Sensor platform using a horizontally oriented nanotube element

• US 20060237805A1
• Filed: 01/17/2006
• Published: 10/26/2006
• Est. Priority Date: 05/14/2003
• Status: Active Grant

• Current Assignee: Nantero Incorporated
• Original Assignee: Nantero Incorporated
• Inventors: Bertin, Claude L., Vogeli, Bernhard, Segal, Brent M., Rueckes, Thomas, Jaiprakash, Venkatachalam C., Brock, Darren
• Granted Patent: US 8,310,015 B2
• Time in Patent Office: Days
• US Class Current: 257/414
• 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: G01N 27/4146 involving nanosized elements, e.g. nanotubes, nanowires
• CPC Class Codes: G11C 13/025 using fullerenes, e.g. C60, or nanotubes, e.g. carbon or silicon nanotubes
• CPC Class Codes: Y10S 977/902 Specified use of nanostructure
• CPC Class Codes: Y10S 977/904 for medical, immunological, body treatment, or diagnosis
• CPC Class Codes: Y10S 977/92 Detection of biochemical
• CPC Class Codes: Y10S 977/921 Of toxic chemical
• CPC Class Codes: Y10S 977/922 Of explosive material
• CPC Class Codes: Y10S 977/924 using nanostructure as support of dna analysis
• CPC Class Codes: Y10T 29/43 Electric condenser making
• CPC Class Codes: Y10T 29/49082 Resistor making

Abstract

Sensor platforms and methods of making them are described, and include platforms having horizontally oriented sensor elements comprising nanotubes or other nanostructures, such as nanowires. Under certain embodiments, a sensor element has an affinity for an analyte. Under certain embodiments, such a sensor element comprises one or more pristine nanotubes, and, under certain embodiments, it comprises derivatized or functionalized nanotubes. Under certain embodiments, a sensor is made by providing a support structure; providing a collection of nanotubes on the structure; defining a pattern within the nanotube collection; removing part of the collection so that a patterned collection remains to form a sensor element; and providing circuitry to electrically sense the sensor'"'"'s electrical characterization. Under certain embodiments, the sensor element comprises pre-derivatized or pre-functionalized nanotubes. Under certain embodiments, sensor material is derivatized or functionalized after provision on the structure or after patterning. Under certain embodiments, a large-scale array includes multiple sensors.

Claims

1. A sensor platform, comprising

a sensor element comprising at least one nanotube and having an electrical characterization;

a support structure, comprising a substrate, for supporting the sensor element so that it may be exposed to a fluid, and having a major surface of the substrate substantially non-parallel to the sensor element;

control circuitry to electrically sense the electrical characterization of the sensor element so that the presence of a corresponding analyte may be detected.

2. The sensor platform of claim 1 wherein the sensor element has an affinity for the corresponding analyte.

3. The sensor platform of claim 2 wherein the sensor element comprises a pristine nanotube.

4. The sensor platform of claim 2 wherein the sensor element comprises a nanotube derivatized to have or to increase the affinity.

5. The sensor platform of claim 2 wherein the sensor element comprises a nanotube functionalized to have or to increase the affinity.

6. The sensor platform of claim 1 wherein the sensor element has an affinity for at least two analytes and wherein the sensor element comprises at least two types of nanotubes, a first type having an affinity for a first analyte and a second type having an affinity for a second analyte.

7. The sensor platform of claim 2 wherein the support structure includes a channel and wherein the sensor element is suspended to span the channel.

8. The sensor platform of claim 7 wherein the support structure includes a first conductive electrode positioned, at least in part, in the channel, and wherein the sensor element is deflectable in response to the control circuitry to contact the electrode so that a gating effect of the nanotubes in the sensor element may be electrically detected.

9. The sensor platform of claim 8 wherein the sensor element is oriented substantially perpendicular to the major surface of the substrate.

10. The sensor platform of claim 8 further including a second conductive electrode positioned on the side of the sensor element opposite the first conductive electrode.

11. The sensor platform of claim 1 including a fluidic separator in fluid communication with the sensor platform to deliver a fluid potentially having the analyte.

12. The sensor platform of claim 1 wherein the sensor element rests flat on a portion of the support structure.

13. The sensor platform of claim 1 wherein the sensor element is oriented substantially perpendicular to the major surface of the substrate.

14. The sensor platform of claim 1 wherein the sensor element is reusable in that, after exposure to the corresponding analyte, the sensor element can be substantially returned to its pre-exposure state by applying a voltage.

15. The sensor platform of claim 1 wherein a conductive element is located apart from the sensor element to form a structure in which the conductive element and sensor element are in a capacitive relationship.

16. The sensor platform of claim 15 wherein the sensor element is on one side of an insulating layer, and the conductive element is a conductive pad that is on another side of the insulating layer.

17. The sensor platform of claim 15 wherein the control circuitry comprises current-mirror circuitry to allow a capacitance associated with the sensor element and the conductive element to be measured.

18. The sensor platform of claim 15 wherein the control circuitry comprises a reference capacitor to allow measurement relative to the capacitance of the reference capacitor of a capacitance associated with the sensor element and the conductive element to be measured.

19. The sensor platform of claim 18 wherein the reference capacitor comprises both a second collection of at least one nanotube and a second conductive element that is separate from the second collection, so that the second collection and the second conductive element form a structure in which the second conductive element and second sensor element are in a capacitive relationship.

20. The sensor platform of claim 1 wherein a first conductive element contacts the sensor element at a first point and a second conductive element contacts the sensor element at a second point so that an electric current can run through the sensor element between the first and second conductive elements.

21. The sensor platform of claim 20 wherein the control circuitry comprises current-mirror circuitry to allow a resistance between the first and second contact points to be measured.

22. The sensor platform of claim 20 wherein the control circuitry comprises a reference resistor to allow measurement relative to the resistance of the reference resistor of the resistance between the first and second contact points.

23. The sensor platform of claim 22 wherein the reference resistor comprises a second collection of nanotubes, and third and fourth conductive elements that contact the sensor element at separate points so that an electric current can run through the second collection of nanotubes between the third and fourth conductive elements.

24. A large-scale array of sensor platforms wherein the array includes a large plurality of sensor platform cells, each cell comprising

a sensor element comprising at least one nanotube and having an electrical characterization;

a support structure for supporting the sensor element so that it may be exposed to a fluid, and having a major surface of the substrate substantially non-parallel to the sensor element;

control circuitry to electrically sense the electrical characterization of at least one sensor element so that the presence of a corresponding analyte may be detected.

25. The large-scale array of claim 24 wherein the sensor element is oriented substantially perpendicular to the major surface of the substrate.

26. A sensor platform, comprising

a sensor element comprising at least one nanotube and having an electrical characterization;

a support structure, comprising a substrate, for supporting the sensor element, and having a major surface of the substrate substantially non-parallel to the sensor element;

a conductive element located apart from the sensor element to form a structure in which the conductive element and the sensor element are in a capacitive relationship;

control circuitry to electrically sense an electrical value reflecting the capacitance associated with the sensor element and the conductive element.

27. The sensor platform of claim 26 wherein the sensor element is on one side of an insulating layer, and the conductive element is a conductive pad on another side of the insulating layer.

28. The sensor platform of claim 26 wherein the sensor element is substantially surrounded by support structure material so that it is not substantially exposed to potential contact with a fluid.

29. The sensor platform of claim 26 wherein the sensor element is oriented substantially perpendicular to the major surface of the substrate.

30. A large-scale array of sensor platforms wherein the array includes a plurality of sensor platform cells, each of which comprises

a sensor element comprising at least one nanotube and having an electrical characterization;

a support structure, comprising a substrate, for supporting the sensor element, and having a major surface of the substrate substantially non-parallel to the sensor element;

a conductive element located apart from the sensor element to form a structure in which the conductive element and the sensor element are in a capacitive relationship;

control circuitry to electrically sense an electrical value reflecting the capacitance associated with the sensor element and the conductive element.

31. The large-scale array of claim 30 wherein the sensor element is oriented substantially perpendicular to the major surface of the substrate.

32. A sensor platform, comprising

a sensor element comprising at least one nanotube and having an electrical characterization;

a support structure, comprising a substrate, for supporting the sensor element, and having a major surface of the substrate substantially non-parallel to the sensor element;

first and second conductive elements that contact the sensor element at separate locations;

control circuitry to electrically sense an electrical value reflecting the resistance associated with the passage of current between the first and second conductive elements through at least a portion of the sensor element.

33. The sensor platform of claim 32 wherein the sensor element is substantially surrounded by support structure material so that it is not substantially exposed to potential contact with a fluid.

34. The sensor platform of claim 32 wherein the sensor element is oriented substantially perpendicular to the major surface of the substrate.

35. A large-scale array of sensor platforms wherein the array includes a plurality of sensor platform cells, each of which comprises

a sensor element comprising at least one nanotube and having an electrical characterization;

a support structure, comprising a substrate, for supporting the sensor element, and having a major surface of the substrate substantially non-parallel to the sensor element;

first and second conductive elements that contact the sensor element at separate locations;

control circuitry to electrically sense an electrical value reflecting the resistance associated with the passage of current between the conductive elements through at least a portion of the sensor element.

36. The large-scale array of claim 35 wherein the sensor element is oriented substantially perpendicular to the major surface of the substrate.

37. A method of making a sensor, comprising:

providing a support structure comprising a substrate;

providing a collection of at least one nanotube in contact with the support structure and oriented substantially non-parallel to a major surface of the substrate, so that at least a portion of the collection can act as a sensor element in contact with the support structure;

providing control circuitry to electrically sense the electrical characterization of the sensor element so that the presence of a corresponding analyte may be detected.

38. The method of claim 37 wherein the sensor element has an affinity for the corresponding analyte.

39. The method of claim 38 wherein the collection comprises a pristine nanotube.

40. The method of claim 38 wherein the collection comprises a nanotube derivatized to have or to increase the affinity.

41. The method of claim 38 wherein the collection comprises a nanotube functionalized to have or to increase the affinity.

42. The method of claim 37 wherein the sensor element has an affinity for at least two analytes and wherein the collection of nanotubes includes at least two types of nanotubes, a first type having an affinity for a first analyte and a second type having an affinity for a second analyte.

43. The method of claim 38 wherein the support structure includes a channel and wherein the sensor element is suspended to span the channel.

44. The method of claim 43 wherein the support structure includes a conductive electrode positioned in the channel, and wherein the sensor element is deflectable in response to the control circuitry to contact the electrode so that a gating effect of the nanotubes in the sensor element may be electrically detected.

45. The method of claim 44 wherein the sensor element is oriented substantially perpendicular to the major surface of the substrate.

46. The method of claim 44 further including an upper electrode positioned above and separated from the sensor element.

47. The method of claim 37 further including defining a fluidic separator in fluid communication with the sensor element to deliver a fluid potentially having the analyte.

48. The method of claim 37 wherein the sensor element rests flat on a portion of the support structure.

49. The method of claim 37 wherein the sensor element is oriented substantially perpendicular to the major surface of the substrate.

50. The method of claim 37 wherein the sensor element is reusable in that, after exposure to the corresponding analyte, the sensor element can be substantially returned to its pre-exposure state by applying a voltage.

51. The method of claim 37 wherein the collection of at least one nanotube is formed by growing the collection on the substrate using a catalyst.

52. The method of claim 51 wherein, during the growing of the collection, a nanotube is derivatized to have an affinity for a corresponding analyte.

53. The method of claim 51 wherein, during the growing of the collection, a nanotube is functionalized to have an affinity for a corresponding analyte.

54. The method of claim 37 wherein the collection is formed by depositing a solution of suspended nanotubes on the substrate.

55. The method of claim 54 wherein the nanotubes are derivatized to have an affinity for a corresponding analyte.

56. The method of claim 54 wherein the nanotubes are functionalized to have an affinity for a corresponding analyte.

57. The method of claim 37 wherein the sensor element comprises a pre-derivatized nanotube.

58. The method of claim 37 wherein the sensor element comprises a pre-functionalized nanotube.

59. The method of claim 37 further comprising derivatizing at least one nanotube associated with the sensor element.

60. The method of claim 37 further comprising functionalizing at least one nanotube associated with the sensor element.

61. The method of claim 37 further comprising

defining a pattern within the collection of at least one nanotube;

removing a portion of the collection so that patterned nanotube material remains on the substrate to form a sensor element having a collection of at least one nanotube and having an electrical characterization.

62. The method of claim 37, further comprising

providing a layer of covering material on one side of the collection of at least one nanotube;

removing a portion of the covering material to expose a portion of the collection.

63. The method of claim 37, further comprising

providing a first layer of a first covering material on one side of the collection of at least one nanotube;

providing a second layer of a second covering material on one side of the collection of at least one nanotube;

removing a portion of the second covering material;

annealing portions of the first and second covering materials.

64. The method of claim 37 further comprising providing a conductive element located separate from the sensor element so that the conductive element and the sensor element are in a capacitive relationship.

65. The method of claim 64 further comprising providing an insulating layer between the conductive element and the sensor element.

66. The method of claim 65 wherein the control circuitry comprises current-mirror circuitry to allow an electrical value corresponding to a capacitance associated with the conductive element and the sensor element to be measured.

67. The method of claim 66 further comprising providing a reference capacitor to allow measurement of a capacitance associated with the sensor element and the conductive element relative to the capacitance of the reference capacitor.

68. The method of claim 67 wherein the reference capacitor comprises both a second collection of at least one nanotube and a second conductive element that is separate from the second nanotube collection so that the second collection and the second conductive element are in a capacitive relationship.

69. The method of claim 37 further comprising providing a first conductive element that contacts the sensor element at a first point and providing a second conductive element that contacts the sensor element at a second point, so that an electric current can run through the sensor element between the first and second conductive elements.

70. The method of claim 69 wherein the control circuitry comprises current-mirror circuitry to allow an electrical value corresponding to the resistance between the first and second contacts to be measured.

71. The method of claim 70 further comprising providing a reference resistor to allow measurement of the electrical value to be measured relative to the resistance of the reference resistor.

72. The method of claim 71 wherein the reference resistor comprises both a second collection of at least one nanotube and a third conductive element and a fourth conductive element that contact the nanotube collection at separate points, so that an electric current can run through the nanotube collection between the conductive elements.

73. A method of making a capacitive structure, comprising

providing a support structure comprising a substrate;

providing a collection of at least one nanotube in contact with the support structure, and oriented substantially non-parallel to a major surface of the substrate;

providing a conductive element located apart from the collection so that the conductive element and the collection are in a capacitive relationship;

providing control circuitry to electrically sense an electrical value reflecting a capacitance associated with the collection and the conductive element.

74. The method of claim 73 further comprising providing covering material in contact with the sensor element so that it is not exposed to substantial potential contact with a fluid.

75. The method of claim 73 wherein the collection is oriented substantially perpendicular to the major surface of the substrate.

76. A method of making a resistive structure, comprising

providing a support structure comprising a substrate;

providing a collection of at least one nanotube in contact with the support structure, and oriented substantially non-parallel to a major surface of the substrate;

providing first and second conductive elements that contact the collection at separate locations;

providing control circuitry to electrically sense an electrical value reflecting the resistance associated with the passage of current between the first and second conductive elements through at least a portion of the collection.

77. The method of claim 76 further comprising providing covering material in contact with the collection so that it is not exposed to substantial potential contact with a fluid.

78. The method of claim 76 wherein the collection is oriented substantially perpendicular to the major surface of the substrate.