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Patent Issued for Highly Organized Single-Walled Carbon Nanotube Networks and Method of Making Using Template Guided Fluidic Assembly

August 6, 2014

By a News Reporter-Staff News Editor at Journal of Engineering -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Xiong, Xugang (Boston, MA); Jaberansari, Laila (Medford, MA); Busnaina, Ahmed (Ashland, MA); Jung, Yung Joon (Lexington, MA); Somu, Sivasubramanian (Boston, MA); Upmanyu, Moneesh (Wakefield, MA), filed on November 16, 2009, was published online on July 22, 2014.

The patent's assignee for patent number 8784673 is Northeastern University (Boston, MA).

News editors obtained the following quote from the background information supplied by the inventors: "Carbon nanotubes (CNT) are promising candidates for the use as components in nanoscale electronics and electromechanical devices due to their superior mechanical properties, high electron mobility, large current capability, and unique one-dimensional nanostructure. In order to implement these applications, it is essential to develop a simple and reliable manufacturing process that controllably assembles CNT in desired locations with controlled orientations and nanoscale dimensions over a large area.

"Previous attempts to assemble CNT into useful structures have utilized chemical vapor deposition (Y. Jung et al., J. Phys. Chem B (2003) 107:6859; K. Hata et al. Science (2004) 306:1362; B. Wei et al., Nature (2002) 416:495; A. Casell et al., J. Phys. Chem. B (1999) 103:6484), chemical functionalization (M. Lee et al., Nat. Nanotech. (2006) 1:66; P. Kamat et al., J. Am. Chem. Soc. (2004) 126:10757), electrophoretic deposition and dielectrophoresis (Lee et al., 2006; P. Makaram et al., Appl. Phys. Lett. (2007) 90:243108(1-3); P. Makaram et al., Nanotechnology (2007) 18:395204(1-5)). Chemical vapor deposition can be used to directly synthesize CNT at desired locations on a substrate by patterning catalyst materials; however, the high temperature of this process ( C.) and difficulty in controlling the growth direction and the density of CNT significantly limits the effectiveness of this method, especially in electronic device applications. Electrophoretic and dielectrophoretic methods can be used to fabricate highly oriented CNT between electrodes, but they are effective only within local areas where the electric field is effective. There remains a need for methods of assembling CNT and other nanoelements over large areas, preferably under ambient conditions."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "The invention presents methods for fabricating templates for nanoelement assembly and methods for assembling nanoelements, such as single-walled carbon nanotubes (SWNT), into stable films, ribbons, and wires of nanoscale thickness and nanoscale or microscale width and length. The nanofilm assemblies prepared according to the invention are highly conducting and can be used in the fabrication of microscale and nanoscale electronic devices.

"One aspect of the invention is a method for fabricating a nanofilm of nanoelement such as SWNT. The method includes the steps of providing a template for fabricating the nanofilm, submersing the template in a suspension of the SWNT, and pulling the submersed template up through the air-water interface of the suspension. The template includes a substrate having an upper hydrophobic surface and one or more nanoscale trenches. The trenches possess a bottom hydrophilic surface that attracts the SWNT suspension, leading to the assembly of a nanofilm of SWNT while the template is pulled through the air-water interface. In some embodiments, the SWNT from the suspension become aligned in the trenches during the assembly process to form a nanofilm having metallic conductance properties. The method can be used to prepare highly conductive nanoscale and microscale components of electrical circuits, including transistors, circuit interconnects, sensors, and batteries.

"Another aspect of the invention is a method for fabricating a template for the assembly of nanoelements. The method includes the steps of etching a surface of a substrate with a plasma to render the surface hydrophilic, coating the etched surface with a hydrophobic mask material, and preparing one or more nanoscale trenches in the mask material by removing selected portions of the mask material using lithography. The lithography process exposes the etched substrate surface to form the bottom surface of the trenches. Templates produced by the method can be used in the above-described method of making nanofilms.

"Yet another aspect of the invention is a nanofilm or nanowire containing a plurality of SWNT. The nanofilm has a thickness in the range from about 10 nm to about 500 nm. The width and length of the nanofilm can range from nanoscale dimensions, 50 nm for example, to microscale dimensions of 10 .mu.m or more. In some embodiments, the nanofilm contains aligned SWNT, and in other embodiments the nanofilm has nonaligned SWNT. In different embodiments, the nanofilm can have ohmic conductance properties or it can be semiconducting, depending on the alignment and density of the nanotubes.

"Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof and from the claims, taken in conjunction with the accompanying drawings."

For additional information on this patent, see: Xiong, Xugang; Jaberansari, Laila; Busnaina, Ahmed; Jung, Yung Joon; Somu, Sivasubramanian; Upmanyu, Moneesh. Highly Organized Single-Walled Carbon Nanotube Networks and Method of Making Using Template Guided Fluidic Assembly. U.S. Patent Number 8784673, filed November 16, 2009, and published online on July 22, 2014. Patent URL:

Keywords for this news article include: Nanoscale, Fullerenes, Nanotechnology, Emerging Technologies, Northeastern University, Chemical Vapor Deposition, Single Walled Carbon Nanotubes.

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Source: Journal of Engineering

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