Controlled Dielectrophoretic Assembly of Multiwalled Carbon Nanotubes

An, Lijia; Cheam, Daw Don; Friedrich, Craig R.

doi:10.1021/jp809502x

Cited by 13 publications

(12 citation statements)

References 15 publications

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“…For the purposes of alignment, dielectrophoresis is a process applicable to a range of nanoscale morphologies including nanorods, particles, and branched structures [ 32 ]. It would be applicable to nanowires and even nanofibers were they broken and dispersed into a suitable solvent (though this negates the direct deposition advantage of electrospinning).…”

Section: Harvesting and Integrationmentioning

confidence: 99%

Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing

Wal

Berger

Kulis

et al. 2009

Sensors

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A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. Both nanostructures possess a one-dimensional morphology. Different synthesis methods are used to produce these materials: thermal evaporation-condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed. Practical issues associated with harvesting, purification, and integration of these materials into sensing devices are detailed. For comparison to the nascent form, these sensing materials are surface coated with Pd and Pt nanoparticles. Gas sensing tests, with respect to H2, are conducted at ambient and elevated temperatures. Comparative normalized responses and time constants for the catalyst and noncatalyst systems provide a basis for identification of the superior metal-oxide nanostructure and catalyst combination. With temperature-dependent data, Arrhenius analyses are made to determine activation energies for the catalyst-assisted systems.

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Section: Harvesting and Integrationmentioning

confidence: 99%

Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing

Wal

Berger

Kulis

et al. 2009

Sensors

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“…[14][15][16][17][18][19] Therefore, finding ways to bridge two electrical conductors by assembling CNTs is an active area of research. 20,21 The nematic phase of an LC shows dielectric anisotropy De(¼e jj À e ? ), where e jj and e ?…”

Section: Introductionmentioning

confidence: 99%

Insulator-to-conductor transition in liquid crystal-carbon nanotube nanocomposites

Basu

Garvey

2016

Journal of Applied Physics

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A small quantity of carbon nanotubes (CNTs) was dispersed in a liquid crystal (LC) and the LC þ CNT hybrid in the isotropic phase was found to exhibit an insulator-to-conductor transition when an external electric field was applied. This effect was probed by measuring the resistance of the system as a function of applied voltage across the LC cell. In an LC þ CNT hybrid, the LC molecules self-assemble themselves at the CNT surface due to p-p electron stacking, creating pseudonematic domains (PNDs) surrounding the CNTs. These CNT-embedded PNDs interact with the external electric field even in the isotropic phase of the LC. When the external field is applied, the PND-encapsulated CNTs start to rotate along the field and form wires due to their natural tendency of entanglement. The CNT-wires eventually short the two electrodes of the LC cell, manifesting an insulator-to-conductor transition in the LC þ CNT hybrid. Additional studies revealed that the cell spacing and the CNT-concentration had a significant impact on the threshold voltage across the LC cell for the insulator-to-conductor transition process. [

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“…Some attention has been given to the assembly of carbon nanotubes, another highly anisotropic nanostructure. These nanotubes can be assembled during or after synthesis. − One lesson to learn from the previous work on manipulating nanoscale materials is the importance of developing techniques that can be appropriately scaled to assemble nanostructures in parallel for a range of concentrations. The challenge is to extend this concept to nanowires that require solution-based techniques for manipulation.…”

mentioning

confidence: 99%

Electrokinetic Assembly of Selenium and Silver Nanowires into Macroscopic Fibers

et al. 2010

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Solution-phase synthesized nanowires with high aspect ratios can be a challenge to assemble into desired structures. As synthesized, these nanostructures readily bend and entangle with each other to form larger aggregates. This manuscript reports a general procedure for directing the assembly of semiconducting and metallic nanowires into fibers that can easily span distances >1 cm. Dispersions of these nanostructures in a low dielectric solution are organized by electrokinetic techniques into fibers that can be isolated from solution. Theoretical studies suggest that the assembled fibers adopt an orientation along electric field lines in the solution. The number of assembled fibers is a function of the duration of the assembly process, the magnitude of the electric potential, and the initial concentration of nanowires dispersed in solution. These findings offer a general method for the assembly of nanowires into macroscopic fibers of tunable dimensions. Fibers of selenium nanowires isolated from solution can reversibly bend in response to a source of electrostatic charges positioned in close proximity to the free-standing fiber. These flexible selenium fibers also exhibit a photoconductive response when illuminated with white light.

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Controlled Dielectrophoretic Assembly of Multiwalled Carbon Nanotubes

Cited by 13 publications

References 15 publications

Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing

Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing

Insulator-to-conductor transition in liquid crystal-carbon nanotube nanocomposites

Electrokinetic Assembly of Selenium and Silver Nanowires into Macroscopic Fibers

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