Carbon Nanotube Tips:  High-Resolution Probes for Imaging Biological Systems

Wong, Stanislaus S.; Harper, James D.; Lansbury, Peter T.; Lieber, Charles M.

doi:10.1021/ja9737735

Cited by 322 publications

(235 citation statements)

References 18 publications

Supporting

Mentioning

225

Contrasting

Unclassified

Order By: Relevance

“…2,7 The procedure to shorten the SWNT in air consists of applying +5 to +30 volt pulses of 20 to 100 µs duration between the AFM tip and a grounded, conductive substrate. Presumably the electrical pulse shortens the nanotube by ablation due to the very high electric field generated at the nanotube end.…”

Section: Shortening Afm Nanotube Tipsmentioning

confidence: 99%

“…The main drawback to this method is that MWNT tips large enough to be seen optically did not improve the resolution much beyond standard silicon tips when imaging isolated amyloid fibrils. 2 We found it fairly efficient to manually attach MWNTs to silicon AFM cantilevers with a 1000x optical microscope. In particular, the rate of assembly was quite high when a 15 V potential was applied between the silicon probe and the nanotubes.…”

mentioning

confidence: 92%

See 1 more Smart Citation

Correlating AFM Probe Morphology to Image Resolution for Single-Wall Carbon Nanotube Tips

Wade

Shapiro

et al. 2004

Nano Lett.

View full text Add to dashboard Cite

Methods we compared for attaching nanotubes to silicon AFM tips include manual assembly, direct growth and pickup.Smalley's group reported the first example of the use of carbon nanotubes as AFM tips in 1996. 1 They manually attached multi-wall carbon nanotubes (MWNT) and ropes of individual SWNTs to the apex of silicon pyramidal tips using tape adhesive and a micromanipulator in an optical microscope. The main drawback to this method is that MWNT tips large enough to be seen optically did not improve the resolution much beyond standard silicon tips when imaging isolated amyloid fibrils. 2 We found it fairly efficient to manually attach MWNTs to silicon AFM cantilevers with a 1000x optical microscope. In particular, the rate of assembly was quite high when a 15 V potential was applied between the silicon probe and the nanotubes. This resulted in nearly perfect and rapid alignment of the nanotube to the silicon tip. However, there was not a clear path to doing so with the thin SWNTs required for very high-resolution imaging.Lieber ,3,4 and Quate's 5 groups later showed that individual single wall carbon nanotubes could be directly grown by chemical vapor deposition (CVD) on the silicon tips themselves by first pre-coating the tip with a metal catalyst. In the CVD synthesis of carbon nanotubes, metal catalyst nanoparticles are heated in the presence of a hydrocarbon gas or carbon monoxide; the gas molecules dissociate on the catalyst surface and carbon is adsorbed into the particle. As the carbon precipitates, a carbon nanotube is grown with a diameter similar to that of the catalyst particle.Two techniques for direct growth have been reported. One involves creating nanopores at the apex of the silicon tip by etching with hydrofluoric acid. Catalyst particles are then deposited inside the nanopores. Carbon nanotubes grown via CVD from such a tip have an appropriate geometry for AFM imaging. While this approach enables fabrication of SWNT tips, the preparation of the porous layer in the silicon is time consuming and placement of the nanotube at the optimal location near the tip apex is

show abstract

Section: Shortening Afm Nanotube Tipsmentioning

confidence: 99%

mentioning

confidence: 92%

Correlating AFM Probe Morphology to Image Resolution for Single-Wall Carbon Nanotube Tips

Wade

Shapiro

et al. 2004

Nano Lett.

View full text Add to dashboard Cite

show abstract

“…Carbon nanotubes (CNTs) have attracted much attention in recent years because of their unique electrical, mechanical, and various physical properties. [1][2][3][4][5][6][7][8] For many potential applications, aligned CNT geometry is important. It is well known that vertically aligned nanotube arrays can be grown by plasma-enhanced chemical vapor deposition (PECVD) processing, either microwave 9 or dc plasma.…”

mentioning

confidence: 99%

Control of carbon nanotube morphology by change of applied bias field during growth

Chen

AuBuchon

Gapin

et al. 2004

Applied Physics Letters

View full text Add to dashboard Cite

Carbon nanotube morphology has been engineered via simple control of applied voltage during dc plasma chemical vapor deposition growth. Below a critical applied voltage, a nanotube configuration of vertically aligned tubes with a constant diameter is obtained. Above the critical voltage, a nanocone-type configuration is obtained. The strongly field-dependent transition in morphology is attributed primarily to the plasma etching and decrease in the size of nanotube-nucleating catalyst particles. A two-step control of applied voltage allows a creation of dual-structured nanotube morphology consisting of a broad base nanocone (ϳ200 nm dia.) with a small diameter nanotube ͑ϳ7 nm͒ vertically emanating from the apex of the nanocone, which may be useful for atomic force microscopy.

show abstract

“…Carbon nanotubes, which have intrinsically small diameters and high aspect ratios and which buckle reversibly, make potentially ideal structures for use as tips in scanning probe microscopies, such as atomic force microscopy (AFM) 1,2,3,4 . However, the present method of mechanically attaching nanotube bundles for tip fabrication is time consuming and selects against the smallest nanotubes, limiting the quality of tips.…”

mentioning

confidence: 99%