Carbon nanotube sensor and method of producing the same

• US 20030218224A1
• Filed: 04/14/2003
• Published: 11/27/2003
• Est. Priority Date: 04/12/2002
• Status: Active Grant

• Current Assignee: University of South Florida (State University System of Florida)
• Original Assignee: University of South Florida (State University System of Florida)
• Inventors: Schlaf, Rudiger, Bhansali, Shekhar
• Granted Patent: US 7,112,816 B2
• Time in Patent Office: Days
• US Class Current: 257/414
• 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 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C23C 16/26 Deposition of carbon only
• CPC Class Codes: C23C 16/56 After-treatment
• CPC Class Codes: G01N 2291/0256 Adsorption, desorption, surface mass change, e.g. on biosensors
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: G11C 13/025 using fullerenes, e.g. C60, or nanotubes, e.g. carbon or silicon nanotubes
• CPC Class Codes: G11C 23/00 Digital stores characterised by movement of mechanical parts to effect storage, e.g. using balls; Storage elements therefor
• CPC Class Codes: H10K 10/466 Lateral bottom-gate IGFETs comprising only a single gate
• CPC Class Codes: H10K 85/221 Carbon nanotubes
• CPC Class Codes: Y10S 977/748 Modified with atoms or molecules bonded to the surface
• CPC Class Codes: Y10S 977/938 Field effect transistors, FETS, with nanowire- or nanotube-channel region

Abstract

A carbon nanotube sensor and a method of producing the carbon nanotube sensor are disclosed. The sensor detects small particles and molecules. The sensor includes a gate, a source and a drain positioned on the gate, and a carbon nanotube grown from a catalytic material and extending from one of the source and the drain. The method includes the step of functionalizing an end of the carbon nanotube with a receptor. As such, the carbon nanotube is receptive to the small particles and molecules. The carbon nanotube is driven at a resonance, and the resonance of the carbon nanotube is measured when the end of the carbon nanotube is free of the small particles and the molecules. The method includes monitoring for a change in the resonance to detect the association of the small particles and molecules with the end of the carbon nanotube.

Claims

1. A method of producing a carbon nanotube sensor for detection of a small particle or molecule, wherein the sensor includes a gate, a source and a drain positioned on the gate, and a carbon nanotube grown from a catalytic material and extending from one of the source and the drain, said method comprising the steps of:

functionalizing an end of the carbon nanotube such that the functionalized carbon nanotube is receptive to at least one of the small particle and the molecule;

driving the functionalized carbon nanotube in a resonance;

measuring the resonance of the functionalized carbon nanotube when the end of the functionalized carbon nanotube is free of the small particle and the molecule; and

monitoring for a change in the resonance to detect the association of at least one of the small particle and the molecule with the end of the functionalized carbon nanotube.

2. A method as set forth in claim 1 further comprising the steps of:

depositing the catalytic material onto one of the source and the drain; and

subjecting the catalytic material to chemical vapor deposition to initiate growth of the carbon nanotube such that the carbon nanotube extends from one of the source and the drain, prior to functionalizing the end of the carbon nanotube.

3. A method as set forth in claim 2 wherein the step of depositing the catalytic material onto one of the source and the drain is further defined as depositing the catalytic material onto the source.

4. A method as set forth in claim 3 wherein the step of subjecting the catalytic material to chemical vapor deposition is further defined as subjecting the catalytic material to chemical vapor deposition to initiate growth of the carbon nanotube such that the carbon nanotube extends from the source.

5. A method as set forth in claim 2 wherein the step of depositing the catalytic material onto one of the source and the drain is further defined as depositing a catalytic material selected from the group consisting of nickel, cobalt, iron, and combinations thereof.

6. A method as set forth in claim 2 wherein the step of subjecting the catalytic material to chemical vapor deposition comprises the step of transforming a gaseous precursor selected from the group consisting of hydrides, halides, metal-organics, and combinations thereof into a solid material.

7. A method as set forth in claim 2 wherein the step of subjecting the catalytic material to chemical vapor deposition is further defined as subjecting the catalytic material to plasma enhanced chemical vapor deposition.

8. A method as set forth in claim 2 wherein the step of depositing the catalytic material onto one of the source and the drain is further defined as depositing the catalytic material onto one of the source and the drain using focused ion beam deposition.

9. A method as set forth in claim 2 wherein the step of depositing the catalytic material onto one of the source and the drain comprises the step of controlling an amount of the catalytic material that is deposited onto one of the source and the drain to vary at least one of a diameter of the carbon nanotube and a number of walls present in the carbon nanotube.

10. A method as set forth in claim 2 wherein the step of subjecting the catalytic material to chemical vapor deposition comprises the step of controlling a duration of the chemical vapor deposition to vary a length of the carbon nanotube.

11. A method as set forth in claim 2 further comprising the step of increasing the rigidity of the carbon nanotube that extends from one of the source and the drain.

12. A method as set forth in claim 11 wherein the step of increasing the rigidity of the carbon nanotube is further defined as depositing platinum onto one of the source and the drain prior to deposition of the catalytic material.

13. A method as set forth in claim 1 wherein the step of functionalizing the end of the carbon nanotube is further defined as chemically modifying the end of the carbon nanotube to be receptive to at least one of the small particle and the molecule.

14. A method as set forth in claim 1 wherein the step of functionalizing the end of the carbon nanotube is further defined as depositing molecules on the end of the carbon nanotube that are receptive to at least one of the small particle and the molecule.

15. A method as set forth in claim 1 wherein the step of functionalizing the end of the carbon nanotube is further defined as placing the end of the carbon nanotube into a solution of molecules that are receptive to at least one of the small particle and the molecule.

16. A method as set forth in claim 1 wherein the step of driving the functionalized carbon nanotube in the resonance is further defined as applying an AC voltage between the functionalized carbon nanotube and the drain such that the functionalized carbon nanotube resonates at a first resonance frequency when the end of the functionalized carbon nanotube is free of the small particle and the molecule.

17. A method as set forth in claim 16 wherein the step of monitoring for the change in the resonance is further defined as monitoring for a change from the first resonance frequency to a second resonance frequency that is different than the first resonance frequency, wherein the second resonance frequency indicates that at least one of the small particle and the molecule is associated with the end of the functionalized carbon nanotube.

18. A method as set forth in claim 16 wherein the step of measuring the resonance of the functionalized carbon nanotube is further defined as measuring a first current that is indicative of the first resonance frequency of the functionalized carbon nanotube when the end is free of the small particles and molecules.

19. A method as set forth in claim 18 wherein the step of monitoring for the change in the resonance is further defined as monitoring for a change from the first current to a second current that is less than the first current, wherein the second current indicates that at least one of the small particle and the molecule is associated with the end of the functionalized carbon nanotube.

20. A method as set forth in claim 2 further comprising the step of controlling an angle that the carbon nanotube grows at relative to one of the source and the drain.

21. A method as set forth in claim 20 wherein the step of controlling the angle that the carbon nanotube grows at is further defined as applying an electric field as the catalytic material is subjected to chemical vapor deposition.

22. A carbon nanotube sensor for detection of a small particle or molecule, said sensor comprising:

a gate;

a source and a drain positioned on said gate;

a carbon nanotube extending from one of said source and said drain and being grown from a catalytic material deposited on one of said source and said drain;

a functional receptor disposed at an end of said carbon nanotube such that said carbon nanotube is receptive to at least one of the small particle and the molecule;

wherein said carbon nanotube resonates at a first resonance frequency when said functional receptor at said end of said carbon nanotube is free of the small particle and the molecule, and said carbon nanotube resonates at a second resonance frequency that is different from said first resonance frequency when at least one of the small particle and the molecule is associated with said functional receptor at said end of said carbon nanotube.

23. A sensor as set forth in claim 22 wherein said catalytic material is selected from the group consisting of nickel, cobalt, iron, and combinations thereof.

24. A sensor as set forth in claim 22 further comprising an electrical source for resonating said carbon nanotube.

25. A sensor as set forth in claim 24 wherein said electrical source is further defined as an AC voltage source such that a first current can be measured when said functional receptor is free of the small particle and the molecule and said carbon nanotube is resonating at said first resonance frequency, and a second current can be measured when at least one of the small particle and the molecule is associated with said functional receptor and said carbon nanotube is resonating at said second resonance frequency.

26. A sensor as set forth in claim 25 further comprising a detection mechanism for measuring a change from said first current to said second current.

27. A sensor as set forth in claim 26 wherein said detection mechanism is further defined as an amp meter.

28. A sensor as set forth in claim 22 wherein said carbon nanotube is grown by subjecting said catalytic material to chemical vapor deposition.