Carbon nanotube oscillator surface profiling device and method of use
View Patent ↗The proposed device is based on a carbon nanotube oscillator consisting of a finite length outer stationary nanotube and a finite length inner oscillating nanotube. Its main function is to measure changes in the characteristics of the motion of the carbon nanotube oscillating near a sample surface, and profile the roughness of this surface. The device operates in a non-contact mode, thus it can be virtually non-wear and non-fatigued system. It is an alternative to the existing atomic force microscope (AFM) tips used to scan surfaces to determine their roughness.
1. A method for profiling a sample surface, the method comprising:
positioning an open-ended double wall carbon nanotube oscillator in close proximity to a sample surface such that the axis of the carbon nanotube oscillator is substantially perpendicular to a sample surface, the carbon nanotube oscillator comprising a stationary carbon nanotube having a first length and a first interior diameter and an oscillatory carbon nanotube positioned within the interior of the stationary carbon nanotube, the oscillatory carbon nanotube having a second length and a second interior diameter that is smaller than the first interior diameter;
initiating the oscillation of the oscillatory carbon nanotube;
measuring the frequency of oscillation of the oscillatory carbon nanotube; and
re-positioning the carbon nanotube oscillator at a plurality of locations perpendicular to the sample surface, re-initiating the oscillation of the oscillatory carbon nanotube and re-measuring the frequency of oscillation at each of the plurality of locations to profile the sample surface.
2. The method of claim 1 , wherein initiating the oscillation of the oscillatory carbon nanotube comprises:
extruding the oscillatory carbon nanotube from the stationary carbon nanotube, along the common axis of the stationary and oscillator carbon nanotubes, to a first distance from a first edge of the stationary carbon nanotube; and
releasing the oscillatory carbon nanotube to initiate the oscillation.
3. The method of claim 2 , wherein extruding the oscillatory carbon nanotube comprises electrostatically telescoping the oscillatory carbon nanotube.
4. The method of claim 2 , wherein extruding the oscillatory carbon nanotube further comprises extruding the oscillatory carbon nanotube to a first distance from the first edge of the stationary carbon nanotube wherein the first distance is less than 30% of the first length of the stationary carbon nanotube.
5. The method of claim 1 , wherein measuring the frequency of the oscillation of the oscillatory carbon nanotube comprises:
positioning a laser at a first edge, distal from the sample surface, of the stationary carbon nanotube, the laser to emit a laser beam; and
positioning a laser detector at a first edge, distal from the sample surface, of the stationary carbon nanotube and in-line with the laser, the detector to measure the intensity of the laser beam emitted by the laser as the oscillatory tube oscillates.
6. The method of claim 1 , wherein measuring the frequency of the oscillation of the oscillatory nanotube comprises measuring the frequency at a first period of the oscillations.
7. The method of claim 1 , wherein measuring the frequency of the oscillation of the oscillatory nanotube comprises measuring the frequency at a friction-free period of the oscillations.
8. The method of claim 1 , wherein re-positioning the carbon nanotube oscillator at a plurality of locations perpendicular to the sample surface comprises moving the sample surface along an xy-plane.
9. The method of claim 1 , where re-positioning the carbon nanotube oscillator at a plurality of locations perpendicular to the sample surface comprises moving the carbon nanotube oscillator along an xy-plane.
10. A system for profiling a sample surface, the system comprising:
an open-ended double wall carbon nanotube oscillator comprising a stationary carbon nanotube having a first length and a first interior diameter and an oscillatory carbon nanotube positioned within the interior of the stationary carbon nanotube, the oscillatory carbon nanotube having a second length and a second interior diameter that is smaller than the first interior diameter; and
a laser-detector positioned at a first edge, distal from a sample surface, of the stationary carbon nanotube, the laser-detector for measuring the frequency of oscillation of the oscillatory carbon nanotube.
11. The system of claim 10 , further comprises means for initiating the oscillation of the oscillatory carbon nanotube.
12. The system of claim 11 , wherein the means for initiating the oscillation of the oscillatory carbon nanotube further comprises an electrostatic telescoping device to extrude the oscillatory carbon nanotube from the stationary carbon nanotube by an initial extrusion distance.
13. The system of the 12 , wherein the initial extrusion distance is equal to less than about ⅓ of the first length of the stationary carbon nanotube.
14. The system of claim 10 , wherein the carbon nanotube oscillator is a (5,0)@(7,9) double wall carbon nanotube and wherein the first length and the second length are equal to 150 Å.
15. The system of claim 10 , wherein the laser-detector comprises:
a laser to emit a laser beam; and
a laser detector positioned in-line with the laser, the detector to measure the intensity of the laser beam emitted by the laser as the oscillatory tube oscillates.
16. The system of claim 10 , wherein the first diameter is larger than the second diameter by approximately 6.8 angstroms.
17. The system of claim 10 , wherein the stationary carbon nanotube and the oscillatory carbon nanotube are incommensurate.
18. The system of claim 10 , wherein the ends of the carbon nanotube oscillator are saturated to prevent chemical reactions with the environment.
19. The system of claim 10 , wherein the carbon nanotube oscillator is positionable in close proximity to, and substantially perpendicular to, the sample surface.
20. The system of claim 19 , wherein the carbon nanotube oscillator is re-positionable along an xy-axis relative to the sample surface, and substantially perpendicular to, the sample surface.