in the carbon nanotube layer or by application or incorporation of platinum to the carbon nanotube conductive ink.

Claims

1. An electrochemical test device for determining the presence or concentration of an analyte in an aqueous fluid sample, said electrochemical test device comprising:

(a) a substrate, the substrate comprising a non-conductive material;

(b) a working electrode comprising a conductive film formed with carbon nanotubes and other conductive and non conductive materials affixed to the non-conductive coating, said working electrode having a first electrode area, a first lead and a first contact pad;

(c) a counter electrode comprising an conductive film formed with carbon nanotubes and other conductive and non conductive materials affixed to the non-conductive substrate, said counter electrode having a second electrode area, a second lead and a second contact pad; and

(d) a reagent capable of reacting with the analyte to produce a measurable change in potential which can be correlated to the presence or concentration of the analyte in the fluid sample, said reagent overlaying at least a portion of the first electrode area of the working electrode.

2. The device of claim 1, wherein said device further comprises a reference electrode comprising a conductive coating formed with carbon nanotubes and other conductive and non conductive materials affixed to the non-conductive surface, said reference electrode having a third electrode area, a third lead, and a third contact pad, and wherein at least a portion of the third electrode area is overlaid with a reference material.

3. The device of claim 2, wherein said reference material is silver/silver chloride.

4. The device of claim 1, wherein the substrate comprises a flexible material.

5. The device of claim 1, wherein the conductive film is formed from single and multi walled carbon nanotubes and the average outer diameter size of the carbon nanotubes is greater than 0.5 nm.

6. The device of claim 1, wherein said nanotubes are selected from the group consisting of single-walled nanotubes (SWNTs), double-walled nanotubes (DWNTs), multi-walled nanotubes (MWNTs), and mixtures thereof.

7. The device of claim 1, wherein said nanotubes are substantially single-walled nanotubes (SWNTs).

8. The device of claim 1, wherein said nanotubes are present in said film at about 0.001 to about 10% based on weight.

9. The device of claim 1, wherein said nanotubes are present in said film at about 0.5%.

10. The device of claim 1, wherein the film has a surface resistance in the range of less than about 50,000 ohms/square.

11. The device of claim 1, further comprising a polymeric material.

12. The device of claim 1, wherein said nanotubes are selected from the group consisting of single-walled nanotubes (SWNTs), double-walled nanotubes (DWNTs), multi-walled nanotubes (MWNTs), and mixtures thereof to form a dispersion.

13. A device of claim 12, wherein the dispersion comprises a plurality of nanotubes with an outer diameter of less than 10 nm.

14. The device of claim 13, wherein said nanotubes have an outer diameter of about 0.5 to 10 nm.

15. The device of claim 13, wherein said nanotubes are substantially single-walled nanotubes (SWNTs).

16. The device of claim 12, wherein the dispersion further comprising a polymeric material, wherein the polymeric material comprises a material selected from the group consisting of thermoplastics, thermosetting polymers, elastomers, conducting polymers and combinations thereof.

17. The device of claim 12, the dispersion further comprising a polymeric material, wherein the polymeric material comprises a material selected from the group consisting of ceramic hybrid polymers, and phosphine oxides chalcogenides.

18. The device of claim 12, the dispersion further comprising a plasticizer, softening agent, filler, reinforcing agent, processing aid, stabilizer, antioxidant, dispersing agent, binder, a cross-linking agent, a coloring agent, a UV absorbent agent, or a charge adjusting agent.

19. The device of claim 12, the dispersion further comprising conductive organic materials, inorganic materials, or combinations or mixtures thereof.

20. The device of claim 19, wherein the conductive organic materials are selected from the group consisting of buckeyballs, carbon black, fullerenes, nanotubes with an outer diameter of greater than about 0.5 nm, and combinations and mixtures thereof.

21. The device of claim 20, wherein the conductive inorganic materials are selected from the group consisting of antimony tin oxide, iridium tin oxide, aluminum, antimony, beryllium, cadmium, chromium, cobalt, copper, doped metal oxides, iron, gold, lead, manganese, magnesium, mercury, metal oxides, nickel, platinum, silver, steel, titanium, zinc, and combinations and mixtures thereof.

22. The device of claim 21, further comprising a conductive material selected from the group consisting of tin-indium mixed oxide, antimony-tin mixed oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide and combinations and mixtures thereof.

23. The device of claim 21, further comprising conductors, fluids, gelatins, ionic compounds, semiconductors, solids, surfactants, or combinations or mixtures thereof.

24. The device of claim 1, wherein the conductive coating is formed from single and multi walled carbon nanotubes and the average outer diameter size of the carbon nanotubes is less than 10 nm.

25. The device of claim 24, wherein said nanotubes are present in said coating at about 0.001 to about 10% based on weight.

26. The device of claim 24, wherein said nanotubes are present in said coating at about 0.05%.

27. The device of claim 1, wherein said film has a total light transmittance of about 90% or more.

28. The device of claim 1, wherein said film has a total light transmittance of about 95% or more.

29. The device of claim 1, wherein said film has a haze value less than 2.0%.

30. The device of claim 1, wherein said film has a haze value less than 0.1%.

31. The device of claim 1, wherein said film has a thickness between about 0.5 nm to about 1000 microns.

32. The device of claim 1, wherein the nanotubes are oriented.

33. The device of claim 1, wherein the nanotubes are oriented in the plane of the film.

34. The device of claim 1, wherein the nanotubes are oriented, further comprising an additional layer of oriented nanotubes.

35. A method for making conductive film specified in claim 1 comprising:

providing a plurality of nanotubes with an outer diameter of less than 3.5 nm; and

forming a film of said nanotubes on a surface of a substrate.

36. The method of claim 35, wherein the step of forming the film comprises a method selected from the group consisting of spray painting, dip coating, spin coating, knife coating, kiss coating, gravure coating, screen printing, ink jet printing, and pad printing.

67. The device of claim 1, wherein the conductive coating contains platinum.

68. The device of claim 1, wherein the conductive coating forms at least one electrode that has a platinum layer.

69. The device of claim 1, wherein the substrate comprises a polymeric sheet.

70. The device of claim 1, wherein the conductive coating is formed with carbon nanotubes and other conductive materials.

71. The device of claim 1, wherein the reagent comprises an enzyme and a redox mediator.

72. The device of claim 71, wherein the enzyme is glucose oxidase.

73. The device of claim 71, wherein the redox mediator is potassium ferricyanide.

74. The device of claim 1, wherein the conductive coating formed with carbon nano tubes and other conductive and non conductive materials has a surface texture less than 0.33 microns.

75. The device of claim 1, wherein the conductive coating formed with carbon nano tubes and other conductive materials has a surface texture less than 0.33 microns.

76. The device of claim 1, wherein the conductive coating formed with carbon nanotubes and other conductive materials and the leads are formed from course solid conductive material.

77. The device of claim 69, wherein the polymeric sheet material is selected from the group consisting of polyesters, polycarbonates and polyimides.

37. A multi-layered structure comprising:

an electrically conductive film comprising a plurality of nanotubes with an outer diameter of less than 10 nm; and

a polymeric layer disposed on at least a portion of said electrically conductive film.

38. The multi-layered structure of claim 37, wherein said nanotubes are selected from the group consisting of single-walled nanotubes (SWNTs), double-walled nanotubes (DWNTs), multi-walled nanotubes (MWNTs), and mixtures thereof.

39. The multi-layered structure of claim 37, wherein said nanotubes are substantially single-walled nanotubes (SWNTs).

40. The multi-layered structure of claim 37, wherein said nanotubes are present in said film at about 0.001 to about 10% based on weight.

41. The multi-layered structure of claim 37, wherein the film has a volume resistance in the range of about 100 ohms/cm² to about 50,000 ohms/cm².

42. The multi-layered structure of claim 37, wherein the film is in the form of a solid film, a foam, or a fluid.

43. The multi-layered structure of claim 37, further comprising a polymeric material, wherein the polymeric material comprises a material selected from the group consisting of thermoplastics, thermosetting polymers, elastomers, conducting polymers and combinations thereof.

44. The multi-layered structure of claim 37, further comprising a polymeric material, wherein the polymeric material comprises a material selected from the group consisting of ceramic hybrid polymers, phosphine oxides and chalcogenides.

45. The multi-layered structure of claim 37, further comprising a polymeric material wherein the nanotubes are dispersed substantially homogenously throughout the polymeric material.

46. The multi-layered structure of claim 37, further comprising a polymeric material wherein the nanotubes are present in a gradient fashion.

47. The multi-layered structure of claim 37, further comprising a polymeric material wherein the nanotubes are present on a surface of said polymeric material.

48. The multi-layered structure of claim 37, further comprising a polymeric material wherein the nanotubes are formed in an internal layer of said polymeric material.

49. The multi-layered structure of claim 37, further comprising an opaque substrate, wherein the nanotubes are present on a surface of said opaque substrate.

50. The multi-layered structure of claim 37, further comprising an additive selected from the group consisting of a dispersing agent, a binder, a cross-linking agent, a stabilizer agent, a coloring agent, a UV absorbent agent, and a charge adjusting agent.

51. The multi-layered structure of claim 37, wherein the film has a total transmittance of at least about 60%.

52. The multi-layered structure of claim 37, wherein said film has a thickness between about 0.005 to about 1,000 microns.

53. The multi-layered structure of claim 37, wherein the nanotubes are oriented.

54. The multi-layered structure of claim 37, wherein the nanotubes are oriented in the plane of the film.

55. A dispersion of nanotubes comprising a plurality of nanotubes with an outer diameter of less than 10 nm.

56. The dispersion of claim 55, wherein said nanotubes have an outer diameter of about 0.5 to 10 nm.

57. The dispersion of claim 55, wherein said nanotubes are selected from the group consisting of single-walled nanotubes (SWNTs), double-walled nanotubes (DWNTs), multi-walled nanotubes (MWNTs), and mixtures thereof.

58. The dispersion of claim 55, wherein said nanotubes are substantially single-walled nanotubes (SWNTs).

59. The dispersion of claim 55, further comprising a polymeric material, wherein the polymeric material comprises a material selected from the group consisting of thermoplastics, thermosetting polymers, elastomers, conducting polymers and combinations thereof.

60. The dispersion of claim 55, further comprising a polymeric material, wherein the polymeric material comprises a material selected from the group consisting of ceramic hybrid polymers, and phosphine oxides chalcogenides.

61. The dispersion of claim 55, further comprising a plasticizer, softening agent, filler, reinforcing agent, processing aid, stabilizer, antioxidant, dispersing agent, binder, a cross-linking agent, a coloring agent, a UV absorbent agent, or a charge adjusting agent.

62. The dispersion of claim 55, further comprising conductive organic materials, inorganic materials, or combinations or mixtures thereof.

63. The dispersion of claim 55, wherein the conductive organic materials are selected from the group consisting of buckeyballs, carbon black, fullerenes, nanotubes with an outer diameter of greater than about 0.5 nm, and combinations and mixtures thereof.

64. The dispersion of claim 55, wherein the conductive inorganic materials are selected from the group consisting of aluminum, antimony, beryllium, cadmium, chromium, cobalt, copper, doped metal oxides, iron, gold, lead, manganese, magnesium, mercury, metal oxides, nickel, platinum, silver, steel, titanium, zinc, and combinations and mixtures thereof.

65. The dispersion of claim 55, further comprising a conductive material selected from the group consisting of tin-indium mixed oxide, antimony-tin mixed oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide and combinations and mixtures thereof.

66. The dispersion of claim 55, further comprising conductors, fluids, gelatins, ionic compounds, semiconductors, solids, surfactants, or combinations or mixtures thereof.