84 results about "Multi-Walled Nanotube" patented technology

Method and system for producing a selected pattern or array of at least one of a single wall nanotube and/or a multi-wall nanotube containing primarily carbon. A substrate is coated with a first layer (optional) of a first selected metal (e.g., Al and/or Ir) and with a second layer of a catalyst (e.g., Fe, Co, Ni and/or Mo), having selected first and second layer thicknesses provided by ion sputtering, arc discharge, laser ablation, evaporation or CVD. The first layer and/or the second layer may be formed in a desired non-uniform pattern, using a mask with suitable aperture(s), to promote growth of carbon nanotubes in a corresponding pattern. A selected heated feed gas (primarily CH₄ or C₂H_n with n=2 and/or 4) is passed over the coated substrate and forms primarily single wall nanotubes or multiple wall nanotubes, depending upon the selected feed gas and its temperature. Nanofibers, as well as single wall and multi-wall nanotubes, are produced using plasma-aided growth from the second (catalyst) layer. An overcoating of a selected metal or alloy can be deposited, over the second layer, to provide a coating for the carbon nanotubes grown in this manner.

Single-walled carbon nanotubes have been synthesized by the catalytic decomposition of both carbon monoxide and ethylene over a supported metal catalyst known to produce larger multi-walled nanotubes. Under certain conditions, there is no termination of nanotube growth, and production appears to be limited only by the diffusion of reactant gas through the product nanotube mat that covers the catalyst. The present invention concerns a catalyst-substrate system which promotes the growth of nanotubes that are predominantly single-walled tubes in a specific size range, rather than the large irregular-sized multi-walled carbon fibrils that are known to grow from supported catalysts. With development of the supported catalyst system to provide an effective means for production of single-wall nanotubes, and further development of the catalyst geometry to overcome the diffusion limitation, the present invention will allow bulk catalytic production of predominantly single-wall carbon nanotubes from metal catalysts located on a catalyst supporting surface.

A sensor system that detects a current representative of a compound in a liquid mixture features a multi or three electrode strip adapted for releasable attachment to signal readout circuitry. The strip comprises an elongated support which is preferably flat adapted for releasable attachment to the readout circuitry; a first conductor and a second and a third conductor each extend along the support and comprise means for connection to the circuitry. The circuit is formed with single-walled or multi walled nanotubes conductive traces and may be formed from multiple layers or dispersions containing, carbon nanotubes, carbon nanotubes/antimony tin oxide, carbon nanotubes/platinum, or carbon nanotubes/silver or carbon nanotubes/silver-cloride. An active electrode formed from a separate conductive carbon nanotubes layer or suitable dispersion, positioned to contact the liquid mixture and the first conductor, comprises a deposit of an enzyme capable of catalyzing a reaction involving the compound and preferably an electron mediator, capable of transferring electrons between the enzyme-catalyzed reaction and the first conductor. A reference electrode also formed from a conductive carbon nanotube layer or suitable dispersion is positioned to contact the mixture and the second conductor. The system includes circuitry adapted to provide an electrical signal representative of the current which is formed from printing conductive inks made with nano size particles such as conductive carbon or carbon/platinum or carbon/silver, or carbon nanotubes/antimony tin oxide to form a conductive carbon nanotube layers. The multiple-electrode strip is manufactured, by then applying the enzyme and preferably the mediator onto the electrode. Alternatively the electrode can have a carbon nanotubes/antimony tin oxide, carbon nanotubes/platinum, or carbon nanotubes/silver or carbon nanotubes/silver-cloride surface and or a conductive carbon or silver ink surface connecting leg. The carbon nanotube solution is first coated and patterned into electro shapes and the conductive carbon nanotubes, carbon or silver ink can be attached by printing the ink to interface with the carbon nanotube electro surface. A platinum electrode test strip is also disclosed that is formed from either nano platinum distributed in the carbon nanotube layer or by application or incorporation of platinum to the carbon nanotube conductive ink.

A thermal interface includes nanofibrils. The nanofibrils may be attached to a flat base or membrane, or may be attached to the tip portions of larger diameter fibers. The nanofibrils have a diameter of less than about 1 micron, and may advantageously be formed from single walled and/or multi-walled nanotubes.

A flame retardant composite and a method for its fabrication are disclosed. The flame retardant composite shows both improved mechanical properties and flame retardancy. The composite comprises a matrix material and carbon nanotubes, such as single walled nanotubes, multi-walled nanotubes or fishbone-like graphitic cylinders, exhibiting a hollow core. For example, the outer diameters of the carbon nanofibers may be in the range from 1.2 to 500 nm. For example, a carbon nanotube may be incorporated as a layer in or on the surface of the composite. The method of fabrication of the composite may include a step of de-agglomeration.

Single-walled carbon nanotubes have been synthesized by the catalytic decomposition of both carbon monoxide and ethylene over a supported metal catalyst known to produce larger multi-walled nanotubes. Under certain conditions, there is no termination of nanotube growth, and production appears to be limited only by the diffusion of reactant gas through the product nanotube mat that covers the catalyst The present invention concerns a catalyst-substrate system which promotes the growth of nanotubes that are predominantly single-walled tubes in a specific size range, rather than the large irregular-sized multi-walled carbon fibrils that are known to grow from supported catalysts. With development of the supported catalyst system to provide an effective means for production of single-wall nanotubes, and further development of the catalyst geometry to overcome the diffusion limitation, the present invention will allow bulk catalytic production of predominantly single-wall carbon nanotubes from metal catalysts located on a catalyst supporting surface.

Coatings for implantable electrodes consisting of single- or multi-walled nanotubes, nanotube ropes, carbon whiskers, and a combination of these are described. The nanotubes can be carbon or other conductive nanotube-forming materials such as a carbon-doped boron nitride. The nanotube coatings are grown “in situ” on a catalytic substrate surface from thermal decomposition, or they are bonded to the substrate using a metal or conductive metal oxide thin film binder deposited by means of a metal compound precursor in liquid form. In the latter case, the precursor/nanotube coating is then converted to a pure metal or conductive metal oxide, resulting in the desired surface coating with imbedded nanotubes.

The invention relates to a method for forming a telescoped multiwall nanotube. Such a telescoped multiwall nanotube may find use as a linear or rotational bearing in microelectromechanical systems or may find use as a constant force nanospring. In the method of the invention, a multiwall nanotube is affixed to a solid, conducting substrate at one end. The tip of the free end of the multiwall nanotube is then removed, revealing the intact end of the inner wall. A nanomanipulator is then attached to the intact end, and the intact, core segments of the multiwall nanotube are partially extracted, thereby telescoping out a segment of nanotube.

Systems and methods are provided to improve the performance of electronic and optoelectronic devices made using organic semiconductor processing technology. An ink-jet device dispenses an organic composite mixture onto a substrate. The mixture includes a semiconducting polymer and nanomaterials dispersed into an organic solvent. The type of solvent used preferably achieves effective dispersion of the polymer and nanomaterials in the solvent to minimize the occurrence of clogging of the ink-jet nozzles. The range of nanomaterials include, but are not limited to, organic and inorganic, single or multi-walled nanotubes, nanowires, nanodots, quantum dots, nanorods, nanocrystals, nanotetrapods, nanotripods, nanobipods, nanoparticles, nanosaws, nanosprings, nanoribbons, any branched nanostructure, and any mixture of these nanoshaped materials. The nanostructures can be aligned on the substrate to improve the carrier mobility in the organic semiconductors.

Fabricating single-walled carbon nanotube transistor devices includes removing undesirable types of nanotubes. These undesirable types of nanotubes may include nonsemiconducting nanotubes, multiwalled nanotubes, and others. The undesirable nanotubes may be removed electrically using voltage or current, or a combination of these. This approach to removing undesirable nanotubes is sometimes referred to as “burn-off.” The undesirable nanotubes may be removed chemically or using radiation. The undesirable nanotubes of an integrated circuit may be removed in sections or one transistor (or a group of transistors) at a time in order to reduce the electrical current used or prevent damage to the integrated circuit during burn-off.

A carbon nanotube, a method of preparing the same, a supported catalyst including the same, and a fuel cell using the supported catalyst are provided. The method of preparing the carbon nanotube includes: depositing a metal catalyst in single wall nanotubes and growing multi wall nanotubes over the single wall nanotubes using the metal catalyst. The carbon nanotubes of the present invention have satisfactory specific surface area and low surface resistance. Thus, the carbon nanotubes perform remarkably better than a conventional catalyst carrier. Accordingly, the carbon nanotubes, when used as a catalyst carrier of an electrode for a fuel cell, can improve the electrical conductivity of the fuel cell. In addition, a fuel cell employing the electrode has excellent efficiency and overall performance.

Disclosed is a device whereby the thermal conductance of a multiwalled nanostructure such as a multiwalled carbon nanotube (MWCNT) can be controllably and reversibly tuned by sliding one or more outer shells with respect to the inner core. As one example, the thermal conductance of an MWCNT dropped to 15% of the original value after extending the length of the MWCNT by 190 nm. The thermal conductivity returned when the tube was contracted. The device may comprise numbers of multiwalled nanotubes or other graphitic layers connected to a heat source and a heat drain and various means for tuning the overall thermal conductance for applications in structure heat management, heat flow in nanoscale or microscale devices and thermal logic devices.

The invention relates to an apparatus for producing nanotubes, the apparatus being adapted to produce doped and/or undoped single-walled or multi-walled nanotubes, the apparatus comprising at least a thermal reactor. In accordance with the invention, the reactor is at least of the hottest part thereof and at least partly manufactured from a material that is at least partly sublimed into the thermal reactor as a result of the thermal reactor being heated, and the sublimed material at least partly participates in the growth of the nanotubes.

A boron filled hybrid nanotube and a method for producing and rendering boron filled hybrid nanotubes suitable for applications are provided. A mixture of a boron containing nanowire producing compound and catalysts is prepared and ground for a predetermined time period. The ground mixture is subjected to a vapor deposition process including passing an inert gas over the ground mixture after adding a nanotube producing compound to the ground mixture or after passing a reactant gas on the ground mixture in a reactor at a configurable reaction temperature and a configurable reaction pressure for a configurable reaction time to produce the boron filled hybrid nanotubes with enhanced mechanical, thermal and electrical properties. Each boron filled hybrid nanotube includes one or more boron based nanowires embedded within one or more single walled or multi-walled nanotubes. The boron filled hybrid nanotubes are further purified and functionalized using acids, and/or bases, and/or surfactants.

A system and method for manufacturing carbon nanotubes via epitaxial growth from a source of supersaturated carbon solution is disclosed, whereby selection of the diameter, length, and chirality of single-walled or multi-walled nanotubes is enabled.

A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

A membrane electrode assembly for a solid electrolyte fuel cell comprises: an electrode having a layer of nano-structured material on one of its faces, an electrocatalyst deposited on the nano-structured material and an electrolyte deposited on the electrocatalyst/nano-structured material. The nano-structured material can comprise carbon, silicon, graphite, boron, titanium and be in the form of multi-walled nano-tubes (MWNTs), single-walled nano-tubes (SWNTs), nano-fibers, nano-rods or a combination thereof. The nano-structured material can be grown or deposited on one face of an electrode of the cell or on a substrate such as a flexible sheet material of carbon fibers using chemical vapor deposition. The electrocatalyst and electrolyte can be incorporated in the nano structured material using physical vapor deposition (PVD), ion beam sputtering or molecular beam epitaxy (MBE).