2006 Fiscal Year Final Research Report Summary
Fabrication and Application of Carbon Nanotube Probes
| Project/Area Number |
16510080
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nanostructural science
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| Research Institution | NATIONAL INSTITUTE FOR MATERIALS SCIENCE |
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Principal Investigator |
TANG Jie National Institute for Materials Science, Materials Engineering Laboratory, Group Leader, 材料ラボ, グループリーダー (80354158)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Taizo National Institute for Materials Science, Computational Materials Science Center, Group Leader, 計算科学センター, グループリーダー (60343852)
MATSUSHITA Akiyuki National Institute for Materials Science, Photocatalytic Materials Center, Group Leader, 光触媒材料センター, グルーブリーダー (30343859)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Carbon Nan tubes / dielectrophoresis / AFM probes based on CNTs / CNTs assembly / CNTs fibrils / STM probes based on CNTs / point electron sources / field emission property |
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| Research Abstract |
The unique geometry and novel properties of nanotubes and nanorods make them attractive building blocks for new functional materials and devices. Recent experiments have demonstrated their potentials as high-resolution microscopy probes, conducting fibers, and high performance composite fillers. Although considerable progress has been made in the synthesis of nanostructured materials, development in this field in general is hindered by the lack of bottom-up manufacturing processes that can efficiently assemble functional structures and devices using these nanostructured building blocks.
We have developed a dielectrophoresic technique to manipulate, align and assemble one-dimensional nanostructures using an alternating-current (AC) electric field in this project. Pre-formed carbon nanotubes (CNTs) dispersed in water are assembled into micro-electrodes and sub-micron diameter fibrils with variable lengths from〜1 μm to more than 1 cm. The CNTs within the fibril are bonded by van der Waals
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forces and are aligned along the fibril axis. This method affords a fine control of the fibril length and is capable of parallel fabrication of many fibrils using the same source. The short CNT fibrils can potentially be used as the probes for scanning probe microscopes and the long ones as electrodes and conducting wires.
This method is reliable and has a high throughput for fabrication of CNT-based atomic force microscope (AFM) probes to measure fine structures on the nanometer scale. The process to fabricate carbon nanotube probes with high reproducibility and simple profile control has been long sought because of the difficulty of profile control, low reproducibility and the difficulty of manufacturing process in the currently available technologies. The carbon nanotube probes (detection needles) are assembled at high success rate using a dielectrophoresic method developed in this research. The successful fabrication of such nanotube probes advances the AFM technique in several fronts, for example, the horizontal resolution is improved, and the service life of AFM probes is greatly increased. This method can also potentially be used for processes of parallel fabrication of probes from carbon nanotubes as well as other nanostructures.
Carbon nanotube point electron field emitters with controllable dimension were also assembled by the same dielectrophoresic method using processed nanotubes. The electron field emission characteristics were investigated using point-plane geometry at 5x10^<-7> Torr base pressure. A stable emission current of more than 3 μA (10^5A/cm^2) was extracted from a 50 nm diameter CNT emitter with no current decay over 10 hours at 100% duty cycle. The emitters are mechanically rigid. The dielectrophoresic method enables rapid and re-producible fabrication of CNT tips which can potentially be used as field emission point electron sources for precision vacuum electronic instruments. Less
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