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Sample records for carbon nanotube nanoelectrode

  1. Carbon nanotube nanoelectrode arrays

    DOEpatents

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  2. Nanoelectrode Arrays Based on Low Site Density Aligned Carbon Nanotubes

    SciTech Connect

    Yi, Tu; Lin, Yuehe ); Ren, Zhifeng N.

    2003-01-29

    Nanoelectrode arrays (NEAs) were fabricated from the low site density aligned carbon nanotubes (CNTs). The CNTs were grown by plasma enhanced chemical vapor deposition (PECVD) on Ni nanoparticles made by the electrochemical deposition.

  3. Carbon Nanotube Nanoelectrode Array for Ultrasensitive DNA Detection

    NASA Technical Reports Server (NTRS)

    Li, Jun; Koehne, Jessica; Chen, Hua; Cassell, Alan; Ng, Hou Tee; Fan, Wendy; Ye, Qi; Han, Jie; Meyyappan, M.

    2003-01-01

    A reliable nanoelectrode array based on vertically aligned multi-walled carbon nanotubes (MWNTs) embedded in SiO2 is used for ultrasensitive DNA detection. Characteristic nanoelectrode behavior is observed using low-density MWNT arrays for measuring both bulk and surface immobilized redox species such as K4Fe(CN)6. The open-end of MWNTs present similar properties as graphite edge-plane electrodes with wide potential window, flexible chemical functionalities, and good biocompatibility. Oligonucleotide probes are selectively functionalized at the open ends cf the nanotube array and specifically hybridized with oligonucleotide targets. The guanine groups are employed as the signal moieties in the electrochemical measurements. Ru(bpy)3(2+) mediator is used to further amplify the guanine oxidation signal. The hybridization of subattomoles of PCR amplified DNA targets is detected electrochemically by combining the MWNT nanoelectrode array with the Ru(bpy)32' amplification mechanism. This system provides a general platform of molecular diagnostics for applications requiring ultrahigh sensitivity, high-degree of miniaturization, and simple sample preparations.

  4. Glucose Biosensors Based on Carbon Nanotube Nanoelectrode Ensembles

    SciTech Connect

    Lin, Yuehe ); Lu, Fang; Tu, Yi; Ren, Zhifeng

    2004-02-12

    This paper describes the development of glucose biosensors based on carbon nanotube (CNT) nanoelectrode ensembles (NEEs) for the selective detection of glucose. Glucose oxidase was covalently immobilized on CNT NEEs via carbodiimide chemistry by forming amide linkages between their amine residues and carboxylic acid groups on the CNT tips. The catalytic reduction of hydrogen peroxide liberated from the enzymatic reaction of glucose oxidase upon the glucose and oxygen on CNT NEEs leads to the selective detection of glucose. The biosensor effectively performs selective electrochemical analysis of glucose in the presence of common interferents (e.g. acetaminophen, uric and ascorbic acids), avoiding the generation of an overlapping signal from such interferents. Such an operation eliminates the need for permselective membrane barriers or artificial electron mediators, thus greatly simplifying the sensor design and fabrication.

  5. Development of Biosensors Based on Carbon Nanotube Nanoelectrode Arrays

    SciTech Connect

    Lin, Yuehe; Tu, Yi; Lu, Fang; Ren, Zhifeng

    2004-12-28

    The fabrication, electrochemical characterization, and sensing applications of low-site density carbon nanotubes based nanoelectrode arrays (CNT-NEAs) are reported in this work. Spin-coating of an epoxy resin provides a new way to create the electrode passivation layer that effectively reduces the current leakage and eliminates the electrode capacitance by sealing the side-wall of CNTs. The CNT-NEAs fabricated in our work effectively use the open ends of CNTs for electrochemical sensing. The open ends of the CNTs have fast electron transfer rates similar to a graphite edge-plane electrode, while the side-walls present very slow electron transfer rates similar to the graphitic basal plane. Cyclic voltammetry showed the sigmoidal shape curves with low capacitive current and scan-rate-independent limiting current. The successful development of a glucose biosensor based on CNT-NEAs for the selective detection of glucose is also described. Glucose oxidase was covalently immobilized on the CNTs tips via carbodiimide chemistry by forming amide linkages between the amine residues and carboxylic acid groups on the open ends of CNTs. The biosensor effectively performs selective electrochemical detections of glucose in the presence of common interferences.

  6. Carbon Nanotube Nanoelectrode Array as an Electronic Chip for Ultrasensitive Label-free DNA Detection

    NASA Technical Reports Server (NTRS)

    Li, Jun; Koehne, Jessica; Chen, Hua; Cassell, Alan; Ng, Hou Tee; Fan, Wendy; Ye, Qi; Han, Jie; Meyyappan, M.

    2003-01-01

    A reliable nanoelectrode array based on vertically aligned multi-walled carbon nanotubes (MWNTs) embedded in SiO2 is used for ultrasensitive DNA detection. Characteristic nanoelectrode behavior is observed using low-density MWNT arrays for measuring both bulk and surface immobilized redox species such as K4Fe(CN)6 and ferrocene derivatives. The open-end of MWNTs are found to present similar properties as graphite edge-plane electrodes with wide potential window, flexible chemical functionalities, and good biocompatibility. BRCA1 related oligonucleotide probes with 18 bp are selectively functionalized at the open ends of the nanotube array and specifically hybridized with oligonucleotide targets incorporated with a polyG tag. The guanine groups are employed as the signal moieties in the electrochemical measurements. R(bpy)(sup 2+, sub 3) mediator is used to further amplify the guanine oxidation signal. The hybridization of sub-attomoles of DNA targets is detected electrochemically by combining the MWNT nanoelectrode array with the R(bpy)(sup 2+, sub 3) amplification mechanism. This technique was employed for direct electrochemical detection of label-free PCR amplicon from a healthy donor through specific hybridization with the BRCA1 probe. The detection limit is estimated to be less than 1000 DNA molecules since abundant guanine bases in the PCR amplicon provides a large signal. This system provides a general platform for rapid molecular diagnostics in applications requiring ultrahigh sensitivity, high-degree of miniaturization, and simple sample preparation, and low-cost operation.

  7. Ultrasensitive Label-free Electronic Chip for DNA Analysis Using Carbon Nanotube Nanoelectrode Arrays

    NASA Technical Reports Server (NTRS)

    Li, Jun; Koehne, Jessica; Chen, Hua; Cassell, Alan; Ng, Hou Tee; Ye, Qi; Han, Jie; Meyyappan, M.

    2004-01-01

    There is a strong need for faster, cheaper, and simpler methods for nucleic acid analysis in today s clinical tests. Nanotechnologies can potentially provide solutions to these requirements by integrating nanomaterials with biofunctionalities. Dramatic improvement in the sensitivity and multiplexing can be achieved through the high-degree miniaturization. Here, we present our study in the development of an ultrasensitive label-free electronic chip for DNA/RNA analysis based on carbon nanotube nanoelectrode arrays. A reliable nanoelectrode array based on vertically aligned multi-walled carbon nanotubes (MWNTs) embedded in a SiO2 matrix is fabricated using a bottom-up approach. Characteristic nanoelectrode behavior is observed with a low-density MWNT nanoelectrode array in measuring both the bulk and surface immobilized redox species. The open-end of MWNTs are found to present similar properties as graphite edge-plane electrodes, with a wide potential window, flexible chemical functionalities, and good biocompatibility. A BRCA1 related oligonucleotide probe with 18 bases is covalently functionalized at the open ends of the MWNTs and specifically hybridized with an oligonucleotide target as well as a PCR amplicon. The guanine bases in the target molecules are employed as the signal moieties for the electrochemical measurements. Ru(bpy)3(2+) mediator is used to further amplify the guanine oxidation signal. This technique has been employed for direct electrochemical detection of label-free PCR amplicon through specific hybridization with the BRCAl probe. The detection limit is estimated to be less than approximately 1000 DNA molecules, approaching the limit of the sensitivity by laser-based fluorescence techniques in DNA microarray. This system provides a general electronic platform for rapid molecular diagnostics in applications requiring ultrahigh sensitivity, high-degree of miniaturization, simple sample preparation, and low- cost operation.

  8. Ultrasensitive Voltammetric Detection of Trace Heavy Metal Ions Using Carbon Nanotube Nanoelectrode Array

    SciTech Connect

    Liu, Guodong; Lin, Yuehe; Tu, Yi; Ren, Zhifeng

    2005-06-20

    We describe an ultrasensitive voltammetric detection of trace heavy metal ions using nanoelectrode arrays (NEAs) that are based on low-site density carbon nanotubes (CNTs). The NEAs were prepared by sealing the side-walls of CNTs with an epoxy passive layer that reduces the current leakage and eliminates the electrode capacitance, leading to a low background current. This provides a high signal-to-noise ratio. The CNTs-NEAs coated with a bismuth film were used successfully for voltammetric detection of trace cadmium and lead (II) at the sub-ppb level. The detection limit of 0.04 {micro}g/L was obtained under optimum experimental conditions. The attractive behavior of the new carbon NEA sensing platform holds great promise for onsite environmental monitoring and biomonitoring of toxic metals.

  9. Fabrication of nano-electrode arrays of free-standing carbon nanotubes on nano-patterned substrate by imprint method

    NASA Astrophysics Data System (ADS)

    Chang, W. S.; Kim, J. W.; Choi, D. G.; Han, C. S.

    2011-01-01

    The synthesis of isolated carbon nanotubes with uniform outer diameters and ordered spacing over wafer-scale areas was investigated for fabrication of nano-electrode arrays on silicon wafers for field emission and sensor devices. Multi-walled carbon nanotubes (MWCNTs) were grown on TiN electrode layer with iron catalyst patterned by nano-imprint lithography (NIL), which allows the precise placement of individual CNTs on a substrate. The proposed techniques, including plasma-enhanced chemical vapor deposition (PECVD) and NIL, are simple, inexpensive, and reproducible methods for fabrication of nano-scale devices in large areas. The catalyst patterns were defined by an array of circles with 200 nm in diameter, and variable lengths of pitch. The nano-patterned master and Fe catalyst were observed with good pattern fidelity over a large area by atomic force microscope (AFM) and scanning electron microscopy (SEM). Nano-electrodes of MWCNTs had diameters ranging from 50 nm to 100 nm and lengths of about 300 nm. Field emission tests showed the reducing ignition voltage as the geometry of nanotube arrays was controlled by catalyst patterning. These results showed a wafer-scale approach to the control of the size, pitch, and position of nano-electrodes of nanotubes for various applications including electron field-emission sources, electrochemical probes, functionalized sensor elements, and so on.

  10. Miniaturized multiplex label-free electronic chip for rapid nucleic acid analysis based on carbon nanotube nanoelectrode arrays

    NASA Technical Reports Server (NTRS)

    Koehne, Jessica E.; Chen, Hua; Cassell, Alan M.; Ye, Qi; Han, Jie; Meyyappan, Meyya; Li, Jun

    2004-01-01

    BACKGROUND: Reducing cost and time is the major concern in clinical diagnostics, particularly in molecular diagnostics. Miniaturization technologies have been recognized as promising solutions to provide low-cost microchips for diagnostics. With the recent advancement in nanotechnologies, it is possible to further improve detection sensitivity and simplify sample preparation by incorporating nanoscale elements in diagnostics devices. A fusion of micro- and nanotechnologies with biology has great potential for the development of low-cost disposable chips for rapid molecular analysis that can be carried out with simple handheld devices. APPROACH: Vertically aligned multiwalled carbon nanotubes (MWNTs) are fabricated on predeposited microelectrode pads and encapsulated in SiO2 dielectrics with only the very end exposed at the surface to form an inlaid nanoelectrode array (NEA). The NEA is used to collect the electrochemical signal associated with the target molecules binding to the probe molecules, which are covalently attached to the end of the MWNTs. CONTENT: A 3 x 3 microelectrode array is presented to demonstrate the miniaturization and multiplexing capability. A randomly distributed MWNT NEA is fabricated on each microelectrode pad. Selective functionalization of the MWNT end with a specific oligonucleotide probe and passivation of the SiO2 surface with ethylene glycol moieties are discussed. Ru(bpy)2+ -mediator-amplified guanine oxidation is used to directly measure the electrochemical signal associated with target molecules. SUMMARY: The discussed MWNT NEAs have ultrahigh sensitivity in direct electrochemical detection of guanine bases in the nucleic acid target. Fewer than approximately 1000 target nucleic acid molecules can be measured with a single microelectrode pad of approximately 20 x 20 microm2, which approaches the detection limit of laser scanners in fluorescence-based DNA microarray techniques. MWNT NEAs can be easily integrated with microelectronic

  11. Electrodeposition of Various Au Nanostructures on Aligned Carbon Nanotubes as Highly Sensitive Nanoelectrode Ensembles

    NASA Astrophysics Data System (ADS)

    Fayazfar, H.; Afshar, A.; Dolati, A.

    2015-05-01

    An efficient method has been developed to synthesize well-aligned multi-walled carbon nanotubes (MWCNTs) on a conductive Ta substrate by chemical vapor deposition. Free-standing MWCNTs arrays were functionalized through electrochemical oxidation with the formation of hydroxyl and carboxyl functional groups. Facile template-free electrochemical routes were then developed for the shape-selective synthesis of less-common Au nanostructures, including flower, sphere, dendrite, rod, sheet, and cabbage onto the aligned MWCNTs at room temperature. Especially, among all the synthesis methods for Au nanocrystals, this is the first report using electrochemical technique to synthesize wide variety shapes of gold nanostructures (GNs) onto the aligned MWCNTs. The morphology of electrodeposited Au nanostructures was controlled by adjustment of the deposition time and potential, the number of potential cycles, the kind of deposition bath, and electrodeposition method. Transmission electron microscopy and field-emission scanning electron microscopy were used to characterize the products. Cyclic voltammograms showed that the MWCNT/Ta electrodes modified with GNs have higher sensitivity compared to the unmodified electrodes in the presence of Fe2+/Fe3+ redox couple. These kinds of aligned-CNT/Au nanostructure hybrid materials introduced by these efficient and simple electrochemical methods could lead to the development of a new generation device for ultrasensitive catalytic and biological application.

  12. Carbon nanoelectrodes for single-cell probing

    NASA Astrophysics Data System (ADS)

    Anderson, Sean E.; Bau, Haim H.

    2015-05-01

    Carbon nanoelectrodes with tip diameters ranging from tens to hundreds of nanometers are fabricated by pyrolitic deposition of carbon films along the entire inner surfaces of pulled-glass pipettes. The pulled end of each glass pipette is then etched to expose a desired length (typically, a few micrometers) of carbon pipe. The carbon film provides an electrically conductive path from the nanoscopic carbon tip to the distal, macroscopic end of the pipette, bridging between the nanoscale tip and the macroscale handle, without a need for assembly. We used our nanoelectrodes to penetrate into individual cells and cell nuclei and measured the variations in the electrode impedance upon cell and nucleus penetration as well as the electrode impedance as a function of cell penetration depth. Theoretical predictions based on a simple circuit model were in good agreement with experimental data.

  13. Carbon Nanoelectrodes for Single-Cell Probing

    PubMed Central

    Anderson, Sean E.; Bau, Haim H.

    2015-01-01

    Carbon nanoelectrodes with tip diameters ranging from tens to hundreds of nm are fabricated by pyrolitic deposition of carbon films along the entire inner surfaces of pulled-glass pipettes. The pulled end of each glass pipette is then etched to expose a desired length (typically, a few µm) of carbon pipe. The carbon film provides an electrically conductive path from the nanoscopic carbon tip to the distal, macroscopic end of the pipette, bridging between the nanoscale tip and the macroscale handle, without a need for assembly. We used our nanoelectrodes to penetrate into individual cells and cell nuclei and measured the variations in the electrode impedance upon cell and nucleus penetration as well as the electrode impedance as a function of cell penetration depth. Theoretical predictions based on a simple circuit model were in good agreement with experimental data. PMID:25876625

  14. Carbon Nanofiber Nanoelectrodes for Biosensing Applications

    NASA Technical Reports Server (NTRS)

    Koehne, Jessica Erin

    2014-01-01

    A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. Here, we report two studies using vertically aligned CNF nanoelectrodes for biomedical applications. CNF arrays are investigated as neural stimulation and neurotransmitter recording electrodes for application in deep brain stimulation (DBS). Polypyrrole coated CNF nanoelectrodes have shown great promise as stimulating electrodes due to their large surface area, low impedance, biocompatibility and capacity for highly localized stimulation. CNFs embedded in SiO2 have been used as sensing electrodes for neurotransmitter detection. Our approach combines a multiplexed CNF electrode chip, developed at NASA Ames Research Center, with the Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) system, developed at the Mayo Clinic. Preliminary results indicate that the CNF nanoelectrode arrays are easily integrated with WINCS for neurotransmitter detection in a multiplexed array format. In the future, combining CNF based stimulating and recording electrodes with WINCS may lay the foundation for an implantable smart therapeutic system that utilizes neurochemical feedback control while likely resulting in increased DBS application in various neuropsychiatric disorders. In total, our goal is to take advantage of the nanostructure of CNF arrays for biosensing studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.

  15. Manipulation of Bacteriophages with Dielectrophoresis on Carbon Nanofiber Nanoelectrode Arrays

    PubMed Central

    Madiyar, Foram Ranjeet; Syed, Lateef Uddin; Culbertson, Christopher; Li, Jun

    2013-01-01

    This work describes efficient manipulation of bacteriophage virus particles using a nanostructured dielectrophoresis (DEP) device. The non-uniform electric field for DEP is created by utilizing a nanoelectrode array (NEA) made of vertically aligned carbon nanofibers (VACNFs) versus a macroscopic indium tin oxide electrode in a “points-and-lid” configuration integrated in a microfluidic channel. The capture of the virus particles has been systematically investigated versus the flow velocity, sinusoidal AC frequency, peak-to-peak voltage, and virus concentration. The DEP capture at all conditions is reversible and the captured virus particles are released immediately when the voltage is turned off. At the low virus concentration (8.9×104 pfu·ml−1), the DEP capture efficiency up to 60% can be obtained. The virus particles are individually captured at isolated nanoelectrode tips and accumulate linearly with time. Due to the comparable size, it is more effective to capture virus particles than larger bacterial cells with such NEA based DEP devices. This technique can be potentially utilized as a fast sample preparation module in a microfluidic chip to capture, separate, and concentrate viruses and other biological particles in small volumes of dilute solutions in a portable detection system for field applications. PMID:23348683

  16. Biochips Containing Arrays of Carbon-Nanotube Electrodes

    NASA Technical Reports Server (NTRS)

    Li, Jun; Meyyappan, M.; Koehne, Jessica; Cassell, Alan; Chen, Hua

    2008-01-01

    Biochips containing arrays of nanoelectrodes based on multiwalled carbon nanotubes (MWCNTs) are being developed as means of ultrasensitive electrochemical detection of specific deoxyribonucleic acid (DNA) and messenger ribonucleic acid (mRNA) biomarkers for purposes of medical diagnosis and bioenvironmental monitoring. In mass production, these biochips could be relatively inexpensive (hence, disposable). These biochips would be integrated with computer-controlled microfluidic and microelectronic devices in automated hand-held and bench-top instruments that could be used to perform rapid in vitro genetic analyses with simplified preparation of samples. Carbon nanotubes are attractive for use as nanoelectrodes for detection of biomolecules because of their nanoscale dimensions and their chemical properties.

  17. Electrochemical enzymatic biosensors using carbon nanofiber nanoelectrode arrays

    NASA Astrophysics Data System (ADS)

    Li, Jun; Li, Yi-fen; Swisher, Luxi Z.; Syed, Lateef U.; Prior, Allan M.; Nguyen, Thu A.; Hua, Duy H.

    2012-10-01

    The reduction of electrode size down to nanometers could dramatically enhance detection sensitivity and temporal resolution. Nanoelectrode arrays (NEAs) are of particular interest for ultrasensitive biosensors. Here we report the study of two types of biosensors for measuring enzyme activities using NEAs fabricated with vertically aligned carbon nanofibers (VACNFs). VACNFs of ~100 nm in average diameter and 3-5 μm in length were grown on conductive substrates as uniform vertical arrays which were then encapsulated in SiO2 matrix leaving only the tips exposed. We demonstrate that such VACNF NEAs can be used in profiling enzyme activities through monitoring the change in electrochemical signals induced by enzymatic reactions to the peptides attached to the VACNF tip. The cleavage of the tetrapeptide with a ferrocene tag by a cancerrelated protease (legumain) was monitored with AC voltammetry. Real-time electrochemical impedance spectroscopy (REIS) was used for fast label-free detection of two reversible processes, i.e. phosphorylation by c-Src tyrosine kinase and dephosphorylation by protein tyrosine phosphatase 1B (PTP1B). The REIS data of phosphorylation were slow and unreliable, but those of dephosphorylation showed large and fast exponential decay due to much higher activity of phosphatase PTP1B. The kinetic data were analyzed with a heterogeneous Michaelis-Menten model to derive the "specificity constant" kcat/Km, which is 8.2x103 M-1s-1 for legumain and (2.1 ± 0.1) x 107 M-1s-1 for phosphatase (PTP1B), well consistent with literature. It is promising to develop VACNF NEA based electrochemical enzymatic biosensors as portable multiplex electronic techniques for rapid cancer diagnosis and treatment monitoring.

  18. Vertically aligned carbon nanofiber nanoelectrode arrays: electrochemical etching and electrode reusability

    PubMed Central

    Gupta, Rakesh K.; Meyyappan, M.; Koehne, Jessica E.

    2014-01-01

    Vertically aligned carbon nanofibers in the form of nanoelectrode arrays were grown on nine individual electrodes, arranged in a 3 × 3 array geometry, in a 2.5 cm2 chip. Electrochemical etching of the carbon nanofibers was employed for electrode activation and enhancing the electrode kinetics. Here, we report the effects of electrochemical etching on the fiber height and electrochemical properties. Electrode regeneration by amide hydrolysis and electrochemical etching is also investigated for electrode reusability. PMID:25089188

  19. Carbon Nanofiber Nanoelectrodes for Neural Stimulation and Chemical Detection: The Era of Smart Deep Brain Stimulation

    NASA Technical Reports Server (NTRS)

    Koehne, Jessica E.

    2016-01-01

    A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. Here, we report two studies using vertically aligned CNF nanoelectrodes for biomedical applications. CNF arrays are investigated as neural stimulation and neurotransmitter recording electrodes for application in deep brain stimulation (DBS). Polypyrrole coated CNF nanoelectrodes have shown great promise as stimulating electrodes due to their large surface area, low impedance, biocompatibility and capacity for highly localized stimulation. CNFs embedded in SiO2 have been used as sensing electrodes for neurotransmitter detection. Our approach combines a multiplexed CNF electrode chip, developed at NASA Ames Research Center, with the Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) system, developed at the Mayo Clinic. Preliminary results indicate that the CNF nanoelectrode arrays are easily integrated with WINCS for neurotransmitter detection in a multiplexed array format. In the future, combining CNF based stimulating and recording electrodes with WINCS may lay the foundation for an implantable "smart" therapeutic system that utilizes neurochemical feedback control while likely resulting in increased DBS application in various neuropsychiatric disorders. In total, our goal is to take advantage of the nanostructure of CNF arrays for biosensing studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.

  20. Label-Free Detection of Cardiac Troponin-I Using Carbon Nanofiber Based Nanoelectrode Arrays

    NASA Technical Reports Server (NTRS)

    Periyakaruppan, Adaikkappan; Koehne, Jessica Erin; Gandhiraman, Ram P.; Meyyappan, M.

    2013-01-01

    A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. A carbon nanofiber (CNF) multiplexed array has been fabricated with 9 sensing pads, each containing 40,000 carbon nanofibers as nanoelectrodes. Here, we report the use of vertically aligned CNF nanoelectrodes for the detection of cardiac Troponin-I for the early diagnosis of myocardial infarction. Antibody, antitroponin, probe immobilization and subsequent binding to human cardiac troponin-I were characterized using electrochemical impedance spectroscopy and cyclic voltammetry techniques. Each step of the modification process resulted in changes in electrical capacitance or resistance to charge transfer due to the changes at the electrode surface upon antibody immobilization and binding to the specific antigen. This sensor demonstrates high sensitivity, down to 0.2 ng/mL, and good selectivity making this platform a good candidate for early stage diagnosis of myocardial infarction.

  1. Carbon nanotube composite materials

    DOEpatents

    O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2015-03-24

    A material consisting essentially of a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes dissolved in a solvent. Un-functionalized carbon nanotube concentrations up to 30 wt % and hydroxylated carbon nanotube concentrations up to 40 wt % can be used with even small concentrations of each (less than 2 wt %) useful in producing enhanced conductivity properties of formed thin films.

  2. Plumbing carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jin, Chuanhong; Suenaga, Kazu; Iijima, Sumio

    2008-01-01

    Since their discovery, the possibility of connecting carbon nanotubes together like water pipes has been an intriguing prospect for these hollow nanostructures. The serial joining of carbon nanotubes in a controlled manner offers a promising approach for the bottom-up engineering of nanotube structures-from simply increasing their aspect ratio to making integrated carbon nanotube devices. To date, however, there have been few reports of the joining of two different carbon nanotubes. Here we demonstrate that a Joule heating process, and associated electro-migration effects, can be used to connect two carbon nanotubes that have the same (or similar) diameters. More generally, with the assistance of a tungsten metal particle, this technique can be used to seamlessly join any two carbon nanotubes-regardless of their diameters-to form new nanotube structures.

  3. Reinforced Carbon Nanotubes.

    DOEpatents

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2005-06-28

    The present invention relates generally to reinforced carbon nanotubes, and more particularly to reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  4. Glucose sensor based on redox-cycling between selectively modified and unmodified combs of carbon interdigitated array nanoelectrodes.

    PubMed

    Sharma, Deepti; Lim, Yeongjin; Lee, Yunjeong; Shin, Heungjoo

    2015-08-19

    We present a novel electrochemical glucose sensor employing an interdigitated array (IDA) of 1:1 aspect ratio carbon nanoelectrodes for the electrochemical-enzymatic redox cycling of redox species (ferricyanide/ferrocyanide) between glucose oxidase (GOx) and the two comb-shaped nanoelectrodes of the IDA. The carbon nanoelectrodes were fabricated using a simple, cost-effective, reproducible microfabrication technology known as the carbon-microelectromechanical-systems (C-MEMS) process. One comb (comb 1) of the IDA was selectively modified with GOx via the electrochemical reduction of an aryl diazonium salt, while the other comb (comb 2) remained unmodified; this facilitates electrochemically more active surface of comb 2, resulting in sensitive glucose detection. Ferricyanide is reduced to ferrocyanide by the GOx in the presence of glucose, and ferrocyanide diffuses to both combs of the IDA where it is oxidized. The limited electrochemical current collection at the surface-modified comb 1 is counterbalanced by the efficient redox cycling between the enzyme sites at comb 1 and the bare carbon surface of comb 2. Reducing the electrode-to-electrode gap between the two combs (gap = 1.9 μm) increases the diffusion flux of redox species at comb 2 hence, enhanced the sensitivity and limit of detection of the glucose sensor by ∼2.3 and ∼295 times, respectively at comb 2 compared to comb 1. The developed IDA-based glucose sensor demonstrated good amperometric response to glucose, affording two linear ranges from 0.001 to 1 mM and from 1 to 10 mM, with limits of detection of 0.4 and 61 μM and sensitivities of 823.2 and 70.0 μA mM(-1) cm(-2), respectively. PMID:26343443

  5. Shearforce-based constant-distance scanning electrochemical microscopy as fabrication tool for needle-type carbon-fiber nanoelectrodes.

    PubMed

    Hussien, Emad Mohamed; Schuhmann, Wolfgang; Schulte, Albert

    2010-07-01

    Carbon fiber nanoelectrodes with nanometer radii tip curvatures were fabricated using a shearforce-based constant-distance scanning electrochemical microscope and electrochemically induced polymer deposition. A simple DC etching procedure in alkaline solution provided conically sharpened single carbon fibers with well-formed nanocones at their bottom. Coating the stems but not the end of the tips of the tapered structures with anodic electrodeposition paint was the strategy for limiting the bare carbon to the foremost end and restricting a feasible voltammetry current response to exactly this section. The electrodeposition of the polymer was prevented at the foremost end of the tip using a shearforce-based tip-to-sample distance control that allowed approaching the etched tips carefully in just touching distance to a film of a silicone elastomer. Analysis of the steady-state cyclic voltammograms in presence of a reversible redox compound revealed effective radii for the obtained needle-type carbon-fiber nanoelectrodes down to as small as 46 nm. The method offers an alternative pathway toward the fabrication of highly miniaturized carbon electrodes. PMID:20533837

  6. Carbon-Nanotube-Based Electrodes for Biomedical Applications

    NASA Technical Reports Server (NTRS)

    Li, Jun; Meyyappan, M.

    2008-01-01

    A nanotube array based on vertically aligned nanotubes or carbon nanofibers has been invented for use in localized electrical stimulation and recording of electrical responses in selected regions of an animal body, especially including the brain. There are numerous established, emerging, and potential applications for localized electrical stimulation and/or recording, including treatment of Parkinson s disease, Tourette s syndrome, and chronic pain, and research on electrochemical effects involved in neurotransmission. Carbon-nanotube-based electrodes offer potential advantages over metal macroelectrodes (having diameters of the order of a millimeter) and microelectrodes (having various diameters ranging down to tens of microns) heretofore used in such applications. These advantages include the following: a) Stimuli and responses could be localized at finer scales of spatial and temporal resolution, which is at subcellular level, with fewer disturbances to, and less interference from, adjacent regions. b) There would be less risk of hemorrhage on implantation because nano-electrode-based probe tips could be configured to be less traumatic. c) Being more biocompatible than are metal electrodes, carbon-nanotube-based electrodes and arrays would be more suitable for long-term or permanent implantation. d) Unlike macro- and microelectrodes, a nano-electrode could penetrate a cell membrane with minimal disruption. Thus, for example, a nanoelectrode could be used to generate an action potential inside a neuron or in proximity of an active neuron zone. Such stimulation may be much more effective than is extra- or intracellular stimulation via a macro- or microelectrode. e) The large surface area of an array at a micron-scale footprint of non-insulated nanoelectrodes coated with a suitable electrochemically active material containing redox ingredients would make it possible to obtain a pseudocapacitance large enough to dissipate a relatively large amount of electric charge

  7. Applications of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Ajayan, Pulickel M.; Zhou, Otto Z.

    Carbon nanotubes have attracted the fancy of many scientists worldwide. The small dimensions, strength and the remarkable physical properties of these structures make them a very unique material with a whole range of promising applications. In this review we describe some of the important materials science applications of carbon nanotubes. Specifically we discuss the electronic and electrochemical applications of nanotubes, nanotubes as mechanical reinforcements in high performance composites, nanotube-based field emitters, and their use as nanoprobes in metrology and biological and chemical investigations, and as templates for the creation of other nanostructures. Electronic properties and device applications of nanotubes are treated elsewhere in the book. The challenges that ensue in realizing some of these applications are also discussed from the point of view of manufacturing, processing, and cost considerations.

  8. Carbon nanotube macroelectronics

    NASA Astrophysics Data System (ADS)

    Zhang, Jialu

    In this dissertation, I discuss the application of carbon nanotubes in macroelectronis. Due to the extraordinary electrical properties such as high intrinsic carrier mobility and current-carrying capacity, single wall carbon nanotubes are very desirable for thin-film transistor (TFT) applications such as flat panel display, transparent electronics, as well as flexible and stretchable electronics. Compared with other popular channel material for TFTs, namely amorphous silicon, polycrystalline silicon and organic materials, nanotube thin-films have the advantages of low-temperature processing compatibility, transparency, and flexibility, as well as high device performance. In order to demonstrate scalable, practical carbon nanotube macroelectroncis, I have developed a platform to fabricate high-density, uniform separated nanotube based thin-film transistors. In addition, many other essential analysis as well as technology components, such as nanotube film density control, purity and diameter dependent semiconducting nanotube electrical performance study, air-stable n-type transistor fabrication, and CMOS integration platform have also been demonstrated. On the basis of the above achievement, I have further demonstrated various kinds of applications including AMOLED display electronics, PMOS and CMOS logic circuits, flexible and transparent electronics. The dissertation is structured as follows. First, chapter 1 gives a brief introduction to the electronic properties of carbon nanotubes, which serves as the background knowledge for the following chapters. In chapter 2, I will present our approach of fabricating wafer-scale uniform semiconducting carbon nanotube thin-film transistors and demonstrate their application in display electronics and logic circuits. Following that, more detailed information about carbon nanotube thin-film transistor based active matrix organic light-emitting diode (AMOLED) displays is discussed in chapter 3. And in chapter 4, a technology to

  9. Conducting carbonized polyaniline nanotubes

    NASA Astrophysics Data System (ADS)

    Mentus, Slavko; Ćirić-Marjanović, Gordana; Trchová, Miroslava; Stejskal, Jaroslav

    2009-06-01

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 °C min-1 up to a maximum temperature of 800 °C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 µm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 µm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm-1, increased to 0.7 S cm-1 upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  10. Conducting carbonized polyaniline nanotubes.

    PubMed

    Mentus, Slavko; Cirić-Marjanović, Gordana; Trchová, Miroslava; Stejskal, Jaroslav

    2009-06-17

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 degrees C min(-1) up to a maximum temperature of 800 degrees C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 microm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 microm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm(-1), increased to 0.7 S cm(-1) upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy. PMID:19471087

  11. Transport in Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Datta, S.; Xue, Yong-Qinag; Anantram, M. P.; Saini, Subhash (Technical Monitor)

    1999-01-01

    This presentation discusses coupling between carbon nanotubes (CNT), simple metals (FEG) and a graphene sheet. The graphene sheet did not couple well with FEG, but the combination of a graphene strip and CNT did couple well with most simple metals.

  12. Carbon nanotubes: Fibrillar pharmacology

    NASA Astrophysics Data System (ADS)

    Kostarelos, Kostas

    2010-10-01

    The mechanisms by which chemically functionalized carbon nanotubes flow in blood and are excreted through the kidneys illustrate the unconventional behaviour of these fibrillar nanostructures, and the opportunities they offer as components for the design of advanced delivery vehicles.

  13. Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Webber, Stephen E.

    2003-01-01

    These project will explore the functionalization of carbon nanotubes via the formation of molecular complexes with perylene diimide based systems. It is anticipated that these complexes would be soluble in organic solvent and enable the homogenous dispersion of carbon nanotubes in polymer films. Molecular complexes will be prepared and characterized using standard spectroscopic and thermal analytical techniques. Polymer films will be prepared with these complexes and their properties (electrical and thermal conductivity, mechanical properties, stability) evaluated.

  14. Nanotube composite carbon fibers

    NASA Astrophysics Data System (ADS)

    Andrews, R.; Jacques, D.; Rao, A. M.; Rantell, T.; Derbyshire, F.; Chen, Y.; Chen, J.; Haddon, R. C.

    1999-08-01

    Single walled carbon nanotubes (SWNTs) were dispersed in isotropic petroleum pitch matrices to form nanotube composite carbon fibers with enhanced mechanical and electrical properties. We find that the tensile strength, modulus, and electrical conductivity of a pitch composite fiber with 5 wt % loading of purified SWNTs are enhanced by ˜90%, ˜150%, and 340% respectively, as compared to the corresponding values in unmodified isotropic pitch fibers. These results serve to highlight the potential that exits for developing a spectrum of material properties through the selection of the matrix, nanotube dispersion, alignment, and interfacial bonding.

  15. Carbon Nanotube Solar Cells

    PubMed Central

    Klinger, Colin; Patel, Yogeshwari; Postma, Henk W. Ch.

    2012-01-01

    We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement. PMID:22655070

  16. Templated Growth of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Siochik Emilie J. (Inventor)

    2007-01-01

    A method of growing carbon nanotubes uses a synthesized mesoporous si lica template with approximately cylindrical pores being formed there in. The surfaces of the pores are coated with a carbon nanotube precu rsor, and the template with the surfaces of the pores so-coated is th en heated until the carbon nanotube precursor in each pore is convert ed to a carbon nanotube.

  17. Carbon nanotube array based sensor

    DOEpatents

    Lee, Christopher L.; Noy, Aleksandr; Swierkowski, Stephan P.; Fisher, Karl A.; Woods, Bruce W.

    2005-09-20

    A sensor system comprising a first electrode with an array of carbon nanotubes and a second electrode. The first electrode with an array of carbon nanotubes and the second electrode are positioned to produce an air gap between the first electrode with an array of carbon nanotubes and the second electrode. A measuring device is provided for sensing changes in electrical capacitance between the first electrode with an array of carbon nanotubes and the second electrode.

  18. Carbon Nanotubes for Supercapacitor

    PubMed Central

    2010-01-01

    As an electrical energy storage device, supercapacitor finds attractive applications in consumer electronic products and alternative power source due to its higher energy density, fast discharge/charge time, low level of heating, safety, long-term operation stability, and no disposable parts. This work reviews the recent development of supercapacitor based on carbon nanotubes (CNTs) and their composites. The purpose is to give a comprehensive understanding of the advantages and disadvantages of carbon nanotubes-related supercapacitor materials and to find ways for the improvement in the performance of supercapacitor. We first discussed the effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance. The composites, including CNTs/oxide and CNTs/polymer, were further discussed to enhance the supercapacitance and keep the stability of the supercapacitor by optimally engineering the composition, particle size, and coverage. PMID:20672061

  19. Horizontal carbon nanotube alignment.

    PubMed

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies. PMID:27546174

  20. Copper-philic carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Belgamwar, Sachin U.; Sharma, Niti Nipun

    2016-04-01

    Carbon nanotube is having poor wet-ability with copper metal. Wet-ability of carbon nanotube was improved by exposing and creating more active sites on the surface of carbon nanotube. Carbon nanotubes were subjected to the prolong ultrasonication treatment of 20×103 Hz and 500W, which helped in disentanglement of carbon nanotube agglomerates and in breaking the weak bonds like pentagonal or heptagonal structure on the surface and on the CNT cap. Disentanglement of the carbon nanotube, resulted in exposing the defective sites on the surface and breaking of weak bonds, which assisted in creating the new defects on the surface. This process results in generates more active sites on the surface and it helps in improving the wet-ability of the carbon nanotube in copper.

  1. Transport Through Carbon Nanotube Wires

    NASA Technical Reports Server (NTRS)

    Anantram, M. P.; Kwak, Dochan (Technical Monitor)

    2001-01-01

    This viewgraph presentation deals with the use of carbon nanotubes as a transport system. Contact, defects, tubular bend, phonons, and mechanical deformations all contribute to reflection within the nanotube wire. Bragg reflection, however, is native to an ideal energy transport system. Transmission resistance depends primarily on the level of energy present. Finally, the details regarding coupling between carbon nanotubes and simple metals are presented.

  2. Self-assembled ordered carbon-nanotube arrays and membranes.

    SciTech Connect

    Overmyer, Donald L.; Siegal, Michael P.; Yelton, William Graham

    2004-11-01

    Imagine free-standing flexible membranes with highly-aligned arrays of carbon nanotubes (CNTs) running through their thickness. Perhaps with both ends of the CNTs open for highly controlled nanofiltration? Or CNTs at heights uniformly above a polymer membrane for a flexible array of nanoelectrodes or field-emitters? How about CNT films with incredible amounts of accessible surface area for analyte adsorption? These self-assembled crystalline nanotubes consist of multiple layers of graphene sheets rolled into concentric cylinders. Tube diameters (3-300 nm), inner-bore diameters (2-15 nm), and lengths (nanometers - microns) are controlled to tailor physical, mechanical, and chemical properties. We proposed to explore growth and characterize nanotube arrays to help determine their exciting functionality for Sandia applications. Thermal chemical vapor deposition growth in a furnace nucleates from a metal catalyst. Ordered arrays grow using templates from self-assembled hexagonal arrays of nanopores in anodized-aluminum oxide. Polymeric-binders can mechanically hold the CNTs in place for polishing, lift-off, and membrane formation. The stiffness, electrical and thermal conductivities of CNTs make them ideally suited for a wide-variety of possible applications. Large-area, highly-accessible gas-adsorbing carbon surfaces, superb cold-cathode field-emission, and unique nanoscale geometries can lead to advanced microsensors using analyte adsorption, arrays of functionalized nanoelectrodes for enhanced electrochemical detection of biological/explosive compounds, or mass-ionizers for gas-phase detection. Materials studies involving membrane formation may lead to exciting breakthroughs in nanofiltration/nanochromatography for the separation of chemical and biological agents. With controlled nanofilter sizes, ultrafiltration will be viable to separate and preconcentrate viruses and many strains of bacteria for 'down-stream' analysis.

  3. Carbon nanotube intramolecular junctions

    NASA Astrophysics Data System (ADS)

    Yao, Zhen; Postma, Henk W. Ch.; Balents, Leon; Dekker, Cees

    1999-11-01

    The ultimate device miniaturization would be to use individual molecules as functional devices. Single-wall carbon nanotubes (SWNTs) are promising candidates for achieving this: depending on their diameter and chirality, they are either one-dimensional metals or semiconductors. Single-electron transistors employing metallic nanotubes and field-effect transistors employing semiconducting nanotubes have been demonstrated. Intramolecular devices have also been proposed which should display a range of other device functions. For example, by introducing a pentagon and a heptagon into the hexagonal carbon lattice, two tube segments with different atomic and electronic structures can be seamlessly fused together to create intramolecular metal-metal, metal-semiconductor, or semiconductor-semiconductor junctions. Here we report electrical transport measurements on SWNTs with intramolecular junctions. We find that a metal-semiconductor junction behaves like a rectifying diode with nonlinear transport characteristics that are strongly asymmetric with respect to bias polarity. In the case of a metal-metal junction, the conductance appears to be strongly suppressed and it displays a power-law dependence on temperatures and applied voltage, consistent with tunnelling between the ends of two Luttinger liquids. Our results emphasize the need to consider screening and electron interactions when designing and modelling molecular devices. Realization of carbon-based molecular electronics will require future efforts in the controlled production of these intramolecular nanotube junctions.

  4. The Toxicology of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Donaldson, Ken; Poland, Craig; Duffin, Rodger; Bonner, James

    2012-06-01

    1. Carbon nanotube structure, synthesis and applications C. Singh and W. Song; 2. The aerodynamic behaviour and pulmonary deposition of carbon nanotubes A. Buckley, R. Smith and R Maynard; 3. Utilising the concept of the biologically effective dose to define the particle and fibre hazards of carbon nanotubes K. Donaldson, R. Duffin, F. Murphy and C. Poland; 4. CNT, biopersistence and the fibre paradigm D. Warheit and M. DeLorme; 5. Length-dependent retention of fibres in the pleural space C. Poland, F. Murphy and K. Donaldson; 6. Experimental carcinogenicity of carbon nanotubes in the context of other fibres K. Unfried; 7. Fate and effects of carbon nanotubes following inhalation J. Ryman-Rasmussen, M. Andersen and J. Bonner; 8. Responses to pulmonary exposure to carbon nanotubes V. Castranova and R. Mercer; 9. Genotoxicity of carbon nanotubes R. Schins, C. Albrecht, K. Gerloff and D. van Berlo; 10. Carbon nanotube-cellular interactions; macrophages, epithelial and mesothelial cells V. Stone, M. Boyles, A. Kermanizadeh, J. Varet and H. Johnston; 11. Systemic health effects of carbon nanotubes following inhalation J. McDonald; 12. Dosimetry and metrology of carbon nanotubes L. Tran, L. MacCalman and R. Aitken; Index.

  5. Carbon Nanotube Purification and Functionalization

    NASA Technical Reports Server (NTRS)

    Lebron, Marisabel; Mintz, Eric; Smalley, Richard E.; Meador, Michael A.

    2003-01-01

    Carbon nanotubes have the potential to significantly enhance the mechanical, thermal, and electrical properties of polymers. However, dispersion of carbon nanotubes in a polymer matrix is hindered by the electrostatic forces that cause them to agglomerate. Chemical modification of the nanotubes is necessary to minimize these electrostatic forces and promote adhesion between the nanotubes and the polymer matrix. In a collaborative research program between Clark Atlanta University, Rice University, and NASA Glenn Research Center several approaches are being explored to chemically modify carbon nanotubes. The results of this research will be presented.

  6. Superhydrophobic amorphous carbon/carbon nanotube nanocomposites

    NASA Astrophysics Data System (ADS)

    Han, Z. J.; Tay, B. K.; Shakerzadeh, M.; Ostrikov, K.

    2009-06-01

    Superhydrophobic amorphous carbon/carbon nanotube nanocomposites are fabricated by plasma immersion ion implantation with carbon nanotube forests as a template. The microstructure of the fabricated nanocomposites shows arrays of carbon nanotubes capped with amorphous carbon nanoparticles. Contact angle measurements show that both advancing and receding angles close to 180° can be achieved on the nanocomposites. The fabrication here does not require patterning of carbon nanotubes or deposition of conformal coatings with low surface energy, which are usually involved in conventional approaches for superhydrophobic surfaces. The relationship between the observed superhydrophobicity and the unique microstructure of the nanocomposites is discussed.

  7. Carbon nanotubes on a substrate

    DOEpatents

    Gao, Yufei [Kennewick, WA; Liu, Jun [West Richland, WA

    2002-03-26

    The present invention includes carbon nanotubes whose hollow cores are 100% filled with conductive filler. The carbon nanotubes are in uniform arrays on a conductive substrate and are well-aligned and can be densely packed. The uniformity of the carbon nanotube arrays is indicated by the uniform length and diameter of the carbon nanotubes, both which vary from nanotube to nanotube on a given array by no more than about 5%. The alignment of the carbon nanotubes is indicated by the perpendicular growth of the nanotubes from the substrates which is achieved in part by the simultaneous growth of the conductive filler within the hollow core of the nanotube and the densely packed growth of the nanotubes. The present invention provides a densely packed carbon nanotube growth where each nanotube is in contact with at least one nearest-neighbor nanotube. The substrate is a conductive substrate coated with a growth catalyst, and the conductive filler can be single crystals of carbide formed by a solid state reaction between the substrate material and the growth catalyst. The present invention further provides a method for making the filled carbon nanotubes on the conductive substrates. The method includes the steps of depositing a growth catalyst onto the conductive substrate as a prepared substrate, creating a vacuum within a vessel which contains the prepared substrate, flowing H2/inert (e.g. Ar) gas within the vessel to increase and maintain the pressure within the vessel, increasing the temperature of the prepared substrate, and changing the H2/Ar gas to ethylene gas such that the ethylene gas flows within the vessel. Additionally, varying the density and separation of the catalyst particles on the conductive substrate can be used to control the diameter of the nanotubes.

  8. Method of manufacturing carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Benavides, Jeanette M. (Inventor); Leidecker, Henning W. (Inventor); Frazier, Jeffrey (Inventor)

    2004-01-01

    A process for manufacturing carbon nanotubes, including a step of inducing electrical current through a carbon anode and a carbon cathode under conditions effective to produce the carbon nanotubes, wherein the carbon cathode is larger than the carbon anode. Preferably, a welder is used to induce the electrical current via an arc welding process. Preferably, an exhaust hood is placed on the anode, and the process does not require a closed or pressurized chamber. The process provides high-quality, single-walled carbon nanotubes, while eliminating the need for a metal catalyst.

  9. Carbon nanotube network varactor.

    PubMed

    Generalov, A A; Anoshkin, I V; Erdmanis, M; Lioubtchenko, D V; Ovchinnikov, V; Nasibulin, A G; Räisänen, A V

    2015-01-30

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling. PMID:25556375

  10. Carbon nanotube network varactor

    NASA Astrophysics Data System (ADS)

    Generalov, A. A.; Anoshkin, I. V.; Erdmanis, M.; Lioubtchenko, D. V.; Ovchinnikov, V.; Nasibulin, A. G.; Räisänen, A. V.

    2015-01-01

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling.

  11. Carbon nanotube IR detectors (SV)

    SciTech Connect

    Leonard, F. L.

    2012-03-01

    Sandia National Laboratories (Sandia) and Lockheed Martin Corporation (LMC) collaborated to (1) evaluate the potential of carbon nanotubes as channels in infrared (IR) photodetectors; (2) assemble and characterize carbon nanotube electronic devices and measure the photocurrent generated when exposed to infrared light;(3) compare the performance of the carbon nanotube devices with that of traditional devices; and (4) develop and numerically implement models of electronic transport and opto-electronic behavior of carbon nanotube infrared detectors. This work established a new paradigm for photodetectors.

  12. Carbon nanotubes (CNTs) for the development of electrochemical biosensors.

    PubMed

    Lin, Yuehe; Yantasee, Wassana; Wang, Joseph

    2005-01-01

    Carbon nanotube (CNT) is a very attractive material for the development of biosensors because of its capability to provide strong electrocatalytic activity and minimize surface fouling of the sensors. This article reviews our recent developments of oxidase- and dehydrogenase-amperometric biosensors based on the immobilization of CNTs, the co-immobilization of enzymes on the CNTs/Nafion or the CNT/Teflon composite materials, or the attachment of enzymes on the controlled-density aligned CNT-nanoelectrode arrays. The excellent electrocatalytic activities of the CNTs on the redox reactions of hydrogen peroxide, nicotinamide adenine dinucleotide (NADH), and homocysteine have been demonstrated. Successful applications of the CNT-based biosensors reviewed herein include the low-potential detections of glucose, organophosphorus compounds, and alcohol. PMID:15574386

  13. Carbon Nanotubes (CNTs) for the Development of Electrochemical Biosensors

    SciTech Connect

    Lin, Yuehe; Yantasee, Wassana; Wang, Joseph

    2005-01-01

    Carbon nanotube (CNT) is a very attractive material for the development of biosensors because of its capability to provide strong electrocatalytic activity and minimize surface fouling of the sensors. This article reviews our recent developments of oxidase- and dehydrogenase-amperometric biosensors based on the immobilization of CNTs, the co-immobilization of enzymes on the CNTs/Nafion or the CNT/Teflon composite materials, or the attachment of enzymes on the controlled-density aligned CNT-nanoelectrode arrays. The excellent electrocatalytic activities of the CNTs on the redox reactions of hydrogen peroxide, nicotinamide adenine dinucleotide (NADH), and homocysteine have been demonstrated. Successful applications of the CNT-based biosensors reviewed herein include the low-potential detections of glucose, organophosphorus compounds, and alcohol.

  14. Carbon Nanotubes Based Quantum Devices

    NASA Technical Reports Server (NTRS)

    Lu, Jian-Ping

    1999-01-01

    This document represents the final report for the NASA cooperative agreement which studied the application of carbon nanotubes. The accomplishments are reviewed: (1) Wrote a review article on carbon nanotubes and its potentials for applications in nanoscale quantum devices. (2) Extensive studies on the effects of structure deformation on nanotube electronic structure and energy band gaps. (3) Calculated the vibrational spectrum of nanotube rope and the effect of pressure. and (4) Investigate the properties of Li intercalated nanotube ropes and explore their potential for energy storage materials and battery applications. These studies have lead to four publications and seven abstracts in international conferences.

  15. Transport in Carbon Nanotube Junctions

    NASA Astrophysics Data System (ADS)

    Khoo, K. H.; Chelikowsky, James R.

    2008-03-01

    There is growing interest in the use of carbon nanotube thin films as transparent electrical conductors and thin-film transistors owing to their high optical transmittance, low sheet resistivity, and ease of fabrication. [1,2] A major contribution to the sheet resistivity originates at nanotube junctions, as electrical contact is typically poor between adjacent nanotubes. It is thus important to characterize carbon nanotube junctions in order to understand the conduction properties of nanotube thin films. To this end, we have performed ab initio density functional theory calculations to investigate the structural, electronic and transport properties of carbon nanotube junctions as a function of nanotube chirality and contact geometry [1] Z. Wu et al., Science 305, 1273 (2004) [2] E. S. Snow, J. P. Novak, P. M. Campbell, and D. Park, Appl. Phys. Lett. 82, 2145 (2003).

  16. Carbon nanotube core graphitic shell hybrid fibers.

    PubMed

    Hahm, Myung Gwan; Lee, Jae-Hwang; Hart, Amelia H C; Song, Sung Moo; Nam, Jaewook; Jung, Hyun Young; Hashim, Daniel Paul; Li, Bo; Narayanan, Tharangattu N; Park, Chi-Dong; Zhao, Yao; Vajtai, Robert; Kim, Yoong Ahm; Hayashi, Takuya; Ku, Bon-Cheol; Endo, Morinobu; Barrera, Enrique; Jung, Yung Joon; Thomas, Edwin L; Ajayan, Pulickel M

    2013-12-23

    A carbon nanotube yarn core graphitic shell hybrid fiber was fabricated via facile heat treatment of epoxy-based negative photoresist (SU-8) on carbon nanotube yarn. The effective encapsulation of carbon nanotube yarn in carbon fiber and a glassy carbon outer shell determines their physical properties. The higher electrical conductivity (than carbon fiber) of the carbon nanotube yarn overcomes the drawbacks of carbon fiber/glassy carbon, and the better properties (than carbon nanotubes) of the carbon fiber/glassy carbon make up for the lower thermal and mechanical properties of the carbon nanotube yarn via synergistic hybridization without any chemical doping and additional processes. PMID:24224730

  17. Optoelectronics with Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kinoshita, Megumi

    2011-12-01

    The carbon nanotube is a promising material for future micro- and nano-scale electronics because of its unique electronic properties, high carrier mobility and extraordinary capacity for high current density. In particular, semiconducting carbon nanotubes are direct bandgap materials with a typical energy gap in the order of 1 eV, which means they emit light in the near-infrared range, making them an attractive option in telecommunications applications. However, there have been few systematic investigations of electrically-induced light emission (i.e. electroluminescence) from carbon nanotubes, and their emission properties are not well understood. In this dissertation, we explore the characteristics of electroluminescence in three different types of carbon-nanotube devices. The first is a single-tube field-effect transistor (CNTFET), whose emission has previously been found to have a very broad spectral shape and low emission efficiency. We analyze the spectral shape in detail, which reveals that a high electric field near metal contacts contributes most to the bias-dependent component of broadening, in addition to smaller contributions from tube nonuniformity, inelastic scattering of phonons, high temperature, etc. In the second part of the study, single-tube light-emitting diodes are constructed by employing a split top-gate scheme. The split gate creates p- and n-doped regions electrostatically, so that electrons and holes combine between the two sections and can decay radiatively. This configuration creates electron-hole pairs under much lower electric fields and gives us a greater control over carrier distribution in the device channel, resulting in much narrower spectral linewidths and an emission intensity several orders of magnitude larger than that of CNTFETs. The much better signal-to-noise also leads to the observation of emission from defect-induced states. Finally, we extend the idea of the single-tube p-n diode and fabricate CNT film diodes from many

  18. Thermoelectric power in carbon nanotubes

    SciTech Connect

    Mavrinskiy, A. V. Baitinger, E. M.

    2009-04-15

    The theoretical results for the temperature dependence of the thermoelectric power of graphite and semimetal carbon nanotubes are reported. In the calculations, the cylindrical superatomic range structure of nanotubes is taken into account. The Boltzmann equation and the {pi}-electron model of semimetal carbon nanotubes are used. The basic parameters of the calculation are the concentration of electrons, the Fermi energy, and the energy of the local level associated with the cylindrical structure of carbon nanotubes. The theoretical results are compared with the available experimental data.

  19. CARBON NANOTUBES AS MULTIPOLLUTANT SORBENTS

    EPA Science Inventory

    Exploratory Research Program Project - Carbon nanotubes (CNTs) are formed from graphite (or graphene) sheets rolled into tubes, typically with diameters of 1 - 10 nm and lengths of 200 - 500 nm. Carbon nanotubes have unique electrical properties that have led to interest in thei...

  20. Conduction in Carbon Nanotube Networks

    NASA Astrophysics Data System (ADS)

    Kaiser, A. B.; Rogers, S. A.

    2003-10-01

    Recent measurements of the resistivity of single-wall carbon nanotube (SWNT) networks are consistent with our model of metallic conduction interrupted by barriers. We extend our model of thermopower nonlinearities due to peaks in the density of electronic states and apply it to recent thermopower data for carbon nanotube networks.

  1. Studies of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Caneba, Gerard T.

    2005-01-01

    The fellowship experience for this summer for 2004 pertains to carbon nanotube coatings for various space-related applications. They involve the following projects: (a) EMI protection films from HiPco-polymers, and (b) Thermal protection nanosilica materials. EMI protection films are targeted to be eventually applied onto casings of laptop computers. These coatings are composites of electrically-conductive SWNTs and compatible polymers. The substrate polymer will be polycarbonate, since computer housings are typically made of carbon composites of this type of polymer. A new experimental copolymer was used last year to generate electrically-conductive and thermal films with HiPco at 50/50 wt/wt composition. This will be one of the possible formulations. Reference films will be base polycarbonate and neat HiPco onto polycarbonate films. Other coating materials that will be tried will be based on HiPco composites with commercial enamels (polyurethane, acrylic, polyester), which could be compatible with the polycarbonate substrate. Nanosilica fibers are planned for possible use as thermal protection tiles on the shuttle orbiter. Right now, microscale silica is used. Going to the nanoscale will increase the surface-volume-per-unit-area of radiative heat dissipation. Nanoscale carbon fibers/nanotubes can be used as templates for the generation of nanosilica. A sol-gel operation is employed for this purpose.

  2. Teslaphoresis of Carbon Nanotubes.

    PubMed

    Bornhoeft, Lindsey R; Castillo, Aida C; Smalley, Preston R; Kittrell, Carter; James, Dustin K; Brinson, Bruce E; Rybolt, Thomas R; Johnson, Bruce R; Cherukuri, Tonya K; Cherukuri, Paul

    2016-04-26

    This paper introduces Teslaphoresis, the directed motion and self-assembly of matter by a Tesla coil, and studies this electrokinetic phenomenon using single-walled carbon nanotubes (CNTs). Conventional directed self-assembly of matter using electric fields has been restricted to small scale structures, but with Teslaphoresis, we exceed this limitation by using the Tesla coil's antenna to create a gradient high-voltage force field that projects into free space. CNTs placed within the Teslaphoretic (TEP) field polarize and self-assemble into wires that span from the nanoscale to the macroscale, the longest thus far being 15 cm. We show that the TEP field not only directs the self-assembly of long nanotube wires at remote distances (>30 cm) but can also wirelessly power nanotube-based LED circuits. Furthermore, individualized CNTs self-organize to form long parallel arrays with high fidelity alignment to the TEP field. Thus, Teslaphoresis is effective for directed self-assembly from the bottom-up to the macroscale. PMID:27074626

  3. Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2007-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2, or F2, or CnHm) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec.

  4. Functionalization of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2007-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H.sub.2 or F.sub.2 or C.sub.nH.sub.m) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec.

  5. Carbon Nanotube Interconnect

    NASA Technical Reports Server (NTRS)

    Li, Jun (Inventor); Meyyappan, Meyya (Inventor)

    2006-01-01

    Method and system for fabricating an electrical interconnect capable of supporting very high current densities ( 10(exp 6)-10(exp 10) Amps/sq cm), using an array of one or more carbon nanotubes (CNTs). The CNT array is grown in a selected spaced apart pattern, preferably with multi-wall CNTs, and a selected insulating material, such as SiOw, or SiuNv is deposited using CVD to encapsulate each CNT in the array. An exposed surface of the insulating material is planarized to provide one or more exposed electrical contacts for one or more CNTs.

  6. Carbon Nanotubes for Space Applications

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya

    2000-01-01

    The potential of nanotube technology for NASA missions is significant and is properly recognized by NASA management. Ames has done much pioneering research in the last five years on carbon nanotube growth, characterization, atomic force microscopy, sensor development and computational nanotechnology. NASA Johnson Space Center has focused on laser ablation production of nanotubes and composites development. These in-house efforts, along with strategic collaboration with academia and industry, are geared towards meeting the agency's mission requirements. This viewgraph presentation (including an explanation for each slide) outlines the research focus for Ames nanotechnology, including details on carbon nanotubes' properties, applications, and synthesis.

  7. Growth, modification and integration of carbon nanotubes into molecular electronics

    NASA Astrophysics Data System (ADS)

    Moscatello, Jason P.

    Molecules are the smallest possible elements for electronic devices, with active elements for such devices typically a few Angstroms in footprint area. Owing to the possibility of producing ultra-high density devices, tremendous effort has been invested in producing electronic junctions by using various types of molecules. The major issues for molecular electronics include (1) developing an effective scheme to connect molecules with the present micro- and nano-technology, (2) increasing the lifetime and stabilities of the devices, and (3) increasing their performance in comparison to the state-of-the-art devices. In this work, we attempt to use carbon nanotubes (CNTs) as the interconnecting nanoelectrodes between molecules and microelectrodes. The ultimate goal is to use two individual CNTs to sandwich molecules in a cross-bar configuration while having these CNTs connected with microelectrodes such that the junction displays the electronic character of the molecule chosen. We have successfully developed an effective scheme to connect molecules with CNTs, which is scalable to arrays of molecular electronic devices. To realize this far reaching goal, the following technical topics have been investigated. (1) Synthesis of multi-walled carbon nanotubes (MWCNTs) by thermal chemical vapor deposition (T-CVD) and plasma-enhanced chemical vapor deposition (PECVD) techniques (Chapter 3). We have evaluated the potential use of tubular and bamboo-like MWCNTs grown by T-CVD and PE-CVD in terms of their structural properties. (2) Horizontal dispersion of MWCNTs with and without surfactants, and the integration of MWCNTs to microelectrodes using deposition by dielectrophoresis (DEP) (Chapter 4). We have systematically studied the use of surfactant molecules to disperse and horizontally align MWCNTs on substrates. In addition, DEP is shown to produce impurityfree placement of MWCNTs, forming connections between microelectrodes. We demonstrate the deposition density is tunable by

  8. Carbon nanotube based photocathodes

    NASA Astrophysics Data System (ADS)

    Hudanski, Ludovic; Minoux, Eric; Gangloff, Laurent; Teo, Kenneth B. K.; Schnell, Jean-Philippe; Xavier, Stephane; Robertson, John; Milne, William I.; Pribat, Didier; Legagneux, Pierre

    2008-03-01

    This paper describes a novel photocathode which is an array of vertically aligned multi-walled carbon nanotubes (MWCNTs), each MWCNT being associated with one p-i-n photodiode. Unlike conventional photocathodes, the functions of photon-electron conversion and subsequent electron emission are physically separated. Photon-electron conversion is achieved with p-i-n photodiodes and the electron emission occurs from the MWCNTs. The current modulation is highly efficient as it uses an optically controlled reconfiguration of the electric field at the MWCNT locations. Such devices are compatible with high frequency and very large bandwidth operation and could lead to their application in compact, light and efficient microwave amplifiers for satellite telecommunication. To demonstrate this new photocathode concept, we have fabricated the first carbon nanotube based photocathode using silicon p-i-n photodiodes and MWCNT bunches. Using a green laser, this photocathode delivers 0.5 mA with an internal quantum efficiency of 10% and an ION/IOFF ratio of 30.

  9. Carbon nanotube array actuators

    NASA Astrophysics Data System (ADS)

    Geier, S.; Mahrholz, T.; Wierach, P.; Sinapius, M.

    2013-09-01

    Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 750-2000 μm with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 μm and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs.

  10. Carbon nanotube biosensors

    PubMed Central

    Tîlmaciu, Carmen-Mihaela; Morris, May C.

    2015-01-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. PMID:26579509

  11. Carbon Nanotube Biosensors

    NASA Astrophysics Data System (ADS)

    Tilmaciu, Carmen-Mihaela; Morris, May

    2015-10-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  12. Method for synthesizing carbon nanotubes

    DOEpatents

    Fan, Hongyou

    2012-09-04

    A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

  13. Carbon nanotubes in hyperthermia therapy

    PubMed Central

    Singh, Ravi; Torti, Suzy V.

    2013-01-01

    Thermal tumor ablation therapies are being developed with a variety of nanomaterials, including single-and multiwalled carbon nanotubes. Carbon nanotubes (CNTs) have attracted interest due to their potential for simultaneous imaging and therapy. In this review, we highlight in vivo applications of carbon nanotube-mediated thermal therapy (CNMTT) and examine the rationale for use of this treatment in recurrent tumors or those resistant to conventional cancer therapies. Additionally, we discuss strategies to localize and enhance the cancer selectivity of this treatment and briefly examine issues relating the toxicity and long term fate of CNTs. PMID:23933617

  14. Method for producing carbon nanotubes

    DOEpatents

    Phillips, Jonathan; Perry, William L.; Chen, Chun-Ku

    2006-02-14

    Method for producing carbon nanotubes. Carbon nanotubes were prepared using a low power, atmospheric pressure, microwave-generated plasma torch system. After generating carbon monoxide microwave plasma, a flow of carbon monoxide was directed first through a bed of metal particles/glass beads and then along the outer surface of a ceramic tube located in the plasma. As a flow of argon was introduced into the plasma through the ceramic tube, ropes of entangled carbon nanotubes, attached to the surface of the tube, were produced. Of these, longer ropes formed on the surface portion of the tube located in the center of the plasma. Transmission electron micrographs of individual nanotubes revealed that many were single-walled.

  15. Nanoelectrode array for electrochemical analysis

    DOEpatents

    Yelton, William G.; Siegal, Michael P.

    2009-12-01

    A nanoelectrode array comprises a plurality of nanoelectrodes wherein the geometric dimensions of the electrode controls the electrochemical response, and the current density is independent of time. By combining a massive array of nanoelectrodes in parallel, the current signal can be amplified while still retaining the beneficial geometric advantages of nanoelectrodes. Such nanoelectrode arrays can be used in a sensor system for rapid, non-contaminating field analysis. For example, an array of suitably functionalized nanoelectrodes can be incorporated into a small, integrated sensor system that can identify many species rapidly and simultaneously under field conditions in high-resistivity water, without the need for chemical addition to increase conductivity.

  16. Cantilevered carbon nanotube hygrometer

    NASA Astrophysics Data System (ADS)

    Kuroyanagi, Toshinori; Terada, Yuki; Takei, Kuniharu; Akita, Seiji; Arie, Takayuki

    2014-05-01

    We investigate the effects of humidity on the vibrations of carbon nanotubes (CNTs) using two types of CNT cantilevers: open-ended and close-ended CNT cantilevers. As the humidity increases, the resonant frequency of the open-ended CNT cantilever decreases due to the adsorption of water molecules onto the CNT tip, whereas that of the close-ended CNT cantilever increases probably due to the change in the viscosity of the air surrounding the CNT cantilever, which is negatively correlated with the humidity of air. Our findings suggest that a close-ended CNT cantilever is more suitable for a quick-response and ultrasensitive hygrometer because it continuously reads the viscosity change of moist air in the vicinity of the CNT.

  17. On carbon nanotube resonators

    NASA Astrophysics Data System (ADS)

    Caruntu, Dumitru I.; Salinas Trevino, Cone S.

    2011-04-01

    This paper deals with electrostatically actuated Carbon NanoTubes (CNT) cantilevers for sensor applications. There are three kinds of forces acting on the CNT cantilever: electrostatic, elastostatic, and van der Waals. The van der Waals forces are significant for values of 50 nm or lower of the gap between the CNT and the ground plate. As both forces, electrostatic and van der Waals, are nonlinear, and the CNT electrostatic actuation is given by AC voltage, the CNT dynamics is nonlinear parametric. The method of multiple scales is used to investigate the system under soft excitations and/or weakly nonlinearities. The frequency-amplitude and frequency-phase behavior are found in the case of primary resonance.

  18. Carbon nanotube biconvex microcavities

    SciTech Connect

    Butt, Haider Ahmed, Rajib; Yetisen, Ali K.; Yun, Seok Hyun; Dai, Qing

    2015-03-23

    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2–3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  19. Carbon nanotube optical mirrors

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Rabin, Douglas

    2015-01-01

    We report the fabrication of imaging quality optical mirrors with smooth surfaces using carbon nanotubes (CNT) embedded in an epoxy matrix. CNT/epoxy is a multifunctional composite material that has sensing capabilities and can be made to incorporate self-actuation. Moreover, as the precursor is a low density liquid, large and lightweight mirrors can be fabricated by processes such as replication, spincasting, and three-dimensional printing. Therefore, the technology holds promise for the development of a new generation of lightweight, compact "smart" telescope mirrors with figure sensing and active or adaptive figure control. We report on measurements made of optical and mechanical characteristics, active optics experiments, and numerical modeling. We discuss possible paths for future development.

  20. Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2009-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2 or F2 or CnHm) is irradiated to provide a cold plasma of selected target species particles, such as atomic H or F, in a first chamber. The target species particles are d irected toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target species particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. *Discrimination against non-target species is provided by (i) use of a target species having a lifetime that is much greater than a lifetime of a non-target species and/or (2) use of an applied magnetic field to discriminate between charged particle trajectories for target species and for non-target species.

  1. Carbon Nanotube Electron Gun

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  2. Carbon nanotube electron gun

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2010-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  3. Carbon Nanotubes as Thermionic Emitters

    NASA Astrophysics Data System (ADS)

    Loutfy, R. O.; Samandi, M.; Moravsky, A.; Strange, S.

    2004-02-01

    Thermionic converters are an interesting option for lightweight and long-life power generators due to a number of compelling advantages, including all solid construction, no moving parts, and waste heat rejection at high temperature. An experimental set up has been built that allows the screening of thermionic coatings and new nanomaterials from room temperature to 2000 K in high vacuum and at gap sizes as small as 1 μm. A new class of very high temperature compatible materials, carbon nanotubes, has been investigated for their performance as cathodes. Seven different types of carbon nanotubes have been screened as thermionic emitter cathodes and compared to tungsten and nitrogen doped diamond. It has been found that some carbon nanotubes combine excellent temperature stability with good thermal emission performance. Yet, other carbon nanotubes exhibited exceptional combined thermal and field enhanced emission performance.

  4. Carbon Nanotube-Nanocrystal Heterostructures

    SciTech Connect

    Peng, X.; Wong, S.

    2009-04-01

    The importance of generating carbon nanotube-nanoparticle heterostructures is that these composites ought to take advantage of and combine the unique physical and chemical properties of both carbon nanotubes and nanoparticles in one discrete structure. These materials have potential applicability in a range of diverse fields spanning heterogeneous catalysis to optoelectronic device development, of importance to chemists, physicists, materials scientists, and engineers. In this critical review, we present a host of diverse, complementary strategies for the reliable synthesis of carbon nanotube-nanoparticle heterostructures using both covalent as well as non-covalent protocols, incorporating not only single-walled and multi-walled carbon nanotubes but also diverse classes of metallic and semiconducting nanoparticles.

  5. Free standing carbon nanotubes growth on large-area by nanoimprint and plasma-enhanced chemical vapor deposition.

    NASA Astrophysics Data System (ADS)

    Chang, Won Seok; Choi, Dae-Geon; Chung, Jun-Ho; Huh, Kab-Soo

    2008-03-01

    Among various synthesis methods for carbon nanotube growth, chemical vapor deposition (CVD) method has been widely used for various advantages such as high quality, vertical alignment, controlled diameter and length of nanotubes and so on. Especially, vertically aligned multi-wall carbon nanotube could be grown using plasma-enhanced chemical vapor deposition (PECVD). In this paper, we presented growth of free standing carbon nanotubes by PECVD for the fabrication of nano-electrode. For the growth of nanotubes on the large area 50 mm x 50 mm, catalyst dots were formed by nanoimprint and lift-off process. The synthesis of carbon nanotube requires a metal catalyst layer, etchant gas, and a carbon source. Ammonia (NH3) and acetylene (C2H2) were used as the etchant gas and carbon source, respectively. And iron (Fe) of catalyst metal was deposited on silicon wafer substrates. To form Fe nano dots with diameter of 150 nm and thickness of 50 nm, nano holes patterned imprint resin was used for lift-off process. Carbon nanotubes were grown on pretreated substrates at approximately 30% C2H2:NH3 flow ratios for 40 min.

  6. Selective functionalization of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)

    2009-01-01

    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

  7. PECVD Growth of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    McAninch, Ian; Arnold, James O. (Technical Monitor)

    2001-01-01

    Plasma enhanced chemical vapor deposition (PECVD), using inductively coupled plasma, has been used to grow carbon nanotubes (CNTs) and graphitic carbon fibers (GCF) on substrates sputtered with aluminum and iron catalyst. The capacitive plasma's power has been shown to cause a transition from nanotubes to nanofibers, depending on the strength of the plasma. The temperature, placement, and other factors have been shown to affect the height and density of the tube and fiber growth.

  8. Focused-Ion-Beam-Milled Carbon Nanoelectrodes for Scanning Electrochemical Microscopy

    PubMed Central

    Chen, Ran; Hu, Keke; Yu, Yun; Mirkin, Michael V.; Amemiya, Shigeru

    2016-01-01

    Nanoscale scanning electrochemical microscopy (SECM) has emerged as a powerful electrochemical method that enables the study of interfacial reactions with unprecedentedly high spatial and kinetic resolution. In this work, we develop carbon nanoprobes with high electrochemical reactivity and well-controlled size and geometry based on chemical vapor deposition of carbon in quartz nanopipets. Carbon-filled nanopipets are milled by focused ion beam (FIB) technology to yield a flat disk tip with a thin quartz sheath as confirmed by transmission electron microscopy. The extremely high electroactivity of FIB-milled carbon nanotips is quantified by enormously high standard electron-transfer rate constants of ≥10 cm/s for Ru(NH3)63+. The tip size and geometry are characterized in electrolyte solutions by SECM approach curve measurements not only to determine inner and outer tip radii of down to ~27 and ~38 nm, respectively, but also to ensure the absence of a conductive carbon layer on the outer wall. In addition, FIB-milled carbon nanotips reveal the limited conductivity of ~100 nm-thick gold films under nanoscale mass-transport conditions. Importantly, carbon nanotips must be protected from electrostatic damage to enable reliable and quantitative nanoelectrochemical measurements.

  9. Nanotechnology with Carbon Nanotubes: Mechanics, Chemistry, and Electronics

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak

    2003-01-01

    This viewgraph presentation reviews the Nanotechnology of carbon nanotubes. The contents include: 1) Nanomechanics examples; 2) Experimental validation of nanotubes in composites; 3) Anisotropic plastic collapse; 4) Spatio-temporal scales, yielding single-wall nanotubes; 5) Side-wall functionalization of nanotubes; 6) multi-wall Y junction carbon nanotubes; 7) Molecular electronics with Nanotube junctions; 8) Single-wall carbon nanotube junctions; welding; 9) biomimetic dendritic neurons: Carbon nanotube, nanotube electronics (basics), and nanotube junctions for Devices,

  10. Connecting carbon nanotubes using Sn.

    PubMed

    Mittal, Jagjiwan; Lin, Kwang Lung

    2013-08-01

    Process of Sn coating on mutiwalled carbon nanotubes (MWCNT) and formation of interconnections among nanotubes are studied using high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDX). Surface oxidation of nanotubes during heating with HNO3 prior to the SnCl2 treatment and the bonding between functional groups and Sn are found to be responsible for the coating and its stability. Open nanotubes are filled as well as coated during tin chloride treatment. Coating and filling are converted into the coatings on the inner as well as outer walls of the nanotubes during reduction with H2/N2. EDX studies show the formation of intermetallic compounds e.g., Cu6Sn5 and Cu3Sn at the joints between nanotubes. Formation of intermetallic compounds is supposed to be responsible for providing the required strength for bending and twisting of nanotubes joining of nanotubes. Paper presents a detailed mechanism of coating and filling processes, and interconnections among nanotubes. PMID:23882800

  11. Carbon Nanotube Purification

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor); Delzeit, Clement J. (Inventor)

    2005-01-01

    A method for cleaning or otherwise removing amorphous carbon and other residues that arise in growth of a carbon nanotube (CNT) array. The CNT array is exposed to a plurality of hydroxyls or hydrogen, produced from a selected vapor or liquid source such as H2O or H2O2. and the hydroxyls or hydrogen (neutral or electrically charged) react with the residues to produce partly or fully dissolved or hydrogenated or hydroxylizated products that can be removed or separated from the CNT array. The hydroxyls or hydrogen can be produced by heating the CNT array, residue and selected vapor or liquid source or by application of an electromagnetic excitation signal with a selected frequency or range of frequencies to dissociate the selected vapor or liquid. The excitation frequency can be chirped to cover a selected range of frequencies corresponding to dissociation of the selected vapor or liquid. Sonication may be uscd to supplement dissociation of the H2O and/or H2O2.

  12. Carbon Nanotubes for Polymer Photovoltaics

    NASA Astrophysics Data System (ADS)

    Anctil, Annick; Dileo, Roberta; Schauerman, Chris; Landi, Brian; Raffaelle, Ryne

    2007-03-01

    Carbon nanotubes are being investigated for optical absorption, exciton dissociation, and carrier transport in polymer photovoltaic devices. In the present work, single wall carbon nanotubes (SWNTs) were synthesized by an Alexandrite pulsed laser vaporization reactor at standard conditions and purified based upon our previously reported TOP procedure. The SWNTs were dispersed in polymer composites for pure MEH-PPV, pure P3HT, and [C60]-PCBM-P3HT (1:1 by weight) as a function of nanotube weight loading (0.1 -- 5% w/w). The AM0 current-voltage measurements for structures sandwiched between PEDOT/PSS coated ITO substrates and an evaporated aluminum contact demonstrate the dramatic effect of SWNT content on the short circuit current density, with conversions efficiencies consistently greater than 1%. The temperature coefficient for nanotube-containing polymer photovoltaics has been compared to conventional PCBM-P3HT devices, and the general relationship of increasing efficiency with increasing temperature is observed. However, the necessity to control nanotube percolation to prevent device shunting has led to recent developments which focus on controlling nanotube length through oxidative cutting, the deposition of intrinsic polymer layers, and the use of aligned carbon nanotube arrays for preferential charge transport.

  13. Occupational Exposure to Carbon Nanotubes and Nanofibers

    MedlinePlus

    ... Current Intelligence Bulletin 65: Occupational Exposure to Carbon Nanotubes and Nanofibers Recommend on Facebook Tweet Share Compartir ... composed of engineered nanoparticles, such as metal oxides, nanotubes, nanowires, quantum dots, and carbon fullerenes (buckyballs), among ...

  14. Probing Photosensitization by Functionalized Carbon Nanotubes

    EPA Science Inventory

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

  15. Carbon Nanotube Based Molecular Electronics

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1998-01-01

    Carbon nanotubes and the nanotube heterojunctions have recently emerged as excellent candidates for nanoscale molecular electronic device components. Experimental measurements on the conductivity, rectifying behavior and conductivity-chirality correlation have also been made. While quasi-one dimensional simple heterojunctions between nanotubes with different electronic behavior can be generated by introduction of a pair of heptagon-pentagon defects in an otherwise all hexagon graphene sheet. Other complex 3- and 4-point junctions may require other mechanisms. Structural stability as well as local electronic density of states of various nanotube junctions are investigated using a generalized tight-binding molecular dynamics (GDBMD) scheme that incorporates non-orthogonality of the orbitals. The junctions investigated include straight and small angle heterojunctions of various chiralities and diameters; as well as more complex 'T' and 'Y' junctions which do not always obey the usual pentagon-heptagon pair rule. The study of local density of states (LDOS) reveal many interesting features, most prominent among them being the defect-induced states in the gap. The proposed three and four pointjunctions are one of the smallest possible tunnel junctions made entirely of carbon atoms. Furthermore the electronic behavior of the nanotube based device components can be taylored by doping with group III-V elements such as B and N, and BN nanotubes as a wide band gap semiconductor has also been realized in experiments. Structural properties of heteroatomic nanotubes comprising C, B and N will be discussed.

  16. Multiscale Modeling with Carbon Nanotubes

    SciTech Connect

    Maiti, A

    2006-02-21

    Technologically important nanomaterials come in all shapes and sizes. They can range from small molecules to complex composites and mixtures. Depending upon the spatial dimensions of the system and properties under investigation computer modeling of such materials can range from equilibrium and nonequilibrium Quantum Mechanics, to force-field-based Molecular Mechanics and kinetic Monte Carlo, to Mesoscale simulation of evolving morphology, to Finite-Element computation of physical properties. This brief review illustrates some of the above modeling techniques through a number of recent applications with carbon nanotubes: nano electromechanical sensors (NEMS), chemical sensors, metal-nanotube contacts, and polymer-nanotube composites.

  17. Large-Scale Processing of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Finn, John; Sridhar, K. R.; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    1998-01-01

    Scale-up difficulties and high energy costs are two of the more important factors that limit the availability of various types of nanotube carbon. While several approaches are known for producing nanotube carbon, the high-powered reactors typically produce nanotubes at rates measured in only grams per hour and operate at temperatures in excess of 1000 C. These scale-up and energy challenges must be overcome before nanotube carbon can become practical for high-consumption structural and mechanical applications. This presentation examines the issues associated with using various nanotube production methods at larger scales, and discusses research being performed at NASA Ames Research Center on carbon nanotube reactor technology.

  18. Dispersions of Carbon nanotubes in Polymer Matrices

    NASA Technical Reports Server (NTRS)

    Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

    2010-01-01

    Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

  19. Carbon nanotube-polymer composite actuators

    DOEpatents

    Gennett, Thomas; Raffaelle, Ryne P.; Landi, Brian J.; Heben, Michael J.

    2008-04-22

    The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

  20. Gears Based on Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Jaffe, Richard; Han, Jie; Globus, Al; Deardorff, Glenn

    2005-01-01

    Gears based on carbon nanotubes (see figure) have been proposed as components of an emerging generation of molecular- scale machines and sensors. In comparison with previously proposed nanogears based on diamondoid and fullerene molecules, the nanotube-based gears would have simpler structures and are more likely to be realizable by practical fabrication processes. The impetus for the practical development of carbon-nanotube- based gears arises, in part, from rapid recent progress in the fabrication of carbon nanotubes with prescribed diameters, lengths, chiralities, and numbers of concentric shells. The shafts of the proposed gears would be made from multiwalled carbon nanotubes. The gear teeth would be rigid molecules (typically, benzyne molecules), bonded to the nanotube shafts at atomically precise positions. For fabrication, it may be possible to position the molecular teeth by use of scanning tunneling microscopy (STM) or other related techniques. The capability to position individual organic molecules at room temperature by use of an STM tip has already been demonstrated. Routes to the chemical synthesis of carbon-nanotube-based gears are also under investigation. Chemical and physical aspects of the synthesis of molecular scale gears based on carbon nanotubes and related molecules, and dynamical properties of nanotube- based gears, have been investigated by computational simulations using established methods of quantum chemistry and molecular dynamics. Several particularly interesting and useful conclusions have been drawn from the dynamical simulations performed thus far: The forces acting on the gears would be more sensitive to local molecular motions than to gross mechanical motions of the overall gears. Although no breakage of teeth or of chemical bonds is expected at temperatures up to at least 3,000 K, the gears would not work well at temperatures above a critical range from about 600 to about 1,000 K. Gear temperature could probably be controlled by

  1. CMOS Integrated Carbon Nanotube Sensor

    SciTech Connect

    Perez, M. S.; Lerner, B.; Boselli, A.; Lamagna, A.; Obregon, P. D. Pareja; Julian, P. M.; Mandolesi, P. S.; Buffa, F. A.

    2009-05-23

    Recently carbon nanotubes (CNTs) have been gaining their importance as sensors for gases, temperature and chemicals. Advances in fabrication processes simplify the formation of CNT sensor on silicon substrate. We have integrated single wall carbon nanotubes (SWCNTs) with complementary metal oxide semiconductor process (CMOS) to produce a chip sensor system. The sensor prototype was designed and fabricated using a 0.30 um CMOS process. The main advantage is that the device has a voltage amplifier so the electrical measure can be taken and amplified inside the sensor. When the conductance of the SWCNTs varies in response to media changes, this is observed as a variation in the output tension accordingly.

  2. Photodetector based on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pavlov, A.; Kitsyuk, E.; Ryazanov, R.; Timoshenkov, V.; Adamov, Y.

    2015-09-01

    Photodetector based on carbon nanotubes (CNT) was investigated. Sensors were done on quartz and silicon susbtrate. Samples of photodetectors sensors were produced by planar technology. This technology included deposition of first metal layer (Al), lithography for pads formation, etching, and formation of local catalyst area by inverse lithography. Vertically-aligned multi-wall carbon nanotubes were directly synthesized on substrate by PECVD method. I-V analysis and spectrum sensitivity of photodetector were investigated for 0.4 μm - 1.2 μm wavelength. Resistivity of CNT layers over temperature was detected in the range of -20°C to 100°C.

  3. All carbon nanotubes are not created equal

    SciTech Connect

    Geohegan, David B; Puretzky, Alexander A; Rouleau, Christopher M

    2010-01-01

    This chapter presents the various factors that enter into consideration when choosing the source of carbon nanotubes for a specific application. Carbon nanotubes are giant molecules made of pure carbon. They have captured the imagination of the scientific community by the unique structure that provides superior physical, chemical, and electrical properties. However, a surprisingly wide disparity exists between the intrinsic properties determined under ideal conditions and the properties that carbon nanotubes exhibit in real world situations. The lack of uniformity in carbon nanotube properties is likely to be the main obstacle holding back the development of carbon nanotube applications. This tutorial addresses the nonuniformity of carbon nanotube properties from the synthesis standpoint. This synthesis-related nonuniformity is on top of the intrinsic chirality distribution that gives the ~1:2 ratio of metallic to semiconducting nanotubes. From the standpoint of carbon bonding chemistry the variation in the quality and reproducibility of carbon nanotube materials is not unexpected. It is an intrinsic feature that is related to the metastability of carbon structures. The extent to which this effect is manifested in carbon nanotube formation is governed by the type and the kinetics of the carbon nanotube synthesis reaction. Addressing this variation is critical if nanotubes are to live up to the potential already demonstrated by their phenomenal physical properties.

  4. EDITORIAL: Focus on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    2003-09-01

    The study of carbon nanotubes, since their discovery by Iijima in 1991, has become a full research field with significant contributions from all areas of research in solid-state and molecular physics and also from chemistry. This Focus Issue in New Journal of Physics reflects this active research, and presents articles detailing significant advances in the production of carbon nanotubes, the study of their mechanical and vibrational properties, electronic properties and optical transitions, and electrical and transport properties. Fundamental research, both theoretical and experimental, represents part of this progress. The potential applications of nanotubes will rely on the progress made in understanding their fundamental physics and chemistry, as presented here. We believe this Focus Issue will be an excellent guide for both beginners and experts in the research field of carbon nanotubes. It has been a great pleasure to edit the many excellent contributions from Europe, Japan, and the US, as well from a number of other countries, and to witness the remarkable effort put into the manuscripts by the contributors. We thank all the authors and referees involved in the process. In particular, we would like to express our gratitude to Alexander Bradshaw, who invited us put together this Focus Issue, and to Tim Smith and the New Journal of Physics staff for their extremely efficient handling of the manuscripts. Focus on Carbon Nanotubes Contents Transport theory of carbon nanotube Y junctions R Egger, B Trauzettel, S Chen and F Siano The tubular conical helix of graphitic boron nitride F F Xu, Y Bando and D Golberg Formation pathways for single-wall carbon nanotube multiterminal junctions Inna Ponomareva, Leonid A Chernozatonskii, Antonis N Andriotis and Madhu Menon Synthesis and manipulation of carbon nanotubes J W Seo, E Couteau, P Umek, K Hernadi, P Marcoux, B Lukic, Cs Mikó, M Milas, R Gaál and L Forró Transitional behaviour in the transformation from active end

  5. Synthesis of carbon nanotubes and nanotube forests on copper catalyst

    NASA Astrophysics Data System (ADS)

    Kruszka, Bartosz; Terzyk, Artur P.; Wiśniewski, Marek; Gauden, Piotr A.; Szybowicz, Mirosław

    2014-09-01

    The growth of carbon nanotubes on bulk copper is studied. We show for the first time, that super growth chemical vapor deposition method can be successfully applied for preparation of nanotubes on copper catalyst, and the presence of hydrogen is necessary. Next, different methods of copper surface activation are studied, to improve catalyst efficiency. Among them, applied for the first time for copper catalyst in nanotubes synthesis, sulfuric acid activation is the most promising. Among tested samples the surface modified for 10 min is the most active, causing the growth of vertically aligned carbon nanotube forests. Obtained results have potential importance in application of nanotubes and copper in electronic chips and nanodevices.

  6. Modified carbon nanotubes and methods of forming carbon nanotubes

    DOEpatents

    Heintz, Amy M.; Risser, Steven; Elhard, Joel D.; Moore, Bryon P.; Liu, Tao; Vijayendran, Bhima R.

    2016-06-14

    In this invention, processes which can be used to achieve stable doped carbon nanotubes are disclosed. Preferred CNT structures and morphologies for achieving maximum doping effects are also described. Dopant formulations and methods for achieving doping of a broad distribution of tube types are also described.

  7. Formation of ice nanotube with hydrophobic guests inside carbon nanotube.

    PubMed

    Tanaka, Hideki; Koga, Kenichiro

    2005-09-01

    A composite ice nanotube inside a carbon nanotube has been explored by molecular-dynamics and grand canonical Monte Carlo simulations. It is made from an octagonal ice nanotube whose hollow space contains hydrophobic guest molecules such as neon, argon, and methane. It is shown that the attractive interaction of the guest molecules stabilizes the ice nanotube. The guest occupancy of the hollow space is calculated by the same method as applied to clathrate hydrates. PMID:16164361

  8. Hydrogen storage in carbon nanotubes.

    PubMed

    Hirscher, M; Becher, M

    2003-01-01

    The article gives a comprehensive overview of hydrogen storage in carbon nanostructures, including experimental results and theoretical calculations. Soon after the discovery of carbon nanotubes in 1991, different research groups succeeded in filling carbon nanotubes with some elements, and, therefore, the question arose of filling carbon nanotubes with hydrogen by possibly using new effects such as nano-capillarity. Subsequently, very promising experiments claiming high hydrogen storage capacities in different carbon nanostructures initiated enormous research activity. Hydrogen storage capacities have been reported that exceed the benchmark for automotive application of 6.5 wt% set by the U.S. Department of Energy. However, the experimental data obtained with different methods for various carbon nanostructures show an extreme scatter. Classical calculations based on physisorption of hydrogen molecules could not explain the high storage capacities measured at ambient temperature, and, assuming chemisorption of hydrogen atoms, hydrogen release requires temperatures too high for technical applications. Up to now, only a few calculations and experiments indicate the possibility of an intermediate binding energy. Recently, serious doubt has arisen in relation to several key experiments, causing considerable controversy. Furthermore, high hydrogen storage capacities measured for carbon nanofibers did not survive cross-checking in different laboratories. Therefore, in light of today's knowledge, it is becoming less likely that at moderate pressures around room temperature carbon nanostructures can store the amount of hydrogen required for automotive applications. PMID:12908227

  9. Effect of Carbon Nanotubes on Mammalian Cells

    NASA Astrophysics Data System (ADS)

    Chen, Michelle; Ahmed, Asma; Black, Melanie; Kawamoto, Nicole; Lucas, Jessica; Pagala, Armie; Pham, Tram; Stankiewicz, Sara; Chen, Howard

    2010-03-01

    Carbon Nanotubes possess extraordinary electrical, mechanical, and thermal properties. Research on applying the carbon nanotubes for ultrasensitive detection, disease diagnosis, and drug delivery is rapidly developing. While the fundamental and technological findings on carbon nanotubes show great promise, it is extremely important to investigate the effect of the carbon nanotubes on human health. In our experiments, we introduce purified carbon nanotubes in suspension to ovary cells cultured from Hamsters. These cells are chosen since they show robust morphological changes associated with cytotoxicity that can easily be observed under a light microscope. We will discuss the toxicity of carbon nanotubes by characterizing the cell morphology and viability as a function of time and the concentration of carbon nanotube suspension.

  10. Carbon Nanotube Material Quality Assessment

    NASA Technical Reports Server (NTRS)

    Yowell, Leonard; Arepalli, Sivaram; Sosa, Edward; Niolaev, Pavel; Gorelik, Olga

    2006-01-01

    The nanomaterial activities at NASA Johnson Space Center focus on carbon nanotube production, characterization and their applications for aerospace systems. Single wall carbon nanotubes are produced by arc and laser methods. Characterization of the nanotube material is performed using the NASA JSC protocol developed by combining analytical techniques of SEM, TEM, UV-VIS-NIR absorption, Raman, and TGA. A possible addition of other techniques such as XPS, and ICP to the existing protocol will be discussed. Changes in the quality of the material collected in different regions of the arc and laser production chambers is assessed using the original JSC protocol. The observed variations indicate different growth conditions in different regions of the production chambers.

  11. Plasma CVD of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance; Cruden, B.; Hash, D.; Meyyappan, M.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    Carbon nanotubes(CNT) exhibit remarkable mechanical and unique electronic properties and thus have created excitement in the research community about their potential in electronics, computing, sensor and structural applications. Realization of these applications critically depends on the ability to control the properties(such as diameter, chirality) as well purity. We have investigated CNT growth using an inductively coupled plasma(ICP) process using hydrocarbon feedstock. The catalyst required for nanotube growth consists of thin sputtered layers of aluminum and iron(10 nm each) and aligned carbon nanotubes have been obtained. Optical emission diagnostics as well as a plasma modeling effort have been undertaken to understand growth mechanisms. This presentation will discuss growth characteristics under various pressure, power and feedgas compositions and our understanding from modeling and diagnostics.

  12. Conductance Oscillations in Squashed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Mehrez, H.; Anantram, M. P.; Svizhenko, A.

    2003-01-01

    A combination of molecular dynamics and electrical conductance calculations are used to probe the electromechanical properties of squashed metallic carbon nanotubes. We find that the conductance and bandgap of armchair nanotubes show oscillations upon squashing. The physical origin of these oscillations is attributed to interaction of carbon atoms with a fourth neighbor. Squashing of armchair and zigzag nanotubes ultimately leads to metallic behavior.

  13. Supported lipid bilayer/carbon nanotube hybrids

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian; Moran-Mirabal, Jose M.; Craighead, Harold G.; McEuen, Paul L.

    2007-03-01

    Carbon nanotube transistors combine molecular-scale dimensions with excellent electronic properties, offering unique opportunities for chemical and biological sensing. Here, we form supported lipid bilayers over single-walled carbon nanotube transistors. We first study the physical properties of the nanotube/supported lipid bilayer structure using fluorescence techniques. Whereas lipid molecules can diffuse freely across the nanotube, a membrane-bound protein (tetanus toxin) sees the nanotube as a barrier. Moreover, the size of the barrier depends on the diameter of the nanotube-with larger nanotubes presenting bigger obstacles to diffusion. We then demonstrate detection of protein binding (streptavidin) to the supported lipid bilayer using the nanotube transistor as a charge sensor. This system can be used as a platform to examine the interactions of single molecules with carbon nanotubes and has many potential applications for the study of molecular recognition and other biological processes occurring at cell membranes.

  14. Redox sorting of carbon nanotubes.

    PubMed

    Gui, Hui; Streit, Jason K; Fagan, Jeffrey A; Hight Walker, Angela R; Zhou, Chongwu; Zheng, Ming

    2015-03-11

    This work expands the redox chemistry of single-wall carbon nanotubes (SWCNTs) by investigating its role in a number of SWCNT sorting processes. Using a polyethylene glycol (PEG)/dextran (DX) aqueous two-phase system, we show that electron-transfer between redox molecules and SWCNTs triggers reorganization of the surfactant coating layer, leading to strong modulation of nanotube partition in the two phases. While the DX phase is thermodynamically more favored by an oxidized SWCNT mixture, the mildly reducing PEG phase is able to recover SWCNTs from oxidation and extract them successively from the DX phase. Remarkably, the extraction order follows SWCNT bandgap: semiconducting nanotubes of larger bandgap first, followed by semiconducting nanotubes of smaller bandgap, then nonarmchair metallic tubes of small but nonvanishing bandgap, and finally armchair metallic nanotubes of zero bandgap. Furthermore, we show that redox-induced surfactant reorganization is a common phenomenon, affecting nanotube buoyancy in a density gradient field, affinity to polymer matrices, and solubility in organic solvents. These findings establish redox modulation of surfactant coating structures as a general mechanism for tuning a diverse range of SWCNT sorting processes and demonstrate for the first time that armchair and nonarmchair metallic SWCNTs can be separated by their differential response to redox. PMID:25719939

  15. Conductance of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Datta, Supriyo; Anatram, M. P.

    1998-01-01

    The recent report of quantized conductance in a 4 m long multiwalled nanotube (MWNT) raises the exciting possibility of ballistic transport at room temperature over relatively long distances. We argue that this is made possible by the special symmetry of the eigenstates of the lowest propagating modes in metallic nanotubes which suppresses backscattering. This unusual effect is absent for the higher propagating modes so that transport is not ballistic once the bias exceeds the cut-off energy for the higher modes, which is estimated to be approximately 75 meV for nanotubes of diameter approximately 15 nm. Also, we show that the symmetry of the eigenstates can significantly affect their coupling to the reservoir and hence the contact resistance. A simple model is presented that can be used to understand the observed conductance-voltage characteristics.

  16. Thermoelectrics: Carbon nanotubes get high

    NASA Astrophysics Data System (ADS)

    Crispin, Xavier

    2016-04-01

    Waste heat can be converted to electricity by thermoelectric generators, but their development is hindered by the lack of cheap materials with good thermoelectric properties. Now, carbon-nanotube-based materials are shown to have improved properties when purified to contain only semiconducting species and then doped.

  17. Terahertz detection and carbon nanotubes

    ScienceCinema

    Leonard, Francois

    2014-06-13

    Researchers at Sandia National Laboratories, along with collaborators from Rice University and the Tokyo Institute of Technology, are developing new terahertz detectors based on carbon nanotubes that could lead to significant improvements in medical imaging, airport passenger screening, food inspection and other applications.

  18. Terahertz detection and carbon nanotubes

    SciTech Connect

    Leonard, Francois

    2014-06-11

    Researchers at Sandia National Laboratories, along with collaborators from Rice University and the Tokyo Institute of Technology, are developing new terahertz detectors based on carbon nanotubes that could lead to significant improvements in medical imaging, airport passenger screening, food inspection and other applications.

  19. Carbon Nanotubes and Human Cells?

    ERIC Educational Resources Information Center

    King, G. Angela

    2005-01-01

    Single-walled carbon nanotubes that were chemically altered to be water soluble are shown to enter fibroblasts, T cells, and HL60 cells. Nanoparticles adversely affect immortalized HaCaT human keratinocyte cultures, indicating that they may enter cells.

  20. Carbon nanotubes by the metallocene route

    NASA Astrophysics Data System (ADS)

    Sen, Rahul; Govindaraj, A.; Rao, C. N. R.

    1997-03-01

    Pyrolysis of metallocenes such as ferrocene, cobaltocene and nickelocene, is shown to yield carbon nanotubes and metal-filled onion-like structures. Pyrolysis of benzene in the presence of a metallocene gives high yields of nanotubes, the wall thickness of the nanotubes depending on the metallocene content. Pyrolysis of benzene in the absence of any metal however gives monodispersed nanospheres of carbon rather than nanotubes.

  1. Endohedral impurities in carbon nanotubes.

    PubMed

    Clougherty, Dennis P

    2003-01-24

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value. The effective potential is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale. PMID:12570507

  2. Endohedral Impurities in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis P.

    2003-01-01

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value. The effective potential is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale.

  3. Carbon-Nanotube Schottky Diodes

    NASA Technical Reports Server (NTRS)

    Manohara, Harish; Wong, Eric; Schlecht, Erich; Hunt, Brian; Siegel, Peter

    2006-01-01

    Schottky diodes based on semiconducting single-walled carbon nanotubes are being developed as essential components of the next generation of submillimeter-wave sensors and sources. Initial performance predictions have shown that the performance characteristics of these devices can exceed those of the state-of-the-art solid-state Schottky diodes that have been the components of choice for room-temperature submillimeter-wave sensors for more than 50 years. For state-of-the-art Schottky diodes used as detectors at frequencies above a few hundred gigahertz, the inherent parasitic capacitances associated with their semiconductor junction areas and the resistances associated with low electron mobilities limit achievable sensitivity. The performance of such a detector falls off approximately exponentially with frequency above 500 GHz. Moreover, when used as frequency multipliers for generating signals, state-of-the-art solid-state Schottky diodes exhibit extremely low efficiencies, generally putting out only micro-watts of power at frequencies up to 1.5 THz. The shortcomings of the state-of-the-art solid-state Schottky diodes can be overcome by exploiting the unique electronic properties of semiconducting carbon nanotubes. A single-walled carbon nanotube can be metallic or semiconducting, depending on its chirality, and exhibits high electron mobility (recently reported to be approx.= 2x10(exp 5)sq cm/V-s) and low parasitic capacitance. Because of the narrowness of nanotubes, Schottky diodes based on carbon nanotubes have ultra-small junction areas (of the order of a few square nanometers) and consequent junction capacitances of the order of 10(exp -18) F, which translates to cutoff frequency >5 THz. Because the turn-on power levels of these devices are very low (of the order of nano-watts), the input power levels needed for pumping local oscillators containing these devices should be lower than those needed for local oscillators containing state-of-the-art solid

  4. Electrochemical impedance measurement of a carbon nanotube probe electrode.

    PubMed

    Inaba, Akira; Takei, Yusuke; Kan, Tetsuo; Matsumoto, Kiyoshi; Shimoyama, Isao

    2012-12-01

    We measured and analyzed the electrochemical impedance of carbon nanotube (CNT) probe electrodes fabricated through the physical separation of insulated CNT bridges. The fabricated CNT electrodes were free-standing CNTs that were completely covered with an insulator, except for their tips. Typical dimensions of the nanoelectrodes were 1-10 nm in CNT diameter, 80-300 nm in insulator diameter, 0.5-4 μm in exposed CNT length and 1-10 μm in probe length. The electrochemical impedance at frequencies ranging from 40 Hz to 1 MHz was measured in physiological saline. The measured impedance of the CNT electrode was constant at 32 MΩ at frequencies below 1 kHz and was inversely proportional to frequency at frequencies above 10 kHz. By means of comparison with the parasitic capacitive impedance of the insulator membrane, we confirmed that the electrode was sufficiently insulated such that the measured constant impedance was given by the exposed CNT tip. Consequently, we can use the CNT electrode for highly localized electrochemical impedance measurements below 1 kHz. Considering an equivalent circuit and the nanoscopic dimensions of the CNT electrode, we demonstrated that the constant impedance was governed by diffusion impedance, whereas the solution resistance, charge-transfer resistance and double-layer capacitance were negligible. PMID:23124171

  5. Quantum transport in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.; Grove-Rasmussen, Kasper; Nygârd, Jesper; Flensberg, Karsten; Kouwenhoven, Leo P.

    2015-07-01

    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike in conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and valley freedom. The interplay between the two is the focus of this review. The energy levels associated with each degree of freedom, and the spin-orbit coupling between them, are explained, together with their consequences for transport measurements through nanotube quantum dots. In double quantum dots, the combination of quantum numbers modifies the selection rules of Pauli blockade. This can be exploited to read out spin and valley qubits and to measure the decay of these states through coupling to nuclear spins and phonons. A second unique property of carbon nanotubes is that the combination of valley freedom and electron-electron interactions in one dimension strongly modifies their transport behavior. Interaction between electrons inside and outside a quantum dot is manifested in SU(4) Kondo behavior and level renormalization. Interaction within a dot leads to Wigner molecules and more complex correlated states. This review takes an experimental perspective informed by recent advances in theory. As well as the well-understood overall picture, open questions for the field are also clearly stated. These advances position nanotubes as a leading system for the study of spin and valley physics in one dimension where electronic disorder and hyperfine interaction can both be reduced to a low level.

  6. Roping and wrapping carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ausman, Kevin D.; O'Connell, Michael J.; Boul, Peter; Ericson, Lars M.; Casavant, Michael J.; Walters, Deron A.; Huffman, Chad; Saini, Rajesh; Wang, Yuhuang; Haroz, Erik; Billups, Edward W.; Smalley, Richard E.

    2001-11-01

    Single-walled carbon nanotubes can be dispersed into solvents by ultrasonication to the point that primarily individual tubes, cut to a few hundred nanometers in length, are present. However, when such dispersions are filtered to a thick mat, or paper, only tangles of uniform, seemingly endless ropes are observed. The factors contributing to this "roping" phenomenon, akin to aggregation or crystallization, will be discussed. We have developed methods for generating "super-ropes" more than twenty times the diameter of those formed by filtration, involving the extraction of nanotube material from an oleum dispersion. Nanotubes have been solubilized in water, largely individually, by non-covalently wrapping them with linear polymers. The general thermodynamic drive for this wrapping involves the polymer disrupting both the hydrophobic interface with water and the smooth tube-tube interaction in aggregates. The nanotubes can be recovered from their polymeric wrapping by changing their solvent system. This solubilization process opens the door to solution chemistry on pristine nanotubes, as well as their introduction into biologically relevant systems.

  7. Carbon nanotube coatings as chemical absorbers

    DOEpatents

    Tillotson, Thomas M.; Andresen, Brian D.; Alcaraz, Armando

    2004-06-15

    Airborne or aqueous organic compound collection using carbon nanotubes. Exposure of carbon nanotube-coated disks to controlled atmospheres of chemical warefare (CW)-related compounds provide superior extraction and retention efficiencies compared to commercially available airborne organic compound collectors. For example, the carbon nanotube-coated collectors were four (4) times more efficient toward concentrating dimethylmethyl-phosphonate (DMMP), a CW surrogate, than Carboxen, the optimized carbonized polymer for CW-related vapor collections. In addition to DMMP, the carbon nanotube-coated material possesses high collection efficiencies for the CW-related compounds diisopropylaminoethanol (DIEA), and diisopropylmethylphosphonate (DIMP).

  8. Twisting Graphene into Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kit, Oleg O.; Tallinen, Tuomas; Mahadevan, L.; Timonen, Jussi; Koskinen, Pekka

    2012-02-01

    Carbon nanotubes are usually described as being rolled up from graphene sheets; this process, however, have never been realized experimentally. We showed that graphene can indeed be transformed into nanotube by twisting [1]. Further, we showed that tube formation can be well-explained within classical theory of elasticity---in fact the very mechanism of tube formation can be observed by twisting a strap from one's backpack (try now!). Furthermore, we showed that nanotube chirality may not only be predicted, but can also be controlled externally. The quantum molecular dynamic simulations at T=300K were achieved thanks to the revised periodic boundary conditions (RPBC) approach [2-3]. The structures similar to simulated have been recently observed experimentally [4]. This novel rote for nanotube formation opens new opportunities in nanomaterial manipulation not restricted to carbon alone. In the presentation, I will describe tube formation, as well as outline the easy and efficient technique for distorted nanostructures simulation, the RPBC approach. [4pt] [1] O. O. Kit et al. arXiv:1108.0048[0pt] [2] P. Koskinen & O. O. Kit PRL 105, 106401 (2010)[0pt] [3] O. O. Kit, L. Pastewka, P. Koskinen PRB 84, 155431 (2011)[0pt] [4] A. Chuvilin et al. Nature Materials 10, 687 (2011)

  9. Carbon Nanotubes - Polymer Composites with Enhanced Conductivity using Functionalized Nanotubes

    NASA Astrophysics Data System (ADS)

    Ramasubramaniam, Rajagopal; Chen, Jian; Gupta, Rishi

    2003-03-01

    Individual carbon nanotubes show superior electrical, mechanical and thermal properties [1]. Composite materials using carbon nanotubes as fillers are predicted to show similar superior properties. However, realization of such composites has been plagued by poor dispersion of carbon nanotubes in solvents and in polymer matrices. We have developed a method to homogenously disperse carbon nanotubes in polymer matrices using functionalized nanotubes [2]. Thin films of functionalized single walled nanotubes (SWNT) - polystyrene composites and functionalized SWNT - polycarbonate composites were prepared using solution evaporation and spin coating. Both of the composites show several orders of magnitude increase in conductivity for less than 1 wt thresholds of the composites are less than 0.2 wt nanotubes. We attribute the enhanced conduction to the superior dispersion of the functionalized nanotubes in the polymer matrix and to the reduced nanotube waviness resulting from the rigid backbone of the conjugated polymer. References: [1]. R. H. Baughman, A. A. Zakhidov and W. A. de Heer, Science v297, p787 (2002); [2]. J. Chen, H. Liu, W. A. Weimer, M. D. Halls, D. H. Waldeck and G. C. Walker, J. Am. Chem. Soc. v124, p9034 (2002).

  10. Carbon nanotube devices: Sorting, Assembling, Characterizing

    NASA Astrophysics Data System (ADS)

    Krupke, Ralph

    2009-03-01

    Carbon nanotubes have been studied extensively over the last decade. Various exceptional properties have been revealed which still drive the vision about using carbon nanotube in future electronics, for instance as molecular nanoscale transistors or electromigration resistant interconnects. For many years a major obstacle was the inability to grow nanotubes with defined dimensions (length, diameter) and electronic properties (metallic,semiconducting). Recently those problems have been solved to a large extent by advanced sorting techniques. Today the challenge is to assemble nanotubes devices with defined properties to form a complex circuitry. As progress is made in making highly-integrated nanotube device arrays new characterization techniques have to be developed which allow testing large number of devices within an acceptable time. Along this line I will report on the state-of-the-art of sorting of carbon nanotube, as a base for nanotube device fabrication [1]. I will then explain our strategy to assemble high-density arrays of nanotube devices [2] and discuss a new characterization technique for nanotube devices [3]. Finally I will introduce a novel device engineering tool [4]. [4pt] [1] R. Krupke et al., ``Separation techniques for carbon nanotubes'' in Chemistry of Carbon Nanotubes, p.129-139, American Scientific Publishers 2008[0pt] [2] A. Vijayaraghavan et al., ``Ultra-Large-Scale Directed Assembly of Single-Walled Carbon Nanotube Devices'', Nano Lett. 7 (2007) 1556-1560[0pt] [3] A. Vijayaraghavan et al., ``Imaging Electronic Structure of Carbon Nanotubes by Voltage-Contrast Scanning Electron Microscopy'', Nano Resarch 1 (2008) 321-332[0pt] [4] C. W. Marquardt et al., ``Reversible metal-insulator transitions in metallic single-walled carbon nanotubes'', Nano Lett. 9 (2008) 2767-2772

  11. Method of making carbon nanotube composite materials

    DOEpatents

    O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2014-05-20

    The present invention is a method of making a composite polymeric material by dissolving a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes and optionally additives in a solvent to make a solution and removing at least a portion of the solvent after casting onto a substrate to make thin films. The material has enhanced conductivity properties due to the blending of the un-functionalized and hydroxylated carbon nanotubes.

  12. Multilayer Film Assembly of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Cassell, Alan M.; Meyyappan, M.; Han, Jie; Arnold, J. (Technical Monitor)

    2000-01-01

    An approach to assemble multilayers of carbon nanotubes on a substrate is presented. Chemical vapor deposition using a transition metal catalyst formulation is used to grow the nanotubes. Results show a bilayer assembly of nanotubes each with a different density of tubes.

  13. Carbon Nanotubes: Molecular Electronic Components

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1997-01-01

    The carbon Nanotube junctions have recently emerged as excellent candidates for use as the building blocks in the formation of nanoscale molecular electronic networks. While the simple joint of two dissimilar tubes can be generated by the introduction of a pair of heptagon-pentagon defects in an otherwise perfect hexagonal graphene sheet, more complex joints require other mechanisms. In this work we explore structural characteristics of complex 3-point junctions of carbon nanotubes using a generalized tight-binding molecular-dynamics scheme. The study of pi-electron local densities of states (LDOS) of these junctions reveal many interesting features, most prominent among them being the defect-induced states in the gap.

  14. Torsional Carbon Nanotube Artificial Muscles

    NASA Astrophysics Data System (ADS)

    Foroughi, Javad; Spinks, Geoffrey M.; Wallace, Gordon G.; Oh, Jiyoung; Kozlov, Mikhail E.; Fang, Shaoli; Mirfakhrai, Tissaphern; Madden, John D. W.; Shin, Min Kyoon; Kim, Seon Jeong; Baughman, Ray H.

    2011-10-01

    Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

  15. From carbon nanobells to nickel nanotubes

    SciTech Connect

    Ma, S.; Srikanth, V. V. S. S.; Maik, D.; Zhang, G. Y.; Staedler, T.; Jiang, X.

    2009-01-05

    A generic strategy is proposed to prepare one dimensional (1D) metallic nanotubes by using 1D carbon nanostructures as the initial templates. Following the strategy, nickel (Ni) nanotubes are prepared by using carbon nanobells (CNBs) as the initial templates. CNBs are first prepared by microwave plasma enhanced chemical vapor deposition technique. Carbon/nickel core/shell structures are then prepared by electroplating the CNBs in a nickel-Watts electrolytic cell. In the final step, the carbon core is selectively removed by employing hydrogen plasma etching to obtain Ni nanotubes. The mechanism leading to Ni nanotubes is briefly discussed.

  16. EDITORIAL: Focus on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    2003-09-01

    The study of carbon nanotubes, since their discovery by Iijima in 1991, has become a full research field with significant contributions from all areas of research in solid-state and molecular physics and also from chemistry. This Focus Issue in New Journal of Physics reflects this active research, and presents articles detailing significant advances in the production of carbon nanotubes, the study of their mechanical and vibrational properties, electronic properties and optical transitions, and electrical and transport properties. Fundamental research, both theoretical and experimental, represents part of this progress. The potential applications of nanotubes will rely on the progress made in understanding their fundamental physics and chemistry, as presented here. We believe this Focus Issue will be an excellent guide for both beginners and experts in the research field of carbon nanotubes. It has been a great pleasure to edit the many excellent contributions from Europe, Japan, and the US, as well from a number of other countries, and to witness the remarkable effort put into the manuscripts by the contributors. We thank all the authors and referees involved in the process. In particular, we would like to express our gratitude to Alexander Bradshaw, who invited us put together this Focus Issue, and to Tim Smith and the New Journal of Physics staff for their extremely efficient handling of the manuscripts. Focus on Carbon Nanotubes Contents <;A article="1367-2630/5/1/117">Transport theory of carbon nanotube Y junctions R Egger, B Trauzettel, S Chen and F Siano The tubular conical helix of graphitic boron nitride F F Xu, Y Bando and D Golberg Formation pathways for single-wall carbon nanotube multiterminal junctions Inna Ponomareva, Leonid A Chernozatonskii, Antonis N Andriotis and Madhu Menon Synthesis and manipulation of carbon nanotubes J W Seo, E Couteau

  17. LDRD final report on carbon nanotube composites

    SciTech Connect

    Cahill, P.A.; Rand, P.B.

    1997-04-01

    Carbon nanotubes and their composites were examined using computational and experimental techniques in order to modify the mechanical and electrical properties of resins. Single walled nanotubes were the focus of the first year effort; however, sufficient quantities of high purity single walled nanotubes could not be obtained for mechanical property investigations. The unusually high electrical conductivity of composites loaded with <1% of multiwalled nanotubes is useful, and is the focus of continuing, externally funded, research.

  18. Carbon nanotube atomic force microscopy probes

    NASA Astrophysics Data System (ADS)

    Yamanaka, Shigenobu; Okawa, Takashi; Akita, Seiji; Nakayama, Yoshikazu

    2005-05-01

    We have developed a carbon nanotube atomic force microscope probe. Because the carbon nanotube are well known to have high aspect ratios, small tip radii and high stiffness, carbon nanotube probes have a long lifetime and can be applied for the observation deep trenches. Carbon nanotubes were synthesized by a well-controlled DC arc discharge method, because this method can make nanotubes to have straight shape and high crystalline. The nanotubes were aligned on the knife-edge using an alternating current electrophoresis technique. A commercially available Si probe was used for the base of the nanotube probe. The nanotube probe was fabricated by the SEM manipulation method. The nanotube was then attached tightly to the Si probe by deposition of amorphous carbon. We demonstrate the measurement of a fine pith grating that has vertical walls. However, a carbon nanotube has a problem that is called "Sticking". The sticking is a chatter image on vertical like region in a sample. We solved this problem by applying 2 methods, 1. a large cantilever vibration amplitude in tapping mode, 2. an attractive mode measurement. We demonstrate the non-sticking images by these methods.

  19. Improved Process for Fabricating Carbon Nanotube Probes

    NASA Technical Reports Server (NTRS)

    Stevens, R.; Nguyen, C.; Cassell, A.; Delzeit, L.; Meyyappan, M.; Han, Jie

    2003-01-01

    An improved process has been developed for the efficient fabrication of carbon nanotube probes for use in atomic-force microscopes (AFMs) and nanomanipulators. Relative to prior nanotube tip production processes, this process offers advantages in alignment of the nanotube on the cantilever and stability of the nanotube's attachment. A procedure has also been developed at Ames that effectively sharpens the multiwalled nanotube, which improves the resolution of the multiwalled nanotube probes and, combined with the greater stability of multiwalled nanotube probes, increases the effective resolution of these probes, making them comparable in resolution to single-walled carbon nanotube probes. The robust attachment derived from this improved fabrication method and the natural strength and resiliency of the nanotube itself produces an AFM probe with an extremely long imaging lifetime. In a longevity test, a nanotube tip imaged a silicon nitride surface for 15 hours without measurable loss of resolution. In contrast, the resolution of conventional silicon probes noticeably begins to degrade within minutes. These carbon nanotube probes have many possible applications in the semiconductor industry, particularly as devices are approaching the nanometer scale and new atomic layer deposition techniques necessitate a higher resolution characterization technique. Previously at Ames, the use of nanotube probes has been demonstrated for imaging photoresist patterns with high aspect ratio. In addition, these tips have been used to analyze Mars simulant dust grains, extremophile protein crystals, and DNA structure.

  20. Lipid Bilayers Covalently Anchored to Carbon Nanotubes

    PubMed Central

    Dayani, Yasaman; Malmstadt, Noah

    2012-01-01

    The unique physical and electrical properties of carbon nanotubes make them an exciting material for applications in various fields such as bioelectronics and biosensing. Due to the poor water solubility of carbon nanotubes, functionalization for such applications has been a challenge. Of particular need are functionalization methods for integrating carbon nanotubes with biomolecules and constructing novel hybrid nanostructures for bionanoelectronic applications. We present a novel method for the fabrication of dispersible, biocompatible carbon nanotube-based materials. Multi-walled carbon nanotubes (MWCNTs) are covalently modified with primary amine-bearing phospholipids in a carbodiimide-activated reaction. These modified carbon nanotubes have good dispersibility in nonpolar solvents. Fourier transform infrared (FTIR) spectroscopy shows peaks attributable to the formation of amide bonds between lipids and the nanotube surface. Simple sonication of lipid-modified nanotubes with other lipid molecules leads to the formation of a uniform lipid bilayer coating the nanotubes. These bilayer-coated nanotubes are highly dispersible and stable in aqueous solution. Confocal fluorescence microscopy shows labeled lipids on the surface of bilayer-modified nanotubes. Transmission electron microscopy (TEM) shows the morphology of dispersed bilayer-coated MWCNTs. Fluorescence quenching of lipid-coated MWCNTs confirms the bilayer configuration of the lipids on the nanotube surface and fluorescence anisotropy measurements show that the bilayer is fluid above the gel-to-liquid transition temperature. The membrane protein α-hemolysin spontaneously inserts into the MWCNT-supported bilayer, confirming the biomimetic membrane structure. These biomimetic nanostructures are a promising platform for the integration of carbon nanotube-based materials with biomolecules. PMID:22568448

  1. Plasticity and Kinky Chemistry of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Dzegilenko, Fedor

    2000-01-01

    Since their discovery in 1991, carbon nanotubes have been the subject of intense research interest based on early predictions of their unique mechanical, electronic, and chemical properties. Materials with the predicted unique properties of carbon nanotubes are of great interest for use in future generations of aerospace vehicles. For their structural properties, carbon nanotubes could be used as reinforcing fibers in ultralight multifunctional composites. For their electronic properties, carbon nanotubes offer the potential of very high-speed, low-power computing elements, high-density data storage, and unique sensors. In a continuing effort to model and predict the properties of carbon nanotubes, Ames accomplished three significant results during FY99. First, accurate values of the nanomechanics and plasticity of carbon nanotubes based on quantum molecular dynamics simulations were computed. Second, the concept of mechanical deformation catalyzed-kinky-chemistry as a means to control local chemistry of nanotubes was discovered. Third, the ease of nano-indentation of silicon surfaces with carbon nanotubes was established. The elastic response and plastic failure mechanisms of single-wall nanotubes were investigated by means of quantum molecular dynamics simulations.

  2. CARBON NANOTUBES: PROPERTIES AND APPLICATIONS

    SciTech Connect

    Fischer, John, E.

    2009-07-24

    Carbon nanotubes were discovered in 1991 as a minority byproduct of fullerene synthesis. Remarkable progress has been made in the ensuing years, including the discovery of two basic types of nanotubes (single-wall and multi-wall), great strides in synthesis and purification, elucidation of many fundamental physical properties, and important steps towards practical applications. Both the underlying science and technological potential of SWNT can profitably be studied at the scale of individual tubes and on macroscopic assemblies such as fibers. Experiments on single tubes directly reveal many of the predicted quantum confinement and mechanical properties. Semiconductor nanowires have many features in common with nanotubes, and many of the same fundamental and practical issues are in play – quantum confinement and its effect on properties; possible device structures and circuit architectures; thermal management; optimal synthesis, defect morphology and control, etc. In 2000 we began a small effort in this direction, conducted entirely by undergraduates with minimal consumables support from this grant. With DOE-BES approval, this grew into a project in parallel with the carbon nanotube work, in which we studied of inorganic semiconductor nanowire growth, characterization and novel strategies for electronic and electromechanical device fabrication. From the beginnings of research on carbon nanotubes, one of the major applications envisioned was hydrogen storage for fuel-cell powered cars and trucks. Subsequent theoretical models gave mixed results, the most pessimistic indicating that the fundamental H2-SWNT interaction was similar to flat graphite (physisorption) with only modest binding energies implying cryogenic operation at best. New material families with encouraging measured properties have emerged, and materials modeling has gained enormously in predictive power, sophistication, and the ability to treat a realistically representative number of atoms. One of

  3. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    NASA Technical Reports Server (NTRS)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  4. Covalent Sidewall Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Chiang, I.W.; Saini, R. K.; Mickelson, E. T.; Billups, W. E.; Hauge, R. H.; Margrave, J. L.

    2001-01-01

    Progress of fluorination of single-wall carbon nanotubes is being reported. Covalent attachment of alkyl groups including methyl, n-butyl and n-hexyl groups to the sidewalls of single wall carbon nanotubes (SWNTs) has been achieved. Quantitative measurement of the alkylation was done by thermal gravimetric analysis. FTIR, Raman and UV-Vis-NIR were used to characterize these alkylated SWNTs. Application of these nanotubes are being investigated-fibers, composites, batteries, lubricants, etc.

  5. Longitudinal solitons in carbon nanotubes

    SciTech Connect

    Astakhova, T. Yu.; Gurin, O. D.; Menon, M.; Vinogradov, G. A.

    2001-07-15

    We present results on soliton excitations in carbon nanotubes (CNT's) using Brenner's many-body potential. Our numerical simulations demonstrate high soliton stability in (10,10) CNT's. The interactions of solitons and solitary excitation with CNT defect are found to be inelastic if the excitations and defects length scales are comparable, resulting in a substantial part of soliton energy being distributed inhomogeneously over the defect bonds. In these solitary-excitation--cap collisions the local energy of a few bonds in the cap can exceed the average energy by an order of magnitude and more. This phenomenon, denoted the ''Tsunami effect,'' can contribute dynamically to the recently proposed ''kinky chemistry.'' We also present results of changes in the local density of states and variations in the atomic partial charges estimated at different time instants of the solitary-excitation Tsunami at the nanotube cap.

  6. Hydrogen Storage in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Gilbert, Joseph; Gilbert, Matthew; Naab, Fabian; Savage, Lauren; Holland, Wayne; Duggan, Jerome; McDaniel, Floyd

    2004-10-01

    Hydrogen as a fuel source is an attractive, relatively clean alternative to fossil fuels. However, a major limitation in its use for the application of automobiles has been the requirement for an efficient hydrogen storage medium. Current hydrogen storage systems are: physical storage in high pressure tanks, metal hydride, and gas-on-solid absorption. However, these methods do not fulfill the Department of Energy's targeted requirements for a usable hydrogen storage capacity of 6.5 wt.%, operation near ambient temperature and pressure, quick extraction and refueling, reliability and reusability.Reports showing high capacity hydrogen storage in single-walled carbon nanotubes originally prompted great excitement in the field, but further research has shown conflicting results. Results for carbon nanostructures have ranged from less than 1 wt.% to 70 wt.%. The wide range of adsorption found in previous experiments results from the difficulty in measuring hydrogen in objects just nanometers in size. Most previous experiments relied on weight analysis and residual gas analysis to determine the amount of hydrogen being adsorbed by the CNTs. These differing results encouraged us to perform our own analysis on single-walled (SWNTs), double-walled (DWNTs), and multi-walled carbon nanotubes (MWNTs), as well as carbon fiber. We chose to utilize direct measurement of hydrogen in the materials using elastic recoil detection analysis (ERDA). This work was supported by the National Science Foundation's Research Experience for Undergraduates and the University of North Texas.

  7. Ophthalmologial Applications of Carbon Nanotube Nanotechology

    NASA Technical Reports Server (NTRS)

    Loftus, David; Girten, Beverly (Technical Monitor)

    2002-01-01

    The development of an implantable device consisting of an array of carbon nanotubes on a silicon chip for restoration of vision in patients with macular degeneration and other retinal disorders is presented. The use of carbon nanotube bucky paper for retinal cell transplantation is proposed. This paper is in viewgraph form.

  8. Reinforcement and rupture behavior of carbon nanotubes-polymer nanofibers

    NASA Astrophysics Data System (ADS)

    Ye, Haihui; Lam, Hoa; Titchenal, Nick; Gogotsi, Yury; Ko, Frank

    2004-09-01

    High-resolution transmission electron microscopy examination of carbon nanotube-polyacrylonitrile composite fibers synthesized by electrospinning was conducted. Both single-wall carbon nanotubes and multi-wall carbon nanotubes have been used to reinforce the polymer fibers. A two-stage rupture behavior of the composite fibers under tension, including crazing of polymer matrix and pull-out of carbon nanotubes, has been observed. Carbon nanotubes reinforce the polymer fibers by hindering crazing extension, reducing stress concentration, and dissipating energy by pullout. Distribution of nanotubes in the polymer matrix and interfacial adhesion between nanotubes and polymers are two major factors to determine the reinforcement effect of carbon nanotubes in polymer fibers.

  9. Nanocapillarity and chemistry in carbon nanotubes

    SciTech Connect

    Ugarte, D.; Chatelain, A.; Heer, W.A. de

    1996-12-13

    Open carbon nanotubes were filled with molten silver nitrate by capillary forces. Only those tubes with inner diameters of 4 nanometers or more were filled, suggesting a capillarity size dependence as a result of the lowering of the nanotube-salt interface energy with increasing curvature of the nanotube walls. Nanotube cavities should also be less chemically reactive than graphite and may serve as nanosize test tubes. This property has been illustrated by monitoring the decomposition of silver nitrate within nanotubes in situ in an electron microscope, which produced chains of silver nanobeads separated by high-pressure gas pockets. 32 refs., 3 figs.

  10. Supported Lipid Bilayer/Carbon Nanotube Hybrids

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian; Moran-Mirabal, Jose; Craighead, Harold; McEuen, Paul

    2007-03-01

    We form supported lipid bilayers on single-walled carbon nanotubes and use this hybrid structure to probe the properties of lipid membranes and their functional constituents. We first demonstrate membrane continuity and lipid diffusion over the nanotube. A membrane-bound tetanus toxin protein, on the other hand, sees the nanotube as a diffusion barrier whose strength depends on the diameter of the nanotube. Finally, we present results on the electrical detection of specific binding of streptavidin to biotinylated lipids with nanotube field effect transistors. Possible techniques to extract dynamic information about the protein binding events will also be discussed.

  11. Epitaxial Approaches to Carbon Nanotube Organization

    NASA Astrophysics Data System (ADS)

    Ismach, Ariel

    Carbon nanotubes have unique electronic, mechanical, optical and thermal properties, which make them ideal candidates as building blocks in nano-electronic and electromechanical systems. However, their organization into well-defined geometries and arrays on surfaces remains a critical challenge for their integration into functional nanosystems. In my PhD, we developed a new approach for the organization of carbon nanotubes directed by crystal surfaces. The principle relies on the guided growth of single-wall carbon nanotubes (SWNTs) by atomic features presented on anisotropic substrates. We identified three different modes of surface-directed growth (or 'nanotube epitaxy'), in which the growth of carbon nanotubes is directed by crystal substrates: We first observed the nanotube unidirectional growth along atomic steps ('ledge-directed epitaxy') and nanofacets ('graphoepitaxy') on the surface of miscut C-plane sapphire and quartz. The orientation along crystallographic directions ('lattice-directed epitaxy') was subsequently observed by other groups on different crystals. We have proposed a "wake growth" mechanism for the nanotube alignment along atomic steps and nanofacets. In this mechanism, the catalyst nanoparticle slides along the step or facet, leaving the nanotube behind as a wake. In addition, we showed that the combination of surface-directed growth with external forces, such as electric-field and gas flow, can lead to the simultaneous formation of complex nanotube structures, such as grids and serpentines. The "wake growth" model, which explained the growth of aligned nanotubes, could not explain the formation of nanotube serpentines. For the latter, we proposed a "falling spaghetti" mechanism, in which the nanotube first grows by a free-standing process, aligned in the direction of the gas flow, then followed by absorption on the stepped surface in an oscillatory manner, due to the competition between the drag force caused by the gas flow on the suspended

  12. Carbon Nanotubes/Nanofibers by Plasma Enhanced Chemical Vapour Deposition

    NASA Technical Reports Server (NTRS)

    Teo, K. B. K.; Hash, D. B.; Bell, M. S.; Chhowalla, M.; Cruden, B. A.; Amaratunga, G. A. J.; Meyyappan, M.; Milne, W. I.

    2005-01-01

    Plasma enhanced chemical vapour deposition (PECVD) has been recently used for the production of vertically aligned carbon nanotubedfibers (CN) directly on substrates. These structures are potentially important technologically as electron field emitters (e.g. microguns, microwave amplifiers, displays), nanoelectrodes for sensors, filter media, superhydrophobic surfaces and thermal interface materials for microelectronics. A parametric study on the growth of CN grown by glow discharge dc-PECVD is presented. In this technique, a substrate containing thin film Ni catalyst is exposed to C2H2 and NH3 gases at 700 C. Without plasma, this process is essentially thermal CVD which produces curly spaghetti-like CN as seen in Fig. 1 (a). With the plasma generated by biasing the substrate at -6OOV, we observed that the CN align vertically during growth as shown in Fig. l(b), and that the magnitude of the applied substrate bias affects the degree of alignment. The thickness of the thin film Ni catalyst was found to determine the average diameter and inversely the length of the CN. The yield and density of the CN were controlled by the use of different diffusion barrier materials under the Ni catalyst. Patterned CN growth [Fig. l(c)], with la variation in CN diameter of 4.1% and 6.3% respectively, is achieved by lithographically defining the Ni thin film prior to growth. The shape of the structures could be varied from very straight nanotube-like to conical tip-like nanofibers by increasing the ratio of C2H2 in the gas flow. Due to the plasma decomposition of C2H2, amorphous carbon (a-C) is an undesirable byproduct which could coat the substrate during CN growth. Using a combination of depth profiled Auger electron spectroscopy to study the substrate and in-situ mass spectroscopy to examine gas phase neutrals and ions, the optimal conditions for a-C free growth of CN is determined.

  13. Carbon nanotube growth density control

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  14. Endohedral Impurities in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis

    2003-03-01

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Treating the distortion within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value g_c. The effective potential in the symmetry-broken state is found to have O(2) symmetry, in agreement with numerical calculations. The consequences of such a distortion on electronic transport will be discussed.

  15. A tunable carbon nanotube polarizer.

    PubMed

    Kang, Byeong Gyun; Lim, Young Jin; Jeong, Kwang-Un; Lee, Kyu; Lee, Young Hee; Lee, Seung Hee

    2010-10-01

    The electro-optic response of a carbon nanotube (CNT) cluster has been investigated. The cluster absorbs incident light before stretching. In the presence of an electric field, the cluster starts stretching along the field direction and contracts back to its original stage when the applied voltage is removed. The stretched cluster absorbs and transmits incident light with its electric vector propagating parallel and perpendicular to the long axis of the stretched cluster, respectively. Utilizing this selective light absorption property of a CNT cluster, a tunable polarizer or non-emissive light modulator can be realized. PMID:20829567

  16. Coated carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2008-10-28

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  17. Coated carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2006-12-12

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  18. Carbon nanotube cathode with capping carbon nanosheet

    NASA Astrophysics Data System (ADS)

    Li, Xin; Zhao, Dengchao; Pang, Kaige; Pang, Junchao; Liu, Weihua; Liu, Hongzhong; Wang, Xiaoli

    2013-10-01

    Here, we report a vertically aligned carbon nanotube (VACNT) film capped with a few layer of carbon nanosheet (FLCN) synthesized by chemical vapor deposition using a carbon source from iron phthalocyanine pyrolysis. The square resistance of the VACNT film is significantly reduced from 1500 Ω/□ to 300 Ω/□ when it is capped with carbon nanosheet. The VACNT capped with carbon nanosheet was transferred to an ITO glass substrate in an inverted configuration so that the carbon nanosheet served as a flexible transparent electrode at the bottom and the VACNT roots served as emission tips. Because all of the VACNTs start growing from a flat silicon substrate, the VACNT roots are very neat and uniform in height. A field emission test of the carbon nanosheet-capped VACNT film proved that the CNT roots show better uniformity in field emission and the carbon nanosheet cap could also potentially serve as a flexible transparent electrode, which is highly desired in photo-assisted field emission.

  19. Vibration, buckling and impact of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pentaras, Demetris

    Natural frequencies of the double and triple-walled carbon nanotubes are determined exactly and approximately for both types. Approximate solutions are found by using Bubnov-Galerkin and Petrov-Galerkin methods. For the first time explicit expressions are obtained for the natural frequencies of double and triple-walled carbon nanotubes for different combinations of boundary conditions. Comparison of the results with recent studies shows that the above methods constitute quick and effective alternative techniques to exact solution for studying the vibration properties of carbon nanotubes. The natural frequencies of the clamped-clamped double-walled carbon nanotubes are obtained; exact solution is provided and compared with the solution reported in the literature. In contrast to earlier investigation, an analytical criterion is derived to establish the behavior of the roots of the characteristic equation. Approximate Bubnov-Galerkin solution is also obtained to compare natural frequencies at the lower end of the spectrum. Simplified version of the Bresse-Timoshenko theory that incorporates the shear deformation and the rotary inertia is proposed for free vibration study of double-walled carbon nanotubes. It is demonstrated that the suggested set yields extremely accurate results for the lower spectrum of double-walled carbon nanotube. The natural frequencies of double-walled carbon nanotubes based on simplified versions of Donnell shell theory are also obtained. The buckling behavior of the double-walled carbon nanotubes under various boundary conditions is studied. First, the case of the simply supported double-walled carbon nanotubes at both ends is considered which is amenable to exact solution. Then, approximate methods of Bubnov-Galerkin and Petrov-Galerkin are utilized to check the efficacy of these approximations for the simply supported double-walled carbon nanotubes. Once the extreme accuracy is demonstrated for simply supported conditions, the approximate

  20. Cutting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ziegler, Kirk J.; Gu, Zhenning; Shaver, Jonah; Chen, Zheyi; Flor, Erica L.; Schmidt, Daniel J.; Chan, Candace; Hauge, Robert H.; Smalley, Richard E.

    2005-07-01

    A two-step process is utilized for cutting single-walled carbon nanotubes (SWNTs). The first step requires the breakage of carbon-carbon bonds in the lattice while the second step is aimed at etching at these damage sites to create short, cut nanotubes. To achieve monodisperse lengths from any cutting strategy requires control of both steps. Room-temperature piranha and ammonium persulfate solutions have shown the ability to exploit the damage sites and etch SWNTs in a controlled manner. Despite the aggressive nature of these oxidizing solutions, the etch rate for SWNTs is relatively slow and almost no new sidewall damage is introduced. Carbon-carbon bond breakage can be introduced through fluorination to ~C2F, and subsequent etching using piranha solutions has been shown to be very effective in cutting nanotubes. The final average length of the nanotubes is approximately 100 nm with carbon yields as high as 70-80%.

  1. Development of Carbon-Nanotube/Polymer Composites

    NASA Technical Reports Server (NTRS)

    Reynolds, Thomas A.

    2005-01-01

    A report presents a short discussion of one company's effort to develop composites of carbon nanotubes in epoxy and other polymer matrices. The focus of the discussion is on the desirability of chemically modifying carbon nanotubes to overcome their inherent chemical nonreactivity and thereby enable the formation of strong chemical bonds between nanotubes and epoxies (or other polymeric matrix materials or their monomeric precursors). The chemical modification is effected in a process in which discrete functional groups are covalently attached to the nanotube surfaces. The functionalization process was proposed by the company and demonstrated in practice for the first time during this development effort. The covalently attached functional groups are capable of reacting with the epoxy or other matrix resin to form covalent bonds. Furthermore, the company uses this process to chemically modify the nanotube surfaces, affording tunable adhesion to polymers and solubility in select solvents. Flat-sheet composites containing functionalized nanotubes demonstrate significantly improved mechanical, thermal, and electrical properties.

  2. Directional dark matter searches with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Capparelli, L. M.; Cavoto, G.; Mazzilli, D.; Polosa, A. D.

    2015-09-01

    A new solution to the problem of dark matter directional detection might come from the use of large arrays of aligned carbon nanotubes. We calculate the expected rate of carbon ions channeled in single-wall nanotubes once extracted by the scattering with a massive dark matter particle. Depending on its initial kinematic conditions, the ejected carbon ion may be channeled in the nanotube array or stop in the bulk. The orientation of the array with respect to the direction of motion of the Sun has an appreciable effect on the channeling probability. This provides the required anisotropic response for a directional detector.

  3. Characterization of Carbon Nanotube Reinforced Nickel

    NASA Technical Reports Server (NTRS)

    Gill, Hansel; Hudson, Steve; Bhat, Biliyar; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    Carbon nanotubes are cylindrical molecules composed of carbon atoms in a regular hexagonal arrangement. If nanotubes can be uniformly dispersed in a supporting matrix to form structural materials, the resulting structures could be significantly lighter and stronger than current aerospace materials. Work is currently being done to develop an electrolyte-based self-assembly process that produces a Carbon Nanotube/Nickel composite material with high specific strength. This process is expected to produce a lightweight metal matrix composite material, which maintains it's thermal and electrical conductivities, and is potentially suitable for applications such as advanced structures, space based optics, and cryogenic tanks.

  4. Methods for producing reinforced carbon nanotubes

    DOEpatents

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2008-10-28

    Methods for producing reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials are disclosed. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  5. Carbon nanotube fiber spun from wetted ribbon

    DOEpatents

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  6. Carbon Nanotubes for Human Space Flight

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.; Files, Brad; Yowell, Leonard

    2003-01-01

    Single-wall carbon nanotubes offer the promise of a new class of revolutionary materials for space applications. The Carbon Nanotube Project at NASA Johnson Space Center has been actively researching this new technology by investigating nanotube production methods (arc, laser, and HiPCO) and gaining a comprehensive understanding of raw and purified material using a wide range of characterization techniques. After production and purification, single wall carbon nanotubes are processed into composites for the enhancement of mechanical, electrical, and thermal properties. This "cradle-to-grave" approach to nanotube composites has given our team unique insights into the impact of post-production processing and dispersion on the resulting material properties. We are applying our experience and lessons-learned to developing new approaches toward nanotube material characterization, structural composite fabrication, and are also making advances in developing thermal management materials and electrically conductive materials in various polymer-nanotube systems. Some initial work has also been conducted with the goal of using carbon nanotubes in the creation of new ceramic materials for high temperature applications in thermal protection systems. Human space flight applications such as advanced life support and fuel cell technologies are also being investigated. This discussion will focus on the variety of applications under investigation.

  7. Defect-Free Carbon Nanotube Coils.

    PubMed

    Shadmi, Nitzan; Kremen, Anna; Frenkel, Yiftach; Lapin, Zachary J; Machado, Leonardo D; Legoas, Sergio B; Bitton, Ora; Rechav, Katya; Popovitz-Biro, Ronit; Galvão, Douglas S; Jorio, Ado; Novotny, Lukas; Kalisky, Beena; Joselevich, Ernesto

    2016-04-13

    Carbon nanotubes are promising building blocks for various nanoelectronic components. A highly desirable geometry for such applications is a coil. However, coiled nanotube structures reported so far were inherently defective or had no free ends accessible for contacting. Here we demonstrate the spontaneous self-coiling of single-wall carbon nanotubes into defect-free coils of up to more than 70 turns with identical diameter and chirality, and free ends. We characterize the structure, formation mechanism, and electrical properties of these coils by different microscopies, molecular dynamics simulations, Raman spectroscopy, and electrical and magnetic measurements. The coils are highly conductive, as expected for defect-free carbon nanotubes, but adjacent nanotube segments in the coil are more highly coupled than in regular bundles of single-wall carbon nanotubes, owing to their perfect crystal momentum matching, which enables tunneling between the turns. Although this behavior does not yet enable the performance of these nanotube coils as inductive devices, it does point a clear path for their realization. Hence, this study represents a major step toward the production of many different nanotube coil devices, including inductors, electromagnets, transformers, and dynamos. PMID:26708150

  8. Applications and production of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hafner, Jason Howard

    Carbon nanotubes, a recently discovered form of carbon fiber with structural perfection similar to that of a fullerene molecule, have interesting electronic, chemical and mechanical properties due to their size and structure. Nanotubes have great potential as a bulk material for strong, lightweight composite materials, and as individual nano-scale tools or devices. Initial work on applications with individual multiwalled nanotubes as field emission sources and scanning force microscopy tips is described. The nanotubes display intriguing field emission behavior interpreted as the nanotube unraveling under the influence of the electric field. The unraveling process is believed to result in facile field emission from linear atomic carbon chains at the end of the nanotube. Such atomic wires represent an excellent field emitter. The work on multiwalled nanotube SFM tips was equally encouraging. The high aspect ratio of the nanotube allows it to image deep trenches inaccessible to commercially available Si pyramidal tips, and it reduces the interaction with the ambient water layer on the sample which perturbs image quality. The most remarkable advantage of nanotube SFM tips is a result of their mechanical properties. It was found that the nanotubes will remain rigid during normal imaging, but conveniently buckle to the side if circumstances arise which create large forces known to damage the tip and sample. This feature makes the tip more durable than Si tips, and is especially important for soft biological samples. In these two applications, as well as others, and in the measurements of novel nanotube properties, high quality, small diameter (0.5 to 2 nm) diameter single-walled nanotubes are most interesting. Such material can be produced slowly and in small amounts by catalytic arc vaporization and catalytic laser vaporization of graphite. It is well known that nanotubes can be mass produced by catalytic chemical vapor deposition (CCVD), but the product consists only

  9. Quantum conductance of carbon nanotube peapods

    SciTech Connect

    Yoon, Young-Gui; Mazzoni, Mario S.C.; Louie, Steven G.

    2003-08-01

    We present a first-principles study of the quantum conductance of hybrid nanotube systems consisting of single-walled carbon nanotubes (SWCNTs) encapsulating either an isolated single C60 molecule or a chain of C60 molecules (nanotube peapods). The calculations show a rather weak bonding interaction between the fullerenes and the SWCNTs. The conductance of a (10,10) SWCNT with a single C60 molecule is virtually unaffected at the Fermi level, but exhibits quantized resonant reductions at the molecular levels. The nanotube peapod arrangement gives rise to high density of states for the fullerene highest occupied molecular orbital and lowest unoccupied molecular orbital bands.

  10. Flightweight Carbon Nanotube Magnet Technology

    NASA Technical Reports Server (NTRS)

    Chapman, J. N.; Schmidt, H. J.; Ruoff, R. S.; Chandrasekhar, V.; Dikin, D. A.; Litchford, R. J.

    2003-01-01

    Virtually all plasma-based systems for advanced airborne/spaceborne propulsion and power depend upon the future availability of flightweight magnet technology. Unfortunately, current technology for resistive and superconducting magnets yields system weights that tend to counteract the performance advantages normally associated with advanced plasma-based concepts. The ongoing nanotechnology revolution and the continuing development of carbon nanotubes (CNT), however, may ultimately relieve this limitation in the near future. Projections based on recent research indicate that CNTs may achieve current densities at least three orders of magnitude larger than known superconductors and mechanical strength two orders of magnitude larger than steel. In fact, some published work suggests that CNTs are superconductors. Such attributes imply a dramatic increase in magnet performance-to-weight ratio and offer real hope for the construction of true flightweight magnets. This Technical Publication reviews the technology status of CNTs with respect to potential magnet applications and discusses potential techniques for using CNT wires and ropes as a winding material and as an integral component of the containment structure. The technology shortfalls are identified and a research and technology strategy is described that addresses the following major issues: (1) Investigation and verification of mechanical and electrical properties, (2) development of tools for manipulation and fabrication on the nanoscale, (3) continuum/molecular dynamics analysis of nanotube behavior when exposed to practical bending and twisting loads, and (4) exploration of innovative magnet fabrication techniques that exploit the natural attributes of CNTs.

  11. Multiwall carbon nanotube microcavity arrays

    NASA Astrophysics Data System (ADS)

    Ahmed, Rajib; Rifat, Ahmmed A.; Yetisen, Ali K.; Dai, Qing; Yun, Seok Hyun; Butt, Haider

    2016-03-01

    Periodic highly dense multi-wall carbon nanotube (MWCNT) arrays can act as photonic materials exhibiting band gaps in the visible regime and beyond terahertz range. MWCNT arrays in square arrangement for nanoscale lattice constants can be configured as a microcavity with predictable resonance frequencies. Here, computational analyses of compact square microcavities (≈0.8 × 0.8 μm2) in MWCNT arrays were demonstrated to obtain enhanced quality factors (≈170-180) and narrow-band resonance peaks. Cavity resonances were rationally designed and optimized (nanotube geometry and cavity size) with finite element method. Series (1 × 2 and 1 × 3) and parallel (2 × 1 and 3 × 1) combinations of microcavities were modeled and resonance modes were analyzed. Higher order MWCNT microcavities showed enhanced resonance modes, which were red shifted with increasing Q-factors. Parallel microcavity geometries were also optimized to obtain narrow-band tunable filtering in low-loss communication windows (810, 1336, and 1558 nm). Compact series and parallel MWCNT microcavity arrays may have applications in optical filters and miniaturized optical communication devices.

  12. Carbon nanotube transistors, sensors, and beyond

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian

    Carbon nanotubes are tiny hollow cylinders, made from a single graphene sheet, that possess many amazing properties. Another reason why nanotubes have generated intense research activities from scientists of various disciplines is they represent a new class of materials for the study of one-dimensional physics. In this thesis we investigate the electrical transport of semiconducting single-walled carbon nanotubes and their potential applications as biological sensors. Electrons have been predicted, by theoretical physicists, to go through nanotubes without much resistance. But this has not been properly quantified experimentally, and the origin of the routinely observed large resistance in nanotubes is not clear. In this thesis we show that in moderate long high quality nanotubes the electrical transport is limited by electron-phonon scattering. Systematic studies are carried out using many devices of different diameters at various temperatures. The resistance and inverse of peak mobility are observed to decrease linearly with temperature, indicating the influence of phonons. The conductance and peak mobility scales with nanotube diameters also, in a linear fashion and quadratic fashion respectively. Based on electron-phonon scattering, a theory model is developed that can not only predict how the resistance changes with gate voltage but also explain the observed temperature and diameter dependence. This work clarifies the nature of electrical transport in nanotubes and sets a performance limit of nanotube devices in diffusive regime. The electrical transport in nanotubes is extremely sensitive to local electrostatic environment due to their small size, large surface to volume ratio and high mobility, making nanotubes ideal key elements in biological sensors. In the second part of this thesis, we integrate nanotubes with supported lipid bilayers, mimic structures of cell membranes, and use this platform as a way to introduce biomolecules into the vicinity of

  13. Functionalization of carbon nanotubes with silver clusters

    NASA Astrophysics Data System (ADS)

    Cveticanin, Jelena; Krkljes, Aleksandra; Kacarevic-Popovic, Zorica; Mitric, Miodrag; Rakocevic, Zlatko; Trpkov, Djordje; Neskovic, Olivera

    2010-09-01

    In this paper, an advanced method of one-step functionalization of single and multi walled carbon nanotubes (SWCNTs and MWCNTs) using γ-irradiation was described. Two synthesis procedures, related with different reduction species, were employed. For the first time, poly(vinyl alcohol) PVA is successfully utilized as a source to reduce silver (Ag) metal ions without having any additional reducing agents to obtain Ag nanoparticles on CNTs. The decoration of carbon nanotubes with Ag nanoparticles takes place through anchoring of (PVA) on nanotube's surface. Optical properties of as-prepared samples and mechanism responsible for the functionalization of carbon nanotubes were investigated using UV-vis and FTIR spectroscopy, respectively. Decorated carbon nanotubes were visualized using microscopic techniques: transmission electron microscopy and scanning tunneling microscopy. Also, the presence of Ag on the nanotubes was confirmed using energy dispersive X-ray spectroscopy. This simple and effective method of making a carbon nanotube type of composites is of interest not only for an application in various areas of technology and biology, but for investigation of the potential of radiation technology for nanoengineering of materials.

  14. Nanoelectrodes reveal the electrochemistry of single nickelhydroxide nanoparticles.

    PubMed

    Clausmeyer, Jan; Masa, Justus; Ventosa, Edgar; Öhl, Dennis; Schuhmann, Wolfgang

    2016-02-01

    Individual Ni(OH)2 nanoparticles deposited on carbon nanoelectrodes are investigated in non-ensemble measurements with respect to their energy storage properties and electrocatalysis for the oxygen evolution reaction (OER). Charging by oxidation of Ni(OH)2 is limited by the diffusion of protons into the particle bulk and the OER activity is independent of the particle size. PMID:26735684

  15. Carbon Nanotube Composites: Strongest Engineering Material Ever?

    NASA Technical Reports Server (NTRS)

    Mayeaux, Brian; Nikolaev, Pavel; Proft, William; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    The primary goal of the carbon nanotube project at Johnson Space Center (JSC) is to fabricate structural materials with a much higher strength-to-weight ratio than any engineered material today, Single-wall nanotubes present extraordinary mechanical properties along with new challenges for materials processing. Our project includes nanotube production, characterization, purification, and incorporation into applications studies. Now is the time to move from studying individual nanotubes to applications work. Current research at JSC focuses on structural polymeric materials to attempt to lower the weight of spacecraft necessary for interplanetary missions. These nanoscale fibers present unique new challenges to composites engineers. Preliminary studies show good nanotube dispersion and wetting by the epoxy materials. Results of tensile strength tests will also be reported. Other applications of nanotubes are also of interest for energy storage, gas storage, nanoelectronics, field emission, and biomedical uses.

  16. Purification of Carbon Nanotubes: Alternative Methods

    NASA Technical Reports Server (NTRS)

    Files, Bradley; Scott, Carl; Gorelik, Olga; Nikolaev, Pasha; Hulse, Lou; Arepalli, Sivaram

    2000-01-01

    Traditional carbon nanotube purification process involves nitric acid refluxing and cross flow filtration using surfactant TritonX. This is believed to result in damage to nanotubes and surfactant residue on nanotube surface. Alternative purification procedures involving solvent extraction, thermal zone refining and nitric acid refiuxing are used in the current study. The effect of duration and type of solvent to dissolve impurities including fullerenes and P ACs (polyaromatic compounds) are monitored by nuclear magnetic reasonance, high performance liquid chromatography, and thermogravimetric analysis. Thermal zone refining yielded sample areas rich in nanotubes as seen by scanning electric microscopy. Refluxing in boiling nitric acid seem to improve the nanotube content. Different procedural steps are needed to purify samples produced by laser process compared to arc process. These alternative methods of nanotube purification will be presented along with results from supporting analytical techniques.

  17. Deconvoluting hepatic processing of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Alidori, Simone; Bowman, Robert L.; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J. Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L. J.; Ulmert, Hans David S.; Brea, Elliott J.; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A.; McDevitt, Michael R.

    2016-07-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans.

  18. Nanoelectrode array formation by electrolytic nanoparticle impacts

    NASA Astrophysics Data System (ADS)

    Bartlett, T. R.; Holter, J.; Young, N.; Compton, R. G.

    2016-07-01

    We report the fabrication of functional nanoelectrode arrays by the electrolysis of AgBr nanoparticles (NPs) impacting on a glassy carbon electrode from suspension in aqueous solution. The impacted NPs result in Ag NP deposits of similar size to the originating NP, with the coverage of these arrays easily controlled by the time of the deposition step. The NPs constituting the array are deposited randomly across the surface with little aggregation or agglomeration. The fabricated arrays are themselves electrochemically active, mediating the reduction of hydrogen peroxide, H2O2.

  19. Nanoelectrode array formation by electrolytic nanoparticle impacts.

    PubMed

    Bartlett, T R; Holter, J; Young, N; Compton, R G

    2016-07-21

    We report the fabrication of functional nanoelectrode arrays by the electrolysis of AgBr nanoparticles (NPs) impacting on a glassy carbon electrode from suspension in aqueous solution. The impacted NPs result in Ag NP deposits of similar size to the originating NP, with the coverage of these arrays easily controlled by the time of the deposition step. The NPs constituting the array are deposited randomly across the surface with little aggregation or agglomeration. The fabricated arrays are themselves electrochemically active, mediating the reduction of hydrogen peroxide, H2O2. PMID:26758943

  20. Functionalized carbon nanotubes: biomedical applications

    PubMed Central

    Vardharajula, Sandhya; Ali, Sk Z; Tiwari, Pooja M; Eroğlu, Erdal; Vig, Komal; Dennis, Vida A; Singh, Shree R

    2012-01-01

    Carbon nanotubes (CNTs) are emerging as novel nanomaterials for various biomedical applications. CNTs can be used to deliver a variety of therapeutic agents, including biomolecules, to the target disease sites. In addition, their unparalleled optical and electrical properties make them excellent candidates for bioimaging and other biomedical applications. However, the high cytotoxicity of CNTs limits their use in humans and many biological systems. The biocompatibility and low cytotoxicity of CNTs are attributed to size, dose, duration, testing systems, and surface functionalization. The functionalization of CNTs improves their solubility and biocompatibility and alters their cellular interaction pathways, resulting in much-reduced cytotoxic effects. Functionalized CNTs are promising novel materials for a variety of biomedical applications. These potential applications are particularly enhanced by their ability to penetrate biological membranes with relatively low cytotoxicity. This review is directed towards the overview of CNTs and their functionalization for biomedical applications with minimal cytotoxicity. PMID:23091380

  1. Carbon Nanotube Based Light Sensor

    NASA Technical Reports Server (NTRS)

    Wincheski, russell A. (Inventor); Smits, Jan M. (Inventor); Jordan, Jeffrey D. (Inventor); Watkins, Anthony Neal (Inventor); Ingram, JoAnne L. (Inventor)

    2006-01-01

    A light sensor substrate comprises a base made from a semi-conductive material and topped with a layer of an electrically non-conductive material. A first electrode and a plurality of carbon nanotube (CNT)-based conductors are positioned on the layer of electrically non-conductive material with the CNT-based conductors being distributed in a spaced apart fashion about a periphery of the first electrode. Each CNT-based conductor is coupled on one end thereof to the first electrode and extends away from the first electrode to terminate at a second free end. A second or gate electrode is positioned on the non-conductive material layer and is spaced apart from the second free end of each CNT-based conductor. Coupled to the first and second electrode is a device for detecting electron transfer along the CNT-based conductors resulting from light impinging on the CNT-based conductors.

  2. Photonics based on carbon nanotubes

    PubMed Central

    2013-01-01

    Among direct-bandgap semiconducting nanomaterials, single-walled carbon nanotubes (SWCNT) exhibit strong quasi-one-dimensional excitonic optical properties, which confer them a great potential for their integration in future photonics devices as an alternative solution to conventional inorganic semiconductors. In this paper, we will highlight SWCNT optical properties for passive as well as active applications in future optical networking. For passive applications, we directly compare the efficiency and power consumption of saturable absorbers (SAs) based on SWCNT with SA based on conventional multiple quantum wells. For active applications, exceptional photoluminescence properties of SWCNT, such as excellent light-emission stabilities with temperature and excitation power, hold these nanometer-scale materials as prime candidates for future active photonics devices with superior performances. PMID:23803293

  3. Photonics based on carbon nanotubes.

    PubMed

    Gu, Qingyuan; Gicquel-Guézo, Maud; Loualiche, Slimane; Pouliquen, Julie Le; Batte, Thomas; Folliot, Hervé; Dehaese, Olivier; Grillot, Frederic; Battie, Yann; Loiseau, Annick; Liang, Baolai; Huffaker, Diana

    2013-01-01

    Among direct-bandgap semiconducting nanomaterials, single-walled carbon nanotubes (SWCNT) exhibit strong quasi-one-dimensional excitonic optical properties, which confer them a great potential for their integration in future photonics devices as an alternative solution to conventional inorganic semiconductors. In this paper, we will highlight SWCNT optical properties for passive as well as active applications in future optical networking. For passive applications, we directly compare the efficiency and power consumption of saturable absorbers (SAs) based on SWCNT with SA based on conventional multiple quantum wells. For active applications, exceptional photoluminescence properties of SWCNT, such as excellent light-emission stabilities with temperature and excitation power, hold these nanometer-scale materials as prime candidates for future active photonics devices with superior performances. PMID:23803293

  4. Carbon nanotube polymer composition and devices

    DOEpatents

    Liu, Gao; Johnson, Stephen; Kerr, John B.; Minor, Andrew M.; Mao, Samuel S.

    2011-06-14

    A thin film device and compound having an anode, a cathode, and at least one light emitting layer between the anode and cathode, the at least one light emitting layer having at least one carbon nanotube and a conductive polymer.

  5. Carbon nanotube heat-exchange systems

    DOEpatents

    Hendricks, Terry Joseph; Heben, Michael J.

    2008-11-11

    A carbon nanotube heat-exchange system (10) and method for producing the same. One embodiment of the carbon nanotube heat-exchange system (10) comprises a microchannel structure (24) having an inlet end (30) and an outlet end (32), the inlet end (30) providing a cooling fluid into the microchannel structure (24) and the outlet end (32) discharging the cooling fluid from the microchannel structure (24). At least one flow path (28) is defined in the microchannel structure (24), fluidically connecting the inlet end (30) to the outlet end (32) of the microchannel structure (24). A carbon nanotube structure (26) is provided in thermal contact with the microchannel structure (24), the carbon nanotube structure (26) receiving heat from the cooling fluid in the microchannel structure (24) and dissipating the heat into an external medium (19).

  6. Fundamental optical processes in armchair carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hároz, Erik H.; Duque, Juan G.; Tu, Xiaomin; Zheng, Ming; Hight Walker, Angela R.; Hauge, Robert H.; Doorn, Stephen K.; Kono, Junichiro

    2013-01-01

    Single-wall carbon nanotubes provide ideal model one-dimensional (1-D) condensed matter systems in which to address fundamental questions in many-body physics, while, at the same time, they are leading candidates for building blocks in nanoscale optoelectronic circuits. Much attention has been recently paid to their optical properties, arising from 1-D excitons and phonons, which have been revealed via photoluminescence, Raman scattering, and ultrafast optical spectroscopy of semiconducting carbon nanotubes. On the other hand, dynamical properties of metallic nanotubes have been poorly explored, although they are expected to provide a novel setting for the study of electron-hole pairs in the presence of degenerate 1-D electrons. In particular, (n,n)-chirality, or armchair, metallic nanotubes are truly gapless with massless carriers, ideally suited for dynamical studies of Tomonaga-Luttinger liquids. Unfortunately, progress towards such studies has been slowed by the inherent problem of nanotube synthesis whereby both semiconducting and metallic nanotubes are produced. Here, we use post-synthesis separation methods based on density gradient ultracentrifugation and DNA-based ion-exchange chromatography to produce aqueous suspensions strongly enriched in armchair nanotubes. Through resonant Raman spectroscopy of the radial breathing mode phonons, we provide macroscopic and unambiguous evidence that density gradient ultracentrifugation can enrich ensemble samples in armchair nanotubes. Furthermore, using conventional, optical absorption spectroscopy in the near-infrared and visible range, we show that interband absorption in armchair nanotubes is strongly excitonic. Lastly, by examining the G-band mode in Raman spectra, we determine that observation of the broad, lower frequency (G-) feature is a result of resonance with non-armchair ``metallic'' nanotubes. These findings regarding the fundamental optical absorption and scattering processes in metallic carbon nanotubes

  7. Controlled Deposition and Alignment of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Smits, Jan M. (Inventor); Wincheski, Russell A. (Inventor); Ingram, JoAnne L. (Inventor); Watkins, Anthony Neal (Inventor); Jordan, Jeffrey D. (Inventor)

    2009-01-01

    A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the . substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a carver liquid having carbon nanotubes (CNTs) suspended therein. A portion of the CNTs align with the electric field and adhere to The CNT attraction material. The carrier liquid and any CNTs not adhered to the CNT attraction material are then removed.

  8. Carbon nanotube electrodes in organic transistors.

    PubMed

    Valitova, Irina; Amato, Michele; Mahvash, Farzaneh; Cantele, Giovanni; Maffucci, Antonio; Santato, Clara; Martel, Richard; Cicoira, Fabio

    2013-06-01

    The scope of this Minireview is to provide an overview of the recent progress on carbon nanotube electrodes applied to organic thin film transistors. After an introduction on the general aspects of the charge injection processes at various electrode-semiconductor interfaces, we discuss the great potential of carbon nanotube electrodes for organic thin film transistors and the recent achievements in the field. PMID:23639944

  9. Controlled Deposition and Alignment of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Smits, Jan M. (Inventor); Wincheski, Russell A. (Inventor); Patry, JoAnne L. (Inventor); Watkins, Anthony Neal (Inventor); Jordan, Jeffrey D. (Inventor)

    2012-01-01

    A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a carrier liquid having carbon nanotubes (CNTs) suspended therein. A portion of the CNTs align with the electric field and adhere to the CNT attraction material. The carrier liquid and any CNTs not adhered to the CNT attraction material are then removed.

  10. Carbon nanotube temperature and pressure sensors

    DOEpatents

    Ivanov, Ilia N; Geohegan, David Bruce

    2013-10-29

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  11. Filling of carbon nanotubes and nanofibres

    PubMed Central

    Gately, Reece D

    2015-01-01

    Summary The reliable production of carbon nanotubes and nanofibres is a relatively new development, and due to their unique structure, there has been much interest in filling their hollow interiors. In this review, we provide an overview of the most common approaches for filling these carbon nanostructures. We highlight that filled carbon nanostructures are an emerging material for biomedical applications. PMID:25821693

  12. Method for manufacturing high quality carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Benavides, Jeanette M. (Inventor)

    2006-01-01

    A non-catalytic process for the production of carbon nanotubes includes supplying an electric current to a carbon anode and a carbon cathode which have been securely positioned in the open atmosphere with a gap between them. The electric current creates an electric arc between the carbon anode and the carbon cathode, which causes carbon to be vaporized from the carbon anode and a carbonaceous residue to be deposited on the carbon cathode. Inert gas is pumped into the gap to flush out oxygen, thereby preventing interference with the vaporization of carbon from the anode and preventing oxidation of the carbonaceous residue being deposited on the cathode. The anode and cathode are cooled while electric current is being supplied thereto. When the supply of electric current is terminated, the carbonaceous residue is removed from the cathode and is purified to yield carbon nanotubes.

  13. Method for nano-pumping using carbon nanotubes

    DOEpatents

    Insepov, Zeke; Hassanein, Ahmed

    2009-12-15

    The present invention relates generally to the field of nanotechnology, carbon nanotubes and, more specifically, to a method and system for nano-pumping media through carbon nanotubes. One preferred embodiment of the invention generally comprises: method for nano-pumping, comprising the following steps: providing one or more media; providing one or more carbon nanotubes, the one or more nanotubes having a first end and a second end, wherein said first end of one or more nanotubes is in contact with the media; and creating surface waves on the carbon nanotubes, wherein at least a portion of the media is pumped through the nanotube.

  14. Fabrication of nylon-6/carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Xu, C.; Jia, Z.; Wu, D.; Han, Q.; Meek, T.

    2006-05-01

    A new technique to fabricate nylon-6/carbon nanotube (PA6/CNT) composites is presented. The method involves a pretreatment of carbon nanotubes synthesized by catalytic pyrolysis of hydrocarbon and an improved in-situ process for mixing nanotubes with the nylon 6 matrix. A good bond between carbon nanotubes and the nylon-6 matrix is obtained. Mechanical property measurements indicate that the tensile strength of PA6/CNT composites is improved significantly while the toughness and elongation are somewhat compromised. Scanning electron microscopy (SEM) analysis of the fractured tensile specimens reveals cracking initiated at the wrapping of the CNTs PA6 layer/PA6 matrix interface rather than at the PA6/CNT interface.

  15. Carbon Nanotube Based Microfluidic Elements for Filtration and Concentration

    SciTech Connect

    Bakajin, O; Ben-Barak, N; Peng, J; Noy, A

    2003-06-25

    We have developed a method for integration of patterned arrays of carbon nanotubes or the ''nanotube mesh'' into microfabricated channels. The method includes standard lithographic methods for patterning and etching the substrate, followed by catalyst patterning, CVD deposition of nanotubes, and anodic bonding of coverslip top. We will describe a carbon nanotube filtering device fabricated using this method and discuss the use of carbon nanotube arrays as molecular concentration and separation media.

  16. Polymerization initated at sidewalls of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)

    2011-01-01

    The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

  17. Liquid crystal-carbon nanotubes mixtures

    NASA Astrophysics Data System (ADS)

    Popa-Nita, V.; Kralj, S.

    2010-01-01

    The self-organizing properties of nematic liquid crystals (LCs) can be used to align carbon nanotubes (CNTs) dispersed in them. In the previous paper [P. van der Schoot, V. Popa-Nita, and S. Kralj, J. Phys. Chem. B 112, 4512 (2008)], we have considered the weak anchoring limit of the nematic LC molecules at the nanotube's surface, where the CNT alignment is caused by the anisotropic interfacial tension of the nanotubes in the nematic host fluid. In this paper, we present the theoretical results obtained for strong enough anchoring at the CNT-LC interface for which the nematic ordering around nanotube is apparently distorted. Consequently, relatively strong long-range and anisotropic interactions can emerge within the system. In order to get insight into the impact of LC ordering on the alignment of nanotubes we treat the two mixture components on the same footing and combine Landau-de Gennes free energy for the thermotropic ordering of the liquid crystal and Doi free energy for lyotropic nematic ordering of carbon nanotubes caused by their mutually excluded volume. The phase ordering of the binary mixture is analyzed as a function of the volume fraction of the carbon nanotubes, the strength of coupling, and the temperature. We find that the degree of ordering of the nanorods can be tuned by raising or lowering the temperature or by increasing or decreasing their concentration.

  18. Carbon linear chains inside multiwalled nanotubes

    NASA Astrophysics Data System (ADS)

    Cazzanelli, E.; Caputi, L.; Castriota, M.; Cupolillo, A.; Giallombardo, C.; Papagno, L.

    2007-09-01

    Multiwalled carbon nanotubes have been deposited on graphite cathodes by using an arc discharge technique in He atmosphere, with the insertion of a catalytic Ni-Cr mixture as well as without catalysers. The topography of such deposition has been investigated by SEM, while a parallel micro-Raman study has revealed, in particular regions of the deposited cathodes, strong bands in the range 1780-1860 cm -1, assignable to linear carbon chains inside the nanotubes. The variation of intensity, frequency and bandwidth of such bands has been investigated, in relation with the spectral characters of the host multiwalled carbon nanotube. In the cathode deposited without catalyst a quite ordered configuration of multiwalled carbon nanotubes is obtained in the central zone, while the maximum concentration of linear carbon chains is found in a ring shaped zone just inside the border. In sample obtained with catalyst the deposited multiwalled carbon nanotubes appear always more disordered, and a remarkable concentration of carbon chains appears in some zones, with a more casual distribution.

  19. Modeling of carbon nanotubes and carbon nanotube-polymer composites

    NASA Astrophysics Data System (ADS)

    Pal, G.; Kumar, S.

    2016-01-01

    In order to meet stringent environmental, safety and performance requirements from respective regulatory bodies, various technology-based industries are promoting the use of advanced carbon nanotube (CNT) reinforced lightweight and high strength polymer nanocomposites (PNCs) as a substitute to conventional materials both in structural and non-structural applications. The superior mechanical properties of PNCs made up of CNTs or bundles of CNTs can be attributed to the interfacial interaction between the CNTs and matrix, CNT's morphologies and to their uniform dispersion in the matrix. In PNCs, CNTs physically bond with polymeric matrix at a level where the assumption of continuum level interactions is not applicable. Modeling and prediction of mechanical response and failure behavior of CNTs and their composites becomes a complex task and is dealt with the help of up-scale modeling strategies involving multiple spatial and temporal scales in hierarchical or concurrent manner. Firstly, the article offers an insight into various modeling techniques in studying the mechanical response of CNTs; namely, equivalent continuum approach, quasi-continuum approach and molecular dynamics (MD) simulation. In the subsequent steps, these approaches are combined with analytical and numerical micromechanics models in a multiscale framework to predict the average macroscopic response of PNCs. The review also discusses the implementation aspects of these computational approaches, their current status and associated challenges with a future outlook.

  20. Carbon Nanotube and Graphene Nanoelectromechanical Systems

    NASA Astrophysics Data System (ADS)

    Aleman, Benjamin Jose

    One-dimensional and two-dimensional forms of carbon are composed of sp 2-hybridized carbon atoms arranged in a regular hexagonal, honeycomb lattice. The two-dimensional form, called graphene, is a single atomic layer of hexagonally-bonded carbon atoms. The one-dimensional form, known as a carbon nanotube, can be conceptualized as a rectangular piece of graphene wrapped into a seamless, high-aspect-ratio cylinder or tube. This dissertation addresses the physics and applied physics of these one and two-dimensional carbon allotropes in nanoelectromechanical systems (NEMS). First, we give a theoretical background on the electrodynamics and mechanics of carbon nanotube NEMS. We then describe basic experimental techniques, such as electron and scanning probe microscopy, that we then use to probe static and dynamic mechanical and electronic behavior of the carbon nanotube NEMS. For example, we observe and control non-linear beam bending and single-electron quantum tunneling effects in carbon nanotube resonators. We then describe parametric amplification, self-oscillation behavior, and dynamic, non-linear effects in carbon nanotube mechanical resonators. We also report a novel approach to fabricate carbon nanotube atomic force microscopy (AFM) probes, and show that they can lead to exceptional lateral resolution enhancement in AFM when imaging both hard and soft (biological) materials. Finally, we describe novel fabrication techniques for large-area, suspended graphene membranes, and utilize these membranes as TEM-transparent, AFM-compatible, NEMS resonators. Laser-driven mechanical vibrations of the graphene resonators are detected by optical interferometry and several vibration harmonics are observed. A degeneracy splitting is observed in the vibrational modes of square-geometry resonators. We then attribute the observed degeneracy splitting to local mass inhomogeneities and membrane defects, and find good overall agreement with the developed theoretical model.

  1. Splitting and joining in carbon nanotube/nanoribbon/nanotetrahedron growth.

    PubMed

    Hasegawa, Takayuki; Kohno, Hideo

    2015-02-01

    We report a novel phenomenon for carbon nanotube growth that results in a new carbon nanotube morphology. A carbon nanotube grown via metal nanoparticle-catalyzed chemical vapor deposition splits into two flattened nanotubes during growth and the two flattened nanotubes merge to form a ring of carbon nanotube/nanoribbon. This novel process is revealed by transmission electron microscopy observations of the carbon nanostructures. We propose that the splitting-and-joining process involves only one metal catalyst nanoparticle and a self-folding mechanism that we have named the origami mechanism to explain the process and the formation of nanoribbons and nanotetrahedra. PMID:25559588

  2. Selective Functionalization of Carbon Nanotubes: Part II

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya; Khare, Bishun

    2010-01-01

    An alternative method of low-temperature plasma functionalization of carbon nanotubes provides for the simultaneous attachment of molecular groups of multiple (typically two or three) different species or different mixtures of species to carbon nanotubes at different locations within the same apparatus. This method is based on similar principles, and involves the use of mostly the same basic apparatus, as those of the methods described in "Low-Temperature Plasma Functionalization of Carbon Nanotubes" (ARC-14661-1), NASA Tech Briefs, Vol. 28, No. 5 (May 2004), page 45. The figure schematically depicts the basic apparatus used in the aforementioned method, with emphasis on features that distinguish the present alternative method from the other. In this method, one exploits the fact that the composition of the deposition plasma changes as the plasma flows from its source in the precursor chamber toward the nanotubes in the target chamber. As a result, carbon nanotubes mounted in the target chamber at different flow distances (d1, d2, d3 . . .) from the precursor chamber become functionalized with different species or different mixtures of species. In one series of experiments to demonstrate this method, N2 was used as the precursor gas. After the functionalization process, the carbon nanotubes from three different positions in the target chamber were examined by Fourier-transform infrared spectroscopy to identify the molecular groups that had become attached. On carbon nanotubes from d1 = 1 cm, the attached molecular groups were found to be predominantly C-N and C=N. On carbon nanotubes from d2 = 2.5 cm, the attached molecular groups were found to be predominantly C-(NH)2 and/or C=NH2. (The H2 was believed to originate as residual hydrogen present in the nanotubes.) On carbon nanotubes from d3 = 7 cm no functionalization could be detected - perhaps, it was conjectured, because this distance is downstream of the plasma source, all of the free ions and free radicals of

  3. New carbon nanotube antenna array simulation and fabrication

    NASA Astrophysics Data System (ADS)

    Zareie, Hosein; Davoudzadeh, Nima; Koohsorkhi, Javad; Mohajerzadeh, Shamsoddin; Rouhi, Nima

    2009-03-01

    A novel THz antenna structure, made of carbon nanotube arrays is suggested. Using CST MICROWAVE STUDIO (CST MWS), the capabilities of carbon nanotube terahertz (THz) antenna arrays have been simulated and this CNT antenna array has been fabricated.

  4. Methods for Gas Sensing with Single-Walled Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama B. (Inventor)

    2013-01-01

    Methods for gas sensing with single-walled carbon nanotubes are described. The methods comprise biasing at least one carbon nanotube and exposing to a gas environment to detect variation in temperature as an electrical response.

  5. Conformational changes of fibrinogen in dispersed carbon nanotubes

    PubMed Central

    Park, Sung Jean; Khang, Dongwoo

    2012-01-01

    The conformational changes of plasma protein structures in response to carbon nanotubes are critical for determining the nanotoxicity and blood coagulation effects of carbon nanotubes. In this study, we identified that the functional intensity of carboxyl groups on carbon nanotubes, which correspond to the water dispersity or hydrophilicity of carbon nanotubes, can induce conformational changes in the fibrinogen domains. Also, elevation of carbon nanotube density can alter the secondary structures (ie, helices and beta sheets) of fibrinogen. Furthermore, fibrinogen that had been in contact with the nanoparticle material demonstrated a different pattern of heat denaturation compared with free fibrinogen as a result of a variation in hydrophilicity and concentration of carbon nanotubes. Considering the importance of interactions between carbon nanotubes and plasma proteins in the drug delivery system, this study elucidated the correlation between nanoscale physiochemical material properties of carbon nanotubes and associated structural changes in fibrinogen. PMID:22915854

  6. Release characteristics of selected carbon nanotube polymer composites

    EPA Science Inventory

    Multi-walled carbon nanotubes (MWCNTs) are commonly used in polymer formulations to improve strength, conductivity, and other attributes. A developing concern is the potential for carbon nanotube polymer nanocomposites to release nanoparticles into the environment as the polymer ...

  7. Carbon Nanotube Reinforced Polymers for Radiation Shielding Applications

    NASA Technical Reports Server (NTRS)

    Thibeault, S. (Technical Monitor); Vaidyanathan, Ranji

    2004-01-01

    This viewgraph presentation provides information on the use of Extrusion Freeform Fabrication (EEF) for the fabrication of carbon nanotubes. The presentation addresses TGA analysis, Raman spectroscopy, radiation tests, and mechanical properties of the carbon nanotubes.

  8. Carbon Nanotube Tower-Based Supercapacitor

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya (Inventor)

    2012-01-01

    A supercapacitor system, including (i) first and second, spaced apart planar collectors, (ii) first and second arrays of multi-wall carbon nanotube (MWCNT) towers or single wall carbon nanotube (SWCNT) towers, serving as electrodes, that extend between the first and second collectors where the nanotube towers are grown directly on the collector surfaces without deposition of a catalyst and without deposition of a binder material on the collector surfaces, and (iii) a porous separator module having a transverse area that is substantially the same as the transverse area of at least one electrode, where (iv) at least one nanotube tower is functionalized to permit or encourage the tower to behave as a hydrophilic structure, with increased surface wettability.

  9. Carbon Nanotube-Based Permeable Membranes

    SciTech Connect

    Holt, J K; Park, H G; Bakajin, O; Noy, A; Huser, T; Eaglesham, D

    2004-04-06

    A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Assuming Knudsen diffusion through this nanotube membrane, a maximum helium transport rate (for a pressure drop of 1 atm) of 0.25 cc/sec is predicted. Helium flow measurements of a nanoporous silicon nitride membrane, fabricated by sacrificial removal of carbon, give a flow rate greater than 1x10{sup -6} cc/sec. For viscous, laminar flow conditions, water is estimated to flow across the nanotube membrane (under a 1 atm pressure drop) at up to 2.8x10{sup -5} cc/sec (1.7 {micro}L/min).

  10. Agglomeration defects on irradiated carbon nanotubes

    SciTech Connect

    Steini Moura, Cassio; Balzaretti, Naira Maria; Amaral, Livio; Gribel Lacerda, Rodrigo; Pimenta, Marcos A.

    2012-03-15

    Aligned carbon nanotubes (CNT) were irradiated in the longitudinal and perpendicular directions, with low energy carbon and helium ions in order to observe the formation of defects in the atomic structure. Analysis through Raman spectroscopy and scanning electron microscopy indicated bundle rupture and ion track formation on nanotube bundles. Aligned CNT presented a kind of defect comprising ravine formation and tube agglomeration on top of the substrate. The latter structure is possibly caused by static charge accumulation induced by the incoming ions. Fluence plays a role on the short range order. Higher fluence irradiation transforms CNT into amorphous carbon nanowires.

  11. Electromagnetic SERS effect in carbon nanotube systems

    NASA Astrophysics Data System (ADS)

    Bondarev, I. V.; Gulyuk, A. V.

    2015-11-01

    Quantum electrodynamics theory of the resonance Raman scattering is developed for an atom in a close proximity to a carbon nanotube. The theory describes both weak and strong atomic coupling to nanotube plasmon near fields, and predicts a dramatic enhancement of the Raman intensity in the strong coupling regime. This resonance scattering is a manifestation of the surface enhanced Raman scattering effect, and can be used in designing efficient nanotube based optical sensing substrates for single atom detection, precision spontaneous emission control, and manipulation.

  12. Localized Excitons in Carbon Nanotubes.

    NASA Astrophysics Data System (ADS)

    Adamska, Lyudmyla; Doorn, Stephen K.; Tretiak, Sergei

    2015-03-01

    It has been historically known that unintentional defects in carbon nanotubes (CNTs) may fully quench the fluorescence. However, some dopants may enhance the fluorescence by one order of magnitude thus turning the CNTs, which are excellent light absorbers, in good emitters. We have correlated the experimentally observed photoluminescence spectra to the electronic structure simulations. Our experiment reveals multiple sharp asymmetric emission peaks at energies 50-300 meV red-shifted from that of the lowest bright exciton peak. Our simulations suggest an association of these peaks with deep trap states tied to different specific chemical adducts. While the wave functions of excitons in undoped CNTs are delocalized, those of the deep-trap states are strongly localized and pinned to the dopants. These findings are consistent with the experimental observation of asymmetric broadening of the deep trap emission peaks, which can result from scattering of acoustic phonons on localized excitons. Our work lays the foundation to utilize doping as a generalized route for wave function engineering and direct control of carrier dynamics in SWCNTs toward enhanced light emission properties for photonic applications.

  13. Bending fracture in carbon nanotubes.

    PubMed

    Kuo, Wen-Shyong; Lu, Hsin-Fang

    2008-12-10

    A novel approach was adopted to incur bending fracture in carbon nanotubes (CNTs). Expanded graphite (EG) was made by intercalating and exfoliating natural graphite flakes. The EG was deposited with nickel particles, from which CNTs were grown by chemical vapor deposition. The CNTs were tip-grown, and their roots were fixed on the EG flakes. The EG flakes were compressed, and many CNTs on the surface were fragmented due to the compression-induced bending. Two major modes of the bending fracture were observed: cone-shaped and shear-cut. High-resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the crack growth within the graphene layers. The bending fracture is characterized by two-region crack growth. An opening crack first appears around the outer-tube due to the bending-induced tensile stress. The crack then branches to grow along an inclined direction toward the inner-tube due to the presence of the shear stress in between graphene layers. An inner-tube pullout with inclined side surface is formed. The onset and development of the crack in these two regions are discussed. PMID:21730690

  14. Thermal Transport in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Christman, Jeremy; Moore, Andrew; Khatun, Mahfuza

    2011-10-01

    Recent advances in nanostructure technology have made it possible to create small devices at the nanoscale. Carbon nanotubes (CNT's) are among the most exciting building blocks of nanotechnology. Their versatility and extremely desirable properties for electronic and other devices have driven intense research and development efforts in recent years. A review of electrical and thermal conduction of the structures will be presented. The theoretical investigation is mainly based on molecular dynamics. Green Kubo relation is used for the study of thermal conductivity. Results include kinetic energy, potential energy, heat flux autocorrelation function, and heat conduction of various CNT structures. Most of the computation and simulation has been conducted on the Beowulf cluster at Ball State University. Various software packages and tools such as Visual Molecular Dynamics (VMD), Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), and NanoHUB, the open online resource at Purdue University have been used for the research. The work has been supported by the Indiana Academy of Science Research Fund, 2010-2011.

  15. Carbon nanotube fiber terahertz polarizer

    NASA Astrophysics Data System (ADS)

    Zubair, Ahmed; Tsentalovich, Dmitri E.; Young, Colin C.; Heimbeck, Martin S.; Everitt, Henry O.; Pasquali, Matteo; Kono, Junichiro

    2016-04-01

    Conventional, commercially available terahertz (THz) polarizers are made of uniformly and precisely spaced metallic wires. They are fragile and expensive, with performance characteristics highly reliant on wire diameters and spacings. Here, we report a simple and highly error-tolerant method for fabricating a freestanding THz polarizer with nearly ideal performance, reliant on the intrinsically one-dimensional character of conduction electrons in well-aligned carbon nanotubes (CNTs). The polarizer was constructed on a mechanical frame over which we manually wound acid-doped CNT fibers with ultrahigh electrical conductivity. We demonstrated that the polarizer has an extinction ratio of ˜-30 dB with a low insertion loss (<0.5 dB) throughout a frequency range of 0.2-1.1 THz. In addition, we used a THz ellipsometer to measure the Müller matrix of the CNT-fiber polarizer and found comparable attenuation to a commercial metallic wire-grid polarizer. Furthermore, based on the classical theory of light transmission through an array of metallic wires, we demonstrated the most striking difference between the CNT-fiber and metallic wire-grid polarizers: the latter fails to work in the zero-spacing limit, where it acts as a simple mirror, while the former continues to work as an excellent polarizer even in that limit due to the one-dimensional conductivity of individual CNTs.

  16. Elastomer Reinforced with Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Hudson, Jared L.; Krishnamoorti, Ramanan

    2009-01-01

    Elastomers are reinforced with functionalized, single-walled carbon nanotubes (SWNTs) giving them high-breaking strain levels and low densities. Cross-linked elastomers are prepared using amine-terminated, poly(dimethylsiloxane) (PDMS), with an average molecular weight of 5,000 daltons, and a functionalized SWNT. Cross-link densities, estimated on the basis of swelling data in toluene (a dispersing solvent) indicated that the polymer underwent cross-linking at the ends of the chains. This thermally initiated cross-linking was found to occur only in the presence of the aryl alcohol functionalized SWNTs. The cross-link could have been via a hydrogen-bonding mechanism between the amine and the free hydroxyl group, or via attack of the amine on the ester linage to form an amide. Tensile properties examined at room temperature indicate a three-fold increase in the tensile modulus of the elastomer, with rupture and failure of the elastomer occurring at a strain of 6.5.

  17. Does water dope carbon nanotubes?

    SciTech Connect

    Bell, Robert A.; Payne, Michael C.; Mostofi, Arash A.

    2014-10-28

    We calculate the long-range perturbation to the electronic charge density of carbon nanotubes (CNTs) as a result of the physisorption of a water molecule. We find that the dominant effect is a charge redistribution in the CNT due to polarisation caused by the dipole moment of the water molecule. The charge redistribution is found to occur over a length-scale greater than 30 Å, highlighting the need for large-scale simulations. By comparing our fully first-principles calculations to ones in which the perturbation due to a water molecule is treated using a classical electrostatic model, we estimate that the charge transfer between CNT and water is negligible (no more than 10{sup −4} e per water molecule). We therefore conclude that water does not significantly dope CNTs, a conclusion that is consistent with the poor alignment of the relevant energy levels of the water molecule and CNT. Previous calculations that suggest water n-dopes CNTs are likely due to the misinterpretation of Mulliken charge partitioning in small supercells.

  18. Electrical properties of multiwalled carbon nanotube film

    SciTech Connect

    Antonenko, S. V. Malinovskaya, O. S.; Mal'tsev, S. N.

    2007-07-15

    The multiwalled carbon nanotube films examined in this study are produced by two methods: current annealing of carbon paper and dc magnetron sputtering. The conductivity and the temperature dependence of resistance of the samples are measured. The thermal conductivity of the film-substrate system is evaluated.

  19. Carbon Nanotube Doped Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Raffaelle, Ryne P.; Difelice, Ron; van Derveer, William R.; Gennett, Tom; Maranchi, Jeff; Kumta, Prashant; Hepp, Aloysius F.

    2002-03-01

    We have characterized thin film lithium ion batteries that contain high purity single wall carbon nanotube-doped polymer anodes. Highly purified single-walled carbon nanotubes (SWCNT) were obtained through chemical refinement of soot generated by pulsed laser ablation. The purity of the nanotubes was determined via thermogravimetric analysis, two wavelength Raman spectroscopy, spectrophotometry, scanning electron microscopy and transmission electron microscopy. The specific surface area and lithium capacity of the SWCNT was compared to that of other conventional anode materials (i.e., carbon black, graphite, and multi-walled carbon nanotubes). The SWCNT exhibited a specific surface area that greatly exceeded the other carbonaceous materials. Anodes were prepared by casting thin films directly onto copper foil of several ionically conductive polymers (i.e., PAN, PVDF, PEO) doped with the SWCNT. The lithium-ion capacity of the materials was measured using a standard 3-electrode cell. The electrochemical discharge capacity of the purified single walled carbon nanotubes in PVDF was in excess of 1300 mAh/g after 30 charge/discharge cycles when tested using a current density of 20µA/cm^2. The SWCNT anodes were incorporated into all-polymer thin film batteries containing LiNiCoO_2-doped polymer cathodes. Cycling results on the various SWCNT polymer combinations will be presented.

  20. Chemical reactions confined within carbon nanotubes.

    PubMed

    Miners, Scott A; Rance, Graham A; Khlobystov, Andrei N

    2016-08-22

    In this critical review, we survey the wide range of chemical reactions that have been confined within carbon nanotubes, particularly emphasising how the pairwise interactions between the catalysts, reactants, transition states and products of a particular molecular transformation with the host nanotube can be used to control the yields and distributions of products of chemical reactions. We demonstrate that nanoscale confinement within carbon nanotubes enables the control of catalyst activity, morphology and stability, influences the local concentration of reactants and products thus affecting equilibria, rates and selectivity, pre-arranges the reactants for desired reactions and alters the relative stability of isomeric products. We critically evaluate the relative advantages and disadvantages of the confinement of chemical reactions inside carbon nanotubes from a chemical perspective and describe how further developments in the controlled synthesis of carbon nanotubes and the incorporation of multifunctionality are essential for the development of this ever-expanding field, ultimately leading to the effective control of the pathways of chemical reactions through the rational design of multi-functional carbon nanoreactors. PMID:27301444

  1. Different Technical Applications of Carbon Nanotubes.

    PubMed

    Abdalla, S; Al-Marzouki, F; Al-Ghamdi, Ahmed A; Abdel-Daiem, A

    2015-12-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact. PMID:26377211

  2. Different Technical Applications of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Abdalla, S.; Al-Marzouki, F.; Al-Ghamdi, Ahmed A.; Abdel-Daiem, A.

    2015-09-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact.

  3. Measurement Challenges for Carbon Nanotube Material

    NASA Technical Reports Server (NTRS)

    Sosa, Edward; Arepalli, Sivaram; Nikolaev, Pasha; Gorelik, Olga; Yowell, Leonard

    2006-01-01

    The advances in large scale applications of carbon nanotubes demand a reliable supply of raw and processed materials. It is imperative to have a consistent quality control of these nanomaterials to distinguish material inconsistency from the modifications induced by processing of nanotubes for any application. NASA Johnson Space Center realized this need five years back and started a program to standardize the characterization methods. The JSC team conducted two workshops (2003 and 2005) in collaboration with NIST focusing on purity and dispersion measurement issues of carbon nanotubes [1]. In 2004, the NASA-JSC protocol was developed by combining analytical techniques of SEM, TEM, UV-VIS-NIR absorption, Raman, and TGA [2]. This protocol is routinely used by several researchers across the world as a first step in characterizing raw and purified carbon nanotubes. A suggested practice guide consisting of detailed chapters on TGA, Raman, electron microscopy and NIR absorption is in the final stages and is undergoing revisions with input from the nanotube community [3]. The possible addition of other techniques such as XPS, and ICP to the existing protocol will be presented. Recent activities at ANSI and ISO towards implementing these protocols as nanotube characterization standards will be discussed.

  4. Bulk Cutting of Carbon Nanotubes Using Electron Beam Irradiation

    NASA Technical Reports Server (NTRS)

    Ziegler, Kirk J. (Inventor); Rauwald, Urs (Inventor); Hauge, Robert H. (Inventor); Schmidt, Howard K. (Inventor); Smalley, Richard E. (Inventor); Kittrell, W. Carter (Inventor); Gu, Zhenning (Inventor)

    2013-01-01

    According to some embodiments, the present invention provides a method for attaining short carbon nanotubes utilizing electron beam irradiation, for example, of a carbon nanotube sample. The sample may be pretreated, for example by oxonation. The pretreatment may introduce defects to the sidewalls of the nanotubes. The method is shown to produces nanotubes with a distribution of lengths, with the majority of lengths shorter than 100 tun. Further, the median length of the nanotubes is between about 20 nm and about 100 nm.

  5. Formation of Carbon Nanotubes in a Microgravity Environment

    NASA Technical Reports Server (NTRS)

    Alford, J. M.; Mason, G. R.; Feikema, D. A.

    2001-01-01

    Even though nanotube science has become one of the worlds most rapidly advancing areas of research, very little is known about the processes involved in nanotube synthesis. To study the formation of carbon nanotubes in an environment unhindered by the buoyancy induced flows generated by the high temperatures necessary to vaporize carbon and grow nanotubes, we have designed a miniature carbon arc apparatus that can produce carbon nanotubes under microgravity conditions. During the first phase of this project, we designed, built, and successfully tested the mini carbon arc in both 1g and 2.2 sec drop tower microgravity conditions. We have demonstrated that microgravity can eliminate the strong convective flows from the carbon arc and we have successfully produced single-walled carbon nanotubes in microgravity. We believe that microgravity processing will allow us to better understand the nanotube formation process and eventually allow us to grow nanotubes that are superior to ground-based production.

  6. Mechanics of Carbon Nanotubes and their Polymer Composites

    NASA Technical Reports Server (NTRS)

    Wei, Chenyu; Cho, K. J.; Srivastava, Deepak; Tang, Harry (Technical Monitor)

    2002-01-01

    Contents include the folloving: carbon nanotube (CNT): structures, application of carbon nanotubes, simulation method, Elastic properties of carbon nanotubes, yield strain of CNT, yielding under tensile stress, yielding: strain-rate and temperature dependence, yield strain under tension, yielding at realistic conditions, nano fibers, polymer CNT composite, force field, density dependency on temperature, diffusion coefficients, young modulus, and conclusions.

  7. Carbon nanotube suspensions, dispersions, & composites

    NASA Astrophysics Data System (ADS)

    Simmons, Trevor John

    Carbon Nanotubes (CNTs) are amazing structures that hold the potential to revolutionize many areas of scientific research. CNTs can be behave both as semiconductors and metals, can be grown in highly ordered arrays and patterns or in random orientation, and can be comprised of one graphene cylinder (single wall nanotube, SWNT) or several concentric graphene cylinders (multi-wall nanotube, MWNT). Although these structures are usually only a few nanometers wide, they can be grown up to centimeter lengths, and in massive quantities. CNTs can be produced in a variety of processes ranging from repeated combustion of organic material such as dried grass, arc-discharge with graphite electrodes, laser ablation of a graphitic target, to sophisticated chemical vapor deposition (CVD) techniques. CNTs are stronger than steel but lighter than aluminum, and can be more conductive than copper or semiconducting like silicon. This variety of properties has been matched by the wide variety of applications that have been developed for CNTs. Many of these applications have been limited by the inability of researchers to tame these structures, and incorporating CNTs into existing technologies can be exceedingly difficult and prohibitively expensive. It is therefore the aim of the current study to develop strategies for the solution processing and deposition of CNTs and CNT-composites, which will enable the use of CNTs in existing and emerging technologies. CNTs are not easily suspended in polar solvents and are extremely hydrophobic materials, which has limited much of the solution processing to organic solvents, which also cannot afford high quality dispersions of CNTs. The current study has developed a variety of aqueous CNT solutions that employ surfactants, water-soluble polymers, or both to create suspensions of CNTs. These CNT 'ink' solutions were deposited with a variety of techniques that have afforded many interesting structures, both randomly oriented as well as highly

  8. Geometric and electronic structure of carbon nanotube networks: 'super'-carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Coluci, V. R.; Galvão, D. S.; Jorio, A.

    2006-02-01

    Structures of the so-called super-carbon nanotubes are proposed. These structures are built from single walled carbon nanotubes connected by Y-like junctions forming a 'super'-sheet that is then rolled into a seamless cylinder. Such a procedure can be repeated several times, generating a fractal structure. This procedure is not limited to carbon nanotubes, and can be easily modified for application to other systems. Tight binding total energy and density of states calculations showed that the 'super'-sheets and tubes are stable and predicted to present metallic and semiconducting behaviour.

  9. Detection of gas atoms with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Arash, B.; Wang, Q.

    2013-05-01

    Owning to their unparalleled sensitivity resolution, nanomechanical resonators have excellent capabilities in design of nano-sensors for gas detection. The current challenge is to develop new designs of the resonators for differentiating distinct gas atoms with a recognizably high sensitivity. In this work, the characteristics of impulse wave propagation in carbon nanotube-based sensors are investigated using molecular dynamics simulations to provide a new method for detection of noble gases. A sensitivity index based on wave velocity shifts in a single-walled carbon nanotube, induced by surrounding gas atoms, is defined to explore the efficiency of the nano-sensor. The simulation results indicate that the nano-sensor is able to differentiate distinct noble gases at the same environmental temperature and pressure. The inertia and the strengthening effects by the gases on wave characteristics of carbon nanotubes are particularly discussed, and a continuum mechanics shell model is developed to interpret the effects.

  10. Detection of gas atoms with carbon nanotubes

    PubMed Central

    Arash, B.; Wang, Q.

    2013-01-01

    Owning to their unparalleled sensitivity resolution, nanomechanical resonators have excellent capabilities in design of nano-sensors for gas detection. The current challenge is to develop new designs of the resonators for differentiating distinct gas atoms with a recognizably high sensitivity. In this work, the characteristics of impulse wave propagation in carbon nanotube-based sensors are investigated using molecular dynamics simulations to provide a new method for detection of noble gases. A sensitivity index based on wave velocity shifts in a single-walled carbon nanotube, induced by surrounding gas atoms, is defined to explore the efficiency of the nano-sensor. The simulation results indicate that the nano-sensor is able to differentiate distinct noble gases at the same environmental temperature and pressure. The inertia and the strengthening effects by the gases on wave characteristics of carbon nanotubes are particularly discussed, and a continuum mechanics shell model is developed to interpret the effects.

  11. Carbon Nanotube Bolometer for Absolute FTIR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Woods, Solomon; Neira, Jorge; Tomlin, Nathan; Lehman, John

    We have developed and calibrated planar electrical-substitution bolometers which employ absorbers made from vertically-aligned carbon nanotube arrays. The nearly complete absorption of light by the carbon nanotubes from the visible range to the far-infrared can be exploited to enable a device with read-out in native units equivalent to optical power. Operated at cryogenic temperatures near 4 K, these infrared detectors are designed to have time constant near 10 ms and a noise floor of about 10 pW. Built upon a micro-machined silicon platform, each device has an integrated heater and thermometer, either a carbon nanotube thermistor or superconducting transition edge sensor, for temperature control. We are optimizing temperature-controlled measurement techniques to enable high resolution spectral calibrations using these devices with a Fourier-transform spectrometer.

  12. Modelling Carbon Nanotubes-Based Mediatorless Biosensor

    PubMed Central

    Baronas, Romas; Kulys, Juozas; Petrauskas, Karolis; Razumiene, Julija

    2012-01-01

    This paper presents a mathematical model of carbon nanotubes-based mediatorless biosensor. The developed model is based on nonlinear non-stationary reaction-diffusion equations. The model involves four layers (compartments): a layer of enzyme solution entrapped on a terylene membrane, a layer of the single walled carbon nanotubes deposited on a perforated membrane, and an outer diffusion layer. The biosensor response and sensitivity are investigated by changing the model parameters with a special emphasis on the mediatorless transfer of the electrons in the layer of the enzyme-loaded carbon nanotubes. The numerical simulation at transient and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate. PMID:23012537

  13. Modelling carbon nanotubes-based mediatorless biosensor.

    PubMed

    Baronas, Romas; Kulys, Juozas; Petrauskas, Karolis; Razumiene, Julija

    2012-01-01

    This paper presents a mathematical model of carbon nanotubes-based mediatorless biosensor. The developed model is based on nonlinear non-stationary reaction-diffusion equations. The model involves four layers (compartments): a layer of enzyme solution entrapped on a terylene membrane, a layer of the single walled carbon nanotubes deposited on a perforated membrane, and an outer diffusion layer. The biosensor response and sensitivity are investigated by changing the model parameters with a special emphasis on the mediatorless transfer of the electrons in the layer of the enzyme-loaded carbon nanotubes. The numerical simulation at transient and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate. PMID:23012537

  14. Boron-Filled Hybrid Carbon Nanotubes

    PubMed Central

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  15. Nanocrystalline cobalt oxides for carbon nanotube growth

    NASA Astrophysics Data System (ADS)

    Guo, Kun; Jayatissa, Ahalapitiya H.; Jayasuriya, Ambalangodage C.

    2007-09-01

    Thin Films of nanocrystalline cobalt oxide were formed by sol-gel method. Structure, optical properties and surface properties of these films were investigated by numerous characterization techniques. These films were successfully fabricated on glass substrates below 500°C. . Micropatterns of cobalt oxide thin films were also fabricated on glass and silicon substrates by employing a lift-off method. Crystal size of these nanocrystalline cobalt films could be successfully controllable by varying the amount of cobalt precursors and number of layers. These films were used as the seeding layers for carbon nanotube growth in a CVD process By changing the concentration of monomer precursors in the solgel coating solutions, different size nanoclusters hence different size carbon nanotubes could be synthesized in CVD process. This method can be used for controlled growth of carbon nanotubes for many different applications. In this paper, detail of these experimental results will be presented.

  16. Boron-Filled Hybrid Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-07-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs.

  17. Boron-Filled Hybrid Carbon Nanotubes.

    PubMed

    Patel, Rajen B; Chou, Tsengming; Kanwal, Alokik; Apigo, David J; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  18. Piezoresistive effect in carbon nanotube fibers.

    PubMed

    Lekawa-Raus, Agnieszka; Koziol, Krzysztof K K; Windle, Alan H

    2014-11-25

    The complex structure of the macroscopic assemblies of carbon nanotubes and variable intrinsic piezoresistivity of nanotubes themselves lead to highly interesting piezoresistive performance of this new type of conductive material. Here, we present an in-depth study of the piezoresistive effect in carbon nanotube fibers, i.e., yarnlike assemblies made purely of aligned carbon nanotubes, which are expected to find applications as electrical and electronic materials. The resistivity changes of carbon nanotube fibers were measured on initial loading, through the elastic/plastic transition, on cyclic loading and on stress relaxation. The various regimes of stress/strain behavior were modeled using a standard linear solid model, which was modified with an additional element in series to account for the observed creep behavior. On the basis of the experimental and modeling results, the origin of piezoresistivity is discussed. An additional effect on the resistivity was found as the fiber was held under load which led to observations of the effect of humidity and the associated water adsorption level on the resistivity. We show that the equilibrium uptake of moisture leads to the decrease in gauge factor of the fiber decrease, i.e., the reduction in the sensitivity of fiber resistivity to loading. PMID:25337627

  19. Carbon Nanotubes Synthesis Through Gamma Radiation

    NASA Astrophysics Data System (ADS)

    Tirado, Pablo; Garcia, Rafael; Montes, Jorge; Melendrez, Rodrigo; Barboza, Marcelino; Contreras, Oscar

    2015-03-01

    Carbon nanotubes show a great potential of applications since there discovery by Iijima in 1991[1] due to their numerous physical-chemical properties such as their high weight to strength relationship, which make them ideal to use in high resistance compound materials, and in many other applications[2] In this work, a novel method for the synthesis of carbon nanotubes is presented, starting from an ultra-thin sheet of graphite synthesized by the chemical vapor decomposition technique (CVD), using ultra high purity methane and hydrogen at 1200°C in a horizontal quartz reactor. For the synthesis of carbon nanotubes, the graphite sheets were exposed to different doses of radiation, with the objective of breaking the graphite bonds and form carbon nanotubes; a Gammacell equipment model 220 Excel was used for the purpose, which counts with a radiation source of cobalt 60, and a current radiation rate of 0.9 Gy/seconds. The time of exposure to radiation was varied in each sample, according to the desired dose of radiation in each case, afterwards the samples were characterized using the Raman spectroscopy and TEM microscopy techniques with the objective of observing the kind of nanotubes formed, their morphology and their number of defects. Results will be shown during the poster session.

  20. Orientational Growth of Carbon Nanotube for Applications

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Cochrane, J. C.; Lehoczky, S.; Cui, Y.; Burger, A.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Since the superior properties of multi-wall carbon nanotubes (MWCNT) could improve numerous devices such as electronics and sensors, many efforts have been made in investigating the growth mechanism of MWCNT to synthesize high quality MWCNT. Most applications require uniform aligned CNT. In this presentation, a directional growth of CNT will be reported. Carbon nanotubes are synthesized using thermal chemical vapor deposition. Temperature and pressure are two important growth parameters for fabricating carbon nanotubes. It is found that the nanotube diameter distribution mainly depends on the growth-temperature. With the substrate surface normal either along or against the gravity vector, different growth orientations of MWCNT are observed by scanning electron microscopy although the Raman spectra are similar for samples synthesized at different locations. The sizes of these carbon nanotubes in each sample are quite uniform and the length of the tube is up to several tens of micrometers. These results suggest the gravitation effects in the growth of long and small diameter CNT.

  1. Molecular Dynamics Modeling of Carbon Nanotubes and Their Composites

    NASA Astrophysics Data System (ADS)

    Jensen, Lars R.; Pyrz, Ryszard

    2004-06-01

    The tensile modulus of individual nanotubes and nanotube-polypropylene composites has been determined using molecular dynamics simulations. Simulations of individual single-walled carbon nanotubes showed that their tensile modulus was dependent on the tube structure and the diameter if the diameter was below 1,6 nm. The tensile modulus was determined for an infinite single-walled carbon nanotube embedded in an amorphous polypropylene matrix and for a finite and capped single-walled carbon nanotube embedded in a polypropylene matrix. For the infinite nanotube-polypropylene system the modulus was found to correspond to the one given by the Voigt approximation. For the finite nanotube-polypropylene system the reinforcing effect of the nanotube was not very pronounced. A pull out simulation showed that the length of the nanotube in the simulation was much smaller than the critical length and hence no load transfer between the nanotube and the matrix existed.

  2. Lipid nanoscaffolds in carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Paukner, Catharina; Koziol, Krzysztof K. K.; Kulkarni, Chandrashekhar V.

    2013-09-01

    We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields.We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields. Electronic supplementary information (ESI) available: Additional wide angle X-ray scattering (WAXS) data on the alignment of lipid nanostructures, control and time resolved 2-d images of egg ovalbumin encapsulation and a summary picture of the present work. See DOI: 10.1039/c3nr02068a

  3. A carbon nanotube optical rectenna.

    PubMed

    Sharma, Asha; Singh, Virendra; Bougher, Thomas L; Cola, Baratunde A

    2015-12-01

    An optical rectenna--a device that directly converts free-propagating electromagnetic waves at optical frequencies to direct current--was first proposed over 40 years ago, yet this concept has not been demonstrated experimentally due to fabrication challenges at the nanoscale. Realizing an optical rectenna requires that an antenna be coupled to a diode that operates on the order of 1 PHz (switching speed on the order of 1 fs). Diodes operating at these frequencies are feasible if their capacitance is on the order of a few attofarads, but they remain extremely difficult to fabricate and to reliably couple to a nanoscale antenna. Here we demonstrate an optical rectenna by engineering metal-insulator-metal tunnel diodes, with a junction capacitance of ∼2 aF, at the tip of vertically aligned multiwalled carbon nanotubes (∼10 nm in diameter), which act as the antenna. Upon irradiation with visible and infrared light, we measure a d.c. open-circuit voltage and a short-circuit current that appear to be due to a rectification process (we account for a very small but quantifiable contribution from thermal effects). In contrast to recent reports of photodetection based on hot electron decay in a plasmonic nanoscale antenna, a coherent optical antenna field appears to be rectified directly in our devices, consistent with rectenna theory. Finally, power rectification is observed under simulated solar illumination, and there is no detectable change in diode performance after numerous current-voltage scans between 5 and 77 °C, indicating a potential for robust operation. PMID:26414198

  4. Ultralight multiwalled carbon nanotube aerogel.

    PubMed

    Zou, Jianhua; Liu, Jianhua; Karakoti, Ajay Singh; Kumar, Amit; Joung, Daeha; Li, Qiang; Khondaker, Saiful I; Seal, Sudipta; Zhai, Lei

    2010-12-28

    Ultralight multiwalled carbon nanotube (MWCNT) aerogel is fabricated from a wet gel of well-dispersed pristine MWCNTs. On the basis of a theoretical prediction that increasing interaction potential between CNTs lowers their critical concentration to form an infinite percolation network, poly(3-(trimethoxysilyl) propyl methacrylate) (PTMSPMA) is used to disperse and functionalize MWCNTs where the subsequent hydrolysis and condensation of PTMSPMA introduces strong and permanent chemical bonding between MWCNTs. The interaction is both experimentally and theoretically proven to facilitate the formation of a MWCNT percolation network, which leads to the gelation of MWCNT dispersion at ultralow MWCNT concentration. After removing the liquid component from the MWCNT wet gel, the lightest ever free-standing MWCNT aerogel monolith with a density of 4 mg/cm(3) is obtained. The MWCNT aerogel has an ordered macroporous honeycomb structure with straight and parallel voids in 50-150 μm separated by less than 100 nm thick walls. The entangled MWCNTs generate mesoporous structures on the honeycomb walls, creating aerogels with a surface area of 580 m(2)/g which is much higher than that of pristine MWCNTs (241 m(2)/g). Despite the ultralow density, the MWCNT aerogels have an excellent compression recoverable property as demonstrated by the compression test. The aerogels have an electrical conductivity of 3.2 × 10(-2) S·cm(-1) that can be further increased to 0.67 S·cm(-1) by a high-current pulse method without degrading their structures. The excellent compression recoverable property, hierarchically porous structure with large surface area, and high conductivity grant the MWCNT aerogels exceptional pressure and chemical vapor sensing capabilities. PMID:21090673

  5. A carbon nanotube optical rectenna

    NASA Astrophysics Data System (ADS)

    Sharma, Asha; Singh, Virendra; Bougher, Thomas L.; Cola, Baratunde A.

    2015-12-01

    An optical rectenna—a device that directly converts free-propagating electromagnetic waves at optical frequencies to direct current—was first proposed over 40 years ago, yet this concept has not been demonstrated experimentally due to fabrication challenges at the nanoscale. Realizing an optical rectenna requires that an antenna be coupled to a diode that operates on the order of 1 PHz (switching speed on the order of 1 fs). Diodes operating at these frequencies are feasible if their capacitance is on the order of a few attofarads, but they remain extremely difficult to fabricate and to reliably couple to a nanoscale antenna. Here we demonstrate an optical rectenna by engineering metal-insulator-metal tunnel diodes, with a junction capacitance of ˜2 aF, at the tip of vertically aligned multiwalled carbon nanotubes (˜10 nm in diameter), which act as the antenna. Upon irradiation with visible and infrared light, we measure a d.c. open-circuit voltage and a short-circuit current that appear to be due to a rectification process (we account for a very small but quantifiable contribution from thermal effects). In contrast to recent reports of photodetection based on hot electron decay in a plasmonic nanoscale antenna, a coherent optical antenna field appears to be rectified directly in our devices, consistent with rectenna theory. Finally, power rectification is observed under simulated solar illumination, and there is no detectable change in diode performance after numerous current-voltage scans between 5 and 77 °C, indicating a potential for robust operation.

  6. Crosstalk analysis of carbon nanotube bundle interconnects.

    PubMed

    Zhang, Kailiang; Tian, Bo; Zhu, Xiaosong; Wang, Fang; Wei, Jun

    2012-01-01

    Carbon nanotube (CNT) has been considered as an ideal interconnect material for replacing copper for future nanoscale IC technology due to its outstanding current carrying capability, thermal conductivity, and mechanical robustness. In this paper, crosstalk problems for single-walled carbon nanotube (SWCNT) bundle interconnects are investigated; the interconnect parameters for SWCNT bundle are calculated first, and then the equivalent circuit has been developed to perform the crosstalk analysis. Based on the simulation results using SPICE simulator, the voltage of the crosstalk-induced glitch can be reduced by decreasing the line length, increasing the spacing between adjacent lines, or increasing the diameter of SWCNT. PMID:22340628

  7. Laser ablative synthesis of carbon nanotubes

    DOEpatents

    Smith, Michael W.; Jordan, Kevin; Park, Cheol

    2010-03-02

    An improved method for the production of single walled carbon nanotubes that utilizes an RF-induction heated side-pumped synthesis chamber for the production of such. Such a method, while capable of producing large volumes of carbon nanotubes, concurrently permits the use of a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization. The method of the present invention utilizes a free electron laser operating at high average and peak fluence to illuminate a rotating and translating graphite/catalyst target to obtain high yields of SWNTs without the use of a vacuum chamber.

  8. Carbon Nanotube-Enhanced Carbon-Phenenolic Ablator Material

    NASA Technical Reports Server (NTRS)

    Kikolaev, P.; Stackpoole, M.; Fan, W.; Cruden, B. A.; Waid, M.; Moloney, P.; Arepalli, S.; Arnold, J.; Partridge, H.; Yowell, L.

    2006-01-01

    This viewgraph presentation reviews the use of PICA (phenolic impregnated carbon ablator) as the selected material for heat shielding for future earth return vehicles. It briefly reviews the manufacturing of PICA and the advantages for the use of heat shielding, and then explains the reason for using Carbon Nanotubes to improve strength of phenolic resin that binds carbon fibers together. It reviews the work being done to create a carbon nanotube enhanced PICA. Also shown are various micrographic images of the various PICA materials.

  9. Geckolike high shear strength by carbon nanotube fiber adhesives

    NASA Astrophysics Data System (ADS)

    Maeno, Y.; Nakayama, Y.

    2009-01-01

    Carbon nanotube adhesives can adhere strongly to surfaces as a gecko does. The number of carbon nanotube layers is an important determinant of the contact area for adhesion. Balancing the catalyst ratio and buffer layer used for chemical vapor deposition processing controls the number of carbon nanotube layers and their distribution. The features of carbon nanotubes determine the shear strength of adhesion. Carbon nanotubes with a broad distribution of layers exhibit enhanced shear strength with equivalent adhesive capability to that of a natural Tokay Gecko (Gekko gecko)

  10. The Use of Plasma Vortexes in Creating Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Leith, Alexander; Alexander Leith Collaboration

    2016-03-01

    Carbon nanotubes have been created in a variety of ways such as arc discharge, laser ablation, and chemical vapor deposition (CVD). Each of these techniques has been proven to produce carbon nanotubes in small quantities in a lab setting. This is the problem that we have been addressing. Over the course of 16 months, we have been working on a new method of carbon nanotube production that is based around fluid dynamics and plasma. We have created the basic components to test this new way to produce carbon nanotubes. This research will ideally provide a new avenue for carbon nanotube production. Worked with Dr. Randal Tagg of the University of Colorado Denver.

  11. Computational Nanomechanics of Carbon Nanotubes and Composites

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Wei, Chenyu; Cho, Kyeongjae; Biegel, Bryan (Technical Monitor)

    2002-01-01

    Nanomechanics of individual carbon and boron-nitride nanotubes and their application as reinforcing fibers in polymer composites has been reviewed with interplay of theoretical modeling, computer simulations and experimental observations. The emphasis in this work is on elucidating the multi-length scales of the problems involved, and of different simulation techniques that are needed to address specific characteristics of individual nanotubes and nanotube polymer-matrix interfaces. Classical molecular dynamics simulations are shown to be sufficient to describe the generic behavior such as strength and stiffness modulus but are inadequate to describe elastic limit and nature of plastic buckling at large strength. Quantum molecular dynamics simulations are shown to bring out explicit atomic nature dependent behavior of these nanoscale materials objects that are not accessible either via continuum mechanics based descriptions or through classical molecular dynamics based simulations. As examples, we discus local plastic collapse of carbon nanotubes under axial compression and anisotropic plastic buckling of boron-nitride nanotubes. Dependence of the yield strain on the strain rate is addressed through temperature dependent simulations, a transition-state-theory based model of the strain as a function of strain rate and simulation temperature is presented, and in all cases extensive comparisons are made with experimental observations. Mechanical properties of nanotube-polymer composite materials are simulated with diverse nanotube-polymer interface structures (with van der Waals interaction). The atomistic mechanisms of the interface toughening for optimal load transfer through recycling, high-thermal expansion and diffusion coefficient composite formation above glass transition temperature, and enhancement of Young's modulus on addition of nanotubes to polymer are discussed and compared with experimental observations.

  12. Compressed carbon nanotubes: A family of new multifunctional carbon allotropes

    PubMed Central

    Hu, Meng; Zhao, Zhisheng; Tian, Fei; Oganov, Artem R.; Wang, Qianqian; Xiong, Mei; Fan, Changzeng; Wen, Bin; He, Julong; Yu, Dongli; Wang, Hui-Tian; Xu, Bo; Tian, Yongjun

    2013-01-01

    The exploration of novel functional carbon polymorphs is an enduring topic of scientific investigations. In this paper, we present simulations demonstrating metastable carbon phases as the result of pressure induced carbon nanotube polymerization. The configuration, bonding, electronic, and mechanical characteristics of carbon polymers strongly depend on the imposed hydrostatic/non-hydrostatic pressure, as well as on the geometry of the raw carbon nanotubes including diameter, chirality, stacking manner, and wall number. Especially, transition processes under hydrostatic/non-hydrostatic pressure are investigated, revealing unexpectedly low transition barriers and demonstrating sp2→sp3 bonding changes as well as peculiar oscillations of electronic property (e.g., semiconducting→metallic→semiconducting transitions). These polymerized nanotubes show versatile and superior physical properties, such as superhardness, high tensile strength and ductility, and tunable electronic properties (semiconducting or metallic). PMID:23435585

  13. Improved Method of Purifying Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D.

    2004-01-01

    An improved method of removing the residues of fabrication from carbon nanotubes has been invented. These residues comprise amorphous carbon and metal particles that are produced during the growth process. Prior methods of removing the residues include a variety of processes that involved the use of halogens, oxygen, or air in both thermal and plasma processes. Each of the prior methods entails one or more disadvantages, including non-selectivity (removal or damage of nanotubes in addition to removal of the residues), the need to dispose of toxic wastes, and/or processing times as long as 24 hours or more. In contrast, the process described here does not include the use of toxic chemicals, the generation of toxic wastes, causes little or no damage to the carbon nanotubes, and involves processing times of less than 1 hour. In the improved method, purification is accomplished by flowing water vapor through the reaction chamber at elevated temperatures and ambient pressures. The impurities are converted to gaseous waste products by the selective hydrogenation and hydroxylation by the water in a reaction chamber. This process could be performed either immediately after growth or in a post-growth purification process. The water used needs to be substantially free of oxygen and can be obtained by a repeated freeze-pump-thaw process. The presence of oxygen will non-selectively attach the carbon nanotubes in addition to the amorphous carbon.

  14. Carbon Nanotube Membranes: Carbon Nanotube Membranes for Energy-Efficient Carbon Sequestration

    SciTech Connect

    2010-03-01

    Broad Funding Opportunity Announcement Project: Porifera is developing carbon nanotube membranes that allow more efficient removal of CO2 from coal plant exhaust. Most of today’s carbon capture methods use chemical solvents, but capture methods that use membranes to draw CO2 out of exhaust gas are potentially more efficient and cost effective. Traditionally, membranes are limited by the rate at which they allow gas to flow through them and the amount of CO2 they can attract from the gas. Smooth support pores and the unique structure of Porifera’s carbon nanotube membranes allows them to be more permeable than other polymeric membranes, yet still selective enough for CO2 removal. This approach could overcome the barriers facing membrane-based approaches for capturing CO2 from coal plant exhausts.

  15. Nanoelectrodes: Recent Advances and New Directions

    NASA Astrophysics Data System (ADS)

    Cox, Jonathan T.; Zhang, Bo

    2012-07-01

    This article reviews recent work involving the development and application of nanoelectrodes in electrochemistry and related areas. We first discuss common analytical methods for characterizing the size, shape, and quality of nanoelectrodes, including electron microscopy, steady-state cyclic voltammetry, scanning electrochemical microscopy, and surface modification. We then emphasize recent developments in fabrication techniques that have led to structurally well-defined nanoelectrodes. We highlight recent advances in the application of nanoelectrodes in important analytical chemistry areas, such as single-molecule studies, single-nanoparticle electrochemistry, and measurements of neurotransmitters from single neuronal cells.

  16. Quantum Monte Carlo calculations for carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Luu, Thomas; Lähde, Timo A.

    2016-04-01

    We show how lattice quantum Monte Carlo can be applied to the electronic properties of carbon nanotubes in the presence of strong electron-electron correlations. We employ the path-integral formalism and use methods developed within the lattice QCD community for our numerical work. Our lattice Hamiltonian is closely related to the hexagonal Hubbard model augmented by a long-range electron-electron interaction. We apply our method to the single-quasiparticle spectrum of the (3,3) armchair nanotube configuration, and consider the effects of strong electron-electron correlations. Our approach is equally applicable to other nanotubes, as well as to other carbon nanostructures. We benchmark our Monte Carlo calculations against the two- and four-site Hubbard models, where a direct numerical solution is feasible.

  17. CARBON NANOTUBES IN MICROWAVE ENVIRONMENT-IGNITION AND RECONSTRUCTION

    EPA Science Inventory

    The unusual property of single-walled carbon nanotubes (SWNT), multi-wall (MWNT) nanotubes and Buckminsterfullerene (C-60) is observed upon exposure to microwave-assisted ignition. Carbon nanotubes known for a range of mechanical and electronic properties because of their unique...

  18. Deconvoluting hepatic processing of carbon nanotubes.

    PubMed

    Alidori, Simone; Bowman, Robert L; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L J; Ulmert, Hans David S; Brea, Elliott J; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A; McDevitt, Michael R

    2016-01-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans. PMID:27468684

  19. Deconvoluting hepatic processing of carbon nanotubes

    PubMed Central

    Alidori, Simone; Bowman, Robert L.; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J. Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L. J.; Ulmert, Hans David S.; Brea, Elliott J.; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A.; McDevitt, Michael R.

    2016-01-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans. PMID:27468684

  20. In-line manufacture of carbon nanotubes

    DOEpatents

    Brambilla, Nicol Michele; Signorelli, Riccardo; Martini, Fabrizio; Corripio Luna, Oscar Enrique

    2015-04-28

    Mass production of carbon nanotubes (CNT) are facilitated by methods and apparatus disclosed herein. Advantageously, the methods and apparatus make use of a single production unit, and therefore provide for uninterrupted progress in a fabrication process. Embodiments of control systems for a variety of CNT production apparatus are included.

  1. Functionalized carbon nanotubes for potential medicinal applications

    PubMed Central

    Zhang, Yi; Bai, Yuhong; Yan, Bing

    2016-01-01

    Functionalized carbon nanotubes display unique properties that enable a variety of medicinal applications, including the diagnosis and treatment of cancer, infectious diseases and central nervous system disorders, and applications in tissue engineering. These potential applications are particularly encouraged by their ability to penetrate biological membranes and relatively low toxicity. PMID:20451656

  2. Reactions over catalysts confined in carbon nanotubes.

    PubMed

    Pan, Xiulian; Bao, Xinhe

    2008-12-21

    We review a new concept for modifying the redox properties of transition metals via confinement within the channels of carbon nanotubes (CNTs), and thus tuning their catalytic performance. Attention is also devoted to novel techniques for homogeneous dispersion of metal nanoparticles inside CNTs since these are essential for optimization of the catalytic activity. PMID:19048128

  3. Photothermal effects of immunologically modified carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Griswold, Ryan T.; Henderson, Brock; Goddard, Jessica; Tan, Yongqiang; Hode, Tomas; Liu, Hong; Nordquist, Robert E.; Chen, Wei R.

    2013-02-01

    Carbon nanotubes have a great potential in the biomedical applications. To use carbon nanotubes in the treatment of cancer, we synthesized an immunologically modified single-walled carbon nanotube (SWNT) using a novel immunomodifier, glycated chitosan (GC), as an effective surfactant for SWNT. This new composition SWNT-GC was stable due to the strong non-covalent binding between SWNT and GC. The structure of SWNT-GC is presented in this report. The photothermal effect of SWNT-GC was investigated under irradiation of a near-infrared laser. SWNT-GC retained the optical properties of SWNT and the immunological properties of GC. Specifically, the SWNT-GC could selectively absorb a 980-nm light and induce desirable thermal effects in tissue culture and in animals. It could also induce tumor cell destruction, controlled by the laser settings and the doses of SWNT and GC. Laser+SWNT-GC treatment could also induce strong expression of heat shock proteins on the surface of tumor cells. This immunologically modified carbon nanotube could be used for selective photothermal interactions in noninvasive tumor treatment.

  4. Conductance of AFM Deformed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Svizhenko, Alexei; Maiti, Amitesh; Anatram, M. P.; Biegel, Bryan (Technical Monitor)

    2002-01-01

    This viewgraph presentation provides information on the electrical conductivity of carbon nanotubes upon deformation by atomic force microscopy (AFM). The density of states and conductance were computed using four orbital tight-binding method with various parameterizations. Different chiralities develop bandgap that varies with chirality.

  5. Chemistry of Carbon Nanotubes for Everyone

    ERIC Educational Resources Information Center

    Basu-Dutt, Sharmistha; Minus, Marilyn L.; Jain, Rahul; Nepal, Dhriti; Kumar, Satish

    2012-01-01

    Carbon nanotubes (CNTs) have the extraordinary potential to change our lives by improving existing products and enabling new ones. Current and future research and industrial workforce professionals are very likely to encounter some aspects of nanotechnology including CNT science and technology in their education or profession. The simple structure…

  6. Scalable dielectrophoresis of single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Fitzhugh, William A.

    Single Walled Carbon Nanotubes (SWNTs) have attracted much attention as a candidate material for future nano-scale 'beyond silicon' devices. However industrial scale operations have been impeded by difficulties in separating the metallic and semiconducting species. This paper addresses the use of highly inhomogeneous alternating electric fields, dielectrophoresis, to isolate SWNT species in scaled systems. Both numerical and experimental methods will be discussed.

  7. Heat Transport in Liquid Polyester Resin with Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Vales-Pinzón, C.; Quiñones-Weiss, G.; Alvarado-Gil, J. J.; Medina-Esquivel, R. A.

    2015-11-01

    Carbon nanotubes represent one of the most important materials in nanoscience and nanotechnology, due to their outstanding structural, mechanical, electrical, and thermal properties. It has been shown that when incorporated in a polymeric matrix, carbon nanotubes can improve its physical properties. In this work, thermal-diffusivity measurements of composite materials, prepared by mixing carbon nanotubes in liquid polyester resin, were performed by means of the thermal-wave resonant cavity. The results show an increase of the thermal diffusivity when the volume fraction of carbon nanotubes grows. It is also shown that this increase depends strongly on the diameter of the nanotubes.

  8. Carbon Nanotubes: From Symmetry to Applications

    NASA Astrophysics Data System (ADS)

    Damnjanović, M.

    In this chapter, we show how the concept of symmetry gives theoretical explanation of the properties, which made carbon nanotubes (NTs) one of the most interesting materials of nanotechnology. First, in Sect. 3.1, we consider basic facts on single-wall carbon nanotubes (SWCNTs), including their configuration and symmetry. Then, we discuss double-wall nanotubes.Next, Sect. 3.2 is devoted to elementary symmetry-based physical properties. More precisely, we explain the energy spectrum of electrons and phonons, showing that as the consequence of the symmetry, energies must be arranged in the so-called bands. Elementary properties of these band structures may be a priory discussed, yielding easily famous conducting law, showing strong dependence of conductivity on the type of nanotube. Conserved quantum numbers enable us to extract selection rules for various physical processes. This way, radial breathing mode appears to be very important for the characterization of the samples by Raman spectroscopy. Also, optical properties are derived.Finally, in Sect. 3.3, mutual interaction between the walls of double-wall nanotubes is discussed. It is explained why this interaction is very weak, which is used to propose nanomachines with almost superslippery parts.

  9. Cratylia mollis lectin nanoelectrode for differential diagnostic of prostate cancer and benign prostatic hyperplasia based on label-free detection.

    PubMed

    Silva, Priscila M S; Lima, Amanda L R; Silva, Bárbara V M; Coelho, Luana C B B; Dutra, Rosa F; Correia, Maria T S

    2016-11-15

    The research for new biomarkers of cancer has studied the role of fetuin glycoprotein on the metastatic disease diagnosis. Cratylia mollis is a lectin with high finity to fetuin, and used here to differentiate prostate cancer and benign prostatic hyperplasia. A label-free electrochemical nanosensor based on assembled carboxylated carbon nanotubes (COOH-CNTs) and poly-L-lysine (PLL) film was developed and applied to serum samples of prostate cancer positive for Gleason score. The electrode analytical response to fetuin in PBS samples, obtained by square wave voltammetry, exhibited a linear range from 0.5 to 25µgmL(-1), with a high correlation coefficient (r=0.994, p<0.001) and low limit of detection (0.017µgmL(-1)). The lectin nanoelectrode showed a good repeatability (1.24% RSD) and reproducibility (4.24% RSD). A pool of serum samples from prostate cancer patients with known the Gleason score were tested showing a significant statistically correlation. Thus, the lectin nanoelectrode was able to distinguish the degree of staging prostate cancer, providing the diagnostic differentiation of benign and malign hyperplasia. To the best of our knowledge, it is the first biosensor for this application using a lectin. PMID:27176915

  10. Pure carbon nanoscale devices: Nanotube heterojunctions

    SciTech Connect

    Chico, L.; Crespi, V.H.; Benedict, L.X.; Louie, S.G.; Cohen, M.L. |

    1996-02-01

    Introduction of pentagon-heptagon pair defects into the hexagonal network of a single carbon nanotube can change the helicity of the tube and alter its electronic structure. Using a tight-binding method to calculate the electronic structure of such systems we show that they behave as nanoscale metal/semiconductor or semiconductor/semiconductor junctions. These junctions could be the building blocks of nanoscale electronic devices made entirely of carbon. {copyright} {ital 1996 The American Physical Society.}

  11. Carbon nanotubes on a spider silk scaffold

    PubMed Central

    Steven, Eden; Saleh, Wasan R.; Lebedev, Victor; Acquah, Steve F. A.; Laukhin, Vladimir; Alamo, Rufina G.; Brooks, James S.

    2013-01-01

    Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations. PMID:24022336

  12. Carbon nanotubes on a spider silk scaffold

    NASA Astrophysics Data System (ADS)

    Steven, Eden; Saleh, Wasan R.; Lebedev, Victor; Acquah, Steve F. A.; Laukhin, Vladimir; Alamo, Rufina G.; Brooks, James S.

    2013-09-01

    Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations.

  13. Carbon nanotubes on a spider silk scaffold.

    PubMed

    Steven, Eden; Saleh, Wasan R; Lebedev, Victor; Acquah, Steve F A; Laukhin, Vladimir; Alamo, Rufina G; Brooks, James S

    2013-01-01

    Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations. PMID:24022336

  14. Adjustable thermal conductivity in carbon nanotube nanofluids

    NASA Astrophysics Data System (ADS)

    Xie, Huaqing; Chen, Lifei

    2009-05-01

    Homogeneous and stable nanofluids have been produced by suspending well dispersible multi-walled carbon nanotubes (CNTs) into ethylene glycol base fluid. CNT nanofluids have enhanced thermal conductivity and the enhancement ratios increase with the nanotube loading and the temperature. Thermal conductivity enhancement was adjusted by ball milling and cutting the treated CNTs suspended in the nanofluids to relatively straight CNTs with an appropriate length distribution. Our findings indicate that the straightness ratio, aspect ratio, and aggregation have collective influence on the thermal conductivity of CNT nanofluids.

  15. Transmission Through Carbon Nanotubes with Polyhedral Caps

    NASA Technical Reports Server (NTRS)

    Anantram, M. P.; Govindan, T. R.

    1999-01-01

    We study electron transport between capped carbon nanotubes and a substrate, and relate this transport to the local density of states in the cap. Our results show that that the transmission probability mimics the behavior of the density of states at all energies except those that correspond to localized states. For a capped carbon nanotube that is not connected to a substrate, the localized states do not couple to the coexisting continuum states. However, close proximity of a substrate causes hybridization between these states. As a result, new transmission paths open from substrate states to nanotube continuum states via the localized states in the cap. We show that the interference between various paths gives rise to transmission antiresonances with the minimum equal to zero at the energy of the localized state. The presence of defects in the tube places close to the cap transforms antiresonances into resonances. Depending on the spatial position of defects, these resonant states are capable of carrying a large current. The results of this paper are of relevance to carbon nanotube based studies on molecular electronics and probe tip applications.

  16. Functionalization of vertically aligned carbon nanotubes

    PubMed Central

    Snyders, Rony; Colomer, Jean-François

    2013-01-01

    Summary This review focuses and summarizes recent studies on the functionalization of carbon nanotubes oriented perpendicularly to their substrate, so-called vertically aligned carbon nanotubes (VA-CNTs). The intrinsic properties of individual nanotubes make the VA-CNTs ideal candidates for integration in a wide range of devices, and many potential applications have been envisaged. These applications can benefit from the unidirectional alignment of the nanotubes, the large surface area, the high carbon purity, the outstanding electrical conductivity, and the uniformly long length. However, practical uses of VA-CNTs are limited by their surface characteristics, which must be often modified in order to meet the specificity of each particular application. The proposed approaches are based on the chemical modifications of the surface by functionalization (grafting of functional chemical groups, decoration with metal particles or wrapping of polymers) to bring new properties or to improve the interactions between the VA-CNTs and their environment while maintaining the alignment of CNTs. PMID:23504581

  17. Adsorption of Gases on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Mbaye, Mamadou Thiao

    This research focus in studying the interaction between various classical and quantum gases with novel carbon nanostructures, mainly carbon nanotubes (CNTs). Since their discovery by the Japanese physicist Sumio Iijima [1] carbon nanotubes have, experimentally and theoretically, been subjected to many scientific investigation. Studies of adsorption on CNTs are particularly directed toward their better usage in gas storage, gas separation, catalyst, drug delivery, and water purification. We explore the adsorption of different gases entrapped in a single, double, or multi-bundles of CNTs using computer simulations. The first system we investigate consists of Ar and Kr films adsorbed on zigzag or armchair nanotubes. Our simulations revealed that Kr atoms on intermediate size zigzag NTs undergo two phase transitions: A liquid-vapor (L→V), and liquid-commensurate (L→CS) with a fractional coverage of one Kr atoms adsorbed for every four carbon atoms. For Ar on zigzag and armchair NTs, the only transition observed is a L→V. In the second problem, we explore the adsorption of CO2 molecules in a nanotube bundle and calculate the isosteric heat of adsorption of the entrapped molecules within the groove. We observed that the lower the temperature, the higher the isosteric of adsorption. Last, we investigate the adsorption of hydrogen, Helium, and Neon gases on the groove site of two parallel nanotubes. At low temperature, the transverse motion on the plane perpendicular to the tubes' axis is frozen out and as a consequence, the heat capacity is reduced to 1/2. At high temperature, the atoms gain more degree of freedom and as a consequence the heat capacity is 5/2.

  18. Diffusion through Carbon Nanotube Semipermeable membranes

    SciTech Connect

    Bakajin, O

    2006-02-13

    The goal of this project is to measure transport through CNTs and study effects of confinement at molecular scale. This work is motivated by several simulation papers in high profile journals that predict significantly higher transport rates of gases and liquids through carbon nanotubes as compared with similarly-sized nanomaterials (e.g. zeolites). The predictions are based on the effects of confinement, atomically smooth pore walls and high pore density. Our work will provide the first measurements that would compare to and hopefully validate the simulations. Gas flux is predicted to be >1000X greater for SWNTs versus zeolitesi. A high flux of 6-30 H2O/NT/ns {approx} 8-40 L/min for a 1cm{sup 2} membrane is also predicted. Neutron diffraction measurements indicate existence of a 1D water chain within a cylindrical ice sheet inside carbon nanotubes, which is consistent with the predictions of the simulation. The enabling experimental platform that we are developing is a semipermeable membrane made out of vertically aligned carbon nanotubes with gaps between nanotubes filled so that the transport occurs through the nanotubes. The major challenges of this project included: (1) Growth of CNTs in the suitable vertically aligned configuration, especially the single wall carbon nanotubes; (2) Development of a process for void-free filling gaps between CNTs; and (3) Design of the experiments that will probe the small amounts of analyte that go through. Knowledge of the behavior of water upon nanometer-scale confinement is key to understanding many biological processes. For example, the protein folding process is believed to involve water confined in a hydrophobic environment. In transmembrane proteins such as aquaporins, water transport occurs under similar conditions. And in fields as far removed as oil recovery and catalysis, an understanding of the nanoscale molecular transport occurring within the nanomaterials used (e.g. zeolites) is the key to process optimization

  19. The Highly Robust Electrical Interconnects and Ultrasensitive Biosensors Based on Embedded Carbon Nanotube Arrays

    NASA Technical Reports Server (NTRS)

    Li, Jun; Cassell, Alan; Koehne, Jessica; Chen, Hua; Ng, Hou Tee; Ye, Qi; Stevens, Ramsey; Han, Jie; Meyyappan, M.

    2003-01-01

    We report on our recent breakthroughs in two different applications using well-aligned carbon nanotube (CNT) arrays on Si chips, including (1) a novel processing solution for highly robust electrical interconnects in integrated circuit manufacturing, and (2) the development of ultrasensitive electrochemical DNA sensors. Both of them rely on the invention of a bottom-up fabrication scheme which includes six steps, including: (a) lithographic patterning, (b) depositing bottom conducting contacts, (c) depositing metal catalysts, (d) CNT growth by plasma enhanced chemical vapor deposition (PECVD), (e) dielectric gap-filling, and (f) chemical mechanical polishing (CMP). Such processes produce a stable planarized surface with only the open end of CNTs exposed, whch can be further processed or modified for different applications. By depositing patterned top contacts, the CNT can serve as vertical interconnects between the two conducting layers. This method is fundamentally different fiom current damascene processes and avoids problems associated with etching and filling of high aspect ratio holes at nanoscales. In addition, multiwalled CNTs (MWCNTs) are highly robust and can carry a current density of 10(exp 9) A/square centimeters without degradation. It has great potential to help extending the current Si technology. The embedded MWCNT array without the top contact layer can be also used as a nanoelectrode array in electrochemical biosensors. The cell time-constant and sensitivity can be dramatically improved. By functionalizing the tube ends with specific oligonucleotide probes, specific DNA targets can be detected with electrochemical methods down to subattomoles.

  20. Spin-based optomechanics with carbon nanotubes.

    PubMed

    Li, Jin-Jin; Zhu, Ka-Di

    2012-01-01

    A simple scheme for determination of spin-orbit coupling strength in spinbased optomechanics with carbon nanotubes is introduced, under the control of a strong pump field and a weak signal field. The physical mechanism comes from the phonon induced transparency (PIT), by relying on the coherent coupling of electron spin to vibrational motion of the nanotube, which is analogous to electromagnetically induced transparency (EIT) effect in atom systems. Based on this spin-nanotube optomechanical system, we also conceptually design a single photon router and a quantum microwave transistor, with ultralow pump power (~ pW) and tunable switching time, which should provide a unique platform for the study of spin-based microwave quantum optics and quantum information processing. PMID:23198093

  1. Spin-based Optomechanics with Carbon Nanotubes

    PubMed Central

    Li, Jin-Jin; Zhu, Ka-Di

    2012-01-01

    A simple scheme for determination of spin-orbit coupling strength in spinbased optomechanics with carbon nanotubes is introduced, under the control of a strong pump field and a weak signal field. The physical mechanism comes from the phonon induced transparency (PIT), by relying on the coherent coupling of electron spin to vibrational motion of the nanotube, which is analogous to electromagnetically induced transparency (EIT) effect in atom systems. Based on this spin-nanotube optomechanical system, we also conceptually design a single photon router and a quantum microwave transistor, with ultralow pump power (~ pW) and tunable switching time, which should provide a unique platform for the study of spin-based microwave quantum optics and quantum information processing. PMID:23198093

  2. Multiscale simulation of carbon nanotube devices

    NASA Astrophysics Data System (ADS)

    Adessi, C.; Avriller, R.; Blase, X.; Bournel, A.; Cazin d'Honincthun, H.; Dollfus, P.; Frégonèse, S.; Galdin-Retailleau, S.; López-Bezanilla, A.; Maneux, C.; Nha Nguyen, H.; Querlioz, D.; Roche, S.; Triozon, F.; Zimmer, T.

    2009-05-01

    In recent years, the understanding and accurate simulation of carbon nanotube-based devices has become very challenging. Conventional simulation tools of microelectronics are necessary to envision the performance and use of nanotube transistors and circuits, but the models need to be refined to properly describe the full complexity of such novel type of devices at the nanoscale. Indeed, many issues such as contact resistance, low dimensional electrostatics and screening effects, as well as nanotube doping or functionalization, demand for more accurate quantum approaches. In this article, we review our recent progress on multiscale simulations which aim at bridging first principles calculations with compact modelling, including the comparison between semi-classical Monte Carlo and quantum transport approaches. To cite this article: C. Adessi et al., C. R. Physique 10 (2009).

  3. Carbon Nanotubes: Measuring Dispersion and Length

    SciTech Connect

    Fagan, Jeffrey A.; Bauer, Barry J.; Hobbie, Erik K.; Becker, Matthew L.; Hight-Walker, Angela; Simpson, Jeffrey R.; Chun, Jaehun; Obrzut, Jan; Bajpai, Vardhan; Phelan, Fred R.; Simien, Daneesh; Yeon Huh, Ji; Migler, Kalman B.

    2011-03-01

    Advanced technological uses of single-wall carbon nanotubes (SWCNTs) rely on the production of single length and chirality populations that are currently only available through liquid phase post processing. The foundation of all of these processing steps is the attainment of individualized nanotube dispersion in solution; an understanding of the collodial properties of the dispersed SWCNTs can then be used to designed appropriate conditions for separations. In many instances nanotube size, particularly length, is especially active in determining the achievable properties from a given population, and thus there is a critical need for measurement technologies for both length distribution and effective separation techniques. In this Progress Report, we document the current state of the art for measuring dispersion and length populations, including separations, and use examples to demonstrate the desirability of addressing these parameters.

  4. Ag-catalysed cutting of multi-walled carbon nanotubes.

    PubMed

    La Torre, A; Rance, G A; Miners, S A; Herreros Lucas, C; Smith, E F; Fay, M W; Zoberbier, T; Giménez-López, M C; Kaiser, U; Brown, P D; Khlobystov, A N

    2016-04-29

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes. PMID:26987452

  5. Ag-catalysed cutting of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    La Torre, A.; Rance, G. A.; Miners, S. A.; Herreros Lucas, C.; Smith, E. F.; Fay, M. W.; Zoberbier, T.; Giménez-López, M. C.; Kaiser, U.; Brown, P. D.; Khlobystov, A. N.

    2016-04-01

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes.

  6. Electrochemical Characterization of Carbon Nanotubes for Fuel Cell MEA's

    NASA Technical Reports Server (NTRS)

    Panagaris, Jael; Loyselle, Patricia

    2004-01-01

    Single-walled and multi-walled carbon nanotubes from different sources have been evaluated before and after sonication to identify structural differences and evaluate electrochemical performance. Raman spectral analysis and cyclic voltammetry in situ with QCM were the principle means of evaluating the tubes. The raman data indicates that sonication in toluene modifies the structural properties of the nanotubes. Sonication also affects the electrochemical performance of single-walled nanotubes and the multi-walled tubes differently. The characterization of different types of carbon nanotubes leads up to identifying a potential candidate for incorporating carbon nanotubes for fuel cell MEA structures.

  7. Carbon Nanotubes for Space Photovoltaic Applications

    NASA Technical Reports Server (NTRS)

    Efstathiadis, Harry; Haldar, Pradeep; Landi, Brian J.; Denno, Patrick L.; DiLeo, Roberta A.; VanDerveer, William; Raffaelle, Ryne P.

    2007-01-01

    Carbon nanotubes (CNTs) can be envisioned as an individual graphene sheet rolled into a seamless cylinder (single-walled, SWNT), or concentric sheets as in the case of a multi-walled carbon nanotube (MWNT) (1). The role-up vector will determine the hexagonal arrangement and "chirality" of the graphene sheet, which will establish the nanotube to be metallic or semiconducting. The optoelectronic properties will depend directly on this chiral angle and the diameter of the SWNT, with semiconductor types exhibiting a band gap energy (2). Characteristic of MWNTs are the concentric graphene layers spaced 0.34 nm apart, with diameters from 10-200 nm and lengths up to hundreds of microns (2). In the case of SWNTs, the diameters range from 0.4 - 2 nm and lengths have been reported up to 1.5 cm (3). SWNTs have the distinguishable property of "bundling" together due to van der Waal's attractions to form "ropes." A comparison of these different structural types is shown in Figure 1. The use of SWNTS in space photovoltaic (PV) applications is attractive for a variety of reasons. Carbon nanotubes as a class of materials exhibit unprecedented optical, electrical, mechanical properties, with the added benefit of being nanoscale in size which fosters ideal interaction in nanomaterial-based devices like polymeric solar cells. The optical bandgap of semiconducting SWNTs can be varied from approx. 0.4 - 1.5 eV, with this property being inversely proportional to the nanotube diameter. Recent work at GE Global Research has shown where a single nanotube device can behave as an "ideal" pn diode (5). The SWNT was bridged over a SiO2 channel between Mo contacts and exhibited an ideality factor of 1, based on a fit of the current-voltage data using the diode equation. The measured PV efficiency under a 0.8 eV monochromatic illumination showed a power conversion efficiency of 0.2 %. However, the projected efficiency of these junctions is estimated to be > 5 %, especially when one considers the

  8. Inhaled carbon nanotubes reach the subpleural tissue in mice

    NASA Astrophysics Data System (ADS)

    Ryman-Rasmussen, Jessica P.; Cesta, Mark F.; Brody, Arnold R.; Shipley-Phillips, Jeanette K.; Everitt, Jeffrey I.; Tewksbury, Earl W.; Moss, Owen R.; Wong, Brian A.; Dodd, Darol E.; Andersen, Melvin E.; Bonner, James C.

    2009-11-01

    Carbon nanotubes are shaped like fibres and can stimulate inflammation at the surface of the peritoneum when injected into the abdominal cavity of mice, raising concerns that inhaled nanotubes may cause pleural fibrosis and/or mesothelioma. Here, we show that multiwalled carbon nanotubes reach the subpleura in mice after a single inhalation exposure of 30 mg m-3 for 6 h. Nanotubes were embedded in the subpleural wall and within subpleural macrophages. Mononuclear cell aggregates on the pleural surface increased in number and size after 1 day and nanotube-containing macrophages were observed within these foci. Subpleural fibrosis unique to this form of nanotubes increased after 2 and 6 weeks following inhalation. None of these effects was seen in mice that inhaled carbon black nanoparticles or a lower dose of nanotubes (1 mg m-3). This work suggests that minimizing inhalation of nanotubes during handling is prudent until further long-term assessments are conducted.

  9. Carbon nanotube materials from hydrogen storage

    SciTech Connect

    Dillon, A.C.; Bekkedahl, T.A.; Cahill, A.F.

    1995-09-01

    The lack of convenient and cost-effective hydrogen storage is a major impediment to wide scale use of hydrogen in the United States energy economy. Improvements in the energy densities of hydrogen storage systems, reductions in cost, and increased compatibility with available and forecasted systems are required before viable hydrogen energy use pathways can be established. Carbon-based hydrogen adsorption materials hold particular promise for meeting and exceeding the U.S. Department of Energy hydrogen storage energy density targets for transportation if concurrent increases in hydrogen storage capacity and carbon density can be achieved. These two goals are normally in conflict for conventional porous materials, but may be reconciled by the design and synthesis of new adsorbent materials with tailored pore size distributions and minimal macroporosity. Carbon nanotubes offer the possibility to explore new designs for adsorbents because they can be fabricated with small size distributions, and naturally tend to self-assemble by van der Waals forces. This year we report heats of adsorption for hydrogen on nanotube materials that are 2 and 3 times greater than for hydrogen on activated carbon. The hydrogen which is most strongly bound to these materials remains on the carbon surface to temperatures greater than 285 K. These results suggest that nanocapillary forces are active in stabilizing hydrogen on the surfaces of carbon nanotubes, and that optimization of the adsorbent will lead to effective storage at higher temperatures. In this paper we will also report on our activities which are targeted at understanding and optimizing the nucleation and growth of single wall nanotubes. These experiments were made possible by the development of a unique feedback control circuit which stabilized the plasma-arc during a synthesis run.

  10. Sagnac interference in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bishara, Waheb; Refael, Gil; Bockrath, Marc

    2008-10-01

    The Sagnac interference mode arises when two interfering counterpropogating beams traverse a loop, but with their velocities detuned by a small amount 2u , with vR/L=vF±u . In this paper we perform a perturbative nonequilibrium calculation of Sagnac interference in single-channel wires as well as armchair nanotube loops. We study the dependence of the Sagnac conductance oscillations on temperature and interactions. We find that the Sagnac interference is not destroyed by strong interactions, but becomes weakly dependent on the velocity detuning u . In armchairs nanotubes with typical interaction strength, 0.25≤g≤0.5 , we find that the necessary temperature for observing the interference effect, TSAG is also only weakly dependent on the interaction, and is enhanced by a factor of 8 relative to the temperature necessary for observing Fabry-Pérot interference in the same system, TFP .

  11. Synthesis of Carbon Nanotubes Using Sol Gel Route

    NASA Astrophysics Data System (ADS)

    Abdel-Fattah, Tarek

    2002-12-01

    Since 1990, carbon nanotubes were discovered and they have been the object of intense scientific study ever since. A carbon nanotube is a honeycomb lattice rolled into a cylinder. The diameter of a carbon nanotube is of nanometer size and the length is in the range of micrometer. Many of the extraordinary properties attributed to nanotubes, such as tensile strength and thermal stability, have inspired predictions of microscopic robots, dent-resistant car bodies and earthquake-resistant buildings. The first products to use nanotubes were electrical. Some General Motors cars already include plastic parts to which nanotubes were added; such plastic can be electrified during painting so that the paint will stick more readily. Two nanotube-based lighting and display products are well on their way to market. In the long term, perhaps the most valuable applications will take further advantage of nanotubes' unique electronic properties. Carbon nanotubes can in principle play the same role as silicon does in electronic circuits, but at a molecular scale where silicon and other standard semiconductors cease to work. There are several routes to synthesize carbon nanotubes; laser vaporization, carbon arc and vapor growth. We have applied a different route using sol gel chemistry to obtain carbon nanotubes. This work is patent-pending.

  12. Mesoscale mechanics of twisting carbon nanotube yarns.

    PubMed

    Mirzaeifar, Reza; Qin, Zhao; Buehler, Markus J

    2015-03-12

    Fabricating continuous macroscopic carbon nanotube (CNT) yarns with mechanical properties close to individual CNTs remains a major challenge. Spinning CNT fibers and ribbons for enhancing the weak interactions between the nanotubes is a simple and efficient method for fabricating high-strength and tough continuous yarns. Here we investigate the mesoscale mechanics of twisting CNT yarns using full atomistic and coarse grained molecular dynamics simulations, considering concurrent mechanisms at multiple length-scales. To investigate the mechanical response of such a complex structure without losing insights into the molecular mechanism, we applied a multiscale strategy. The full atomistic results are used for training a coarse grained model for studying larger systems consisting of several CNTs. The mesoscopic model parameters are updated as a function of the twist angle, based on the full atomistic results, in order to incorporate the atomistic scale deformation mechanisms in larger scale simulations. By bridging across two length scales, our model is capable of accurately predicting the mechanical behavior of twisted yarns while the atomistic level deformations in individual nanotubes are integrated into the model by updating the parameters. Our results focused on studying a bundle of close packed nanotubes provide novel mechanistic insights into the spinning of CNTs. Our simulations reveal how twisting a bundle of CNTs improves the shear interaction between the nanotubes up to a certain level due to increasing the interaction surface. Furthermore, twisting the bundle weakens the intertube interactions due to excessive deformation in the cross sections of individual CNTs in the bundle. PMID:25732328

  13. A Structural Transition of Carbon Nanotubes?

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Cochrane, J. C.; Lehoczky, S.; Cui, Y.; Burger, A.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    The superior properties of carbon nanotubes (CNT) are good for many applications. A possible temperature-related structural transition is found in the CNT, which may suggest new applications of CNT. CNT materials have been synthesized on Si substrates by pulsed laser vaporization in various temperatures and pressures. Raman spectroscopy and scanning electron microscopy are used to determine the CNT structure and morphology. It is found that the formation of nanotubes depends strongly on the growth temperatures and high quality multi-wall and single-wall nanotubes were produced at 700 and 990 C, respectively. The radial breath modes of Raman spectra measured in the range of 50 cm(exp -1) to 300 cm(exp -1), indicate that one of samples grown at 700 C is to be dependent on the excitation intensity. The spectra of the sample suggest that the structure is similar to that of multi-wall nanotubes at low excitation intensity (2.5 kW per square centimeter) and it converts to the structure of single-wall nanotubes at higher intensity (25 kW per square centimeter). Measurements taken while cycling the light intensity suggests a reversible transition.

  14. Osmotic water transport through carbon nanotube membranes

    PubMed Central

    Kalra, Amrit; Garde, Shekhar; Hummer, Gerhard

    2003-01-01

    We use molecular dynamics simulations to study osmotically driven transport of water molecules through hexagonally packed carbon nanotube membranes. Our simulation setup comprises two such semipermeable membranes separating compartments of pure water and salt solution. The osmotic force drives water flow from the pure-water to the salt-solution compartment. Monitoring the flow at molecular resolution reveals several distinct features of nanoscale flows. In particular, thermal fluctuations become significant at the nanoscopic length scales, and as a result, the flow is stochastic in nature. Further, the flow appears frictionless and is limited primarily by the barriers at the entry and exit of the nanotube pore. The observed flow rates are high (5.8 water molecules per nanosecond and nanotube), comparable to those through the transmembrane protein aquaporin-1, and are practically independent of the length of the nanotube, in contrast to predictions of macroscopic hydrodynamics. All of these distinct characteristics of nanoscopic water flow can be modeled quantitatively by a 1D continuous-time random walk. At long times, the pure-water compartment is drained, and the net flow of water is interrupted by the formation of structured solvation layers of water sandwiched between two nanotube membranes. Structural and thermodynamic aspects of confined water monolayers are studied. PMID:12878724

  15. Carbon nanotubes as long ballistic conductors

    NASA Astrophysics Data System (ADS)

    White, C. T.; Todorov, T. N.

    1998-05-01

    Early theoretical work on single-walled carbon nanotubes predicted that a special achiral subset of these structures known as armchair nanotubes should be metallic. Tans et al. have recently confirmed these predictions experimentally and also showed directly that coherent electron transport can be maintained through these nanowires up to distances of at least 140nm. But single-walled armchair nanotubes are one-dimensional conductors with only two open conduction channels (energy subbands in a laterally confined system that cross the Fermi level). Hence, with increasing length, their conduction electrons ultimately become localized owing to residual disorder in the tube which is inevitably produced by interactions between the tube and its environment. We present here calculations which show, however, that unlike normal metallic wires, conduction electrons in armchair nanotubes experience an effective disorder averaged over the tube's circumference, leading to electron mean free paths that increase with nanotube diameter. This increase should result in exceptional ballistic transport properties and localization lengths of 10µm or more for tubes with the diameters that are typically produced experimentally.

  16. Mesoscale mechanics of twisting carbon nanotube yarns

    NASA Astrophysics Data System (ADS)

    Mirzaeifar, Reza; Qin, Zhao; Buehler, Markus J.

    2015-03-01

    Fabricating continuous macroscopic carbon nanotube (CNT) yarns with mechanical properties close to individual CNTs remains a major challenge. Spinning CNT fibers and ribbons for enhancing the weak interactions between the nanotubes is a simple and efficient method for fabricating high-strength and tough continuous yarns. Here we investigate the mesoscale mechanics of twisting CNT yarns using full atomistic and coarse grained molecular dynamics simulations, considering concurrent mechanisms at multiple length-scales. To investigate the mechanical response of such a complex structure without losing insights into the molecular mechanism, we applied a multiscale strategy. The full atomistic results are used for training a coarse grained model for studying larger systems consisting of several CNTs. The mesoscopic model parameters are updated as a function of the twist angle, based on the full atomistic results, in order to incorporate the atomistic scale deformation mechanisms in larger scale simulations. By bridging across two length scales, our model is capable of accurately predicting the mechanical behavior of twisted yarns while the atomistic level deformations in individual nanotubes are integrated into the model by updating the parameters. Our results focused on studying a bundle of close packed nanotubes provide novel mechanistic insights into the spinning of CNTs. Our simulations reveal how twisting a bundle of CNTs improves the shear interaction between the nanotubes up to a certain level due to increasing the interaction surface. Furthermore, twisting the bundle weakens the intertube interactions due to excessive deformation in the cross sections of individual CNTs in the bundle.

  17. Spectroscopic study of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Curran, Seamus; Weldon, Declan N.; Blau, Werner J.; Zandbergen, Henny W.; Kastner, J.; Kuzmany, Hans

    1994-11-01

    We present a comprehensive experimental study of the vibrational spectra of nanotubes. There are two main lines observed in the Raman spectrum, one positioned at 1350 cm-1, the D line, and the other at 1580 cm-1, the G line. Both these lines are very similar to those seen with disordered graphite. The disorder induced D line is very weak compared to the G line which is indicative of high crystalline materials. The position and intensity of the D line strongly depends on the energy of the exciting laser. This dispersion effect was also observed for graphitic particles and may be explained by a photoselective resonance process of nanotubes with different sizes. There are two optically active modes in the Infrared spectrum for highly orientated polycrystalline graphite which are the E1u and A2u modes. The E1u mode is positioned at 1587 cm-1 while the A2u mode is positioned at 868 cm-1. The Infrared spectrum of the nanotubes shows both modes although the E1u mode is downshifted to 1575 cm-1.

  18. Use of Functionalized Carbon Nanotubes for Covalent Attachment of Nanotubes to Silicon

    NASA Technical Reports Server (NTRS)

    Tour, James M.; Dyke, Christopher A.; Maya, Francisco; Stewart, Michael P.; Chen, Bo; Flatt, Austen K.

    2012-01-01

    The purpose of the invention is to covalently attach functionalized carbon nanotubes to silicon. This step allows for the introduction of carbon nanotubes onto all manner of silicon surfaces, and thereby introduction of carbon nano - tubes covalently into silicon-based devices, onto silicon particles, and onto silicon surfaces. Single-walled carbon nanotubes (SWNTs) dispersed as individuals in surfactant were functionalized. The nano - tube was first treated with 4-t-butylbenzenediazonium tetrafluoroborate to give increased solubility to the carbon nanotube; the second group attached to the sidewall of the nanotube has a silyl-protected terminal alkyne that is de-protected in situ. This gives a soluble carbon nanotube that has functional groups appended to the sidewall that can be attached covalently to silicon. This reaction was monitored by UV/vis/NJR to assure direct covalent functionalization.

  19. Carbon Nanotube Based Nanotechnology for NASA Mission Needs and Societal Applications

    NASA Technical Reports Server (NTRS)

    Li, Jing; Meyyappan, M.

    2011-01-01

    Carbon nanotubes (CNT) exhibit extraordinary mechanical properties and unique electronic properties and therefore, have received much attention for more than a decade now for a variety of applications ranging from nanoelectronics, composites to meeting needs in energy, environmental and other sectors. In this talk, we focus on some near term potential of CNT applications for both NASA and other Agency/societal needs. The most promising and successful application to date is a nano chem sensor at TRL 6 that uses a 16-256 sensor array in the construction of an electronic nose. Pristine, doped, functionalized and metal-loaded SWCNTs are used as conducting materials to provide chemical variation across the individual elements of the sensor array. This miniaturized sensor has been incorporated in an iPhone for homeland security applications. Gases and vapors relevant to leak detection in crew vehicles, biomedical, mining, chemical threats, industrial spills and others have been demonstrated. SWCNTs also respond to radiation exposure via a change in conductivity and therefore, a similar strategy is being pursued to construct a radiation nose to identify radiation sources (gamma, protons, neutrons, X-ray, etc.) with their energy levels. Carbon nanofibers (CNFs) grown using plasma enhanced CVD typically are vertical, individual, freestanding structures and therefore, are ideal for construction of nanoelectrodes. A nanoelectrode array (NEA) can be the basis for an affinity-based biosensor to meet the needs in applications such as lab-on-a-chip, environmental monitoring, cancer diagnostics, biothreat monitoring, water and food safety and others. A couple of demonstrations including detection of e-coli and ricin will be discussed. The NEA is also useful for implantation in the brain for deep brain stimulation and neuroengineering applications. Miniaturization of payload such as science instrumentation and power sources is critical to reduce launch costs. High current density

  20. Developing Carbon Nanotube Standards at NASA

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pasha; Arepalli, Sivaram; Sosa, Edward; Gorelik, Olga; Yowell, Leonard

    2007-01-01

    Single wall carbon nanotubes (SWCNTs) are currently being produced and processed by several methods. Many researchers are continuously modifying existing methods and developing new methods to incorporate carbon nanotubes into other materials and utilize the phenomenal properties of SWCNTs. These applications require availability of SWCNTs with known properties and there is a need to characterize these materials in a consistent manner. In order to monitor such progress, it is critical to establish a means by which to define the quality of SWCNT material and develop characterization standards to evaluate of nanotube quality across the board. Such characterization standards should be applicable to as-produced materials as well as processed SWCNT materials. In order to address this issue, NASA Johnson Space Center has developed a protocol for purity and dispersion characterization of SWCNTs (Ref.1). The NASA JSC group is currently working with NIST, ANSI and ISO to establish purity and dispersion standards for SWCNT material. A practice guide for nanotube characterization is being developed in cooperation with NIST (Ref.2). Furthermore, work is in progress to incorporate additional characterization methods for electrical, mechanical, thermal, optical and other properties of SWCNTs.

  1. Spectroscopy of Optical Excitations in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Ma, Yingzhong

    2006-03-01

    Understanding the optical spectra and electronic excited state dynamics of carbon naotubes is important both for fundamental research and a wide variety of potential applications. In this presentation, we will report the results of a systematic study on semiconducting single-walled carbon nanotubes (SWNTs) obtained by utilizing complementary femtosecond spectroscopic techniques, including fluorescence up-conversion, frequency-resolved transient absorption, and three-pulse photon echo peakshift (3PEPS) spectroscopy. Our efforts have focused on optically selective detection of the spectra and dynamics associated with structurally distinct semiconducting SWNT species. Using individual nanotube enriched micelle-dispersed SWNT preparations, in combination with resonant excitation and detection, has enabled us to independently access selected species, such as the (8,3), (6,5), (7,5), (11,0), (7,6) and (9,5) nanotubes. We will discuss the following topics: (1) the excitonic nature of the elementary excitation and its unambiguous identification from direct determination of the exciton binding energy for a selected semiconducting nanotube, the (8,3) tube; (2) the spectroscopic and dynamical signatures of exciton-exciton annihilation and its predominant role in governing ultrafast excited state relaxation; (3) the annihilation-concomitant exciton dissociation and the spectroscopic and dynamic features of the resulting electron-hole continuum; (4) timescales characterizing the ultrafast thermalization processes. In addition, we will demonstrate the power of 3PEPS spectroscopy to elucidate the spectral properties and dynamics of SWNTs. This work was supported by the NSF.

  2. Developing Carbon Nanotube Standards at NASA

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pasha; Arepalli, Sivaram; Sosa, Edward; Gorelik, Olga; Yowell, Leonard

    2007-01-01

    Single wall carbon nanotubes (SWCNTs) are currently being produced and processed by several methods. Many researchers are continuously modifying existing methods and developing new methods to incorporate carbon nanotubes into other materials and utilize the phenomenal properties of SWCNTs. These applications require availability of SWCNTs with known properties and there is a need to characterize these materials in a consistent manner. In order to monitor such progress, it is critical to establish a means by which to define the quality of SWCNT material and develop characterization standards to evaluate of nanotube quality across the board. Such characterization standards should be applicable to as-produced materials as well as processed SWCNT materials. In order to address this issue, NASA Johnson Space Center has developed a protocol for purity and dispersion characterization of SWCNTs. The NASA JSC group is currently working with NIST, ANSI and ISO to establish purity and dispersion standards for SWCNT material. A practice guide for nanotube characterization is being developed in cooperation with NIST. Furthermore, work is in progress to incorporate additional characterization methods for electrical, mechanical, thermal, optical and other properties of SWCNTs.

  3. Remote Joule heating by a carbon nanotube.

    PubMed

    Baloch, Kamal H; Voskanian, Norvik; Bronsgeest, Merijntje; Cumings, John

    2012-05-01

    Minimizing Joule heating remains an important goal in the design of electronic devices. The prevailing model of Joule heating relies on a simple semiclassical picture in which electrons collide with the atoms of a conductor, generating heat locally and only in regions of non-zero current density, and this model has been supported by most experiments. Recently, however, it has been predicted that electric currents in graphene and carbon nanotubes can couple to the vibrational modes of a neighbouring material, heating it remotely. Here, we use in situ electron thermal microscopy to detect the remote Joule heating of a silicon nitride substrate by a single multiwalled carbon nanotube. At least 84% of the electrical power supplied to the nanotube is dissipated directly into the substrate, rather than in the nanotube itself. Although it has different physical origins, this phenomenon is reminiscent of induction heating or microwave dielectric heating. Such an ability to dissipate waste energy remotely could lead to improved thermal management in electronic devices. PMID:22484913

  4. Graphene nanoribbons production from flat carbon nanotubes

    SciTech Connect

    Melo, W. S.; Guerini, S.; Diniz, E. M.

    2015-11-14

    Graphene nanoribbons are of great interest for pure and applied sciences due to their unique properties which depend on the nanoribbon edges, as, for example, energy gap and antiferromagnetic coupling. Nevertheless, the synthesis of nanoribbons with well-defined edges remains a challenge. To collaborate with this subject, here we propose a new route for the production of graphene nanoribbons from flat carbon nanotubes filled with a one-dimensional chain of Fe atoms by first principles calculations based on density functional theory. Our results show that Fe-filled flat carbon nanotubes are energetically more stable than non flattened geometries. Also we find that by hydrogenation or oxygenation of the most curved region of the Fe-filled flat armchair carbon nanotube, it occurred a spontaneous production of zigzag graphene nanoribbons which have metallic or semiconducting behavior depending on the edge and size of the graphene nanoribbon. Such findings can be used to create a new method of synthesis of regular-edge carbon nanoribbons.

  5. Method of making carbon nanotubes on a substrate

    DOEpatents

    Gao, Yufei; Liu, Jun

    2006-03-14

    The present invention includes carbon nanotubes whose hollow cores are 100% filled with conductive filler. The carbon nanotubes are in uniform arrays on a conductive substrate and are well-aligned and can be densely packed. The uniformity of the carbon nanotube arrays is indicated by the uniform length and diameter of the carbon nanotubes, both which vary from nanotube to nanotube on a given array by no more than about 5%. The alignment of the carbon nanotubes is indicated by the perpendicular growth of the nanotubes from the substrates which is achieved in part by the simultaneous growth of the conductive filler within the hollow core of the nanotube and the densely packed growth of the nanotubes. The present invention provides a densely packed carbon nanotube growth where each nanotube is in contact with at least one nearest-neighbor nanotube. The substrate is a conductive substrate coated with a growth catalyst, and the conductive filler can be single crystals of carbide formed by a solid state reaction between the substrate material and the growth catalyst. The present invention further provides a method for making the filled carbon nanotubes on the conductive substrates. The method includes the steps of depositing a growth catalyst onto the conductive substrate as a prepared substrate, creating a vacuum within a vessel which contains the prepared substrate, flowing H2/inert (e.g. Ar) gas within the vessel to increase and maintain the pressure within the vessel, increasing the temperature of the prepared substrate, and changing the H2/Ar gas to ethylene gas such that the ethylene gas flows within the vessel. Additionally, varying the density and separation of the catalyst particles on the conductive substrate can be used to control the diameter of the nanotubes.

  6. Automated circuit fabrication and direct characterization of carbon nanotube vibrations.

    PubMed

    Zeevi, G; Shlafman, M; Tabachnik, T; Rogachevsky, Z; Rechnitz, S; Goldshtein, I; Shlafman, S; Gordon, N; Alchanati, G; Itzhak, M; Moshe, Y; Hajaj, E M; Nir, H; Milyutin, Y; Izraeli, T Y; Razin, A; Shtempluck, O; Kotchtakov, V; Yaish, Y E

    2016-01-01

    Since their discovery, carbon nanotubes have fascinated many researchers due to their unprecedented properties. However, a major drawback in utilizing carbon nanotubes for practical applications is the difficulty in positioning or growing them at specific locations. Here we present a simple, rapid, non-invasive and scalable technique that enables optical imaging of carbon nanotubes. The carbon nanotube scaffold serves as a seed for nucleation and growth of small size, optically visible nanocrystals. After imaging the molecules can be removed completely, leaving the surface intact, and thus the carbon nanotube electrical and mechanical properties are preserved. The successful and robust optical imaging allowed us to develop a dedicated image processing algorithm through which we are able to demonstrate a fully automated circuit design resulting in field effect transistors and inverters. Moreover, we demonstrate that this imaging method allows not only to locate carbon nanotubes but also, as in the case of suspended ones, to study their dynamic mechanical motion. PMID:27396506

  7. Automated circuit fabrication and direct characterization of carbon nanotube vibrations

    NASA Astrophysics Data System (ADS)

    Zeevi, G.; Shlafman, M.; Tabachnik, T.; Rogachevsky, Z.; Rechnitz, S.; Goldshtein, I.; Shlafman, S.; Gordon, N.; Alchanati, G.; Itzhak, M.; Moshe, Y.; Hajaj, E. M.; Nir, H.; Milyutin, Y.; Izraeli, T. Y.; Razin, A.; Shtempluck, O.; Kotchtakov, V.; Yaish, Y. E.

    2016-07-01

    Since their discovery, carbon nanotubes have fascinated many researchers due to their unprecedented properties. However, a major drawback in utilizing carbon nanotubes for practical applications is the difficulty in positioning or growing them at specific locations. Here we present a simple, rapid, non-invasive and scalable technique that enables optical imaging of carbon nanotubes. The carbon nanotube scaffold serves as a seed for nucleation and growth of small size, optically visible nanocrystals. After imaging the molecules can be removed completely, leaving the surface intact, and thus the carbon nanotube electrical and mechanical properties are preserved. The successful and robust optical imaging allowed us to develop a dedicated image processing algorithm through which we are able to demonstrate a fully automated circuit design resulting in field effect transistors and inverters. Moreover, we demonstrate that this imaging method allows not only to locate carbon nanotubes but also, as in the case of suspended ones, to study their dynamic mechanical motion.

  8. Automated manipulation of carbon nanotubes using atomic force microscopy.

    PubMed

    Zhang, Chao; Wu, Sen; Fu, Xing

    2013-01-01

    The manipulation of carbon nanotubes is an important and essential step for carbon-based nanodevice or nanocircuit assembly. However, the conventional push-and-image approach of manipulating carbon nanotubes using atomic force microscopy has low efficiency on account of the reduplicated scanning process during manipulation. In this article, an automated manipulation system is designed and tested. This automated manipulation system, which includes an atomic force microscope platform and a self-developed computer program for one-dimensional manipulation, is capable of automatically moving any assigned individual carbon nanotube to a defined target location without any intermediate scanning procedure. To demonstrate the high-efficiency of this automated manipulation system and its potential applications in nanoassembly, two experiments were conducted. The first experiment used this system to manipulate a carbon nanotube to a defined target location. In the second experiment, this system was used to automatically manipulate several carbon nanotubes for generating and translating a defined pattern of nanotubes. PMID:23646781

  9. Carbon nanotube catalysts: recent advances in synthesis, characterization and applications.

    PubMed

    Yan, Yibo; Miao, Jianwei; Yang, Zhihong; Xiao, Fang-Xing; Yang, Hong Bin; Liu, Bin; Yang, Yanhui

    2015-05-21

    Carbon nanotubes are promising materials for various applications. In recent years, progress in manufacturing and functionalizing carbon nanotubes has been made to achieve the control of bulk and surface properties including the wettability, acid-base properties, adsorption, electric conductivity and capacitance. In order to gain the optimal benefit of carbon nanotubes, comprehensive understanding on manufacturing and functionalizing carbon nanotubes ought to be systematically developed. This review summarizes methodologies of manufacturing carbon nanotubes via arc discharge, laser ablation and chemical vapor deposition and functionalizing carbon nanotubes through surface oxidation and activation, doping of heteroatoms, halogenation, sulfonation, grafting, polymer coating, noncovalent functionalization and nanoparticle attachment. The characterization techniques detecting the bulk nature and surface properties as well as the effects of various functionalization approaches on modifying the surface properties for specific applications in catalysis including heterogeneous catalysis, photocatalysis, photoelectrocatalysis and electrocatalysis are highlighted. PMID:25855947

  10. Process for derivatizing carbon nanotubes with diazonium species

    NASA Technical Reports Server (NTRS)

    Tour, James M. (Inventor); Bahr, Jeffrey L. (Inventor); Yang, Jiping (Inventor)

    2007-01-01

    The invention incorporates new processes for the chemical modification of carbon nanotubes. Such processes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications and sensor devices. The methods of derivatization include electrochemical induced reactions thermally induced reactions (via in-situ generation of diazonium compounds or pre-formed diazonium compounds), and photochemically induced reactions. The derivatization causes significant changes in the spectroscopic properties of the nanotubes. The estimated degree of functionality is ca. 1 out of every 20 to 30 carbons in a nanotube bearing a functionality moiety. Such electrochemical reduction processes can be adapted to apply site-selective chemical functionalization of nanotubes. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes ##STR00001##.

  11. Thermal Spreading in Carbon Nanotube Coating.

    PubMed

    Kim, Duckjong; Shin, Dong-Sig; Yu, Jeonghwan; Kim, Haesik; Kim, Jae-Hyun; Woo, Chang-Su

    2015-11-01

    Carbon nanomaterials, such as carbon nanotubes (CNTs) and graphene, have attracted significant attention as good candidates for next-generation heat-spreading materials because of their high thermal conductivity, mechanical flexibility, etc. Regarding the thermal spreading performance of carbon-based nanofilms, remarkable test results have been reported mainly from the industrial side, but their validity and the physical mechanism underlying the heat transfer enhancement are still under debate. In this study, we assess the thermal spreading performance of a multi-walled CNT film on a copper foil using a non-contact characterization method in a simple and methodical manner, and discuss the possibility of carbon nanofilms as heat spreaders based on the experimental and numerical results. This study provides useful information on heat transfer enhancement by carbon nanofilms and could contribute to the development of high-performance carbon-based heat-spreading coatings. PMID:26726629

  12. Thermogravimetric Analysis of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivram; Nikolaev, Pavel; Gorelik, Olga

    2010-01-01

    An improved protocol for thermogravimetric analysis (TGA) of samples of single-wall carbon nanotube (SWCNT) material has been developed to increase the degree of consistency among results so that meaningful comparisons can be made among different samples. This improved TGA protocol is suitable for incorporation into the protocol for characterization of carbon nanotube material. In most cases, TGA of carbon nanotube materials is performed in gas mixtures that contain oxygen at various concentrations. The improved protocol is summarized.

  13. Varied morphology carbon nanotubes and method for their manufacture

    DOEpatents

    Li, Wenzhi; Wen, Jian Guo; Ren, Zhi Feng

    2007-01-02

    The present invention describes the preparation of carbon nanotubes of varied morphology, catalyst materials for their synthesis. The present invention also describes reactor apparatus and methods of optimizing and controlling process parameters for the manufacture carbon nanotubes with pre-determined morphologies in relatively high purity and in high yields. In particular, the present invention provides methods for the preparation of non-aligned carbon nanotubes with controllable morphologies, catalyst materials and methods for their manufacture.

  14. A Carbon Nanotube Cable for a Space Elevator

    ERIC Educational Resources Information Center

    Bochnícek, Zdenek

    2013-01-01

    In this paper the mechanical properties of carbon nanotubes are discussed in connection with the possibility to use them for the construction of a space elevator. From the fundamental information about the structure of a carbon nanotube and the chemical bond between carbon atoms, Young's modulus and the ultimate tensile strength are…

  15. Nanoscale fluid transportation through individual carbon nanotubes

    NASA Astrophysics Data System (ADS)

    He, Jin; Cao, Di; Pang, Pei; Luo, Tao; Lindsay, Stuart; Kristic, Predrag; Nuckolls, Colin

    2011-03-01

    There are great interest in both simulation and experiment of fluid flow on the nanoscale. Carbon nanotubes, with their extremely small inner diameter (usually below 2 nm) and atomic smooth inner surface, are ideal materials for studying nanoconfinement and ion and molecule nanoscale translocation. The excellent electrical properties of CNTs can also be integrated to achieve nanoelectrofluidic device. This presentation describes our recent progress in studying fluid transport through individual carbon nanotubes, including simultaneously ionic and electronic measurements during water, ion and molecule translocation. This work was supported by the DNA Sequencing Technology Program of the National Human Genome Research Institute (1RC2HG005625-01, 1R21HG004770-01).

  16. Carbon Nanotube Flexible and Stretchable Electronics

    NASA Astrophysics Data System (ADS)

    Cai, Le; Wang, Chuan

    2015-08-01

    The low-cost and large-area manufacturing of flexible and stretchable electronics using printing processes could radically change people's perspectives on electronics and substantially expand the spectrum of potential applications. Examples range from personalized wearable electronics to large-area smart wallpapers and from interactive bio-inspired robots to implantable health/medical apparatus. Owing to its one-dimensional structure and superior electrical property, carbon nanotube is one of the most promising material platforms for flexible and stretchable electronics. Here in this paper, we review the recent progress in this field. Applications of single-wall carbon nanotube networks as channel semiconductor in flexible thin-film transistors and integrated circuits, as stretchable conductors in various sensors, and as channel material in stretchable transistors will be discussed. Lastly, state-of-the-art advancement on printing process, which is ideal for large-scale fabrication of flexible and stretchable electronics, will also be reviewed in detail.

  17. Carbon Nanotube Flexible and Stretchable Electronics.

    PubMed

    Cai, Le; Wang, Chuan

    2015-12-01

    The low-cost and large-area manufacturing of flexible and stretchable electronics using printing processes could radically change people's perspectives on electronics and substantially expand the spectrum of potential applications. Examples range from personalized wearable electronics to large-area smart wallpapers and from interactive bio-inspired robots to implantable health/medical apparatus. Owing to its one-dimensional structure and superior electrical property, carbon nanotube is one of the most promising material platforms for flexible and stretchable electronics. Here in this paper, we review the recent progress in this field. Applications of single-wall carbon nanotube networks as channel semiconductor in flexible thin-film transistors and integrated circuits, as stretchable conductors in various sensors, and as channel material in stretchable transistors will be discussed. Lastly, state-of-the-art advancement on printing process, which is ideal for large-scale fabrication of flexible and stretchable electronics, will also be reviewed in detail. PMID:26264684

  18. Printed Carbon Nanotube Electronics and Sensor Systems.

    PubMed

    Chen, Kevin; Gao, Wei; Emaminejad, Sam; Kiriya, Daisuke; Ota, Hiroki; Nyein, Hnin Yin Yin; Takei, Kuniharu; Javey, Ali

    2016-06-01

    Printing technologies offer large-area, high-throughput production capabilities for electronics and sensors on mechanically flexible substrates that can conformally cover different surfaces. These capabilities enable a wide range of new applications such as low-cost disposable electronics for health monitoring and wearables, extremely large format electronic displays, interactive wallpapers, and sensing arrays. Solution-processed carbon nanotubes have been shown to be a promising candidate for such printing processes, offering stable devices with high performance. Here, recent progress made in printed carbon nanotube electronics is discussed in terms of materials, processing, devices, and applications. Research challenges and opportunities moving forward from processing and system-level integration points of view are also discussed for enabling practical applications. PMID:26880046

  19. Density controlled carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng F.; Tu, Yi

    2008-12-16

    CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.

  20. Electrical properties of carbon nanotube FETs

    NASA Astrophysics Data System (ADS)

    Mizutani, T.; Ohno, Y.; Kishimoto, S.

    2008-08-01

    The electrical properties of carbon nanotube FETs (CNTFETs) have been studied in detail. The conduction type of the CNTFETs was dependent on the work function of the contact metal, which suggests that Fermi level pinning at the metal/nanotube interface is not strong. Based on the two-probe and four-probe resistance measurements, it has been shown that the carrier transport at the contact is explained by the edge contact model even in the diffusive regime. The chemical doping using F4TCNQ was effective in reducing not only the channel resistance but also the contact resistance. In the CNTFETs fabricated using plasma-enhanced (PE) CVD-grown nanotubes, the drain current of the most of the devices could be modulated by the gate voltage with small OFF current suggesting the preferential growth of the nanotubes with semiconducting behavior. Multichannel top-gate CNTFETs with horizontally-aligned nanotubes as channels have been successfully fabricated using CNT growth on the ST-cut quartz substrate, arc-discharge plasma deposition of the catalyst metal, and ALD gate insulator deposition. The devices show normally-on and n-type conduction property with a relatively-high ON current of 13 mA/mm. CNTFETs with nanotube network have also been fabricated by direct growth on the SiO2/Si substrate using grid-inserted PECVD and using catalyst formed on the channel area of the FETs. The uniformity of the electrical properties of the network channel CNTFETs were very good. Finally, it has been shown that the surface potential profile measurement based on the electrostatic force detection in the scanning probe microscopy was effective in studying the behavior of the CNTFETs such as the transient behavior and the effect of the defects.

  1. Identification of Complex Carbon Nanotube Structures

    NASA Technical Reports Server (NTRS)

    Han, Jie; Saini, Subhash (Technical Monitor)

    1998-01-01

    A variety of complex carbon nanotube (CNT) structures have been observed experimentally. These include sharp bends, branches, tori, and helices. They are believed to be formed by using topological defects such as pentagons and heptagons to connect different CNT. The effects of type, number, and arrangement (separation and orientation) of defects on atomic structures and energetics of complex CNT are investigated using topology, quantum mechanics and molecular mechanics calculations. Energetically stable models are derived for identification of observed complex CNT structures.

  2. Aqueous solution dispersement of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

    2011-01-01

    Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

  3. Quantum conductance of carbon nanotubes with defects

    SciTech Connect

    Chico, L.; Benedict, L.X.; Louie, S.G.; Cohen, M.L. |

    1996-07-01

    We study the conductance of metallic carbon nanotubes with vacancies and pentagon-heptagon pair defects within the Landauer formalism. Using a tight-binding model and a Green{close_quote}s function technique to calculate the scattering matrix, we examine the one-dimensional to two-dimensional crossover in these systems and show the existence of metallic tube junctions in which the conductance is suppressed for symmetry reasons. {copyright} {ital 1996 The American Physical Society.}

  4. Octagonal Defects at Carbon Nanotube Junctions

    PubMed Central

    Jaskólski, W.; Pelc, M.; Chico, Leonor; Ayuela, A.

    2013-01-01

    We investigate knee-shaped junctions of semiconductor zigzag carbon nanotubes. Two dissimilar octagons appear at such junctions; one of them can reconstruct into a pair of pentagons. The junction with two octagons presents two degenerate localized states at Fermi energy (EF). The reconstructed junction has only one state near EF, indicating that these localized states are related to the octagonal defects. The inclusion of Coulomb interaction splits the localized states in the junction with two octagons, yielding an antiferromagnetic system. PMID:24089604

  5. Photon drag effect in carbon nanotube yarns

    NASA Astrophysics Data System (ADS)

    Obraztsov, Alexander N.; Lyashenko, Dmitry A.; Fang, Shaoli; Baughman, Ray H.; Obraztsov, Petr A.; Garnov, Sergei V.; Svirko, Yuri P.

    2009-06-01

    We demonstrate that in graphitic nanocarbon materials, combination of ballistic conductivity and strong electron photon coupling opens a unique opportunity to observe transfer of momentum of the electromagnetic radiation to free carriers. The resulting drag of quasiballistically propagating electrons can be employed, in particular, to visualize the temporal profile, polarization, and propagation direction of the laser pulse. In this letter, we report the giant photon drag effect in yarns made of multiwall carbon nanotubes.

  6. An ultrafast carbon nanotube terahertz polarisation modulator

    SciTech Connect

    Docherty, Callum J.; Stranks, Samuel D.; Habisreutinger, Severin N.; Joyce, Hannah J.; Herz, Laura M.; Nicholas, Robin J.; Johnston, Michael B.

    2014-05-28

    We demonstrate ultrafast modulation of terahertz radiation by unaligned optically pumped single-walled carbon nanotubes. Photoexcitation by an ultrafast optical pump pulse induces transient terahertz absorption in nanowires aligned parallel to the optical pump. By controlling the polarisation of the optical pump, we show that terahertz polarisation and modulation can be tuned, allowing sub-picosecond modulation of terahertz radiation. Such speeds suggest potential for semiconductor nanowire devices in terahertz communication technologies.

  7. An ultrafast carbon nanotube terahertz polarisation modulator

    NASA Astrophysics Data System (ADS)

    Docherty, Callum J.; Stranks, Samuel D.; Habisreutinger, Severin N.; Joyce, Hannah J.; Herz, Laura M.; Nicholas, Robin J.; Johnston, Michael B.

    2014-05-01

    We demonstrate ultrafast modulation of terahertz radiation by unaligned optically pumped single-walled carbon nanotubes. Photoexcitation by an ultrafast optical pump pulse induces transient terahertz absorption in nanowires aligned parallel to the optical pump. By controlling the polarisation of the optical pump, we show that terahertz polarisation and modulation can be tuned, allowing sub-picosecond modulation of terahertz radiation. Such speeds suggest potential for semiconductor nanowire devices in terahertz communication technologies.

  8. Carbon nanotube-polymer nanocomposite infrared sensor.

    PubMed

    Pradhan, Basudev; Setyowati, Kristina; Liu, Haiying; Waldeck, David H; Chen, Jian

    2008-04-01

    The infrared photoresponse in the electrical conductivity of single-walled carbon nanotubes (SWNTs) is dramatically enhanced by embedding SWNTs in an electrically and thermally insulating polymer matrix. The conductivity change in a 5 wt % SWNT-polycarbonate nanocomposite is significant (4.26%) and sharp upon infrared illumination in the air at room temperature. While the thermal effect predominates in the infrared photoresponse of a pure SWNT film, the photoeffect predominates in the infrared photoresponse of SWNT-polycarbonate nanocomposites. PMID:18333623

  9. Carbon Nanotubes by CVD and Applications

    NASA Technical Reports Server (NTRS)

    Cassell, Alan; Delzeit, Lance; Nguyen, Cattien; Stevens, Ramsey; Han, Jie; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    2001-01-01

    Carbon nanotube (CNT) exhibits extraordinary mechanical and unique electronic properties and offers significant potential for structural, sensor, and nanoelectronics applications. An overview of CNT, growth methods, properties and applications is provided. Single-wall, and multi-wall CNTs have been grown by chemical vapor deposition. Catalyst development and optimization has been accomplished using combinatorial optimization methods. CNT has also been grown from the tips of silicon cantilevers for use in atomic force microscopy.

  10. Upper bound to the thermal conductivity of carbon nanotube pellets

    NASA Astrophysics Data System (ADS)

    Chalopin, Yann; Volz, Sebastian; Mingo, Natalio

    2009-04-01

    Using atomistic Green's function calculations, we find that the phonon thermal conductivity of pellets composed of ˜μm long carbon nanotubes has an upper bound of a few W/m K. This is in striking contrast with the extremely high thermal conductivity of individual nanotubes (˜3000 W/m K). We show that, at room temperature, this upper bound does not depend on the nanotube diameter. Conversely, for low temperatures, an inverse proportionality with nanotube diameter is predicted. We present concrete results as a function of nanotube length and chirality, pellet density, and temperature. These results imply that carbon nanotube pellets belong to the category of thermal insulators, contrasting with the good conducting properties of parallel nanotube arrays, or individual nanotubes.

  11. Fabrication and Characterization of Suspended Carbon Nanotube Devices in Liquid

    SciTech Connect

    Artyukhin, A; Stadermann, M; Stroeve, P; Bakajin, O; Noy, A

    2006-10-30

    Suspended carbon nanotube devices are a promising platform for future bio-electronic applications. Suspended carbon nanotube transistors have been previously fabricated in air; however all previous attempts to bring them into liquid failed. We analyze forces acting on the suspended nanotube devices during immersion into liquids and during device operation and show that surface tension forces acting on the suspended nanotubes during transfer into the liquid phase are responsible for the nanotube damage. We have developed a new strategy that circumvents these limitations by coating suspended nanotubes with a rigid inorganic shell in the gas phase. The coating reinforces the nanotubes and allows them to survive transfer through the interface. Subsequent removal of the coating in the solution phase restores pristine suspended nanotubes. We demonstrate that devices fabricated using this technique preserve their original electrical characteristics.

  12. Carbon nanotube based hybrid nanostructures: Synthesis and applications

    NASA Astrophysics Data System (ADS)

    Ou, Fung Suong

    Hybrid nanostructures are fascinating materials for their promising applications in future nanoelectronics, electrical interconnects and energy storage devices. Practical ways of connecting individual carbon nanotubes to metal contacts for their use as interconnects and in electronic devices have been challenging. In this thesis, carbon nanotube based hybrids that combine the best properties of carbon nanotubes and metal nanowires have been fabricated. The electrical properties and Raman spectra of the hybrid nanowires are also studied. This thesis will focus on our recent results in the development of carbon nanotube hybrids for various applications. Various hybrid structures of multiwalled carbon nanotubes and metal nanowires can be fabricated using a combination of electrodeposition and chemical vapor deposition techniques. Controlled fabrication of multi-segmented structures will be studied. Several novel applications of these structures, for example, as electrodes in ultra-high power supercapacitors, multi-functional smart materials are also studied. The thesis will also highlight the development of carbon nanotube hybrids based smart materials. Hybrid nanowires with hydrophobic carbon nanotube tails and hydrophilic metal nanowire heads, allows for the assembly of spheres in solution. The design and manipulation of these carbon nanotube hybrids based smart structures for various novel applications will be discussed. Such new class of carbon nanotube hybrids surfactants are likely to lead as new tools in various fields such as microfluidics or water purification. In addition, we will also look at other variations of hybrid nanostructures fabricated from our method.

  13. Simulation of the Band Structure of Graphene and Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Mina, Aziz N.; Awadallah, Attia A.; Phillips, Adel H.; Ahmed, Riham R.

    2012-02-01

    Simulation technique has been performed to simulate the band structure of both graphene and carbon nanotube. Accordingly, the dispersion relations for graphene and carbon nanotube are deduced analytically, using the tight binding model & LCAO scheme. The results from the simulation of the dispersion relation of both graphene and carbon nanotube were found to be consistent with those in the literature which indicates the correctness of the process of simulation technique. The present research is very important for tailoring graphene and carbon nanotube with specific band structure, in order to satisfy the required electronic properties of them.

  14. New Insight into Carbon Nanotube Electronic Structure Selectivity

    SciTech Connect

    Sumpter, Bobby G; Meunier, Vincent; Jiang, Deen

    2009-01-01

    The fundamental role of aryl diazonium salts for post synthesis selectivity of carbon nanotubes is investigated using extensive electronic structure calculations. The resulting understanding for diazonium salt based selective separation of conducting and semiconducting carbon nanotubes shows how the primary contributions come from the interplay between the intrinsic electronic structure of the carbon nanotubes and that of the anion of the salt. We demonstrate how the electronic transport properties change upon the formation of charge transfer complexes and upon their conversion into covalently attached functional groups. Our results are found to correlate well with experiments and provide for the first time an atomistic description for diazonium salt based chemical separation of carbon nanotubes

  15. Carbon nanotube materials for hydrogen storage

    SciTech Connect

    Dillon, A.C.; Parilla, P.A.; Jones, K.M.; Riker, G.; Heben, M.J.

    1998-08-01

    Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and high energy density adsorbents for hydrogen storage applications. In past work the authors developed methods for preparing and opening SWNTs, discovered the unique adsorption properties of these new materials, confirmed that hydrogen is stabilized by physical rather than chemical interactions, measured the strength of interaction to be {approximately} 5 times higher than for adsorption on planar graphite, and performed infrared absorption spectroscopy to determine the chemical nature of the surface terminations before, during, and after oxidation. This year the authors have made significant advances in synthesis and characterization of SWNT materials so that they can now prepare gram quantities of high-purity SWNT samples and measure and control the diameter distribution of the tubes by varying key parameters during synthesis. They have also developed methods which purify nanotubes and cut nanotubes into shorter segments. These capabilities provide a means for opening the tubes which were unreactive to the oxidation methods that successfully opened tubes, and offer a path towards organizing nanotube segments to enable high volumetric hydrogen storage densities. They also performed temperature programmed desorption spectroscopy on high purity carbon nanotube material obtained from collaborator Prof. Patrick Bernier and finished construction of a high precision Seivert`s apparatus which will allow the hydrogen pressure-temperature-composition phase diagrams to be evaluated for SWNT materials.

  16. Fast Electromechanical Switches Based on Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama; Wong, Eric; Epp, Larry

    2008-01-01

    Electrostatically actuated nanoelectromechanical switches based on carbon nanotubes have been fabricated and tested in a continuing effort to develop high-speed switches for a variety of stationary and portable electronic equipment. As explained below, these devices offer advantages over electrostatically actuated microelectromechanical switches, which, heretofore, have represented the state of the art of rapid, highly miniaturized electromechanical switches. Potential applications for these devices include computer memories, cellular telephones, communication networks, scientific instrumentation, and general radiation-hard electronic equipment. A representative device of the present type includes a single-wall carbon nanotube suspended over a trench about 130 nm wide and 20 nm deep in an electrically insulating material. The ends of the carbon nanotube are connected to metal electrodes, denoted the source and drain electrodes. At bottom of the trench is another metal electrode, denoted the pull electrode (see figure). In the off or open switch state, no voltage is applied, and the nanotube remains out of contact with the pull electrode. When a sufficiently large electric potential (switching potential) is applied between the pull electrode and either or both of the source and drain electrodes, the resulting electrostatic attraction bends and stretches the nanotube into contact with the pull electrode, thereby putting the switch into the "on" or "closed" state, in which substantial current (typically as much as hundreds of nanoamperes) is conducted. Devices of this type for use in initial experiments were fabricated on a thermally oxidized Si wafer, onto which Nb was sputter-deposited for use as the pull-electrode layer. Nb was chosen because its refractory nature would enable it to withstand the chemical and thermal conditions to be subsequently imposed for growing carbon nanotubes. A 200- nm-thick layer of SiO2 was formed on top of the Nb layer by plasma

  17. Vibrations of carbon nanotube-reinforced composites

    NASA Astrophysics Data System (ADS)

    Formica, Giovanni; Lacarbonara, Walter; Alessi, Roberto

    2010-05-01

    This work deals with a study of the vibrational properties of carbon nanotube-reinforced composites by employing an equivalent continuum model based on the Eshelby-Mori-Tanaka approach. The theory allows the calculation of the effective constitutive law of the elastic isotropic medium (matrix) with dispersed elastic inhomogeneities (carbon nanotubes). The devised computational approach is shown to yield predictions in good agreement with the experimentally obtained elastic moduli of composites reinforced with uniformly aligned single-walled carbon nanotubes (CNTs). The primary contribution of the present work deals with the global elastic modal properties of nano-structured composite plates. The investigated composite plates are made of a purely isotropic elastic hosting matrix of three different types (epoxy, rubber, and concrete) with embedded single-walled CNTs. The computations are carried out via a finite element (FE) discretization of the composite plates. The effects of the CNT alignment and volume fraction are studied in depth to assess how the modal properties are influenced both globally and locally. As a major outcome, the lowest natural frequencies of CNT-reinforced rubber composites are shown to increase up to 500 percent.

  18. Ferroelectric-carbon nanotube memory devices.

    PubMed

    Kumar, Ashok; Shivareddy, Sai G; Correa, Margarita; Resto, Oscar; Choi, Youngjin; Cole, Matthew T; Katiyar, Ram S; Scott, James F; Amaratunga, Gehan A J; Lu, Haidong; Gruverman, Alexei

    2012-04-27

    One-dimensional ferroelectric nanostructures, carbon nanotubes (CNT) and CNT-inorganic oxides have recently been studied due to their potential applications for microelectronics. Here, we report coating of a registered array of aligned multi-wall carbon nanotubes (MWCNT) grown on silicon substrates by functional ferroelectric Pb(Zr,Ti)O3 (PZT) which produces structures suitable for commercial prototype memories. Microstructural analysis reveals the crystalline nature of PZT with small nanocrystals aligned in different directions. First-order Raman modes of MWCNT and PZT/MWCNT/n-Si show the high structural quality of CNT before and after PZT deposition at elevated temperature. PZT exists mostly in the monoclinic Cc/Cm phase, which is the origin of the high piezoelectric response in the system. Low-loss square piezoelectric hysteresis obtained for the 3D bottom-up structure confirms the switchability of the device. Current-voltage mapping of the device by conducting atomic force microscopy (c-AFM) indicates very low transient current. Fabrication and functional properties of these hybrid ferroelectric-carbon nanotubes is the first step towards miniaturization for future nanotechnology sensors, actuators, transducers and memory devices. PMID:22460805

  19. Reversible separation of single-walled carbon nanotubes in bundles

    SciTech Connect

    Sahoo, Sangeeta; Lastella, Sarah; Maranganti, Ravi; Sharma, Pradeep; Mallick, Govind; Karna, Shashi; Ajayan, Pulickel M.

    2008-08-25

    We show that electrostatic charging of nanotubes and the consequent repulsion can lead to reversible separation of individual single-walled carbon nanotubes in bundles. Low-energy electron beam irradiation leads to this completely reversible phenomenon. A simple semianalytical model is used to explain the observed separation mechanism. The reversibility of the separation process is attributed to discharging and thermal-fluctuation induced motion of the nanotubes in ambient air. Further, the separation impacts the electrical conductance of small nanotube bundled devices.

  20. Studies of DNA-carbon nanotube interactions

    NASA Astrophysics Data System (ADS)

    Hughes, Mary Elizabeth

    2008-10-01

    Recently a new biomaterial consisting of a DNA-wrapped single-walled carbon nanotube, and known as a DNA/SWNT, has been discovered. The possible applications of this hybrid are varied and range from genomic sequencing to nanoscale electronics to molecular delivery. The realization of these potential applications requires more knowledge about the microscopic properties of this material. In this thesis, I present studies of: the orientation of nucleobases on the nanotube sidewall; the sequence and length dependence of the DNA-nanotube interaction; and solution conditions to manipulate the DNA/SWNT hybrid. The measurement of the UV optical absorbance of DNA/SWNT and the nucleotide absorbance from DNA/SWNT provide the first experimental confirmation that DNA binds to nanotubes through pi-stacking. Because the hypochromic absorbance typical of pi-stacked structures are expected to occur primarily for DNA dipole transitions that lie along the axis of the optically anisotropic SWNTs, the absorbance changes following binding of DNA to the nanotubes reveals the preferred orientation assumed by each of the four bound nucleotides with respect to the nanotube's long axis. The first observations of pronounced sequence- and length-dependent variations in the binding between ssDNA and SWNTs in aqueous solution are presented. These observations rely on the discovery that there exists a range of DNA lengths able to hybridize with SWNTs that can nevertheless be dissociated at temperatures below the boiling point of water. Quantitative results comparing the isochronal dissociation temperatures and binding energies of DNA/SWNT composed of differing DNA sequences and lengths are given. These results indicate variability and complexity in the binding mechanism responsible for the stability of the hybrid system that transcends simple models based on the sum of independent base-nanotube interactions. Binding energies between a DNA base and nanotube (0.05 to 0.09 eV per base) are similar

  1. Adaptive Materials from Carbon Nanotube - Polyurethane Nanocomposites

    NASA Astrophysics Data System (ADS)

    Powers, Daniel; Koerner, Hilmar

    2005-04-01

    Adaptive materials undergo large-scale shape or property change in response to an external stimulus such as stress, temperature, light, or pH. Technological uses range from durable, shape recovery eye-glass frames, to temperature sensitive switches, to the generation of stress to induced mechanical motion. Here in, we demonstrate that the uniform dispersion of 1-5vol% of carbon nanotubes in a thermoplastic elastomer yields nanocomposites that can store and subsequently release, through remote means, up to 50% more recovery stress than the pristine resin. The anisotropic nanotubes increase the rubbery modulus by a factor of 2 to 5 (for 1-5vol%) and improve shape fixity by enhancing strain-induced crystallization. Non-radiative decay of infrared photons absorbed by the nanotubes raises the internal temperature, melting the polymer crystallites (which act as physical cross-links that secure the deformed shape) and remotely triggering the release of the stored strain energy. Comparable effects occur for electrically-induced actuation associated with Joule heating of the matrix when a current is passed through the conductive percolative network of the nanotubes within the resin.

  2. Terahertz Response of Carbon Nanotubes and Graphene

    NASA Astrophysics Data System (ADS)

    Kawano, Yukio

    2015-12-01

    The terahertz (THz) research field is expected to serve as a new platform for studying low-energy excitation in solids and higher-order structures in large molecules, and for realizing applications in medicine, agriculture, security, and high-capacity communications. The THz frequency region, however, is located between the electronic and photonic bands, hampering the development of basic components like detectors and sources. This article presents an overview of basic background information about THz waves and THz detector applications and describes the THz response of carbon-based low-dimensional systems, such as single carbon nanotubes (CNT), CNT-array films, and graphene.

  3. Electron transport through single carbon nanotubes

    SciTech Connect

    Schenkel, Thomas; Chai, G.; Heinrich, H.; Chow, L.; Schenkel, T.

    2007-08-01

    We report on the transport of energetic electrons through single, well aligned multi-wall carbon nanotubes (CNT). Embedding of CNTs in a protective carbon fiber coating enables the application of focused ion beam based sample preparation techniques for the non-destructive isolation and alignment of individual tubes. Aligned tubes with lengths of 0.7 to 3 mu m allow transport of 300 keV electrons in a transmission electron microscope through their hollow cores at zero degree incident angles and for a misalignment of up to 1 degree.

  4. Carbon nanotube materials for hydrogen storage

    SciTech Connect

    Dillon, A.C.; Jones, K.M.; Heben, M.J.

    1996-10-01

    Hydrogen burns pollution-free and may be produced from renewable energy resources. It is therefore an ideal candidate to replace fossil fuels as an energy carrier. However, the lack of a convenient and cost-effective hydrogen storage system greatly impedes the wide-scale use of hydrogen in both domestic and international markets. Although several hydrogen storage options exist, no approach satisfies all of the efficiency, size, weight, cost and safety requirements for transportation or utility use. A material consisting exclusively of micropores with molecular dimensions could simultaneously meet all of the requirements for transportation use if the interaction energy for hydrogen was sufficiently strong to cause hydrogen adsorption at ambient temperatures. Small diameter ({approx}1 mm) carbon single-wall nanotubes (SWNTs) are elongated micropores of molecular dimensions, and materials composed predominantly of SWNTs may prove to be the ideal adsorbent for ambient temperature storage of hydrogen. Last year the authors reported that hydrogen could be adsorbed on arc-generated soots containing 12{Angstrom} diameter nanotubes at temperatures in excess of 285K. In this past year they have learned that such adsorption does not occur on activated carbon materials, and that the cobalt nanoparticles present in their arc-generated soots are not responsible for the hydrogen which is stable at 285 K. These results indicate that enhanced adsorption forces within the internal cavities of the SWNTs are active in stabilizing hydrogen at elevated temperatures. This enhanced stability could lead to effective hydrogen storage under ambient temperature conditions. In the past year the authors have also demonstrated that single-wall carbon nanotubes in arc-generated soots may be selectively opened by oxidation in H{sub 2}O resulting in improved hydrogen adsorption, and they have estimated experimentally that the amount of hydrogen stored is {approximately}10% of the nanotube weight.

  5. Carbon Nanotube-enhanced Carbon-phenolic Ablator Material

    NASA Technical Reports Server (NTRS)

    Nikolaev, P.; Stackpoole, M.; Fan, W.; Cruden, B.; Waid, M.; Maloney, P.; Arepalli, S.; Arnold, J.; Partridge, H.; Yowell, L.

    2006-01-01

    Phenolic impregnated carbon ablator (PICA) is a thermal protection system (TPS) material developed at NASA Ames Research Center in the mid-90 s for Discovery missions. It was used on the Stardust return capsule heat shield which successfully executed the highest speed Earth entry to date on January 15, 2006. PICA is a porous fibrous carbon insulation infiltrated with phenolic resin, and is an excellent ablator that is effective for heating rates up to 1000 W/sq cm. It is one of several candidate TPS materials for the next generation of crewed spacecraft for Lunar and Mars missions. We will describe an ongoing research effort at NASA to improve mechanical properties of the phenolic matrix with carbon nanotubes. The aim is two-fold: to increase overall TPS strength during reentry and to improve Micrometeoroid/Orbital Debris (MMOD) protection in space. The former requires at least a good dispersion of nanotubes in phenolic, while the latter also requires covalent bonding between them to couple and transfer impact energy effectively from matrix to nanotubes. We will discuss the required chemical functionalization of nanotubes, processing issues and test results.

  6. Stretchable Conductive Networks of Carbon Nanotubes Using Plasticised Colloidal Templates

    NASA Astrophysics Data System (ADS)

    Worajittiphon, Patnarin; Large, Matthew; King, Alice; Jurewicz, Izabela; Dalton, Alan

    2015-03-01

    We present a study of the behavior of highly ordered, segregated single-wall carbon nanotube networks under applied strain. Polymer latex templates induce self-assembly of carbon nanotubes into hexagonal (2D) and honeycomb (3D) networks within the matrix. Using mechanical and spectroscopic analysis, we have studied the strain transfer mechanisms between the carbon nanotube network and the polymer matrix. Axial deformation of the nanotube network under applied strain is indicated by downshifts in the 2D mode in the Raman spectra, as well as variation in the Radial Breathing modes. The slippage within nanotube bundles at high strain is indicated by a reduction in the 2D mode rate of change. The fractional resistance change of the composites with strain obeys power law dependence. We present a model for the behavior of carbon nanotube bundles under strain informed by these measurements, and potential applications for such composite materials in elastic electronic devices that can tolerate high strain.

  7. Binding energy of the trion complex in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Meliksetyan, Areg; Bondarev, Igor

    2014-03-01

    We derive an analytical expression for the binding energy of the trion complex (charged exciton) in small diameter (~1nm) carbon nanotubes. We use the (asymptotically exact) Landau-Herring approach that was previously implemented by one of us (Ref.) to evaluate the biexciton binding energy in carbon nanotubes. Within this approach, we find the universal asymptotic relationship between the trion, biexciton and exciton binding energies in the same carbon nanotube. Particularly, the trion binding energy we obtained is estimated to be greater than the corresponding biexciton binding energy by a factor ~1.5 for carbon nanotubes with diameters ~1nm, which reasonably agrees with the latest non-linear optical spectroscopy measurements reported in Refs. and (1.46 for the (6,5) nanotube and 1.42 for the (9,7) nanotube, respectively). ARO-W911NF-11-1-0189 (A.M.), DOE-DE-SC0007117 (I.B.).

  8. Multifunctional brushes made from carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cao, Anyuan; Veedu, Vinod P.; Li, Xuesong; Yao, Zhaoling; Ghasemi-Nejhad, Mehrdad N.; Ajayan, Pulickel M.

    2005-07-01

    Brushes are common tools for use in industry and our daily life, performing a variety of tasks such as cleaning, scraping, applying and electrical contacts. Typical materials for constructing brush bristles include animal hairs, synthetic polymer fibres and metal wires (see, for example, ref. 1). The performance of these bristles has been limited by the oxidation and degradation of metal wires, poor strength of natural hairs, and low thermal stability of synthetic fibres. Carbon nanotubes, having a typical one-dimensional nanostructure, have excellent mechanical properties, such as high modulus and strength, high elasticity and resilience, thermal conductivity and large surface area (50-200 m2 g-1). Here we construct multifunctional, conductive brushes with carbon nanotube bristles grafted on fibre handles, and demonstrate their several unique tasks such as cleaning of nanoparticles from narrow spaces, coating of the inside of holes, selective chemical adsorption, and as movable electromechanical brush contacts and switches. The nanotube bristles can also be chemically functionalized for selective removal of heavy metal ions.

  9. Preparation of array of long carbon nanotubes and fibers therefrom

    DOEpatents

    Arendt, Paul N.; DePaula, Ramond F.; Zhu, Yuntian T.; Usov, Igor O.

    2015-11-19

    An array of carbon nanotubes is prepared by exposing a catalyst structure to a carbon nanotube precursor. Embodiment catalyst structures include one or more trenches, channels, or a combination of trenches and channels. A system for preparing the array includes a heated surface for heating the catalyst structure and a cooling portion that cools gas above the catalyst structure. The system heats the catalyst structure so that the interaction between the precursor and the catalyst structure results in the formation of an array of carbon nanotubes on the catalyst structure, and cools the gas near the catalyst structure and also cools any carbon nanotubes that form on the catalyst structure to prevent or at least minimize the formation of amorphous carbon. Arrays thus formed may be used for spinning fibers of carbon nanotubes.

  10. Metallic single-walled carbon nanotubes for conductive nanocomposites.

    PubMed

    Wang, Wei; Fernando, K A Shiral; Lin, Yi; Meziani, Mohammed J; Veca, L Monica; Cao, Li; Zhang, Puyu; Kimani, Martin M; Sun, Ya-Ping

    2008-01-30

    This article reports an unambiguous demonstration that bulk-separated metallic single-walled carbon nanotubes offer superior performance (consistently and substantially better than the as-produced nanotube sample) in conductive composites with poly(3-hexylthiophene) and also in transparent conductive coatings based on PEDOT:PSS. The results serve as a validation on the widely held view that the carbon nanotubes are competitive in various technologies currently dominated by conductive inorganic materials (such as indium tin oxide). PMID:18173271

  11. Carbon nanotube as a gramicidin analogue

    NASA Astrophysics Data System (ADS)

    Hilder, Tamsyn A.; Chung, Shin-Ho

    2011-01-01

    We have designed a carbon nanotube that is selectively permeable to monovalent cations, binds divalent cations and rejects anions. The nanotubes, with an effective radius of 4.53 Å and length of 36 Å, are terminated with hydrogen atoms and are exohydrogenated in two regions near the entrance and exit. Using molecular and stochastic dynamics simulations we examine the free energy, current-voltage-concentration profiles and ion binding sites. The characteristics of this channel are comparable to the antibiotic gramicidin-A, but the potassium current is six times larger. At 40 mM calcium concentration the current is reduced from 26 pA to 4 pA due to a calcium ion binding at the channel entrance.

  12. Carbon nanotube DNA sensor and sensing mechanism.

    PubMed

    Tang, Xiaowu; Bansaruntip, Sarunya; Nakayama, Nozomi; Yenilmez, Erhan; Chang, Ying-Lan; Wang, Qian

    2006-08-01

    We report the fabrication of single-walled carbon nanotube (SWNT) DNA sensors and the sensing mechanism. The simple and generic protocol for label-free detection of DNA hybridization is demonstrated with random sequence 15mer and 30mer oligonucleotides. DNA hybridization on gold electrodes, instead of on SWNT sidewalls, is mainly responsible for the acute electrical conductance change due to the modulation of energy level alignment between SWNT and gold contact. This work provides concrete experimental evidence on the effect of SWNT-DNA binding on DNA functionality, which will help to pave the way for future designing of SWNT biocomplexes for applications in biotechnology in general and also DNA-assisted nanotube manipulation techniques. PMID:16895348

  13. A carbon nanotube immunosensor for Salmonella

    NASA Astrophysics Data System (ADS)

    Lerner, Mitchell B.; Goldsmith, Brett R.; McMillon, Ronald; Dailey, Jennifer; Pillai, Shreekumar; Singh, Shree R.; Johnson, A. T. Charlie

    2011-12-01

    Antibody-functionalized carbon nanotube devices have been suggested for use as bacterial detectors for monitoring of food purity in transit from the farm to the kitchen. Here we report progress towards that goal by demonstrating specific detection of Salmonella in complex nutrient broth solutions using nanotube transistors functionalized with covalently-bound anti-Salmonella antibodies. The small size of the active device region makes them compatible with integration in large-scale arrays. We find that the on-state current of the transistor is sensitive specifically to the Salmonella concentration and saturates at low concentration (<1000 cfu/ml). In contrast, the carrier mobility is affected comparably by Salmonella and other bacteria types, with no sign of saturation even at much larger concentrations (108 cfu/ml).

  14. Carbon Nanotubes Growth on Graphite Fibers

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehoczky, S. L.; Muntele, I.; Ila, D.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Carbon nanotubes (CNT) were synthesized on graphite fibers by thermal Chemical Vapor Deposition (CVD). On the fiber surface, iron nanoparticles are coated and act as catalysts for CNT growth. The growth temperature ranges from 550 to 1000 C at an ambient pressure. Methane and hydrogen gases with methane contents of 10% to 100% are used for the CNT synthesis. At high growth temperatures (greater than 800 C), the rapid inter-diffusion of the transition metal iron on the graphite surface results in a rough fiber surface with no CNT grown on the surface. When the growth temperature is relatively low (650 - 800 C), CNT are fabricated on the graphite surface with catalytic particles on the nanotube top ends. Using micro Raman spectroscopy in the breath mode region, single-walled or multi-walled CNT can be determined, depending on methane concentrations.

  15. Carbon nanotube electron sources for electron microscopes

    SciTech Connect

    De Jonge, Niels

    2009-01-01

    Electron sources were made from individual multi-walled carbon nanotubes with closed caps and thoroughly cleaned surfaces. Nanotubes from both chemical vapor deposition growth and arc discharge growth were investigated. These emitters provide a highly stable emission current up to a threshold current of a few microamperes. At too large currents several processes take place such as splitting, breaking and cap closing. The emission process is field emission for a workfunction of 5 eV. The electron optical per-formance is highly beneficial for their use as high-brightness point sources in electron microscopes and advantageous with respect to state-of-the-art electron sources. The life-time is at least two years. We have tested the source successfully in a scanning electron microscope.

  16. Catalysts for Efficient Production of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Sun, Ted X.; Dong, Yi

    2009-01-01

    Several metal alloys have shown promise as improved catalysts for catalytic thermal decomposition of hydrocarbon gases to produce carbon nanotubes (CNTs). Heretofore almost every experiment on the production of carbon nanotubes by this method has involved the use of iron, nickel, or cobalt as the catalyst. However, the catalytic-conversion efficiencies of these metals have been observed to be limited. The identification of better catalysts is part of a continuing program to develop means of mass production of high-quality carbon nanotubes at costs lower than those achieved thus far (as much as $100/g for purified multi-wall CNTs or $1,000/g for single-wall CNTs in year 2002). The main effort thus far in this program has been the design and implementation of a process tailored specifically for high-throughput screening of alloys for catalyzing the growth of CNTs. The process includes an integral combination of (1) formulation of libraries of catalysts, (2) synthesis of CNTs from decomposition of ethylene on powders of the alloys in a pyrolytic chemical-vapor-decomposition reactor, and (3) scanning- electron-microscope screening of the CNTs thus synthesized to evaluate the catalytic efficiencies of the alloys. Information gained in this process is put into a database and analyzed to identify promising alloy compositions, which are to be subjected to further evaluation in a subsequent round of testing. Some of these alloys have been found to catalyze the formation of carbon nano tubes from ethylene at temperatures as low as 350 to 400 C. In contrast, the temperatures typically required for prior catalysts range from 550 to 750 C.

  17. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    SciTech Connect

    Abe Fetterman, Yevgeny Raitses, and Michael Keidar

    2008-04-08

    The anode ablation rate is investigated as a function of anode diameter for a carbon nanotube arc plasma. It is found that anomalously high ablation occurs for small anode diameters. This result is explained by the formation of a positive anode sheath. The increased ablation rate due to this positive anode sheath could imply greater production rate for carbon nanotubes.

  18. Apparatus for the laser ablative synthesis of carbon nanotubes

    DOEpatents

    Smith, Michael W.; Jordan, Kevin

    2010-02-16

    An RF-induction heated side-pumped synthesis chamber for the production of carbon nanotubes. Such an apparatus, while capable of producing large volumes of carbon nanotubes, concurrently provides a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization.

  19. Binderless carbon nanotube/carbon fibre composites for electrochemical micropower sources.

    PubMed

    Bordjiba, Tarik; Mohamedi, Mohamed; Dao, Lê H

    2007-01-24

    Interesting architectures built with electrically conductive substrates of interest for microelectrochemical power sources were obtained by directly growing carbon nanotubes on each microfibre constituting a carbon paper. The carbon nanotubes were fabricated by the chemical vapour deposition technique. Results of electrochemical tests showed high-resolution responses in different chemical media, which indicate good electrical contact between the carbon nanotubes and the carbon paper substrate. These architectures hold great promise for incorporation into microelectrochemical power sources. PMID:19636112

  20. A thermodynamic model for growth mechanisms of multiwall carbon nanotubes.

    SciTech Connect

    Kaatz, Forrest H.; Overmyer, Donald L.; Siegal, Michael P.

    2006-02-01

    Multiwall carbon nanotubes are grown via thermal chemical vapor deposition between temperatures of 630 and 830 C using acetylene in nitrogen as the carbon source. This process is modeled using classical thermodynamics to explain the total carbon deposition as a function of time and temperature. An activation energy of 1.60 eV is inferred for nanotube growth after considering the carbon solubility term. Scanning electron microscopy shows growth with diameters increasing linearly with time. Transmission electron microscopy and Raman spectroscopy show multiwall nanotubes surrounded by a glassy-carbon sheath, which grows with increasing wall thickness as growth temperatures and times rise.

  1. Multifunctional Carbon Nanotube Sensors for Environmental Monitoring

    NASA Astrophysics Data System (ADS)

    Liu, Yu

    As a one dimensional material, a Single-walled Carbon Nanotube (SWNT) is made of a rolled up graphene sheet. With a diameter of 1˜2 nm, the SWNTs exhibit many unique properties, such as high aspect ratios, ballistic carrier transport, high mechanical strength and thermal stability. These properties enable SWNTs to have superior performances in various applications including electronics and sensors. SWNT based sensors are extremely sensitive to slight electrostatic changes in their environment and have a fast response where conductance of an SWNT is observed to change in less than 2 sec upon exposure. In addition, SWNT sensors have size advantage over traditional sensors. Hence, SWNTs have been widely explored as active sensing elements for chemical and biomolecule detection. Despite high sensitivities observed from nanotube sensors, one drawback is their lack of selectivity. The conductance of SWNTs is susceptible to many gas molecules in air, including oxygen and moisture which are abundantly present in the ambient environment. Due to this nonspecificity, the presence of any type of gas vapors can possibly interfere with the induced signals from the target gas vapors and hence reduce S/N ratio during detection. To minimize the effects of undesirable interference signals from the environment, several functionalization methods have been developed to customize the affinities of SWNTs to specific targets, including metal nano particles, conducting polymers and biomolecules. The objective of this thesis is to utilize SWNTs in environmental applications. The proposed research topics include: investigating the sensing characteristics of RNA oligomers on carbon nanotubes; analyzing the sensing characteristics of DNA with different sequence lengths on carbon nanotubes; integration of DNA decorated SWNTs onto CMOS chip for toxic and explosive gas monitoring; building nanosensor array based on multi-functionalized SWNTs for air quality monitoring and exploring the sensing

  2. Massive radius-dependent flow slippage in carbon nanotubes.

    PubMed

    Secchi, Eleonora; Marbach, Sophie; Niguès, Antoine; Stein, Derek; Siria, Alessandro; Bocquet, Lydéric

    2016-01-01

    Measurements and simulations have found that water moves through carbon nanotubes at exceptionally high rates owing to nearly frictionless interfaces. These observations have stimulated interest in nanotube-based membranes for applications including desalination, nano-filtration and energy harvesting, yet the exact mechanisms of water transport inside the nanotubes and at the water-carbon interface continue to be debated because existing theories do not provide a satisfactory explanation for the limited number of experimental results available so far. This lack of experimental results arises because, even though controlled and systematic studies have explored transport through individual nanotubes, none has met the considerable technical challenge of unambiguously measuring the permeability of a single nanotube. Here we show that the pressure-driven flow rate through individual nanotubes can be determined with unprecedented sensitivity and without dyes from the hydrodynamics of water jets as they emerge from single nanotubes into a surrounding fluid. Our measurements reveal unexpectedly large and radius-dependent surface slippage in carbon nanotubes, and no slippage in boron nitride nanotubes that are crystallographically similar to carbon nanotubes, but electronically different. This pronounced contrast between the two systems must originate from subtle differences in the atomic-scale details of their solid-liquid interfaces, illustrating that nanofluidics is the frontier at which the continuum picture of fluid mechanics meets the atomic nature of matter. PMID:27604947

  3. Electrical properties and applications of carbon nanotube structures.

    PubMed

    Bandaru, Prabhakar R

    2007-01-01

    The experimentally verified electrical properties of carbon nanotube structures and manifestations in related phenomena such as thermoelectricity, superconductivity, electroluminescence, and photoconductivity are reviewed. The possibility of using naturally formed complex nanotube morphologies, such as Y-junctions, for new device architectures are then considered. Technological applications of the electrical properties of nanotube derived structures in transistor applications, high frequency nanoelectronics, field emission, and biological sensing are then outlined. The review concludes with an outlook on the technological potential of nanotubes and the need for new device architectures for nanotube systems integration. PMID:17450889

  4. Fabrication of Carbon Nanotube Field Effect Transistors Using Plasma-Enhanced Chemical Vapor Deposition Grown Nanotubes

    NASA Astrophysics Data System (ADS)

    Ohnaka, Hirofumi; Kojima, Yoshihiro; Kishimoto, Shigeru; Ohno, Yutaka; Mizutani, Takashi

    2006-06-01

    Single-walled carbon nanotubes are grown using grid-inserted plasma-enhanced chemical vapor deposition (PECVD). The field effect transistor operation was confirmed using the PECVD grown carbon nanotubes (CNTs). The preferential growth of the semiconducting nanotubes was confirmed in the grid-inserted PECVD by measuring current-voltage (I-V) characteristics of the devices. Based on the measurement of the electrical breakdown of the metallic CNTs, the probability of growing the semiconducting nanotubes has been estimated to be more than 90%.

  5. Ecological Uptake and Depuration of Carbon Nanotubes by Lumbriculus variegatus

    PubMed Central

    Petersen, Elijah J.; Huang, Qingguo; Weber, Walter J.

    2008-01-01

    Background Carbon nanotubes represent a class of nanomaterials having broad application potentials and documented cellular uptake and ecotoxicological effects that raise the possibility that they may bioaccumulate in living organisms. Objectives Radioactively labeled nanotubes were synthesized using a novel methane chemical vapor deposition procedure. Single-walled carbon nanotubes (SWNTs), multiwalled carbon nanotubes (MWNTs), and pyrene were spiked to sediment samples, and the respective uptake and depuration of these nanotubes and pyrene were assessed by the oligochaete, Lumbriculus variegatus. Results 14C-labeled carbon nanotubes were developed for these experiments to overcome significant previous limitations for quantifying nanotube materials in environmental and biological media. Biota-sediment accumulation factors for SWNTs and MWNTs were observed to be almost an order of magnitude lower than those for pyrene, a four-ringed polycyclic aromatic hydrocarbon (PAH). The depuration behaviors of the oligochaete suggested that the nanotubes detected in these organisms were associated with sediments remaining in the organism guts and not absorbed into cellular tissues as was the pyrene. The results suggest that, unlike PAHs, purified carbon nanotubes do not readily absorb into organism tissues. PMID:18414633

  6. Carbon Nanotube Synthesis Using Mesoporous Silica Templates

    SciTech Connect

    Zheng, Feng; Liang, Liang; Gao, Yufei; Sukamto, Johanes H.; Aardahl, Chris L.

    2002-07-01

    Well-aligned carbon nanotubes (CNTs) were grown on mesoporous silica films by chemical vapor deposition (CVD). Ethylene was used as the carbon source and CVD was performed at 1023 K and atmospheric pressure. The films were doped with Fe during gelation, and three different structure directing agents were used for mesoporous silica synthesis: polyoxyethylene (10) cetyl ether (C16EO10), Pluronic tri-block copolymer (P123), and cetyltriethylammonium chloride (CTAC). A high degree of CNT alignment on C16EO10-mesoporous silica films was produced at Fe:Si molar ratio of 1.80. Similar alignment of CNTs was achieved on the other two types of films but on CTAC-mesoporous silica films, CNTs only grew parallel to the substrate surface from the cracks in the films because of the in-plane arrangement of the mesopores in such films. Considerable progress has been made in producing multi-walled carbon nanotubes (CNTs) by catalytic CVD techniques. If CNTs are to be integrated into certain useful devices, it is critical to be able to grow highly aligned arrays of CNTs with narrow size distribution and at specific locations on a substrate. Long-range alignment normal to the substrate results from steric crowding if the initial catalyst sites are sufficiently dense. Alignment may be improved with better control of the density of catalytic sites by means of a template of appropriate pore structure. The confinement of CNTs by the pores during the initial growth may also help align CNTs.

  7. Application of Carbon Nanotubes to Nylon Composite

    NASA Astrophysics Data System (ADS)

    Suzuki, Tomoko; Inoue, Sakae; Nojima, Kazuhiro; Tsuchimoto, Akiharu; Chen, Beibei; Kumar, Mukul; Ando, Yoshinori

    2011-01-01

    Carbon nanotubes (CNTs) have many interesting mechanical properties. Therefore, it is expected that an excellent characteristic can be demonstrated by small addition of CNTs in various composite materials. In this study, nylon-6 (N6) was used as the base material and CNTs were mixed to it as a reinforcing agent. Three kinds of CNT were used as filler. Single-wall nanotubes (SWNTs) produced by arc plasma jet (APJ) method, SWNTs produced by ferrum-hydrogen arc (FHA) method, and multiwalled nanotubes (MWNTs) produced by chemical vapor deposition (CVD). Mechanical properties of the composites were measured by tension test, bending test and impact test. In general, when tensile or bending strength goes high, the value of impact energy falls. However, in the case of APJ-SWNT mixing in N6, the impact energy also increases together with the tensile and bending strengths. This study, thus, suggests that APJ-SWNT possesses a characteristic due to which the composite material is strengthened without losing its toughness.

  8. Electronic structures of carbon nanotube peopods

    NASA Astrophysics Data System (ADS)

    Kuk, Young

    2003-03-01

    Carbon nanotubes have been successfully used for nanometer-sized devices such as diodes and transistors. These discrete devices utilize the spatially varying electronic structures of processed nanotubes by creating defect junctions or introducing substitutional or interstitial dopants. It was recently found that adsorption or insertion of molecules inside or outside of a nanotube modifies the electronic structure as observed with a low-temperature scanning tunneling microscope (LTSTM). We report a method to form spatial variation of the electronic structure by inserting various molecules such as fullerenes, metallo-fullerenes, metals or insulators. The results suggest that one can synthesize this band gap-engineered 1-dimensional wire by self-assembly instead of epitaxial growth. We propose a new type of device structure made by this processing technology. 1. J. Lee, H.J. Kim, G. Kim, Y.-W. Son, J. Ihm, S.J. Kahng, H. Kato, Z.W. Wang, T. Okazaki, H. Shinohara, and Y. Kuk, Nature, 415, 1005 (2002)

  9. Single Walled Carbon Nanotube/Silicon Heterojunctions

    NASA Astrophysics Data System (ADS)

    Wu, Zhuangchun

    2005-11-01

    Characterization of the electrical heterojunction between single walled carbon nanotubes (SWNTs) and semiconductors is important for an array of potential applications. Thin, homogeneous, transparent, films of 100% SWNTs exhibiting good electrical conductivity [1] have already been demonstrated as the hole injection electrode in GaN light emitting diodes [2]. The simultaneous transparency and high electrical conductivity of these films makes them similarly promising for the light transmissive electrode in photovoltaic devices. SWNTs have moreover long been proposed as on-chip, device interconnects. To understand the electrical coupling between the nanotubes and semiconductors, likely to have relevance in such devices, we have begun a systematic exploration of the electrical properties of SWNT/silicon hetrojunctions. We will discuss findings as well as a novel test method made possible by the unique morphology of the nanotubes. 1. Z. Wu, Z. Chen, X. Du, J. M. Logan, J. Sippel, M. Nikolou, K. Kamaras, J. R. Reynolds, D. B. Tanner, A. F. Hebard, A. G. Rinzler, Science 305, 1273 (2004) 2. K. Lee, Z. Wu, Z. Chen, F. Ren, S. J. Pearton, A. G. Rinzler, Nano Lett. 4, 911 (2004)

  10. Fibrous composites comprising carbon nanotubes and silica

    DOEpatents

    Peng, Huisheng; Zhu, Yuntian Theodore; Peterson, Dean E.; Jia, Quanxi

    2011-10-11

    Fibrous composite comprising a plurality of carbon nanotubes; and a silica-containing moiety having one of the structures: (SiO).sub.3Si--(CH.sub.2).sub.n--NR.sub.1R.sub.2) or (SiO).sub.3Si--(CH.sub.2).sub.n--NCO; where n is from 1 to 6, and R.sub.1 and R.sub.2 are each independently H, CH.sub.3, or C.sub.2H.sub.5.

  11. Superhydrophobic conductive carbon nanotube coatings for steel.

    PubMed

    Sethi, Sunny; Dhinojwala, Ali

    2009-04-21

    We report the synthesis of superhydrophobic coatings for steel using carbon nanotube (CNT)-mesh structures. The CNT coating maintains its structural integrity and superhydrophobicity even after exposure to extreme thermal stresses and has excellent thermal and electrical properties. The coating can also be reinforced by optimally impregnating the CNT-mesh structure with cross-linked polymers without significantly compromising on superhydrophobicity and electrical conductivity. These superhydrophobic conductive coatings on steel, which is an important structural material, open up possibilities for many new applications in the areas of heat transfer, solar panels, transport of fluids, nonwetting and nonfouling surfaces, temperature resilient coatings, composites, water-walking robots, and naval applications. PMID:19281157

  12. Plasma-Assisted Synthesis of Carbon Nanotubes

    PubMed Central

    2010-01-01

    The application of plasma-enhanced chemical vapour deposition (PECVD) in the production and modification of carbon nanotubes (CNTs) will be reviewed. The challenges of PECVD methods to grow CNTs include low temperature synthesis, ion bombardment effects and directional growth of CNT within the plasma sheath. New strategies have been developed for low temperature synthesis of single-walled CNTs based the understanding of plasma chemistry and modelling. The modification of CNT surface properties and synthesis of CNT hybrid materials are possible with the utilization of plasma. PMID:20802785

  13. Cell mobility after endocytosis of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pirbhai, Massooma; Flores, Thomas; Jedlicka, Sabrina; Rotkin, Slava

    2013-03-01

    Directed cell movement plays a crucial role in cellular behaviors such as neuronal cell division, cell migration, and cell differentiation. There is evidence in preclinical in vivo studies that small fields have successfully been used to enhance regrowth of damages spinal cord axons but with a small success rate. Fortunately, the evolution of functional biomaterials and nanotechnology may provide promising solutions for enhancing the application of electric fields in guiding neuron migration and neurogenesis within the central nervous system. In this work, we studied how endocytosis and subsequent retention of carbon nanotubes affects the mobility of cells under the influence of an electric field, including the directed cell movement.

  14. Carbon Nanotubes Reinforced Composites for Biomedical Applications

    PubMed Central

    Wang, Wei; Zhu, Yuhe; Liao, Susan; Li, Jiajia

    2014-01-01

    This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo. PMID:24707488

  15. Complex Multifunctional Polymer/Carbon-Nanotube Composites

    NASA Technical Reports Server (NTRS)

    Patel, Pritesh; Balasubramaniyam, Gobinath; Chen, Jian

    2009-01-01

    A methodology for developing complex multifunctional materials that consist of or contain polymer/carbon-nanotube composites has been conceived. As used here, "multifunctional" signifies having additional and/or enhanced physical properties that polymers or polymer-matrix composites would not ordinarily be expected to have. Such properties include useful amounts of electrical conductivity, increased thermal conductivity, and/or increased strength. In the present methodology, these properties are imparted to a given composite through the choice and processing of its polymeric and CNT constituents.

  16. Conductivity of carbon nanotube polymer composites

    SciTech Connect

    Wescott, J T; Kung, P; Maiti, A

    2006-11-20

    Dissipative Particle Dynamics (DPD) simulations were used to investigate methods of controlling the assembly of percolating networks of carbon nanotubes (CNTs) in thin films of block copolymer melts. For suitably chosen polymers the CNTs were found to spontaneously self-assemble into topologically interesting patterns. The mesoscale morphology was projected onto a finite-element grid and the electrical conductivity of the films computed. The conductivity displayed non-monotonic behavior as a function of relative polymer fractions in the melt. Results are compared and contrasted with CNT dispersion in small-molecule fluids and mixtures.

  17. Ultrastrong, Stiff and Multifunctional Carbon Nanotube Composites

    SciTech Connect

    Wang, Xin; Yong, Zhenzhong; Li, Qingwen; Bradford, Philip D.; Liu, Wei; Tucker, Dennis S.; Cai, Wei; Wang, Hsin; Yuan, Fuh-Gwo; Zhu, Yuntian

    2012-01-01

    Carbon nanotubes (CNTs) are an order of magnitude stronger than any current engineering fiber. However, for the past two decades it has been a challenge to utilize their reinforcement potential in composites. Here we report CNT composites with unprecedented multifunctionalities, including record high strength (3.8 GPa), Young s modulus (293 GPa), electrical conductivity (1230 S cm-1) and thermal conductivity (41 W m-1 K-1). These superior properties are derived from the long length, high volume fraction, good alignment and reduced waviness of the CNTs, which were produced by a novel processing approach that can be easily scaled up for industrial production.

  18. Mechanical properties of polygonal carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Huang, Ling; Cao, Dapeng

    2012-08-01

    A group of polygonal carbon nanotubes (P-CNTs) have been designed and their mechanical behavior was investigated by classical molecular dynamics simulations. The research aimed at exploring the effects of structure, temperature, and strain rate on the mechanical properties. The results indicate that the Young's modulus of P-CNTs is lower than those of circumcircle carbon nanotubes (C-CNT). Moreover, with an increase in the number of sides to the polygons, the Young's modulus increases and is much closer to that of C-CNT. The effects of temperature and strain rate on the mechanical properties of P-CNTs show that the higher temperature and slower strain rate result in a lower critical strain and weaker tensile strength. In addition, it was found that the critical strains of P-CNTs are dependent on the tube size. Finally, we used the transition-state theory model to predict the critical strain of P-CNTs at given experimental conditions. It is expected that this work could provide feasible means to manipulate the mechanical properties of novel P-CNTs and facilitate the mechanical application of nanostructures as potential electronic devices.A group of polygonal carbon nanotubes (P-CNTs) have been designed and their mechanical behavior was investigated by classical molecular dynamics simulations. The research aimed at exploring the effects of structure, temperature, and strain rate on the mechanical properties. The results indicate that the Young's modulus of P-CNTs is lower than those of circumcircle carbon nanotubes (C-CNT). Moreover, with an increase in the number of sides to the polygons, the Young's modulus increases and is much closer to that of C-CNT. The effects of temperature and strain rate on the mechanical properties of P-CNTs show that the higher temperature and slower strain rate result in a lower critical strain and weaker tensile strength. In addition, it was found that the critical strains of P-CNTs are dependent on the tube size. Finally, we used the

  19. Dispersion of carbon nanotubes in polyurethane matrix

    NASA Astrophysics Data System (ADS)

    Ryszkowska, Joanna; Jurczyk-Kowalska, Magdalena; Szymborski, Tomasz; Kurzydłowski, Krzysztof J.

    2007-07-01

    A high intensity ultrasound has been applied to fabricate polyurethanes/carbon nanotubes (MWCNT) composites. Mixtures of MWCNTs and poly(ethylene adipate) (PEA) were prepared in a two-step process. In the first step, MWCNTs were dispersed with acetone, in the second PEA and acetone. The mixture of PEA and MWCNTs was used to produce polyurethane (PUR) nanocomposites under the agitation of ultrasounds. The effect of ultrasound intensity has been studied by HRSEM and AFM investigation of the microstructure. The mechanical properties of polyurethane nanocomposites were also evaluated.

  20. Carbon Nanotube Integration with a CMOS Process

    PubMed Central

    Perez, Maximiliano S.; Lerner, Betiana; Resasco, Daniel E.; Pareja Obregon, Pablo D.; Julian, Pedro M.; Mandolesi, Pablo S.; Buffa, Fabian A.; Boselli, Alfredo; Lamagna, Alberto

    2010-01-01

    This work shows the integration of a sensor based on carbon nanotubes using CMOS technology. A chip sensor (CS) was designed and manufactured using a 0.30 μm CMOS process, leaving a free window on the passivation layer that allowed the deposition of SWCNTs over the electrodes. We successfully investigated with the CS the effect of humidity and temperature on the electrical transport properties of SWCNTs. The possibility of a large scale integration of SWCNTs with CMOS process opens a new route in the design of more efficient, low cost sensors with high reproducibility in their manufacture. PMID:22319330

  1. Carbon nanotubes: present and future commercial applications.

    PubMed

    De Volder, Michael F L; Tawfick, Sameh H; Baughman, Ray H; Hart, A John

    2013-02-01

    Worldwide commercial interest in carbon nanotubes (CNTs) is reflected in a production capacity that presently exceeds several thousand tons per year. Currently, bulk CNT powders are incorporated in diverse commercial products ranging from rechargeable batteries, automotive parts, and sporting goods to boat hulls and water filters. Advances in CNT synthesis, purification, and chemical modification are enabling integration of CNTs in thin-film electronics and large-area coatings. Although not yet providing compelling mechanical strength or electrical or thermal conductivities for many applications, CNT yarns and sheets already have promising performance for applications including supercapacitors, actuators, and lightweight electromagnetic shields. PMID:23372006

  2. Friction of water slipping in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ma, Ming D.; Shen, Luming; Sheridan, John; Liu, Jefferson Zhe; Chen, Chao; Zheng, Quanshui

    2011-03-01

    Liquid slip is essential in nanofluidic systems, as shrinking channel size leads to a dramatic increase in flow resistance and thus high-energy consumption for driving nonslip flow. Using large-scale nonequilibrium molecular dynamics simulation of water flowing in carbon nanotubes (CNT’s), we show that the relationship between the CNT wall-water interfacial friction stress and slip velocity follows a transition-state-theory-based inverse hyperbolic sine function, which remains universally valid regardless of wetting properties, CNT chiralities, and CNT sizes, and holds for all slip velocities from 0 to 1400 m/s. The finding could benefit the research in desalination and other chemical purification techniques.

  3. Metallic Carbon Nanotubes and Ag Nanocrystals

    SciTech Connect

    Brus, Louis E

    2014-03-04

    The goal of this DOE solar energy research was to understand how visible light interacts with matter, and how to make electric excitations evolve into separated electrons and holes in photovoltaic cells, especially in nanoparticles and nanowires. Our specific experiments focused on A) understanding plasmon enhanced spectroscopy and charge-transfer (metal-to-molecule) photochemistry on the surface of metallic particles and B) the spectroscopy and photochemistry of carbon nanotubes and graphene. I also worked closely with R. Friesner on theoretical studies of photo-excited electrons near surfaces of titanium dioxide nanoparticles; this process is relevant to the Gratzel photovoltaic cell.

  4. Plasma-Assisted Synthesis of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Lim, San Hua; Luo, Zhiqiang; Shen, Zexiang; Lin, Jianyi

    2010-09-01

    The application of plasma-enhanced chemical vapour deposition (PECVD) in the production and modification of carbon nanotubes (CNTs) will be reviewed. The challenges of PECVD methods to grow CNTs include low temperature synthesis, ion bombardment effects and directional growth of CNT within the plasma sheath. New strategies have been developed for low temperature synthesis of single-walled CNTs based the understanding of plasma chemistry and modelling. The modification of CNT surface properties and synthesis of CNT hybrid materials are possible with the utilization of plasma.

  5. Increased Alignment in Carbon Nanotube Growth

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor)

    2007-01-01

    Method and system for fabricating an array of two or more carbon nanotube (CNT) structures on a coated substrate surface, the structures having substantially the same orientation with respect to a substrate surface. A single electrode, having an associated voltage source with a selected voltage, is connected to a substrate surface after the substrate is coated and before growth of the CNT structures, for a selected voltage application time interval. The CNT structures are then grown on a coated substrate surface with the desired orientation. Optionally, the electrode can be disconnected before the CNT structures are grown.

  6. Plasma-Assisted Synthesis of Carbon Nanotubes.

    PubMed

    Lim, San Hua; Luo, Zhiqiang; Shen, Zexiang; Lin, Jianyi

    2010-01-01

    The application of plasma-enhanced chemical vapour deposition (PECVD) in the production and modification of carbon nanotubes (CNTs) will be reviewed. The challenges of PECVD methods to grow CNTs include low temperature synthesis, ion bombardment effects and directional growth of CNT within the plasma sheath. New strategies have been developed for low temperature synthesis of single-walled CNTs based the understanding of plasma chemistry and modelling. The modification of CNT surface properties and synthesis of CNT hybrid materials are possible with the utilization of plasma. PMID:20802785

  7. Growing Aligned Carbon Nanotubes for Interconnections in ICs

    NASA Technical Reports Server (NTRS)

    Li, Jun; Ye, Qi; Cassell, Alan; Ng, Hou Tee; Stevens, Ramsey; Han, Jie; Meyyappan, M.

    2005-01-01

    A process for growing multiwalled carbon nanotubes anchored at specified locations and aligned along specified directions has been invented. Typically, one would grow a number of the nanotubes oriented perpendicularly to a silicon integrated-circuit (IC) substrate, starting from (and anchored on) patterned catalytic spots on the substrate. Such arrays of perpendicular carbon nanotubes could be used as electrical interconnections between levels of multilevel ICs. The process (see Figure 1) begins with the formation of a layer, a few hundred nanometers thick, of a compatible electrically insulating material (e.g., SiO(x) or Si(y)N(z) on the silicon substrate. A patterned film of a suitable electrical conductor (Al, Mo, Cr, Ti, Ta, Pt, Ir, or doped Si), having a thickness between 1 nm and 2 m, is deposited on the insulating layer to form the IC conductor pattern. Next, a catalytic material (usually, Ni, Fe, or Co) is deposited to a thickness between 1 and 30 nm on the spots from which it is desired to grow carbon nanotubes. The carbon nanotubes are grown by plasma-enhanced chemical vapor deposition (PECVD). Unlike the matted and tangled carbon nanotubes grown by thermal CVD, the carbon nanotubes grown by PECVD are perpendicular and freestanding because an electric field perpendicular to the substrate is used in PECVD. Next, the free space between the carbon nanotubes is filled with SiO2 by means of CVD from tetraethylorthosilicate (TEOS), thereby forming an array of carbon nanotubes embedded in SiO2. Chemical mechanical polishing (CMP) is then performed to remove excess SiO2 and form a flat-top surface in which the outer ends of the carbon nanotubes are exposed. Optionally, depending on the application, metal lines to connect selected ends of carbon nanotubes may be deposited on the top surface. The top part of Figure 2 is a scanning electron micrograph (SEM) of carbon nanotubes grown, as described above, on catalytic spots of about 100 nm diameter patterned by

  8. Arrays of Bundles of Carbon Nanotubes as Field Emitters

    NASA Technical Reports Server (NTRS)

    Manohara, Harish; Bronkowski, Michael

    2007-01-01

    Experiments have shown that with suitable choices of critical dimensions, planar arrays of bundles of carbon nanotubes (see figure) can serve as high-current-density field emitter (cold-cathode) electron sources. Whereas some hot-cathode electron sources must be operated at supply potentials of thousands of volts, these cold-cathode sources generate comparable current densities when operated at tens of volts. Consequently, arrays of bundles of carbon nanotubes might prove useful as cold-cathode sources in miniature, lightweight electron-beam devices (e.g., nanoklystrons) soon to be developed. Prior to the experiments, all reported efforts to develop carbon-nanotube-based field-emission sources had yielded low current densities from a few hundred microamperes to a few hundred milliamperes per square centimeter. An electrostatic screening effect, in which taller nanotubes screen the shorter ones from participating in field emission, was conjectured to be what restricts the emission of electrons to such low levels. It was further conjectured that the screening effect could be reduced and thus emission levels increased by increasing the spacing between nanotubes to at least by a factor of one to two times the height of the nanotubes. While this change might increase the emission from individual nanotubes, it would decrease the number of nanotubes per unit area and thereby reduce the total possible emission current. Therefore, to maximize the area-averaged current density, it would be necessary to find an optimum combination of nanotube spacing and nanotube height. The present concept of using an array of bundles of nanotubes arises partly from the concept of optimizing the spacing and height of field emitters. It also arises partly from the idea that single nanotubes may have short lifetimes as field emitters, whereas bundles of nanotubes could afford redundancy so that the loss of a single nanotube would not significantly reduce the overall field emission.

  9. Molecular mechanics methods for individual carbon nanotubes and nanotube assemblies

    NASA Astrophysics Data System (ADS)

    Eberhardt, Oliver; Wallmersperger, Thomas

    2015-04-01

    Since many years, carbon nanotubes (CNTs) have been considered for a wide range of applications due to their outstanding mechanical properties. CNTs are tubular structures, showing a graphene like hexagonal lattice. Our interest in the calculation of the mechanical properties is motivated by several applications which demand the knowledge of the material behavior. One application in which the knowledge of the material behavior is vital is the CNT based fiber. Due to the excellent stiffness and strength of the individual CNTs, these fibers are expected to be a promising successor for state of the art carbon fibers. However, the mechanical properties of the fibers fall back behind the properties of individual CNTs. It is assumed that this gap in the properties is a result of the van-der-Waals interactions of the individual CNTs within the fiber. In order to understand the mechanical behavior of the fibers we apply a molecular mechanics approach. The mechanical properties of the individual CNTs are investigated by using a modified structural molecular mechanics approach. This is done by calculating the properties of a truss-beam element framework representing the CNT with the help of a chemical force field. Furthermore, we also investigate the interactions of CNTs arranged in basic CNT assemblies, mimicking the ones in a simple CNT fiber. We consider the van-der-Waals interactions in the structure and calculate the potential surface of the CNT assemblies.

  10. Ubiquity of Exciton Localization in Cryogenic Carbon Nanotubes.

    PubMed

    Hofmann, Matthias S; Noé, Jonathan; Kneer, Alexander; Crochet, Jared J; Högele, Alexander

    2016-05-11

    We present photoluminescence studies of individual semiconducting single-wall carbon nanotubes at room and cryogenic temperatures. From the analysis of spatial and spectral features of nanotube photoluminescence, we identify characteristic signatures of unintentional exciton localization. Moreover, we quantify the energy scale of exciton localization potentials as ranging from a few to a few tens of millielectronvolts and stemming from both environmental disorder and shallow covalent side-wall defects. Our results establish disorder-induced crossover from the diffusive to the localized regime of nanotube excitons at cryogenic temperatures as a ubiquitous phenomenon in micelle-encapsulated and as-grown carbon nanotubes. PMID:27105355

  11. Computational Nanotechnology of Materials, Devices, and Machines: Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Kwak, Dolhan (Technical Monitor)

    2000-01-01

    The mechanics and chemistry of carbon nanotubes have relevance for their numerous electronic applications. Mechanical deformations such as bending and twisting affect the nanotube's conductive properties, and at the same time they possess high strength and elasticity. Two principal techniques were utilized including the analysis of large scale classical molecular dynamics on a shared memory architecture machine and a quantum molecular dynamics methodology. In carbon based electronics, nanotubes are used as molecular wires with topological defects which are mediated through various means. Nanotubes can be connected to form junctions.

  12. Polyglycerol-derived amphiphiles for single walled carbon nanotube suspension

    NASA Astrophysics Data System (ADS)

    Setaro, A.; Popeney, C. S.; Trappmann, B.; Datsyuk, V.; Haag, R.; Reich, S.

    2010-06-01

    Inspired by the commercially available SDS surfactant, a new polyglycerol-derived amphiphile has been synthesized for functionalizing carbon nanotubes. SDS' sulphate group was replaced by a polyglycerol dendron. The steric hindrance offered by the dendrons makes the compound much more efficient than SDS in isolating and stabilizing nanotubes in solution. Further amphiphiles have been synthesized by adding small aromatic moieties between head and tail groups. We show that this addition leads to selective interaction between surfactants and carbon nanotubes. Excitation photoluminescence and optical absorption spectroscopy analysis confirm the change in the distribution of nanotubes' chiralities in suspension, depending on the amphiphile.

  13. Low-Temperature Plasma Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Khare, Bishun; Meyyappan, M.

    2004-01-01

    A low-temperature plasma process has been devised for attaching specified molecular groups to carbon nanotubes in order to impart desired chemical and/or physical properties to the nanotubes for specific applications. Unlike carbon-nanotube- functionalization processes reported heretofore, this process does not involve the use of wet chemicals, does not involve exposure of the nanotubes to high temperatures, and generates very little chemical residue. In addition, this process can be carried out in a relatively simple apparatus and can readily be scaled up to mass production.

  14. Carbon nanotube oscillator surface profiling device and method of use

    DOEpatents

    Popescu, Adrian; Woods, Lilia M.; Bondarev, Igor V.

    2011-11-15

    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.

  15. Fatigue characteristics of carbon nanotube blocks under compression

    NASA Astrophysics Data System (ADS)

    Suhr, J.; Ci, L.; Victor, P.; Ajayan, P. M.

    2008-03-01

    In this paper we investigate the mechanical response from repeated high compressive strains on freestanding, long, vertically aligned multiwalled carbon nanotube membranes and show that the arrays of nanotubes under compression behave very similar to soft tissue and exhibit viscoelastic behavior. Under compressive cyclic loading, the mechanical response of nanotube blocks shows initial preconditioning and hysteresis characteristic of viscoeleastic materials. Furthermore, no fatigue failure is observed even at high strain amplitudes up to half million cycles. The outstanding fatigue life and extraordinary soft tissue-like mechanical behavior suggest that properly engineered carbon nanotube structures could mimic artificial muscles.

  16. Ubiquity of Exciton Localization in Cryogenic Carbon Nanotubes

    PubMed Central

    2016-01-01

    We present photoluminescence studies of individual semiconducting single-wall carbon nanotubes at room and cryogenic temperatures. From the analysis of spatial and spectral features of nanotube photoluminescence, we identify characteristic signatures of unintentional exciton localization. Moreover, we quantify the energy scale of exciton localization potentials as ranging from a few to a few tens of millielectronvolts and stemming from both environmental disorder and shallow covalent side-wall defects. Our results establish disorder-induced crossover from the diffusive to the localized regime of nanotube excitons at cryogenic temperatures as a ubiquitous phenomenon in micelle-encapsulated and as-grown carbon nanotubes. PMID:27105355

  17. Noncatalytic synthesis of carbon nanotubes by chemical vapor deposition

    SciTech Connect

    Ismagilov, R. R. Shvets, P. V.; Kharin, A. Yu.; Obraztsov, A. N.

    2011-03-15

    A new method is proposed to obtain uniform arrays of multiwall carbon nanotubes without catalysts. Nanotubes have been formed by carbon condensation from a hydrogen-methane gas mixture activated by a dc discharge. Structural and morphological investigations of the obtained material were performed by Raman spectroscopy, scanning and transmission electron microscopy, energy-dispersive X-ray analysis, and electron energy loss spectroscopy. It is shown that the obtained nanotubes contain no impurities that could act as catalysts. Based on these experimental data, it is concluded that the nanotube synthesis under study is noncatalytic. Possible mechanisms of this synthesis are considered.

  18. Covalent Crosslinking of Carbon Nanotube Materials for Improved Tensile Strength

    NASA Technical Reports Server (NTRS)

    Baker, James S.; Miller, Sandi G.; Williams, Tiffany A.; Meador, Michael A.

    2013-01-01

    Carbon nanotubes have attracted much interest in recent years due to their exceptional mechanical properties. Currently, the tensile properties of bulk carbon nanotube-based materials (yarns, sheets, etc.) fall far short of those of the individual nanotube elements. The premature failure in these materials under tensile load has been attributed to inter-tube sliding, which requires far less force than that needed to fracture individual nanotubes.1,2 In order for nanotube materials to achieve their full potential, methods are needed to restrict this tube-tube shear and increase inter-tube forces.Our group is examining covalent crosslinking between the nanotubes as a means to increase the tensile properties of carbon nanotube materials. We are working with multi-walled carbon nanotube (MWCNT) sheet and yarn materials obtained from commercial sources. Several routes to functionalize the nanotubes have been examined including nitrene, aryl diazonium, and epoxide chemistries. The functional nanotubes were crosslinked through small molecule or polymeric bridges. Additionally, electron beam irradiation induced crosslinking of the non-functional and functional nanotube materials was conducted. For example, a nanotube sheet material containing approximately 3.5 mol amine functional groups exhibited a tensile strength of 75 MPa and a tensile modulus of 1.16 GPa, compared to 49 MPa and 0.57 GPa, respectively, for the as-received material. Electron beam irradiation (2.2x 1017 ecm2) of the same amine-functional sheet material further increased the tensile strength to 120 MPa and the modulus to 2.61 GPa. This represents approximately a 150 increase in tensile strength and a 360 increase in tensile modulus over the as-received material with only a 25 increase in material mass. Once we have optimized the nanotube crosslinking methods, the performance of these materials in polymer matrix composites will be evaluated.

  19. Progress toward Making Epoxy/Carbon-Nanotube Composites

    NASA Technical Reports Server (NTRS)

    Tiano, Thomas; Roylance, Margaret; Gassner, John; Kyle, William

    2008-01-01

    A modicum of progress has been made in an effort to exploit single-walled carbon nanotubes as fibers in epoxy-matrix/fiber composite materials. Two main obstacles to such use of carbon nanotubes are the following: (1) bare nanotubes are not soluble in epoxy resins and so they tend to agglomerate instead of becoming dispersed as desired; and (2) because of lack of affinity between nanotubes and epoxy matrices, there is insufficient transfer of mechanical loads between the nanotubes and the matrices. Part of the effort reported here was oriented toward (1) functionalization of single-walled carbon nanotubes with methyl methacrylate (MMA) to increase their dispersability in epoxy resins and increase transfer of mechanical loads and (2) ultrasonic dispersion of the functionalized nanotubes in tetrahydrofuran, which was used as an auxiliary solvent to aid in dispersing the functionalized nanotubes into a epoxy resin. In another part of this effort, poly(styrene sulfonic acid) was used as the dispersant and water as the auxiliary solvent. In one experiment, the strength of composite of epoxy with MMA-functionalized-nanotubes was found to be 29 percent greater than that of a similar composite of epoxy with the same proportion of untreated nanotubes.

  20. A Carbon Nanotube Cable for a Space Elevator

    NASA Astrophysics Data System (ADS)

    Bochníček, Zdeněk

    2013-11-01

    In this paper the mechanical properties of carbon nanotubes are discussed in connection with the possibility to use them for the construction of a space elevator. From the fundamental information about the structure of a carbon nanotube and the chemical bond between carbon atoms, Young's modulus and the ultimate tensile strength are estimated. For this calculation only simple high school physics is necessary. The results, the same as known from experimental data, show that carbon nanotubes could be, at least hypothetically, a possible material for construction of a space elevator cable.

  1. Carbon Nanotubes Hybrid Hydrogels in Drug Delivery: A Perspective Review

    PubMed Central

    Hampel, Silke; Spizzirri, Umile Gianfranco; Parisi, Ortensia Ilaria; Picci, Nevio; Iemma, Francesca

    2014-01-01

    The use of biologics, polymers, silicon materials, carbon materials, and metals has been proposed for the preparation of innovative drug delivery devices. One of the most promising materials in this field are the carbon-nanotubes composites and hybrid materials coupling the advantages of polymers (biocompatibility and biodegradability) with those of carbon nanotubes (cellular uptake, stability, electromagnatic, and magnetic behavior). The applicability of polymer-carbon nanotubes composites in drug delivery, with particular attention to the controlled release by composites hydrogel, is being extensively investigated in the present review. PMID:24587993

  2. Carbon nanotube-based organic light emitting diodes

    NASA Astrophysics Data System (ADS)

    Bansal, Malti; Srivastava, Ritu; Lal, C.; Kamalasanan, M. N.; Tanwar, L. S.

    2009-11-01

    Carbon nanotubes; revolutionary and fascinating from the materials point of view and exceedingly sensational from a research point of view; are standing today at the threshold between inorganic electronics and organic electronics and posing a serious challenge to the big daddies of these two domains in electronics i.e., silicon and indium tin oxide (ITO). In the field of inorganic electronics, carbon nanotubes offer advantages such as high current carrying capacity, ballistic transport, absence of dangling bonds, etc. and on the other hand, in the field of organic electronics, carbon nanotubes offer advantages such as high conductivity, high carrier mobility, optical transparency (in visible and IR spectral ranges), flexibility, robustness, environmental resistance, etc. and hence, they are seriously being considered as contenders to silicon and ITO. This review traces the origin of carbon nanotubes in the field of organic electronics (with emphasis on organic light emitting diodes) and moves on to cover the latest advances in the field of carbon nanotube-based organic light emitting diodes. Topics that are covered within include applications of multi-wall nanotubes and single-wall nanotubes in organic light emitting diodes. Applications of carbon nanotubes as hole-transport layers, as electron-transport layers, as transparent electrodes, etc. in organic light emitting diodes are discussed and the daunting challenges facing this progressive field today are brought into the limelight.

  3. Carbon nanotube/carbon nanotube composite AFM probes prepared using ion flux molding

    NASA Astrophysics Data System (ADS)

    Chesmore, Grace; Roque, Carrollyn; Barber, Richard

    The performance of carbon nanotube-carbon nanotube composite (CNT/CNT composite) atomic force microscopy (AFM) probes is compared to that of conventional Si probes in AFM tapping mode. The ion flux molding (IFM) process, aiming an ion beam at the CNT probe, aligns the tip to a desired angle. The result is a relatively rigid tip that is oriented to offset the cantilever angle. Scans using these probes reveal an improvement in image accuracy over conventional tips, while allowing higher aspect ratio imaging of 3D surface features. Furthermore, the lifetimes of CNT-CNT composite tips are observed to be longer than both conventional tips and those claimed for other CNT technologies. Novel applications include the imaging of embiid silk. Supported by the Clare Boothe Luce Research Scholars Award and Carbon Design Innovations.

  4. Thermionic Emission of Single-Wall Carbon Nanotubes Measured

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Krainsky, Isay L.; Bailey, Sheila G.; Elich, Jeffrey M.; Landi, Brian J.; Gennett, Thomas; Raffaelle, Ryne P.

    2004-01-01

    Researchers at the NASA Glenn Research Center, in collaboration with the Rochester Institute of Technology, have investigated the thermionic properties of high-purity, single-wall carbon nanotubes (SWNTs) for use as electron-emitting electrodes. Carbon nanotubes are a recently discovered material made from carbon atoms bonded into nanometer-scale hollow tubes. Such nanotubes have remarkable properties. An extremely high aspect ratio, as well as unique mechanical and electronic properties, make single-wall nanotubes ideal for use in a vast array of applications. Carbon nanotubes typically have diameters on the order of 1 to 2 nm. As a result, the ends have a small radius of curvature. It is these characteristics, therefore, that indicate they might be excellent potential candidates for both thermionic and field emission.

  5. Charge-induced strains in single-walled carbon nanotubes.

    PubMed

    Li, Chun-Yu; Chou, Tsu-Wei

    2006-09-28

    This paper investigates the electromechanical coupling in single-walled carbon nanotubes. In the model system, the extra electric charge of the nanotube is assumed to be uniformly distributed on carbon atoms. The electrostatic interactions between charged carbon atoms are calculated using the Coulomb law. The deformation of the charged nanotube is obtained by using the molecular structural mechanics method and considering the electrostatic interactions as an external loading acting on carbon atoms. The axial strain is found to be a symmetric function of applied charge, and our predictions are in very good agreement with those from ab initio calculations. The present results indicate that the nanotube aspect ratio has a strong effect on the axial strain when the ratio is less than 10 and the general trend is that the strain increases with the aspect ratio. The peak axial and radial strains occur at nanotube diameters of around 1.2-1.5 nm. PMID:21727586

  6. Oxidation of Carbon Nanotubes in an Ionizing Environment.

    PubMed

    Koh, Ai Leen; Gidcumb, Emily; Zhou, Otto; Sinclair, Robert

    2016-02-10

    In this work, we present systematic studies on how an illuminating electron beam which ionizes molecular gas species can influence the mechanism of carbon nanotube oxidation in an environmental transmission electron microscope (ETEM). We found that preferential attack of the nanotube tips is much more prevalent than for oxidation in a molecular gas environment. We establish the cumulative electron doses required to damage carbon nanotubes from 80 keV electron beam irradiation in gas versus in high vacuum. Our results provide guidelines for the electron doses required to study carbon nanotubes within or without a gas environment, to determine or ameliorate the influence of the imaging electron beam. This work has important implications for in situ studies as well as for the oxidation of carbon nanotubes in an ionizing environment such as that occurring during field emission. PMID:26726919

  7. Double-walled carbon nanotube processing.

    PubMed

    Moore, Katherine E; Tune, Daniel D; Flavel, Benjamin S

    2015-05-27

    Single-walled carbon nanotubes (SWCNTs) have been the focus of intense research, and the body of literature continues to grow exponentially, despite more than two decades having passed since the first reports. As well as extensive studies of the fundamental properties, this has seen SWCNTs used in a plethora of applications as far ranging as microelectronics, energy storage, solar cells, and sensors, to cancer treatment, drug delivery, and neuronal interfaces. On the other hand, the properties and applications of double-walled carbon nanotubes (DWCNTs) have remained relatively under-explored. This is despite DWCNTs not only sharing many of the same unique characteristics of their single-walled counterparts, but also possessing an additional suite of potentially advantageous properties arising due to the presence of the second wall and the often complex inter-wall interactions that arise. For example, it is envisaged that the outer wall can be selectively functionalized whilst still leaving the inner wall in its pristine state and available for signal transduction. A similar situation arises in DWCNT field effect transistors (FETs), where the outer wall can provide a convenient degree of chemical shielding of the inner wall from the external environment, allowing the excellent transconductance properties of the pristine nanotubes to be more fully exploited. Additionally, DWCNTs should also offer unique opportunities to further the fundamental understanding of the inter-wall interactions within and between carbon nanotubes. However, the realization of these goals has so far been limited by the same challenge experienced by the SWCNT field until recent years, namely, the inherent heterogeneity of raw, as-produced DWCNT material. As such, there is now an emerging field of research regarding DWCNT processing that focuses on the preparation of material of defined length, diameter and electronic type, and which is rapidly building upon the experience gained by the broader

  8. Making Macroscopic Assemblies of Aligned Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Smalley, Richard E.; Colbert, Daniel T.; Smith, Ken A.; Walters, Deron A.; Casavant, Michael J.; Qin, Xiaochuan; Yakobson, Boris; Hauge, Robert H.; Saini, Rajesh Kumar; Chiung, Wan-Ting; Huffman, Charles B.

    2005-01-01

    A method of aligning and assembling single-wall carbon nanotubes (SWNTs) to fabricate macroscopic structures has been invented. The method entails suspending SWNTs in a fluid, orienting the SWNTs by use of a magnetic and/or electric field, and then removing the aligned SWNTs from suspension in such a way as to assemble them while maintaining the alignment. SWNTs are essentially tubular extensions of fullerene molecules. It is desirable to assemble aligned SWNTs into macroscopic structures because the common alignment of the SWNTs in such a structure makes it possible to exploit, on a macroscopic scale, the unique mechanical, chemical, and electrical properties that individual oriented SWNTs exhibit at the molecular level. Because of their small size and high electrical conductivity, carbon nanotubes, and especially SWNTs, are useful for making electrical connectors in integrated circuits. Carbon nanotubes can be used as antennas at optical frequencies, and as probes in scanning tunneling microscopes, atomic-force microscopes, and the like. Carbon nanotubes can be used with or instead of carbon black in tires. Carbon nanotubes are useful as supports for catalysts. Ropes of SWNTs are metallic and, as such, are potentially useful in some applications in which electrical conductors are needed - for example, they could be used as additives in formulating electrically conductive paints. Finally, macroscopic assemblies of aligned SWNTs can serve as templates for the growth of more and larger structures of the same type. The great variety of tubular fullerene molecules and of the structures that could be formed by assembling them in various ways precludes a complete description of the present method within the limits of this article. It must suffice to present a typical example of the use of one of many possible variants of the method to form a membrane comprising SWNTs aligned substantially parallel to each other in the membrane plane. The apparatus used in this variant

  9. Nanotube

    Energy Science and Technology Software Center (ESTSC)

    2007-09-13

    This is a source code to calculate the current-voltage characteristics, the charge distribution and the electrostatic potential in carbon nanotube devices. The code utilizes the non-equilibrium Green's function method, implemented in a tight-binding scheme, to calculate the charge distribution and the energy-dependent transmission function, from which the current or the conductance are obtained. The electrostatic potential is obtained by solving Poisson's equation on a grid with boundary conditions on the electrodes, and at other interfaces.more » Self-consistency between the charge and the electrostatic potential is achieved using a linear mixing method. Different versions of the code allow the modeling of different types of nanotube devices: Version 1.0: Modeling of carbon nanotube electronic devices with cylindrical symmetry Version 1.1: Modeling of planar carbon nanotube electronic devices Version 1.2: Modeling of photocurrent in carbon nanotube devices« less

  10. Channeling of protons in radially compressed carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Karabarbounis, A.; Sarros, S.; Trikalinos, Ch

    2014-05-01

    Channeling of 10 MeV protons in radially compressed chiral carbon nanotubes is considered. Monte Carlo simulation program is used for the calculation of the trajectories, energy losses and angular distributions of protons in nanotubes of various lengths, where the potential in Doyle-Turner approximation is used to describe the interaction between a proton and a nanotube. Calculations were carried out for different incident angles between proton beam and the nanotube axis. The results show that a decreased angular distribution of the beam is observed, compared with propagation through a straight nanotube, in case when it enters from the compressed end of the nanotube. The energy and spatial distribution of channeled protons in compressed nanotubes is examined.

  11. Carbon nanotubes enhanced the lead toxicity on the freshwater fish

    NASA Astrophysics Data System (ADS)

    Martinez, D. S. T.; Alves, O. L.; Barbieri, E.

    2013-04-01

    Carbon nanotubes are promising nanostructures for many applications in materials industry and biotechnology. However, it is mandatory to evaluate their toxicity and environmental implications. We evaluated nitric acid treated multiwalled carbon nanotubes (HNO3-MWCNT) toxicity in Nile tilapia (Oreochromis niloticus) and also the lead (Pb) toxicity modulation after the nanotube interaction. Industrial grade multiwalled carbon nanotubes [Ctube 100, CNT Co. Ltd] were treated with 9M HNO3 for 12h at 150°C to generate oxygenated groups on the nanotube surface, to improve water dispersion and heavy metal interaction. The HNO3-treated multiwalled carbon nanotubes were physico-chemically characterized by several techniques [e.g. TEM, FE-SEM, TGA, ζ-potential and Raman spectroscopy]. HNO3-MWCNT did not show toxicity on Nile tilapia when the concentration ranged from 0.1 to 3.0 mg/L, and the maximum exposure time was 96h. After 24, 48, 72 and 96h the LC50 values of Pb were 1.65, 1.32, 1.10 and 0.99 mg/L, respectively. To evaluate the Pb-nanotube interaction influence on the ecotoxicity, we submitted the Nile tilapia to different concentrations of Pb mixed with a non-toxic concentration of HNO3-MWCNT (1.0 mg/L). After 24, 48, 72, 96 h the LC50 values of Pb plus nanotubes were: 0.32, 0.25, 0.20, 0.18 mg/L, respectively. These values showed a synergistic effect after Pb-nanotube interaction since Pb toxicity increased over five times. X-ray energy dispersive spectroscopy (EDS) was used to confirm lead adsorption on the carbon nanotube oxidized surface. The exposure of Nile tilapia to Pb plus HNO3-MWCNT caused both oxygen consumption and ammonium excretion decrease, when compared to the control. Finally, our results show that carbon nanotubes interact with classical pollutants drawing attention to the environmental implications.

  12. Adsorption of selected volatile organic vapors on multiwall carbon nanotubes.

    PubMed

    Shih, Yang-hsin; Li, Mei-syue

    2008-06-15

    Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. This study examines the adsorption behaviors of volatile organic compounds (VOCs), n-hexane, benzene, trichloroethylene and acetone on two multiwall carbon nanotubes (MWCNTs), CNT1 and CNT2. Among these VOCs, acetone exhibits the highest adsorption capacity. The highest adsorption enthalpies and desorption energies of acetone were also observed. The strong chemical interactions between acetone and both MWCNTs may be the result from chemisorption on the topological defects. The adsorption heats of trichloroethylene, benzene, and n-hexane are indicative of physisorption on the surfaces of both MWCNTs. CNT2 presents a higher adsorption capacity than CNT1 due to the existence of an exterior amorphous carbon layer on CNT2. The amorphous carbon enhances the adsorption capacity of organic chemicals on carbon nanotubes. The morphological and structure order of carbon nanotubes are the primary affects on the adsorption process of organic chemicals. PMID:17980962

  13. Photoexcitation dynamics of coupled semiconducting carbon nanotube thin films.

    PubMed

    Mehlenbacher, Randy D; Wu, Meng-Yin; Grechko, Maksim; Laaser, Jennifer E; Arnold, Michael S; Zanni, Martin T

    2013-04-10

    Carbon nanotubes are a promising means of capturing photons for use in solar cell devices. We time-resolved the photoexcitation dynamics of coupled, bandgap-selected, semiconducting carbon nanotubes in thin films tailored for photovoltaics. Using transient absorption spectroscopy and anisotropy measurements, we found that the photoexcitation evolves by two mechanisms with a fast and long-range component followed by a slow and short-range component. Within 300 fs of optical excitation, 20% of nanotubes transfer their photoexcitation over 5-10 nm into nearby nanotube fibers. After 3 ps, 70% of the photoexcitation resides on the smallest bandgap nanotubes. After this ultrafast process, the photoexcitation continues to transfer on a ~10 ps time scale but to predominantly aligned tubes. Ultimately the photoexcitation hops twice on average between fibers. These results are important for understanding the flow of energy and charge in coupled nanotube materials and light-harvesting devices. PMID:23464618

  14. Fermentation based carbon nanotube multifunctional bionic composites

    PubMed Central

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

    2016-01-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal. PMID:27279425

  15. Trion electroluminescence from semiconducting carbon nanotubes.

    PubMed

    Jakubka, Florian; Grimm, Stefan B; Zakharko, Yuriy; Gannott, Florentina; Zaumseil, Jana

    2014-08-26

    Near-infrared emission from semiconducting single-walled carbon nanotubes (SWNTs) usually results from radiative relaxation of excitons. By binding an additional electron or hole through chemical or electrochemical doping, charged three-body excitons, so-called trions, are created that emit light at lower energies. The energy difference is large enough to observe weak trion photoluminescence from doped SWNTs even at room temperature. Here, we demonstrate strong trion electroluminescence from electrolyte-gated, light-emitting SWNT transistors with three different polymer-sorted carbon nanotube species, namely, (6,5), (7,5) and (10,5). The red-shifted trion emission is equal to or even stronger than the exciton emission, which is attributed to the high charge carrier density in the transistor channel. The possibility of trions as a radiative relaxation pathway for triplets and dark excitons that are formed in large numbers by electron-hole recombination is discussed. The ratio of trion to exciton emission can be tuned by the applied voltages, enabling voltage-controlled near-infrared light sources with narrow line widths that are solution-processable and operate at low voltages (<3 V). PMID:25029479

  16. Elemental superdoping of graphene and carbon nanotubes.

    PubMed

    Liu, Yuan; Shen, Yuting; Sun, Litao; Li, Jincheng; Liu, Chang; Ren, Wencai; Li, Feng; Gao, Libo; Chen, Jie; Liu, Fuchi; Sun, Yuanyuan; Tang, Nujiang; Cheng, Hui-Ming; Du, Youwei

    2016-01-01

    Doping of low-dimensional graphitic materials, including graphene, graphene quantum dots and single-wall carbon nanotubes with nitrogen, sulfur or boron can significantly change their properties. We report that simple fluorination followed by annealing in a dopant source can superdope low-dimensional graphitic materials with a high level of N, S or B. The superdoping results in the following doping levels: (i) for graphene, 29.82, 17.55 and 10.79 at% for N-, S- and B-doping, respectively; (ii) for graphene quantum dots, 36.38 at% for N-doping; and (iii) for single-wall carbon nanotubes, 7.79 and 10.66 at% for N- and S-doping, respectively. As an example, the N-superdoping of graphene can greatly increase the capacitive energy storage, increase the efficiency of the oxygen reduction reaction and induce ferromagnetism. Furthermore, by changing the degree of fluorination, the doping level can be tuned over a wide range, which is important for optimizing the performance of doped low-dimensional graphitic materials. PMID:26941178

  17. Exciton Dynamics in Semiconducting Carbon Nanotubes

    SciTech Connect

    Graham, Matt; Chmeliov, Javgenij; Ma, Yingzhong; Shinohara, Nori; Green, Alexander A.; Hersam, Mark C.; Valkunas, Leonas; Fleming, Graham

    2010-01-01

    We report femtosecond transient absorption spectroscopic study on the (6, 5) single-walled carbon nanotubes and the (7, 5) inner tubes of a dominant double-walled carbon nanotube species. We found that the dynamics of exciton relaxation probed at the first transition-allowed state (E11) of a given tube type exhibits a markedly slower decay when the second transition-allowed state (E22) is excited than that measured by exciting its first transition-allowed state (E11). A linear intensity dependence of the maximal amplitude of the transient absorption signal is found for the E22 excitation, whereas the corresponding amplitude scales linearly with the square root of the E11 excitation intensity. Theoretical modeling of these experimental findings was performed by developing a continuum model and a stochastic model with explicit consideration of the annihilation of coherent excitons. Our detailed numerical simulations show that both models can reproduce reasonably well the initial portion of decay kinetics measured upon the E22 and E11 excitation of the chosen tube species, but the stochastic model gives qualitatively better agreement with the intensity dependence observed experimentally than those obtained with the continuum model.

  18. Elemental superdoping of graphene and carbon nanotubes

    PubMed Central

    Liu, Yuan; Shen, Yuting; Sun, Litao; Li, Jincheng; Liu, Chang; Ren, Wencai; Li, Feng; Gao, Libo; Chen, Jie; Liu, Fuchi; Sun, Yuanyuan; Tang, Nujiang; Cheng, Hui-Ming; Du, Youwei

    2016-01-01

    Doping of low-dimensional graphitic materials, including graphene, graphene quantum dots and single-wall carbon nanotubes with nitrogen, sulfur or boron can significantly change their properties. We report that simple fluorination followed by annealing in a dopant source can superdope low-dimensional graphitic materials with a high level of N, S or B. The superdoping results in the following doping levels: (i) for graphene, 29.82, 17.55 and 10.79 at% for N-, S- and B-doping, respectively; (ii) for graphene quantum dots, 36.38 at% for N-doping; and (iii) for single-wall carbon nanotubes, 7.79 and 10.66 at% for N- and S-doping, respectively. As an example, the N-superdoping of graphene can greatly increase the capacitive energy storage, increase the efficiency of the oxygen reduction reaction and induce ferromagnetism. Furthermore, by changing the degree of fluorination, the doping level can be tuned over a wide range, which is important for optimizing the performance of doped low-dimensional graphitic materials. PMID:26941178

  19. Design and Characterization of Carbon Nanotube Nanocomposites

    NASA Technical Reports Server (NTRS)

    Siochi, Emilie J.; Lillehei, Peter T.; Wise, Kristopher E.; Park, Cheol; Rouse, Jason H.

    2003-01-01

    Revolutionary design concepts in future aerospace vehicles will depend on extraordinary material properties to permit significant reduction of mass and size of components, while imparting intelligence. Due to their combination of remarkable electrical and mechanical properties, carbon nanotubes (CNT) are expected to enable this paradigm shift in design concepts. However, significant challenges still exist in translating these CNT properties into the macrostructures required for future generations of aerospace vehicles. While an accepted route for making the leap from nanostructures to useful macrostructures has not been fully charted, this paper will give an overview of the approach taken by some researchers at NASA Langley Research Center to sort out issues involved in the development of CNT nanocomposites for multifunctional structures. Specifically, the dispersion of carbon nanotubes in polymer matrices, characterization of nanocomposites, the role of quantum computation in providing guidance for processing and the use of computational analysis in data interpretation will be covered. Significant improvements in mechanical and electrical properties of CNT nanocomposites with very low loadings of CNTs are described and lend credence to the potential for using CNTs in achieving technological leaps in composite development.

  20. Carbon Nanotube Thin-Film Antennas.

    PubMed

    Puchades, Ivan; Rossi, Jamie E; Cress, Cory D; Naglich, Eric; Landi, Brian J

    2016-08-17

    Multiwalled carbon nanotube (MWCNT) and single-walled carbon nanotube (SWCNT) dipole antennas have been successfully designed, fabricated, and tested. Antennas of varying lengths were fabricated using flexible bulk MWCNT sheet material and evaluated to confirm the validity of a full-wave antenna design equation. The ∼20× improvement in electrical conductivity provided by chemically doped SWCNT thin films over MWCNT sheets presents an opportunity for the fabrication of thin-film antennas, leading to potentially simplified system integration and optical transparency. The resonance characteristics of a fabricated chlorosulfonic acid-doped SWCNT thin-film antenna demonstrate the feasibility of the technology and indicate that when the sheet resistance of the thin film is >40 ohm/sq no power is absorbed by the antenna and that a sheet resistance of <10 ohm/sq is needed to achieve a 10 dB return loss in the unbalanced antenna. The dependence of the return loss performance on the SWCNT sheet resistance is consistent with unbalanced metal, metal oxide, and other CNT-based thin-film antennas, and it provides a framework for which other thin-film antennas can be designed. PMID:27454334

  1. A cell nanoinjector based on carbon nanotubes

    SciTech Connect

    Chen, Xing; Kis, Andras; Zettl, Alex; Bertozzi, Carolyn R.

    2007-01-30

    Technologies for introducing molecules into living cells are vital for probing the physical properties and biochemical interactions that govern the cell's behavior. Here we report the development of a nanoscale cell injection system-termed the nanoinjector-that uses carbon nanotubes to deliver cargo into cells. A single multi-walled carbon nanotube attached to an atomic force microscope tip was functionalized with cargo via a disulfide-based linker. Penetration of cell membranes with this 'nanoneedle', followed by reductive cleavage of the disulfide bonds within the cell's interior, resulted in the release of cargo inside the cells. The capability of the nanoinjector was demonstrated by injection of protein-coated quantum dots into live human cells. Single-particle tracking was employed to characterize the diffusion dynamics of injected quantum dots in the cytosol. This new technique causes no discernible membrane or cell damage, and can deliver a discrete number of molecules to the cell's interior without the requirement of a carrier solvent.

  2. X-ray generation using carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Parmee, Richard J.; Collins, Clare M.; Milne, William I.; Cole, Matthew T.

    2015-01-01

    Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have remained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication, remain central to almost all X-ray applications, there have been few fundamental technological advances. However, with the emergence of ever more demanding medical and inspection techniques, including computed tomography and tomosynthesis, security inspection, high throughput manufacturing and radiotherapy, has resulted in a considerable level of interest in the development of new fabrication methods. The use of conventional thermionic sources is limited by their slow temporal response and large physical size. In response, field electron emission has emerged as a promising alternative means of deriving a highly controllable electron beam of a well-defined distribution. When coupled to the burgeoning field of nanomaterials, and in particular, carbon nanotubes, such systems present a unique technological opportunity. This review provides a summary of the current state-of-the-art in carbon nanotube-based field emission X-ray sources. We detail the various fabrication techniques and functional advantages associated with their use, including the ability to produce ever smaller electron beam assembles, shaped cathodes, enhanced temporal stability and emergent fast-switching pulsed sources. We conclude with an overview of some of the commercial progress made towards the realisation of an innovative and disruptive technology.

  3. Carbon nanotube and graphene for photonic applications

    NASA Astrophysics Data System (ADS)

    Yamashita, Shinji; Martinez, Amos; Xu, Bo

    2013-09-01

    We review the optical properties of carbon nanotubes (CNTs) and graphene and discuss how those properties can be used in photonic applications. In particular, we will give an overview of the benefits of using their highly nonlinear optical response in fiber lasers and other nonlinear fiber optic devices. Both graphene and CNTs exhibit high third order susceptibility and a broadband saturable absorption with sub-picosecond response. We will discuss the advantages and limitations of using the saturable absorption of carbon nanotubes and graphene for the passive mode-locking of fiber lasers, introduce the different methods that we have developed to integrate these materials in the fiber system and summarize the main contributions of these materials towards advancing fiber laser technology. In addition, these materials also exhibit an extremely high third order susceptibility which is responsible for nonlinear processes such as four wave mixing (FWM), Kerr focusing and third harmonic generation (THG) of great interest for optical switching and wavelength conversion. The large absorption of CNTs and graphene however limits the dimensions of these devices and, thus, their applicability. We review our efforts towards enhancing and exploiting the nonlinearity of CNT and graphene fiber optics devices.

  4. Multiwalled carbon nanotube film for strain sensing

    NASA Astrophysics Data System (ADS)

    Li, X.; Levy, C.; Elaadil, L.

    2008-01-01

    We have studied the possibility of using multiwalled carbon nanotube (MWCNT) films as strain sensors. The MWCNT films were prepared by a solution/filtration method and were bonded directly onto specimens by a nonconductive adhesive. For comparison, conventional foil strain gages were also bonded to the structure on the opposite side. The specimens then underwent a uniaxial tensile load-unload cycle to evaluate them as strain sensors. To ensure good electrical contact between carbon nanotube film and the wires, a thin layer of copper was thermally deposited on both ends of the film as electrodes, and the wires were connected to the electrodes by silver ink. Wheatstone bridges were used to convert the resistance changes of the MWCNTs to voltage output. Results indicated that the output voltages were proportional to the strain readings from the stain indicator. The effect of temperature on the resistance was measured and the MWCNT film resistance was found to be independent of temperature over the range 273-363 K. The optimal film dimension for strain sensing was evaluated as well. Dynamic tests suggest that the MWCNTs were able to extract the structural signature. Our results indicate that MWCNT film is potentially useful for structural health monitoring and vibration control applications.

  5. Protein stability at a carbon nanotube interface

    NASA Astrophysics Data System (ADS)

    Vaitheeswaran, S.; Garcia, A. E.

    2011-03-01

    The interactions of proteins with solid surfaces occur in a variety of situations. Motivated by the many nanoengineering applications of protein-carbon nanotube hybrids, we investigate the conformational transitions of hen egg white lysozyme adsorbed on a carbon nanotube. Using a Cα structure-based model and replica exchange molecular dynamics, we show how the folding/unfolding equilibrium of the adsorbed protein varies with the strength of its coupling to the surface. The stability of the native state depends on the balance between the favorable entropy and unfavorable enthalpy change on adsorption. In the case of a weakly attractive surface when the former dominates, the protein is stabilized. In this regime, the protein can fold and unfold while maintaining the same binding fraction. With increasing surface attraction, the unfavorable enthalpic effect dominates, the native state is destabilized, and the protein has to extensively unbind before changing states from unfolded to folded. At the highest surface coupling, the entropic penalty of folding vanishes, and a folding intermediate is strongly stabilized. In this intermediate state, the α-domain of lysozyme is disrupted, while the β-sheet remains fully structured. We rationalize the relative stability of the two domains on the basis of the residue contact order.

  6. Fermentation based carbon nanotube multifunctional bionic composites.

    PubMed

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M

    2016-01-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal. PMID:27279425

  7. Fermentation based carbon nanotube multifunctional bionic composites

    NASA Astrophysics Data System (ADS)

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

    2016-06-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal.

  8. Multiwalled Carbon nanotube - Strength to polymer composite

    NASA Astrophysics Data System (ADS)

    Pravin, Jagdale; Khan, Aamer. A.; Massimo, Rovere; Carlo, Rosso; Alberto, Tagliaferro

    2016-02-01

    Carbon nanotubes (CNTs), a rather fascinating material, are among the pillars of nanotechnology. CNTs exhibit unique electrical, mechanical, adsorption, and thermal properties with high aspect ratio, exceptional stiffness, excellent strength, and low density, which can be exploited in the manufacturing of revolutionary smart nano composite materials. The demand for lighter and stronger polymer composite material in various applications is increasing every day. Among all the possibilities to research and exploit the exceptional properties of CNTs in polymer composites we focused on the reinforcement of epoxy resin with different types of multiwalled carbon nano tubes (MWCNTs). We studied mechanical properties such as stress, strain, ultimate tensile strength, yield point, modulus and fracture toughness, and Young's modulus by plotting and calculating by means of the off-set method. The mechanical strength of epoxy composite is increased intensely with 1 and 3 wt.% of filler.

  9. Carbon Nanotube-Graphene Nanoscroll Hybrid Structures

    NASA Astrophysics Data System (ADS)

    Martynov, Oleg; Yeom, Sinchul; Bockrath, Marc

    2015-03-01

    Graphene nanoscrolls (GNS) are a spiral one-dimensional tubular form of graphitic carbon. Recently a number of methods have been devised to produce GNS; however, they suffer from low yield and poor controllability. Consequently, GNS provide a relatively unexplored system with some theoretically promising and unique properties. We will discuss our progress towards GNS synthesis using a wet process modeled after Xie et al, producing a GNS from single or multilayer graphene on an Si/SiO2 substrate. We propose a novel method to produce a nested multiwalled carbon nanotube (MWCNT)-nanoscroll structure using aligned MWCNT transfer onto exfoliated graphene. Latest progress and measurements on these MWCNT-nanoscroll hybrids will be presented.

  10. Advanced physical chemistry of carbon nanotubes.

    PubMed

    Li, Jun; Pandey, Gaind P

    2015-04-01

    The past decade has seen a surge of exciting research and applications of carbon nanotubes (CNTs) stimulated by deeper understanding of their fundamental properties and increasing production capability. The intrinsic properties of various CNTs were found to strongly depend on their internal microstructures. This review summarizes the fundamental structure-property relations of seamless tube-like single- and multiwalled CNTs and conically stacked carbon nanofibers, as well as the organized architectures of these CNTs (including randomly stacked thin films, parallel aligned thin films, and vertically aligned arrays). It highlights the recent development of CNTs as key components in selected applications, including nanoelectronics, filtration membranes, transparent conductive electrodes, fuel cells, electrical energy storage devices, and solar cells. Particular emphasis is placed on the link between the basic physical chemical properties of CNTs and the organized CNT architectures with their functions and performance in each application. PMID:25580625

  11. Advanced Physical Chemistry of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Jun; Pandey, Gaind P.

    2015-04-01

    The past decade has seen a surge of exciting research and applications of carbon nanotubes (CNTs) stimulated by deeper understanding of their fundamental properties and increasing production capability. The intrinsic properties of various CNTs were found to strongly depend on their internal microstructures. This review summarizes the fundamental structure-property relations of seamless tube-like single- and multiwalled CNTs and conically stacked carbon nanofibers, as well as the organized architectures of these CNTs (including randomly stacked thin films, parallel aligned thin films, and vertically aligned arrays). It highlights the recent development of CNTs as key components in selected applications, including nanoelectronics, filtration membranes, transparent conductive electrodes, fuel cells, electrical energy storage devices, and solar cells. Particular emphasis is placed on the link between the basic physical chemical properties of CNTs and the organized CNT architectures with their functions and performance in each application.

  12. Carbon Nanotube Microarrays Grown on Nanoflake Substrates

    NASA Technical Reports Server (NTRS)

    Schmidt, Howard K.; Hauge, Robert H.; Pint, Cary; Pheasant, Sean

    2013-01-01

    This innovation consists of a new composition of matter where single-walled carbon nanotubes (SWNTs) are grown in aligned arrays from nanostructured flakes that are coated in Fe catalyst. This method of growth of aligned SWNTs, which can yield well over 400 percent SWNT mass per unit substrate mass, exceeds current yields for entangled SWNT growth. In addition, processing can be performed with minimal wet etching treatments, leaving aligned SWNTs with superior properties over those that exist in entangled mats. The alignment of the nanotubes is similar to that achieved in vertically aligned nanotubes, which are called "carpets. " Because these flakes are grown in a state where they are airborne in a reactor, these flakes, after growing SWNTs, are termed "flying carpets. " These flakes are created in a roll-to-roll evaporator system, where three subsequent evaporations are performed on a 100-ft (approx. =30-m) roll of Mylar. The first layer is composed of a water-soluble "release layer, " which can be a material such as NaCl. After depositing NaCl, the second layer involves 40 nm of supporting layer material . either Al2O3 or MgO. The thickness of the layer can be tuned to synthesize flakes that are larger or smaller than those obtained with a 40-nm deposition. Finally, the third layer consists of a thin Fe catalyst layer with a thickness of 0.5 nm. The thickness of this layer ultimately determines the diameter of SWNT growth, and a layer that is too thick will result in the growth of multiwalled carbon nanotubes instead of single-wall nanotubes. However, between a thickness of 0.5 nm to 1 nm, single-walled carbon nanotubes are known to be the primary constituent. After this three-layer deposition process, the Mylar is rolled through a bath of water, which allows catalyst-coated flakes to detach from the Mylar. The flakes are then collected and dried. The method described here for making such flakes is analogous to that which is used to make birefringent ink that is

  13. Ultrasonic Spraying of Carbon Nanotubes using Organic Solvents

    NASA Astrophysics Data System (ADS)

    Willey, Anthony; Davis, Robert; Vanfleet, Richard

    2012-10-01

    Because of their unique electrical and mechanical properties, thin films of carbon nanotubes have several potential applications, especially in the fields of organic electronics and photovoltaics. We present a method for spraying thin films of nanotubes that have been suspended in organic solvents N-methyl Pyrollidone (NMP) and N-Cyclohexyl-2-pyrrolidone (CHP). The sprayed nanotubes are randomly oriented, and films are transparent, conductive, and mechanically stable.

  14. Dynamic terahertz polarization in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Xu, X. L.; Parkinson, P.; Chuang, K.-C.; Johnston, M. B.; Nicholas, R. J.; Herz, L. M.

    2010-08-01

    We have investigated the anisotropic dynamic dielectric response of aligned and well-isolated single-walled carbon nanotubes using optical-pump terahertz (THz)-probe techniques. The polarization anisotropy measurements demonstrate that the THz radiation interacts only with radiation polarized parallel to the nanotubes which have been selectively excited by a polarized pump pulse thus allowing controlled THz polarization to be achieved from unaligned nanotubes.

  15. Carbon nanotubes on carbon fibers: Synthesis, structures and properties

    NASA Astrophysics Data System (ADS)

    Zhang, Qiuhong

    The interface between carbon fibers (CFs) and the resin matrix in traditional high performance composites is characterized by a large discontinuity in mechanical, electrical, and thermal properties which can cause inefficient energy transfer. Due to the exceptional properties of carbon nanotubes (CNTs), their growth at the surface of carbon fibers is a promising approach to controlling interfacial interactions and achieving the enhanced bulk properties. However, the reactive conditions used to grow carbon nanotubes also have the potential to introduce defects that can degrade the mechanical properties of the carbon fiber (CF) substrate. In this study, using thermal chemical vapor deposition (CVD) method, high density multi-wall carbon nanotubes have been successfully synthesized directly on PAN-based CF surface without significantly compromising tensile properties. The influence of CVD growth conditions on the single CF tensile properties and carbon nanotube (CNT) morphology was investigated. The experimental results revealed that under high temperature growth conditions, the tensile strength of CF was greatly decreased at the beginning of CNT growth process with the largest decrease observed for sized CFs. However, the tensile strength of unsized CFs with CNT was approximately the same as the initial CF at lower growth temperature. The interfacial shear strength of CNT coated CF (CNT/CF) in epoxy was studied by means of the single-fiber fragmentation test. Results of the test indicate an improvement in interfacial shear strength with the addition of a CNT coating. This improvement can most likely be attributed to an increase in the interphase yield strength as well as an improvement in interfacial adhesion due to the presence of the nanotubes. CNT/CF also offers promise as stress and strain sensors in CF reinforced composite materials. This study investigates fundamental mechanical and electrical properties of CNT/CF using nanoindentation method by designed

  16. Carbon nanotube-based electrochemical biosensing platforms: fundamentals, applications, and future possibilities.

    PubMed

    Luong, John H T; Male, Keith B; Hrapovic, Sabahudin

    2007-01-01

    Biosensors can be considered as a most plausible and exciting application area for nanobiotechnology. The recent bloom of nanofabrication technology and biofunctionalization methods of carbon nanotubes (CNTs) has stimulated significant research interest to develop CNT-based biosensors for monitoring biorecognition events and biocatalytic processes. The unique properties of CNTs, rolled-up sheets of carbon atoms with a diameter less than 1 nm, offer excellent prospects for interfacing biological recognition events with electronic signal transduction. CNT-based biosensors could be developed to sense only a few or even a single molecule of a chemical or biological agent. Both hydrogen peroxide and NADH, two by-products of over 300 oxidoreductases, are efficiently oxidized by CNT-modified electrodes at significantly lower potentials with minimal surface fouling. This appealing feature enables the development of useful biosensors for diversified applications. Aligned CNT "forests" can act as molecular wires to allow efficient electron transfer between the detecting electrode and the redox centers of enzymes to fabricate reagentless biosensors. Electrochemical sensing for DNA can greatly benefit from the use of CNT based platforms since guanine, one of the four bases, can be detected with significantly enhanced sensitivity. CNTs fluoresce, or emit light after absorbing light, in the near infrared region and retain their ability to fluoresce over time. This feature will allow CNT-based sensors to transmit information from inside the body. The combination of micro/nanofabrication and chemical functionalization, particularly nanoelectrode assembly interfaced with biomolecules, is expected to pave the way to fabricate improved biosensors for proteins, chemicals, and pathogens. However, several technical challenges need to be overcome to tightly integrate CNT-based platforms with sampling, fluidic handling, separation, and other detection principles. The biosensing platform

  17. Local gate control in carbon nanotube quantum devices

    NASA Astrophysics Data System (ADS)

    Biercuk, Michael Jordan

    This thesis presents transport measurements of carbon nanotube electronic devices operated in the quantum regime. Nanotubes are contacted by source and drain electrodes, and multiple lithographically-patterned electrostatic gates are aligned to each device. Transport measurements of device conductance or current as a function of local gate voltages reveal that local gates couple primarily to the proximal section of the nanotube, hence providing spatially localized control over carrier density along the nanotube length. Further, using several different techniques we are able to produce local depletion regions along the length of a tube. This phenomenon is explored in detail for different contact metals to the nanotube. We utilize local gating techniques to study multiple quantum dots in carbon nanotubes produced both by naturally occurring defects, and by the controlled application of voltages to depletion gates. We study double quantum dots in detail, where transport measurements reveal honeycomb charge stability diagrams. We extract values of energy-level spacings, capacitances, and interaction energies for this system, and demonstrate independent control over all relevant tunneling rates. We report rf-reflectometry measurements of gate-defined carbon nanotube quantum dots with integrated charge sensors. Aluminum rf-SETs are electrostatically coupled to carbon nanotube devices and detect single electron charging phenomena in the Coulomb blockade regime. Simultaneous correlated measurements of single electron charging are made using reflected rf power from the nanotube itself and from the rf-SET on microsecond time scales. We map charge stability diagrams for the nanotube quantum dot via charge sensing, observing Coulomb charging diamonds beyond the first order. Conductance measurements of carbon nanotubes containing gated local depletion regions exhibit plateaus as a function of gate voltage, spaced by approximately 1e2/h, the quantum of conductance for a single

  18. Rotational actuator of motor based on carbon nanotubes

    DOEpatents

    Zettl, Alexander K.; Fennimore, Adam M.; Yuzvinsky, Thomas D.

    2008-11-18

    A rotational actuator/motor based on rotation of a carbon nanotube is disclosed. The carbon nanotube is provided with a rotor plate attached to an outer wall, which moves relative to an inner wall of the nanotube. After deposit of a nanotube on a silicon chip substrate, the entire structure may be fabricated by lithography using selected techniques adapted from silicon manufacturing technology. The structures to be fabricated may comprise a multiwall carbon nanotube (MWNT), two in plane stators S1, S2 and a gate stator S3 buried beneath the substrate surface. The MWNT is suspended between two anchor pads and comprises a rotator attached to an outer wall and arranged to move in response to electromagnetic inputs. The substrate is etched away to allow the rotor to freely rotate. Rotation may be either in a reciprocal or fully rotatable manner.

  19. Rotational actuator or motor based on carbon nanotubes

    DOEpatents

    Zetti, Alexander K.; Fennimore, Adam M.; Yuzvinsky, Thomas D.

    2006-05-30

    A rotational actuator/motor based on rotation of a carbon nanotube is disclosed. The carbon nanotube is provided with a rotor plate attached to an outer wall, which moves relative to an inner wall of the nanotube. After deposit of a nanotube on a silicon chip substrate, the entire structure may be fabricated by lithography using selected techniques adapted from silicon manufacturing technology. The structures to be fabricated may comprise a multiwall carbon nanotube (MWNT), two in plane stators S1, S2 and a gate stator S3 buried beneath the substrate surface. The MWNT is suspended between two anchor pads and comprises a rotator attached to an outer wall and arranged to move in response to electromagnetic inputs. The substrate is etched away to allow the rotor to freely rotate. Rotation may be either in a reciprocal or fully rotatable manner.

  20. Structural and surface features of multiwall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Hembram, K. P. S. S.; Rao, G. Mohan

    2011-04-01

    We present the direct evidence of defective and disorder places on the surface of multiwall carbon nanotube (MWCNT), visualizing the presence of amorphous carbon at those sites. These defective surfaces being higher in energy are the key features of functionalization with different materials. The interaction of the π orbital electrons of different carbon atoms of adjacent layers is more at the bent portion, than that of regular portion of the CNT. Hence the tubular structure of the bent portion of nanotubes is spaced more than that of regular portion of the nanotubes, minimizing the stress.

  1. Applications of Carbon Nanotubes in Biotechnology and Biomedicine.

    PubMed

    Bekyarova, Elena; Ni, Yingchun; Malarkey, Erik B; Montana, Vedrana; McWilliams, Jared L; Haddon, Robert C; Parpura, Vladimir

    2005-03-01

    Due to their electrical, chemical, mechanical and thermal properties, carbon nanotubes are one of the most promising materials for the electronics, computer and aerospace industries. Here, we discuss their properties in the context of future applications in biotechnology and biomedicine. The purification and chemical modification of carbon nanotubes with organic, polymeric and biological molecules are discussed. Additionally we review their uses in biosensors, assembly of structures and devices, scanning probe microscopy and as substrates for neuronal growth. We note that additional toxicity studies of carbon nanotubes are necessary so that exposure guidelines and safety regulations can be established in a timely manner. PMID:19763242

  2. Applications of Carbon Nanotubes in Biotechnology and Biomedicine

    PubMed Central

    Bekyarova, Elena; Ni, Yingchun; Malarkey, Erik B.; Montana, Vedrana; McWilliams, Jared L.; Haddon, Robert C.; Parpura, Vladimir

    2009-01-01

    Due to their electrical, chemical, mechanical and thermal properties, carbon nanotubes are one of the most promising materials for the electronics, computer and aerospace industries. Here, we discuss their properties in the context of future applications in biotechnology and biomedicine. The purification and chemical modification of carbon nanotubes with organic, polymeric and biological molecules are discussed. Additionally we review their uses in biosensors, assembly of structures and devices, scanning probe microscopy and as substrates for neuronal growth. We note that additional toxicity studies of carbon nanotubes are necessary so that exposure guidelines and safety regulations can be established in a timely manner. PMID:19763242

  3. Theoretical Modeling of Mechanical-Electrical Coupling of Carbon Nanotubes

    SciTech Connect

    Lu, Jun-Qiang; Jiang, Hanqiang

    2008-01-01

    Carbon nanotubes have been studied extensively due to their unique properties, ranging from electrical, mechanical, optical, to thermal properties. The coupling between the electrical and mechanical properties of carbon nanotubes has emerged as a new field, which raises both interesting fundamental problems and huge application potentials. In this article, we will review our recently work on the theoretical modeling on mechanical-electrical coupling of carbon nanotubes subject to various loading conditions, including tension/compression, torsion, and squashing. Some related work by other groups will be also mentioned.

  4. Enhanced Hole Extraction in Perovskite Solar Cells Through Carbon Nanotubes.

    PubMed

    Habisreutinger, Severin N; Leijtens, Tomas; Eperon, Giles E; Stranks, Samuel D; Nicholas, Robin J; Snaith, Henry J

    2014-12-01

    Here, we report the use of polymer-wrapped carbon nanotubes as a means to enhance charge extraction through undoped spiro-OMeTAD. With this approach a good solar cell performance is achieved without the implementation of conventional doping methods. We demonstrate that a stratified two-layer architecture of sequentially deposited layers of carbon nanotubes and spiro-OMeTAD, outperforms a conventional blend of the hole-conductor and the carbon nanotubes. We also provide insights into the mechanism of the rapid hole extraction observed in the two-layer approach. PMID:26278955

  5. Pressure sensitive multifunctional solar cells using carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Somani, Prakash R.

    2010-04-01

    A unique multifunctional device combining the photovoltaic action and pressure sensitivity is demonstrated which is based on the heterojunction of n-Si and carbon nanotubes (double walled carbon nanotubes or multiwalled carbon nanotubes) and using copper phthalocyanine surface modified indium-tin-oxide electrode and shows pressure dependent photovoltaic action. The device can work as a solar cell, pressure sensor, or photovoltaic pressure sensor. Such multifunctional organic/organic-inorganic hybrid solar cells are expected to find many applications in the near future.

  6. Highly effective metal vapor absorbents based on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Liu, Zongwen; Gao, Yihua; Bando, Yoshio

    2002-12-01

    It was shown that, when filled with gallium, carbon nanotubes can absorb copper vapor with extraordinarily high efficiency. The copper vapor generated from the supporting copper grid upon heating to 800 °C in an electron microscope under a pressure of 1.0×10-5 Pa quickly deposited into the carbon nanotubes and formed an alloy with gallium where the vapor pressure is up to 500 times higher (5×10-3 Pa). These filled carbon nanotubes may be used as highly sensitive toxic or radioactive metal vapor absorbents since gallium also tends to form alloys with metals like mercury and uranium.

  7. Optimizing the thermoelectric performance of zigzag and chiral carbon nanotubes

    PubMed Central

    2012-01-01

    Using nonequilibrium molecular dynamics simulations and nonequilibrium Green's function method, we investigate the thermoelectric properties of a series of zigzag and chiral carbon nanotubes which exhibit interesting diameter and chirality dependence. Our calculated results indicate that these carbon nanotubes could have higher ZT values at appropriate carrier concentration and operating temperature. Moreover, their thermoelectric performance can be significantly enhanced via isotope substitution, isoelectronic impurities, and hydrogen adsorption. It is thus reasonable to expect that carbon nanotubes may be promising candidates for high-performance thermoelectric materials. PMID:22325623

  8. Tensile Yielding of Multi-Wall Carbon Nanotube

    NASA Technical Reports Server (NTRS)

    Wei, Chenyu; Cho, Kyeongjae; Srivastava, Deepak; Parks, John W. (Technical Monitor)

    2002-01-01

    The tensile yielding of multiwall carbon nanotubes (MWCNTs) has been studied using Molecular Dynamics simulations and a Transition State Theory based model. We find a strong dependence of the yielding on the strain rate. A critical strain rate has been predicted above/below which yielding strain of a MWCNT is larger/smaller than that of the corresponding single-wall carbon nanotubes. At experimentally feasible strain rate of 1% /hour and T = 300K, the yield strain of a MWCNT is estimated to be about 3-4 % higher than that of an equivalent SWCNT (Single Wall Carbon Nanotube), in good agreement with recent experimental observations.

  9. Force-strain relation of bundles of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Xiao, Tan; Ren, Yu; Wu, Ping; Liao, Kin

    2006-07-01

    The force-strain relation and tensile strength of carbon nanotube bundles are studied based on the assumption that the tensile strength of individual carbon nanotubes (CNTs) obeys the Weibull distribution, with nonlinear stress-strain behavior. The Weibull modulus of the CNT that characterizes the dispersion of tensile strength can be estimated in terms of the maximum sustained force and the failure strain of the bundle. Bundles of single-walled carbon nanotubes (SWNTs) were subjected to tensile testing using a nanomechanical testing device. Results show that the nonlinear behavior of SWNTs does affect the force-strain relation of SWNT bundles, more apparent at large strain.

  10. Interaction of microwaves with carbon nanotubes to facilitate modification

    NASA Technical Reports Server (NTRS)

    Tour, James M. (Inventor); Dyke, Christopher A. (Inventor); Stephenson, Jason J. (Inventor); Yakobson, Boris I. (Inventor)

    2011-01-01

    The present invention is directed toward methods of crosslinking carbon nanotubes to each other using microwave radiation, articles of manufacture produced by such methods, compositions produced by such methods, and applications for such compositions and articles of manufacture. The present invention is also directed toward methods of radiatively modifying composites and/or blends comprising carbon nanotubes with microwaves, and to the compositions produced by such methods. In some embodiments, the modification comprises a crosslinking process, wherein the carbon nanotubes serve as a conduit for thermally and photolytically crosslinking the host matrix with microwave radiation.

  11. Synthesis of carbon nanotubes with and without catalyst particles

    PubMed Central

    2011-01-01

    The initial development of carbon nanotube synthesis revolved heavily around the use of 3d valence transition metals such as Fe, Ni, and Co. More recently, noble metals (e.g. Au) and poor metals (e.g. In, Pb) have been shown to also yield carbon nanotubes. In addition, various ceramics and semiconductors can serve as catalytic particles suitable for tube formation and in some cases hybrid metal/metal oxide systems are possible. All-carbon systems for carbon nanotube growth without any catalytic particles have also been demonstrated. These different growth systems are briefly examined in this article and serve to highlight the breadth of avenues available for carbon nanotube synthesis. PMID:21711812

  12. Carbon Nanotube Materials for Substrate Enhanced Control of Catalytic Activity

    SciTech Connect

    Heben, M.; Dillon, A. C.; Engtrakul, C.; Lee, S.-H.; Kelley, R. D.; Kini, A. M.

    2007-05-01

    Carbon SWNTs are attractive materials for supporting electrocatalysts. The properties of SWNTs are highly tunable and controlled by the nanotube's circumferential periodicity and their surface chemistry. These unique characteristics suggest that architectures constructed from these types of carbon support materials would exhibit interesting and useful properties. Here, we expect that the structure of the carbon nanotube support will play a major role in stabilizing metal electrocatalysts under extreme operating conditions and suppress both catalyst and support degradation. Furthermore, the chemical modification of the carbon nanotube surfaces can be expected to alter the interface between the catalyst and support, thus, enhancing the activity and utilization of the electrocatalysts. We plan to incorporate discrete reaction sites into the carbon nanotube lattice to create intimate electrical contacts with the catalyst particles to increase the metal catalyst activity and utilization. The work involves materials synthesis, design of electrode architectures on the nanoscale, control of the electronic, ionic, and mass fluxes, and use of advanced optical spectroscopy techniques.

  13. Diamond-Coated Carbon Nanotubes for Efficient Field Emission

    NASA Technical Reports Server (NTRS)

    Dimitrijevic, Stevan; Withers, James C.

    2005-01-01

    Field-emission cathodes containing arrays of carbon nanotubes coated with diamond or diamondlike carbon (DLC) are undergoing development. Multiwalled carbon nanotubes have been shown to perform well as electron field emitters. The idea underlying the present development is that by coating carbon nanotubes with wideband- gap materials like diamond or DLC, one could reduce effective work functions, thereby reducing threshold electric-field levels for field emission of electrons and, hence, improving cathode performance. To demonstrate feasibility, experimental cathodes were fabricated by (1) covering metal bases with carbon nanotubes bound to the bases by an electrically conductive binder and (2) coating the nanotubes, variously, with diamond or DLC by plasma-assisted chemical vapor deposition. In tests, the threshold electric-field levels for emission of electrons were reduced by as much as 40 percent, relative to those of uncoated- nanotube cathodes. Coating with diamond or DLC could also make field emission-cathodes operate more stably by helping to prevent evaporation of carbon from nanotubes in the event of overheating of the cathodes. Cathodes of this type are expected to be useful principally as electron sources for cathode-ray tubes and flat-panel displays.

  14. Multiporous carbon allotropes transformed from symmetry-matched carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cai, Yingxiang; Wang, Hao; Xu, Shengliang; Hu, Yujie; Liu, Ning; Xu, Xuechun

    2016-06-01

    Carbon nanotubes (CNTs) with homogeneous diameters have been proven to transform into new carbon allotropes under pressure but no studies on the compression of inhomogeneous CNTs have been reported. In this study, we propose to build new carbon allotropes from the bottom-up by applying pressure on symmetry-matched inhomogeneous CNTs. We find that the (3,0) CNT with point group C3v and the (6,0) CNT with point group C6v form an all sp3 hybridized hexagonal 3060-Carbon crystal, but the (4,0) CNT with point group D4h and the (8,0) CNT with point group D8h polymerize into a sp2+sp3 hybridized tetragonal 4080-Carbon structure. Their thermodynamic, mechanical and dynamic stabilities show that they are potential carbon allotropes to be experimentally synthesized. The multiporous structures, excellently mechanical properties and special electronic structures (semiconductive 3060-Carbon and semimetallic 4080-Carbon) imply their many potential applications, such as gases purification, hydrogen storage and lightweight semiconductor devices. In addition, we simulate their feature XRD patterns which are helpful for identifying the two carbon crystals in future experimental studies.

  15. A Computational Experiment on Single-Walled Carbon Nanotubes

    ERIC Educational Resources Information Center

    Simpson, Scott; Lonie, David C.; Chen, Jiechen; Zurek, Eva

    2013-01-01

    A computational experiment that investigates single-walled carbon nanotubes (SWNTs) has been developed and employed in an upper-level undergraduate physical chemistry laboratory course. Computations were carried out to determine the electronic structure, radial breathing modes, and the influence of the nanotube's diameter on the…

  16. Gas Composition Sensing Using Carbon Nanotube Arrays

    NASA Technical Reports Server (NTRS)

    Li, Jing; Meyyappan, Meyya

    2012-01-01

    This innovation is a lightweight, small sensor for inert gases that consumes a relatively small amount of power and provides measurements that are as accurate as conventional approaches. The sensing approach is based on generating an electrical discharge and measuring the specific gas breakdown voltage associated with each gas present in a sample. An array of carbon nanotubes (CNTs) in a substrate is connected to a variable-pulse voltage source. The CNT tips are spaced appropriately from the second electrode maintained at a constant voltage. A sequence of voltage pulses is applied and a pulse discharge breakdown threshold voltage is estimated for one or more gas components, from an analysis of the current-voltage characteristics. Each estimated pulse discharge breakdown threshold voltage is compared with known threshold voltages for candidate gas components to estimate whether at least one candidate gas component is present in the gas. The procedure can be repeated at higher pulse voltages to estimate a pulse discharge breakdown threshold voltage for a second component present in the gas. The CNTs in the gas sensor have a sharp (low radius of curvature) tip; they are preferably multi-wall carbon nanotubes (MWCNTs) or carbon nanofibers (CNFs), to generate high-strength electrical fields adjacent to the tips for breakdown of the gas components with lower voltage application and generation of high current. The sensor system can provide a high-sensitivity, low-power-consumption tool that is very specific for identification of one or more gas components. The sensor can be multiplexed to measure current from multiple CNT arrays for simultaneous detection of several gas components.

  17. Carbon Nanotube Assemblies for Transparent Conducting Electrodes

    SciTech Connect

    Garrett, Matthew P; Gerhardt, Rosario

    2012-01-01

    . We will review recent literature on TCCs composed of carbon nanotubes of different types in terms of the FOM.

  18. Directed Growth of Carbon Nanotubes Across Gaps

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance; Meyyapan, Meyya

    2008-01-01

    An experiment has shown that when single-walled carbon nanotubes (SWNTs) are grown by chemical vapor deposition in the presence of an electric field of suitable strength, the nanotubes become aligned along the electric field. In an important class of contemplated applications, one would exploit this finding in fabricating nanotube transistors; one would grow SWNTs across gaps between electrodes that would serve, subsequently, as source and drain contacts during operation of the transistors. In preparation for the experiment, a multilayer catalyst comprising a 20-nmthick underlayer of iridium (platinum group), a 1-nm-thick middle layer of iron, and a 0.2-nm-thick outer layer of molybdenum was ion-beam sputtered onto a quartz substrate. A 25 micrometers-diameter iron wire was used as a shadow mask during the sputtering to create a 25 micrometers gap in the catalyst. Then electrical leads were connected to the catalyst areas separated by the gap so that these catalyst areas would also serve as electrodes. The substrate as thus prepared was placed in a growth chamber that consisted of a quartz tube of 1-in. (2.54-cm) diameter enclosed in a furnace. SWNTs of acceptably high quantity and quality were grown in 10 minutes with methane at atmospheric pressure flowing through the chamber at a rate of 1,000 standard cubic centimeters per minute at a temperature of 900 C. To prevent oxidation of the SWNTs, the chamber was purged with 99.999-percent pure argon before and after growth, and the chamber was cooled to less than 300 C before opening it to the atmosphere after growth. When no voltage was applied across the gap, the SWNTs grew in random directions extending out from the edges of the catalyst at the gap. When a potential of 10 V was applied between the catalyst/electrode areas to create an electric field across the gap, the SWNTs grew across the gap, as shown in the figure.

  19. Carbon Nanotubes: Printed Carbon Nanotube Electronics and Sensor Systems (Adv. Mater. 22/2016).

    PubMed

    Chen, Kevin; Gao, Wei; Emaminejad, Sam; Kiriya, Daisuke; Ota, Hiroki; Nyein, Hnin Yin Yin; Takei, Kuniharu; Javey, Ali

    2016-06-01

    Printed electronics and sensors enable new applications ranging from low-cost disposable analytical devices to large-area sensor networks. Recent progress in printed carbon nanotube electronics in terms of materials, processing, devices, and applications is discussed on page 4397 by A. Javey and co-workers. The research challenges and opportunities regarding the processing and system-level integration are also discussed for enabling of practical applications. PMID:27273439

  20. Synthesis, assembly, and applications of single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Ryu, Koungmin

    This dissertation presents the synthesis and assembly of aligned carbon nanotubes, and their applications in both nano-electronics such as transistor and integrated circuits and macro-electronics in energy conversion devices as transparent conducting electrodes. Also, the high performance chemical sensor using metal oxide nanowire has been demonstrated. Chapter 1 presents a brief introduction of carbon nanotube, followed by discussion of a new synthesis technique using nanosphere lithography to grow highly aligned single-walled carbon nanotubes atop quartz and sapphire substrates. This method offers great potential to produce carbon nanotube arrays with simultaneous control over the nanotube orientation, position, density, diameter and even chirality. Chapter 3 introduces the wafer-scale integration and assembly of aligned carbon nanotubes, including full-wafer scale synthesis and transfer of massively aligned carbon nanotube arrays, and nanotube device fabrication on 4 inch Si/SiO2 wafer to yield submicron channel transistors with high on-current density ˜ 20 muA/mum and good on/off ratio and CMOS integrated circuits. In addition, various chemical doping methods for n-type nanotube transistors are studied to fabricate CMOS integrated nanotube circuits such as inverter, NAND and NOR logic devices. Furthermore, defect-tolerant circuit design for NAND and NOR is proposed and demonstrated to guarantee the correct operation of logic circuit, regardless of the presence of mis-aligned or mis-positioned nanotubes. Carbon nanotube flexible electronics and smart textiles for ubiquitous computing and sensing are demonstrated in chapter 4. A facile transfer printing technique has been introduced to transfer massively aligned single-walled carbon nanotubes from the original sapphire/quartz substrates to virtually any other substrates, including glass, silicon, polymer sheets, and even fabrics. The characterization of transferred nanotubes reveals that the transferred

  1. Fracture of Carbon Nanotube - Amorphous Carbon Composites: Molecular Modeling

    NASA Technical Reports Server (NTRS)

    Jensen, Benjamin D.; Wise, Kristopher E.; Odegard, Gregory M.

    2015-01-01

    Carbon nanotubes (CNTs) are promising candidates for use as reinforcements in next generation structural composite materials because of their extremely high specific stiffness and strength. They cannot, however, be viewed as simple replacements for carbon fibers because there are key differences between these materials in areas such as handling, processing, and matrix design. It is impossible to know for certain that CNT composites will represent a significant advance over carbon fiber composites before these various factors have been optimized, which is an extremely costly and time intensive process. This work attempts to place an upper bound on CNT composite mechanical properties by performing molecular dynamics simulations on idealized model systems with a reactive forcefield that permits modeling of both elastic deformations and fracture. Amorphous carbon (AC) was chosen for the matrix material in this work because of its structural simplicity and physical compatibility with the CNT fillers. It is also much stiffer and stronger than typical engineering polymer matrices. Three different arrangements of CNTs in the simulation cell have been investigated: a single-wall nanotube (SWNT) array, a multi-wall nanotube (MWNT) array, and a SWNT bundle system. The SWNT and MWNT array systems are clearly idealizations, but the SWNT bundle system is a step closer to real systems in which individual tubes aggregate into large assemblies. The effect of chemical crosslinking on composite properties is modeled by adding bonds between the CNTs and AC. The balance between weakening the CNTs and improving fiber-matrix load transfer is explored by systematically varying the extent of crosslinking. It is, of course, impossible to capture the full range of deformation and fracture processes that occur in real materials with even the largest atomistic molecular dynamics simulations. With this limitation in mind, the simulation results reported here provide a plausible upper limit on

  2. Carbon nanotubes and graphene towards soft electronics

    NASA Astrophysics Data System (ADS)

    Chae, Sang Hoon; Lee, Young Hee

    2014-04-01

    Although silicon technology has been the main driving force for miniaturizing device dimensions to improve cost and performance, the current application of Si to soft electronics (flexible and stretchable electronics) is limited due to material rigidity. As a result, various prospective materials have been proposed to overcome the rigidity of conventional Si technology. In particular, nano-carbon materials such as carbon nanotubes (CNTs) and graphene are promising due to outstanding elastic properties as well as an excellent combination of electronic, optoelectronic, and thermal properties compared to conventional rigid silicon. The uniqueness of these nano-carbon materials has opened new possibilities for soft electronics, which is another technological trend in the market. This review covers the recent progress of soft electronics research based on CNTs and graphene. We discuss the strategies for soft electronics with nano-carbon materials and their preparation methods (growth and transfer techniques) to devices as well as the electrical characteristics of transparent conducting films (transparency and sheet resistance) and device performances in field effect transistor (FET) (structure, carrier type, on/off ratio, and mobility). In addition to discussing state of the art performance metrics, we also attempt to clarify trade-off issues and methods to control the trade-off on/off versus mobility). We further demonstrate accomplishments of the CNT network in flexible integrated circuits on plastic substrates that have attractive characteristics. A future research direction is also proposed to overcome current technological obstacles necessary to realize commercially feasible soft electronics.

  3. Carbon Nanotube Synthesis Using Coal Pyrolysis.

    PubMed

    Moothi, Kapil; Simate, Geoffrey S; Falcon, Rosemary; Iyuke, Sunny E; Meyyappan, M

    2015-09-01

    This study investigates carbon nanotube (CNT) production from coal pyrolysis wherein the output gases are used in a chemical vapor deposition reactor. The carbon products are similar to those using commercial coal gas as feedstock, but coal is a relatively cheaper feedstock compared to high purity source gases. A Gibbs minimization model has been developed to predict the volume percentages of product gases from coal pyrolysis. Methane and carbon monoxide were the largest carbon components of the product stream and thus formed the primary source for CNT synthesis. Both the model and the observations showed that increasing the furnace temperature led to a decrease in the absolute quantities of "useful" product gases, with the optimal temperature between 400 and 500 °C. Based on the experimental data, a kinetic rate law for CNT from coal pyrolysis was derived as d[CNT]/dt = K([CO][CH4])(1/2), where K is a function of several equilibrium constants representing various reactions in the CNT formation process. PMID:26262467

  4. Flame Synthesis Used to Create Metal-Catalyzed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    VanderWal, Randy L.

    2001-01-01

    Metal-catalyzed carbon nanotubes are highly ordered carbon structures of nanoscale dimensions. They may be thought of as hollow cylinders whose walls are formed by single atomic layers of graphite. Such cylinders may be composed of many nested, concentric atomic layers of carbon or only a single layer, the latter forming a single-walled carbon nanotube. This article reports unique results using a flame for their synthesis. Only recently were carbon nanotubes discovered within an arc discharge and recognized as fullerene derivatives. Today metal-catalyzed carbon nanotubes are of great interest for many reasons. They can be used as supports for the metal catalysts like those found in catalytic converters. Open-ended nanotubes are highly desirable because they can be filled by other elements, metals or gases, for battery and fuel cell applications. Because of their highly crystalline structure, they are significantly stronger than the commercial carbon fibers that are currently available (10 times as strong as steel but possessing one-sixth of the weight). This property makes them highly desirable for strengthening polymer and ceramic composite materials. Current methods of synthesizing carbon nanotubes include thermal pyrolysis of organometallics, laser ablation of metal targets within hydrocarbon atmospheres at high temperatures, and arc discharges. Each of these methods is costly, and it is unclear if they can be scaled for the commercial synthesis of carbon nanotubes. In contrast, flame synthesis is an economical means of bulk synthesis of a variety of aerosol materials such as carbon black. Flame synthesis of carbon nanotubes could potentially realize an economy of scale that would enable their use in common structural materials such as car-body panels. The top figure is a transmission electron micrograph of a multiwalled carbon nanotube. The image shows a cross section of the atomic structure of the nanotube. The dark lines are individual atomic layer planes of

  5. Patterned Growth of Carbon Nanotubes or Nanofibers

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D.

    2004-01-01

    A method and apparatus for the growth of carbon nanotubes or nanofibers in a desired pattern has been invented. The essence of the method is to grow the nanotubes or nanofibers by chemical vapor deposition (CVD) onto a patterned catalyst supported by a substrate. The figure schematically depicts salient aspects of the method and apparatus in a typical application. A substrate is placed in a chamber that contains both ion-beam sputtering and CVD equipment. The substrate can be made of any of a variety of materials that include several forms of silicon or carbon, and selected polymers, metals, ceramics, and even some natural minerals and similar materials. Optionally, the substrate is first coated with a noncatalytic metal layer (which could be a single layer or could comprise multiple different sublayers) by ion-beam sputtering. The choice of metal(s) and thickness(es) of the first layer (if any) and its sublayers (if any) depends on the chemical and electrical properties required for subsequent deposition of the catalyst and the subsequent CVD of the carbon nanotubes. A typical first-sublayer metal is Pt, Pd, Cr, Mo, Ti, W, or an alloy of two or more of these elements. A typical metal for the second sublayer or for an undivided first layer is Al at a thickness .1 nm or Ir at a thickness .5 nm. Proper choice of the metal for a second sublayer of a first layer makes it possible to use a catalyst that is chemically incompatible with the substrate. In the next step, a mask having holes in the desired pattern is placed over the coated substrate. The catalyst is then deposited on the coated substrate by ion-beam sputtering through the mask. Optionally, the catalyst could be deposited by a technique other than sputtering and/or patterned by use of photolithography, electron- beam lithography, or another suitable technique. The catalytic metal can be Fe, Co, Ni, or an alloy of two or more of these elements, deposited to a typical thickness in the range from 0.1 to 20 nm.

  6. Capillarity-induced disassembly of virions in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Fan, Xiaobin; Barclay, J. Elaine; Peng, Wenchao; Li, Yang; Li, Xianyu; Zhang, Guoliang; Evans, David J.; Zhang, Fengbao

    2008-04-01

    Studying the transport and fate of viruses through nanochannels is of great importance. By using the nanochannel of a carbon nanotube (CNT) as an ideal model, we evaluated the possibility of capillarity-induced viral transport through a closely fitting nanochannel and explored the mechanisms involved. It is shown both experimentally and theoretically that Cowpea mosaic virus can enter CNTs by capillarity. However, when introduced into a nanotube the protein capsid may disassemble. During the initial capillary filling stage, anomalous needle-shaped high pressure exists in the centre of the nanotube's entrance. This high pressure, combining with the significant negative pressure within the nanotube, may account for the disassembly of the virions.

  7. Compression behaviour of thick vertically aligned carbon nanotube blocks.

    PubMed

    Pavese, Matteo; Musso, Simone; Pugno, Nicola M

    2010-07-01

    Blocks of vertically aligned multiwall carbon nanotubes were prepared by thermal chemical vapor deposition starting from camphor and ferrocene precursors. The blocks, having a thickness of approximately 2 mm and composed of nanotubes with diameter ranging between 30 and 80 nm, were submitted to compression tests. The results were analyzed accordingly with a simple model consisting in a parallel array of nanotubes under compression and bending suffering microscopic instability and compaction. The model mostly fits the experimental stress-strain curves, with a small deviation attributed to dissipative phenomena, such as frictional forces and nanotube wall breakage. PMID:21128406

  8. Engineered Carbon Nanotube Materials for High-Q Nanomechanical Resonators

    NASA Technical Reports Server (NTRS)

    Choi, Daniel S.; Hunt, Brian; Bronikowski, Mike; Epp, Larry; Hoenk, Michael; Hoppe, Dan; Kowalczyk, Bob; Wong, Eric; Xu, Jimmy; Adam, Douglas; Young, Rob

    2003-01-01

    This document represents a presentation offered by the Jet Propulsion Laboratory, with assistance from researchers from Brown University and Northrop Grumman. The presentation took place in Seoul, Korea in July 2003 and attempted to demonstrate the fabrication approach regarding the development of high quality factor (high-Q) mechanical oscillators (in the forms of a tunable nanotube resonator and a nanotube array radio frequency [RF] filter) aimed at signal processing and based on carbon nanotubes. The presentation also addressed parallel efforts to develop both in-plane single nanotube resonators as well as vertical array power devices.

  9. Small Si clusters on surfaces of carbon nanotubes

    SciTech Connect

    Meng, Lijun; Zhang, Kaiwang; Stocks, George Malcolm; Zhong, Jianxin

    2006-01-01

    Structures of small Si clusters, Sin, on surfaces of carbon nanotubes have been studied by molecular dynamics simulation. We show that the lowest-energy structures of Sin are three-dimensional clusters rather than thin Si sheets covering the surface of a nanotube. As n increases from 10 to 30, Sin undergoes structural transitions from a tent-like structure (with nanotube surface as its base) to a cage-like structure (without interior atoms) and further to a spherical compact structure (with interior atoms). Our results are different from the structures of small Si clusters found in a free space without Si-nanotube interaction.

  10. Improvement of thermal contact resistance by carbon nanotubes and nanofibers

    NASA Technical Reports Server (NTRS)

    Chuang, Helen F.; Cooper, Sarah M.; Meyyappan, M.; Cruden, Brett A.

    2004-01-01

    Interfacial thermal resistance results of various nanotube and nanofiber coatings, prepared by chemical vapor deposition (CVD) methods, are reported at relatively low clamping pressures. The five types of samples examined include multi-walled and single-walled nanotubes growth by CVD, multi-walled nanotubes grown by plasma enhanced CVD (PECVD) and carbon nanofibers of differing aspect ratio grown by PECVD. Of the samples examined, only high aspect ratio nanofibers and thermally grown multi-walled nanotubes show an improvement in thermal contact resistance. The improvement is approximately a 60% lower thermal resistance than a bare Si-Cu interface and is comparable to that attained by commercially available thermal interface materials.

  11. Cross-polarized excitons in carbon nanotubes.

    PubMed

    Kilina, Svetlana; Tretiak, Sergei; Doorn, Stephen K; Luo, Zhengtang; Papadimitrakopoulos, Fotios; Piryatinski, Andrei; Saxena, Avadh; Bishop, Alan R

    2008-05-13

    Polarization of low-lying excitonic bands in finite-size semiconducting single-walled carbon nanotubes (SWNTs) is studied by using quantum-chemical methodologies. Our calculations elucidate properties of cross-polarized excitons, which lead to the transverse optical absorption of nanotubes and presumably couple to intermediate-frequency modes recently observed in resonance Raman excitation spectroscopy. We identify up to 12 distinct excitonic transitions below the second fundamental band associated with the E(22) van Hove singularity. Calculations for several chiral SWNTs distinguish the optically active "bright" excitonic band polarized parallel to the tube axis and several optically "weak" cross-polarized excitons. The rest are optically (near) forbidden "dark" transitions. An analysis of the transition density matrices related to excitonic bands provides detailed information about delocalization of excitonic wavefunction along the tube. Utilization of the natural helical coordinate system accounting for the tube chirality allows one to disentangle longitudinal and circumferential components. The distribution of the transition density matrix along a tube axis is similar for all excitons. However, four parallel-polarized excitons associated with the E(11) transition are more localized along the circumference of a tube, compared with others related to the E(12) and E(21) cross-polarized transitions. Calculated splitting between optically active parallel- and cross-polarized transitions increases with tube diameter, which compares well with experimental spectroscopic data. PMID:18463293

  12. Carbon nanotube based NEMS actuators and sensors

    NASA Astrophysics Data System (ADS)

    Forney, Michael; Poler, Jordan

    2011-03-01

    Single-walled carbon nanotubes (SWNTs) have been widely studied due to superior mechanical and electrical properties. We have grown vertically aligned SWNTs (VA-SWNTs) onto microcantilever (MC) arrays, which provides an architecture for novel actuators and sensors. Raman spectroscopy confirms that the CVD-grown nanotubes are SWNTs and SEM confirms aligned growth. As an actuator, this hybrid MC/VA-SWNT system can be electrostatically modulated. SWNTs are excellent electron acceptors, so we can charge up the VA-SWNT array by applying a voltage. The electrostatic repulsion among the charged SWNTs provides a surface stress that induces MC deflection. Simulation results show that a few electrons per SWNT are needed for measureable deflections, and experimental actuators are being characterized by SEM, Raman, and an AFM optical lever system. The applied voltage is sinusoidally modulated, and deflection is measured with a lock-in amplifier. These actuators could be used for nano-manipulation, release of drugs from a capsule, or nano-valves. As a sensor, this MC/VA-SWNT system offers an improved sensitivity for chemical and bio-sensing compared to surface functionalized MC-based sensors. Those sensors only have a 2D sensing surface, but a MC/VA-SWNT system has significantly more sensing surface because the VA-SWNTs extend microns off the MC surface.

  13. Tailored Carbon Nanotubes for Tissue Engineering Applications

    PubMed Central

    Veetil, Jithesh V.; Ye, Kaiming

    2008-01-01

    A decade of aggressive researches on carbon nanotubes (CNTs) has paved way for extending these unique nanomaterials into a wide range of applications. In the relatively new arena of nanobiotechnology, a vast majority of applications are based on CNTs, ranging from miniaturized biosensors to organ regeneration. Nevertheless, the complexity of biological systems poses a significant challenge in developing CNT-based tissue engineering applications. This review focuses on the recent developments of CNT-based tissue engineering, where the interaction between living cells/tissues and the nanotubes have been transformed into a variety of novel techniques. This integration has already resulted in a revaluation of tissue engineering and organ regeneration techniques. Some of the new treatments that were not possible previously become reachable now. Because of the advent of surface chemistry, the CNT’s biocompatibility has been significantly improved, making it possible to serve as tissue scaffolding materials to enhance the organ regeneration. The superior mechanic strength and chemical inert also makes it ideal for blood compatible applications, especially for cardiopulmonary bypass surgery. The applications of CNTs in these cardiovascular surgeries led to a remarkable improvement in mechanical strength of implanted catheters and reduced thrombogenecity after surgery. Moreover, the functionalized CNTs have been extensively explored for in vivo targeted drug or gene delivery, which could potentially improve the efficiency of many cancer treatments. However, just like other nanomaterials, the cytotoxicity of CNTs has not been well established. Hence, more extensive cytotoxic studies are warranted while converting the hydrophobic CNTs into biocompatible nanomaterials. PMID:19496152

  14. Cross-polarized excitons in carbon nanotubes

    PubMed Central

    Kilina, Svetlana; Tretiak, Sergei; Doorn, Stephen K.; Luo, Zhengtang; Papadimitrakopoulos, Fotios; Piryatinski, Andrei; Saxena, Avadh; Bishop, Alan R.

    2008-01-01

    Polarization of low-lying excitonic bands in finite-size semiconducting single-walled carbon nanotubes (SWNTs) is studied by using quantum-chemical methodologies. Our calculations elucidate properties of cross-polarized excitons, which lead to the transverse optical absorption of nanotubes and presumably couple to intermediate-frequency modes recently observed in resonance Raman excitation spectroscopy. We identify up to 12 distinct excitonic transitions below the second fundamental band associated with the E22 van Hove singularity. Calculations for several chiral SWNTs distinguish the optically active “bright” excitonic band polarized parallel to the tube axis and several optically “weak” cross-polarized excitons. The rest are optically (near) forbidden “dark” transitions. An analysis of the transition density matrices related to excitonic bands provides detailed information about delocalization of excitonic wavefunction along the tube. Utilization of the natural helical coordinate system accounting for the tube chirality allows one to disentangle longitudinal and circumferential components. The distribution of the transition density matrix along a tube axis is similar for all excitons. However, four parallel-polarized excitons associated with the E11 transition are more localized along the circumference of a tube, compared with others related to the E12 and E21 cross-polarized transitions. Calculated splitting between optically active parallel- and cross-polarized transitions increases with tube diameter, which compares well with experimental spectroscopic data. PMID:18463293

  15. Universal nonresonant absorption in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Vialla, Fabien; Malic, Ermin; Langlois, Benjamin; Chassagneux, Yannick; Diederichs, Carole; Deleporte, Emmanuelle; Roussignol, Philippe; Lauret, Jean-Sébastien; Voisin, Christophe

    2014-10-01

    Photoluminescence excitation measurements in semiconducting carbon nanotubes show a systematic nonresonant contribution between the well-known excitonic resonances. Using a global analysis method, we were able to delineate the contribution of each chiral species, including its tiny nonresonant component. By comparison with the recently reported excitonic absorption cross section on the S22 resonance, we found a universal nonresonant absorbance which turns out to be of the order of one-half of that of an equivalent graphene sheet. This value, as well as the absorption line shape in the nonresonant window, is in excellent agreement with microscopic calculations based on the density-matrix formalism. This nonresonant absorption of semiconducting nanotubes is essentially frequency independent over 0.5-eV-wide windows and reaches approximately the same value between the S11 and S22 resonances and between the S22 and S33 resonances. In addition, the nonresonant absorption cross section turns out to be the same for all the chiral species we measured in this study. From a practical point of view, this study provides a solid framework for sample content analysis based on photoluminescence studies by targeting specific excitation wavelengths that lead to almost uniform excitation of all the chiral species of a sample within a given diameter range.

  16. Metal Nanoparticle Catalysts for Carbon Nanotube Growth

    NASA Technical Reports Server (NTRS)

    Pierce, Benjamin F.

    2003-01-01

    Work this summer involved and new and unique process for producing the metal nanoparticle catalysts needed for carbon nanotube (CNT) growth. There are many applications attributed to CNT's, and their properties have deemed them to be a hot spot in research today. Many groups have demonstrated the versatility in CNT's by exploring a wide spectrum of roles that these nanotubes are able to fill. A short list of such promising applications are: nanoscaled electronic circuitry, storage media, chemical sensors, microscope enhancement, and coating reinforcement. Different methods have been used to grow these CNT's. Some examples are laser ablation, flame synthesis, or furnace synthesis. Every single approach requires the presence of a metal catalyst (Fe, Co, and Ni are among the best) that is small enough to produce a CNT. Herein lies the uniqueness of this work. Microemulsions (containing inverse micelles) were used to generate these metal particles for subsequent CNT growth. The goal of this summer work was basically to accomplish as much preliminary work as possible. I strived to pinpoint which variable (experimental process, metal product, substrate, method of application, CVD conditions, etc.) was the determining factor in the results. The resulting SEM images were sufficient for the appropriate comparisons to be made. The future work of this project consists of the optimization of the more promising experimental procedures and further exploration onto what exactly dictated the results.

  17. Process for separating metallic from semiconducting single-walled carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Sun, Ya-Ping (Inventor)

    2008-01-01

    A method for separating semiconducting single-walled carbon nanotubes from metallic single-walled carbon nanotubes is disclosed. The method utilizes separation agents that preferentially associate with semiconducting nanotubes due to the electrical nature of the nanotubes. The separation agents are those that have a planar orientation, .pi.-electrons available for association with the surface of the nanotubes, and also include a soluble portion of the molecule. Following preferential association of the separation agent with the semiconducting nanotubes, the agent/nanotubes complex is soluble and can be solubilized with the solution enriched in semiconducting nanotubes while the residual solid is enriched in metallic nanotubes.

  18. Production and Characterization of Carbon Nanotubes and Nanotube-Based Composites

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pavel; Arepalli, Sivaram; Holmes, William; Gorelik, Olga; Files, Brad; Scott, Carl; Santos, Beatrice; Mayeaux, Brian; Victor, Joe

    1999-01-01

    The Nobel Prize winning discovery of the Buckuball (C60) in 1985 at Rice University by a group including Dr. Richard Smalley led to the whole new class of carbon allotropes including fullerenes and nanotubes. Especially interesting from many viewpoints are single-walled carbon nanotubes, which structurally are like a single graphitic sheet wrapped around a cylinder and capped at the ends. This cylinders have diameter as small as 0.5 - 2 nm (1/100,000th the diameter of a human hair) and are as long as 0.1 - 1 mm. Nanotubes are really individual molecules and believed to be defect-free, leading to high tensile strength despite their low density. Additionally, these fibers exhibit electrical conductivity as high as copper, thermal conductivity as high as diamond, strength 100 times higher than steel at one-sixth the weight, and high strain to failure. Thus it is believed that developments in the field of nanotechnology will lead to stronger and lighter composite materials for next generation spacecraft. Lack of a bulk method of production is the primary reason nanotubes are not used widely today. Toward this goal JSC nanotube team is exploring three distinct production techniques: laser ablation, arc discharge and chemical vapor deposition (CVD, in collaboration with Rice University). In laser ablation technique high-power laser impinges on the piece of carbon containing small amount of catalyst, and nanotubes self-assemble from the resulting carbon vapor. In arc generator similar vapor is created in arc discharge between carbon electrodes with catalyst. In CVD method nanotubes grow at much lower temperature on small catalyst particles from carbon-containing feedstock gas (methane or carbon monoxide). As of now, laser ablation produces cleanest material, but mass yield is rather small. Arc discharge produces grams of material, but purity is low. CVD technique is still in baby steps, but preliminary results look promising, as well as perspective of scaling the process

  19. Fluorescence labeling of carbon nanotubes and visualization of a nanotube-protein hybrid under fluorescence microscope.

    PubMed

    Yoshimura, Shige H; Khan, Shahbaz; Maruyama, Hiroyuki; Nakayama, Yoshikazu; Takeyasu, Kunio

    2011-04-11

    Biological applications of carbon nanotubes have been hampered by the inability to visualize them using conventional optical microscope, which is the most common tool for the observation and measurement of biological processes. Recently, a number of fluorescence labeling methods for biomolecules and various fluorescence probes have been developed and widely utilized in biological fields. Therefore, labeling carbon nanotubes with such fluorophores under physiological conditions will be highly useful in their biological applications. In this Article, we present a method to fluorescently label nanotubes by combining a detergent and a fluorophore commonly used in biological experiments. Fluorophores carrying an amino group (Texas Red hydrazide or BODIPY FL-hydrazide) were covalently attached to the hydroxyl groups of Tween 20 using carbonyldiimidazole. Fluorescence microscopy demonstrated that nanotubes were efficiently solubilized and labeled by this fluorescently labeled detergent. By using this technique, we also demonstrated multicolor fluorescence imaging of a nanotube-protein hybrid. PMID:21395219

  20. Copper Decoration of Carbon Nanotubes and High Resolution Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Probst, Camille

    A new process of decorating carbon nanotubes with copper was developed for the fabrication of nanocomposite aluminum-nanotubes. The process consists of three stages: oxidation, activation and electroless copper plating on the nanotubes. The oxidation step was required to create chemical function on the nanotubes, essential for the activation step. Then, catalytic nanoparticles of tin-palladium were deposited on the tubes. Finally, during the electroless copper plating, copper particles with a size between 20 and 60 nm were uniformly deposited on the nanotubes surface. The reproducibility of the process was shown by using another type of carbon nanotube. The fabrication of nanocomposites aluminum-nanotubes was tested by aluminum vacuum infiltration. Although the infiltration of carbon nanotubes did not produce the expected results, an interesting electron microscopy sample was discovered during the process development: the activated carbon nanotubes. Secondly, scanning transmitted electron microscopy (STEM) imaging in SEM was analysed. The images were obtained with a new detector on the field emission scanning electron microscope (Hitachi S-4700). Various parameters were analysed with the use of two different samples: the activated carbon nanotubes (previously obtained) and gold-palladium nanodeposits. Influences of working distance, accelerating voltage or sample used on the spatial resolution of images obtained with SMART (Scanning Microscope Assessment and Resolution Testing) were analysed. An optimum working distance for the best spatial resolution related to the sample analysed was found for the imaging in STEM mode. Finally, relation between probe size and spatial resolution of backscattered electrons (BSE) images was studied. An image synthesis method was developed to generate the BSE images from backscattered electrons coefficients obtained with CASINO software. Spatial resolution of images was determined using SMART. The analysis shown that using a probe

  1. Carbon nanotubes grown on bulk materials and methods for fabrication

    DOEpatents

    Menchhofer, Paul A.; Montgomery, Frederick C.; Baker, Frederick S.

    2011-11-08

    Disclosed are structures formed as bulk support media having carbon nanotubes formed therewith. The bulk support media may comprise fibers or particles and the fibers or particles may be formed from such materials as quartz, carbon, or activated carbon. Metal catalyst species are formed adjacent the surfaces of the bulk support material, and carbon nanotubes are grown adjacent the surfaces of the metal catalyst species. Methods employ metal salt solutions that may comprise iron salts such as iron chloride, aluminum salts such as aluminum chloride, or nickel salts such as nickel chloride. Carbon nanotubes may be separated from the carbon-based bulk support media and the metal catalyst species by using concentrated acids to oxidize the carbon-based bulk support media and the metal catalyst species.

  2. Plasma-assembled carbon nanotubes: electric field-related effects.

    PubMed

    Levchenko, I; Ostrikov, K; Keidar, M

    2008-11-01

    The paper presents results of comparative investigation of carbon nanotubes growth processes in dense low-temperature plasma and on substrate surface. Hybrid/Monte-Carlo numerical simulations were used to demonstrate the differences in the ion fluxes, growth rates and kinetics of adsorbed atoms re-distribution on substrate and nanotubes surfaces. We show that the plasma parameters significantly affect the nanotubes growth kinetics. We demonstrate that the growth rates of the nanotubes in plasma and on surface can differ by three orders, and the specific fluxes to the nanotube in the plasma can exceed the flux to surface-grown nanotube by six orders. We also show that the metal catalyst used for the nanotubes production on surface and in arc is a subject to very different conditions and this may be a key factor for the nanotube growth mode. The obtained dependencies for the ion fluxes to the nanotubes and nanotubes growth rates on the plasma parameters may be useful for selection of the production methods. PMID:19198353

  3. Carbon Nanotube-Based Chemical Sensors.

    PubMed

    Meyyappan, M

    2016-04-01

    The need to sense gases and vapors arises in numerous scenarios in industrial, environmental, security and medical applications. Traditionally, this activity has utilized bulky instruments to obtain both qualitative and quantitative information on the constituents of the gas mixture. It is ideal to use sensors for this purpose since they are smaller in size and less expensive; however, their performance in the field must match that of established analytical instruments in order to gain acceptance. In this regard, nanomaterials as sensing media offer advantages in sensitivity, preparation of chip-based sensors and construction of electronic nose for selective detection of analytes of interest. This article provides a review of the use of carbon nanotubes in gas and vapor sensing. PMID:26959284

  4. Mechanical strength of carbon nanotube nickel nanocomposites

    NASA Astrophysics Data System (ADS)

    Sun, Ying; Sun, Jianren; Liu, Miao; Chen, Quanfang

    2007-12-01

    Carbon nanotubes (CNTs), including single-walled CNT (SWCNT) and multi-walled CNT (MWCNT), have been regarded as the stiffest and strongest materials ever developed and are promising reinforcement fillers for developing nanocomposites. However, the scientific community has been puzzled about the reinforcement efficiency. Here we report CNT-reinforced nickel nanocomposites fabricated with an innovative electrochemical co-deposition process for achieving good interfacial bonding between CNT and metallic matrices. Test results show that Ni/SWCNT composite produces a tensile strength as high as 2 GPa, which is more than three times stronger than that of pure nickel. The mechanical strength of Ni/CNT nanocomposites is dependent on CNT addition, while the fracture strain remains similar or better than that of pure nickel. The good reinforcement of CNT/metal nanocomposites is attributed to the good interfacial bonding as well as the stiffer matrix nature.

  5. Alkali-metal intercalation in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Béguin, F.; Duclaux, L.; Méténier, K.; Frackowiak, E.; Salvetat, J. P.; Conard, J.; Bonnamy, S.; Lauginie, P.

    1999-09-01

    We report on successful intercalation of multiwall (MWNT) and single wall (SWNT) carbon nanotubes with alkali metals by electrochemical and vapor phase reactions. A LiC10 compound was produced by full electrochemical reduction of MWNT. KC8 and CsC8-MWNT first stage derivatives were synthesized in conditions of alkali vapor saturation. Their identity periods and the 2×2 R 0° alkali superlattice are comparable to their parent graphite compounds. The dysonian shape of KC8 EPR line and the temperature-independent Pauli susceptibility are both characteristic of a metallic behavior, which was confirmed by 13C NMR anisotropic shifts. Exposure of SWNT bundles to alkali vapor led to an increase of the pristine triangular lattice from 1.67 nm to 1.85 nm and 1.87 nm for potassium and rubidium, respectively.

  6. Rotational actuators based on carbon nanotubes.

    PubMed

    Fennimore, A M; Yuzvinsky, T D; Han, Wei-Qiang; Fuhrer, M S; Cumings, J; Zettl, A

    2003-07-24

    Nanostructures are of great interest not only for their basic scientific richness, but also because they have the potential to revolutionize critical technologies. The miniaturization of electronic devices over the past century has profoundly affected human communication, computation, manufacturing and transportation systems. True molecular-scale electronic devices are now emerging that set the stage for future integrated nanoelectronics. Recently, there have been dramatic parallel advances in the miniaturization of mechanical and electromechanical devices. Commercial microelectromechanical systems now reach the submillimetre to micrometre size scale, and there is intense interest in the creation of next-generation synthetic nanometre-scale electromechanical systems. We report on the construction and successful operation of a fully synthetic nanoscale electromechanical actuator incorporating a rotatable metal plate, with a multi-walled carbon nanotube serving as the key motion-enabling element. PMID:12879064

  7. Thermal analysis of polyethylene + X% carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lozovyi, Fedir; Ivanenko, Kateryna; Nedilko, Sergii; Revo, Sergiy; Hamamda, Smail

    2016-02-01

    The aim of this research is to study the influence of the multi-walled carbon nanotubes (MWCNTs) on the thermomechanical and structural properties of high-density polyethylene. Several, complementary experimental techniques were used, namely, dilatometry, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Raman spectroscopy, and infrared (IR) spectroscopy. Dilatometry data showed that nanocomposites exhibit anisotropic behavior, and intensity of the anisotropy depends on the MWCNT concentration. The shapes of the dilatometric curves of the nanocomposites under study differ significantly for the radial and longitudinal directions of the samples. DSC results show that MWCNTs weekly influence calorimetry data, while Raman spectra show that the I D/ I G ratio decreases when MWCNT concentration increases. The IR spectra demonstrate improvement of the crystallinity of the samples as the content in MWCNTs rises.

  8. Carbon Nanotube Amperometric Chips with Pneumatic Micropumps

    NASA Astrophysics Data System (ADS)

    Tsujita, Yuichi; Maehashi, Kenzo; Matsumoto, Kazuhiko; Chikae, Miyuki; Torai, Soichiro; Takamura, Yuzuru; Tamiya, Eiichi

    2008-04-01

    We fabricated carbon nanotube (CNT) amperometric chips with pneumatic micropumps by the combination of amperometric biosensors based on CNT-arrayed electrodes and microchannels with pneumatic micropumps made of poly(dimethylsiloxane). On the chip, phosphate buffer solution and potassium ferricyanide, K3[Fe(CN)6], were introduced into the CNT electrodes using each pneumatic micropump and electrochemically measured by differential pulse voltammetry. The results indicate that our chip can automatically exchange reagents on the CNT electrodes and clearly detect molecules. Moreover, by modifying the CNT electrodes with enzyme glucose oxidase, glucose molecules could be detected using our chips by cyclic voltammetry and chronoamperometry. We conclude that microfluidic chips with CNT-arrayed electrodes are a promising candidate for the development of hand-held electrochemical biosensors.

  9. Exploring Carbon Nanotubes for Nanoscale Devices

    NASA Technical Reports Server (NTRS)

    Han, Jie; Dai; Anantram; Jaffe; Saini, Subhash (Technical Monitor)

    1998-01-01

    Carbon nanotubes (CNTs) are shown to promise great opportunities in nanoelectronic devices and nanoelectromechanical systems (NEMS) because of their inherent nanoscale sizes, intrinsic electric conductivities, and seamless hexagonal network architectures. I present our collaborative work with Stanford on exploring CNTs for nanodevices in this talk. The electrical property measurements suggest that metallic tubes are quantum wires. Furthermore, two and three terminal CNT junctions have been observed experimentally. We have proposed and studied CNT-based molecular switches and logic devices for future digital electronics. We also have studied CNTs based NEMS inclusing gears, cantilevers, and scanning probe microscopy tips. We investigate both chemistry and physics based aspects of the CNT NEMS. Our results suggest that CNT have ideal stiffness, vibrational frequencies, Q-factors, geometry-dependent electric conductivities, and the highest chemical and mechanical stabilities for the NEMS. The use of CNT SPM tips for nanolithography is presented for demonstration of the advantages of the CNT NEMS.

  10. Retinal Light Processing Using Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Loftus, David J. (Inventor); Leng, Theodore (Inventor); Fishman, Harvey (Inventor)

    2004-01-01

    Method and system for processing light signals received by the eye of a human or other animal, where the eye may be compromised or non-functioning. Incident light is received at first and second pixels in a photodetector array and provides a pixel electrical signal representing the received light. Each of an array of carbon nanotube (CNT) towers is connected to a pixel, has a first tower end penetrating a retinal active layer of the animal and has a second tower end positioned to receive to receive and transport the pixel electrical signal to the retinal active layer. The CNT tower may be coated with a biologically active substance or chemically modified to promote neurite connections with the tower. The photoreceptor array can be provide with a signal altering mechanism that alters at least one of light intensity and wavelength intensity sensed by a first pixel relative to a second pixel, to correct for one or more selected eye problems.

  11. Functionalization of Carbon Nanotubes using Atomic Hydrogen

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N.; Cassell, Alan M.; Nguyen, Cattien V.; Meyyappan, M.; Han, Jie; Arnold, Jim (Technical Monitor)

    2001-01-01

    We have investigated the irradiation of multi walled and single walled carbon nanotubes (SWNTs) with atomic hydrogen. After irradiating the SWNT sample, a band at 2940/cm (3.4 microns) that is characteristic of the C-H stretching mode is observed using Fourier transform infrared (FTIR) spectroscopy. Additional confirmation of SWNT functionalization is tested by irradiating with atomic deuterium. A weak band in the region 1940/cm (5.2 micron) to 2450/cm (4.1 micron) corresponding to C-D stretching mode is also observed in the FTIR spectrum. This technique provides a clean gas phase process for the functionalization of SWNTs, which could lead to further chemical manipulation and/or the tuning of the electronic properties of SWNTs for nanodevice applications.

  12. Superconductive niobium films coating carbon nanotube fibers

    NASA Astrophysics Data System (ADS)

    Salvato, M.; Lucci, M.; Ottaviani, I.; Cirillo, M.; Behabtu, N.; Young, C. C.; Pasquali, M.; Vecchione, A.; Fittipaldi, R.; Corato, V.

    2014-11-01

    Superconducting niobium (Nb) has been successfully obtained by sputter deposition on carbon nanotube fibers. The transport properties of the niobium coating the fibers are compared to those of niobium thin films deposited on oxidized Si substrates during the same deposition run. For niobium films with thicknesses above 300 nm, the niobium coating the fibers and the thin films show similar normal state and superconducting properties with critical current density, measured at T = 4.2 K, of the order of 105 A cm-2. Thinner niobium layers coating the fibers also show the onset of the superconducting transition in the resistivity versus temperature dependence, but zero resistance is not observed down to T = 1 K. We evidence by scanning electron microscopy (SEM) and current-voltage measurements that the granular structure of the samples is the main reason for the lack of true global superconductivity for thicknesses below 300 nm.

  13. Reversible high-pressure carbon nanotube vessel

    SciTech Connect

    Ma, Ming D.; Zheng Quanshui; Liu, Jefferson Z.; Wang Lifeng; Shen Luming; Xie Lin; Zhu Jing; Wei Fei; Gong Qianming; Liang Ji

    2010-06-15

    Applying a full pressure loop, i.e., loading and unloading, on a nanocrystal with in situ observation remains a challenge to experimentalists up until now. Using a multiwalled carbon nanotube, we realize the pressure loop acting on a Fe{sub 3}C nanocrystal (with peak value 20 GPa) by electron-beam irradiation with in situ observations inside transmission electron microscopy at 500 deg. C/ambient temperature. Using density-functional theory calculations, we attribute the unloading process to the formation of one dangling-bond single vacancies under the electron-beam irradiation at room temperature. A theoretical model is presented to understand the process and the results agree well with the experimental measurements.

  14. Flow-induced dynamics of carbon nanotubes.

    PubMed

    Chen, Chao; Xu, Zhiping

    2011-10-01

    The high aspect ratio and bending resilience of a carbon nanotube (CNT) enables it to have remarkable responses to fluid flow. The structural deformation and vibration of a CNT under fluid flow are discussed in this paper, closely tied to their applications in mechanosensing and energy harvesting. We perform molecular dynamics (MD) simulations and a theoretical analysis based on the elastic beam theory, and find that the performance of these applications is critically defined by thermal noise at low flow speeds and flow-induced elastic instabilities at high speeds. We provide a map of operating mechanisms as defined by the properties of both nanostructures and fluid. The results and understanding obtained here could shed some light on the design of nanomechanical devices operating in fluidic environments. PMID:21909582

  15. Magnetically Active Carbon Nanotubes at Work.

    PubMed

    Stopin, Antoine; Pineux, Florent; Marega, Riccardo; Bonifazi, Davide

    2015-06-22

    Endohedral and exohedral assembly of magnetic nanoparticles (MNPs) and carbon nanotubes (CNTs) recently gave birth to a large body of new hybrid nanomaterials (MNPs-CNTs) featuring properties that are otherwise not in reach with only the graphitic or metallic cores themselves. These materials feature enhanced magnetically guided motions (rotation and translation), magnetic saturation and coercivity, large surface area, and thermal stability. By guiding the reader through the most significant examples in this Concept paper, we describe how researchers in the field engineered and exploited the synergistic combination of these two types of nanoparticles in a large variety of current and potential applications, such as magnetic fluid hyperthermia therapeutics and in magnetic resonance imaging to name a few. PMID:26017389

  16. Carbon-Nanotube-Based Chemical Gas Sensor

    NASA Technical Reports Server (NTRS)

    Kaul, Arunpama B.

    2010-01-01

    Conventional thermal conductivity gauges (e.g. Pirani gauges) lend themselves to applications such as leak detectors, or in gas chromatographs for identifying various gas species. However, these conventional gauges are physically large, operate at high power, and have a slow response time. A single-walled carbon-nanotube (SWNT)-based chemical sensing gauge relies on differences in thermal conductance of the respective gases surrounding the CNT as it is voltage-biased, as a means for chemical identification. Such a sensor provides benefits of significantly reduced size and compactness, fast response time, low-power operation, and inexpensive manufacturing since it can be batch-fabricated using Si integrated-circuit (IC) process technology.

  17. Carbon nanotube bundles under electric field perturbations

    NASA Astrophysics Data System (ADS)

    Hammes, I.; Latgé, A.

    2012-03-01

    Here we address the important role played by electric fields applied in carbon nanotube bundles in providing convenient scenarios for their use in electronic devices. We show that a gap modulation may be derived depending on the bundle configuration and the details of the applied field configuration. The system is described by a tight binding Hamiltonian and the Green function formalism is used to calculate the local density of states. Small bundles were used to validate our model on the basis of ab initio calculations. Further analysis shows that the number of tubes, geometrical configuration details and field intensities may be controlled to tune the electronic structure close to the Fermi energy, envisaging atomic-scale devices.

  18. Sorption of indium (III) onto carbon nanotubes.

    PubMed

    Alguacil, F J; Lopez, F A; Rodriguez, O; Martinez-Ramirez, S; Garcia-Diaz, I

    2016-08-01

    Indium has numerous applications in different industrial sectors and is not an abundant element. Therefore appropriate technology to recover this element from various process wastes is needed. This research reports high adsorption capacity of multiwalled carbon nanotubes (MWCNT) for In(III). The effects of pH, kinetics, isotherms and adsorption mechanism of MWCNT on In(III) adsorption were investigated and discussed in detail. The pH increases improves the adsorption capacity for In(III). The Langmuir adsorption model is the best fit with the experimental data. For the kinetic study, the adsorption onto MWCNT could be fitted to pseudo second-order. The adsorption of indium(III) can be described to a mechanism which consists of a film diffusion controlled process. Metal desorption can be achieved with acidic solutions. PMID:27085001

  19. Water transport control in carbon nanotube arrays

    PubMed Central

    2014-01-01

    Based on a recent scaling law of the water mobility under nanoconfined conditions, we envision novel strategies for precise modulation of water diffusion within membranes made of carbon nanotube arrays (CNAs). In a first approach, the water diffusion coefficient D may be tuned by finely controlling the size distribution of the pore size. In the second approach, D can be varied at will by means of externally induced electrostatic fields. Starting from the latter strategy, switchable molecular sieves are proposed, where membranes are properly designed with sieving and permeation features that can be dynamically activated/deactivated. Areas where a precise control of water transport properties is beneficial range from energy and environmental engineering up to nanomedicine. PMID:25313305

  20. Magnetic Carbon Nanotubes Tethered with Maghemite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kim, Il Tae; Nunnery, Grady; Jacob, Karl; Schwartz, Justin; Liu, Xiaotao; Tannenbaum, Rina

    2011-03-01

    We describe a novel, facile method for the synthesis of magnetic carbon nanotubes (m-CNTs) decorated with monodisperse γ - Fe 2 O3 magnetic (maghemite) nanoparticles and their aligned feature in a magnetic field. The tethering of the nanoparticles was achieved by the initial activation of the surface of the CNTs with carboxylic acid groups, followed by the attachment of the γ - Fe 2 O3 nanoparticles via a modified sol-gel process. Sodium dodecylbenzene sulfonate (NaDDBS) was introduced into the suspension to prevent the formation of an iron oxide 3D network. Various characterization methods were used to confirm the formation of well-defined maghemite nanoparticles. The tethered nanoparticles imparted magnetic characteristics to the CNTs, which became superparamagnetic. The m-CNTs were oriented parallel to the direction of a magnetic field. This has the potential of enhancing various properties, e.g. mechanical and electrical properties, in composite materials.