Carbon Nanotube Alignment Using Dielectrophoresis: A design guideline for realizing future multiwalled carbon nanotube-based devices

The excellent electrical, mechanical, and thermal properties of single- and multiwalled carbon nanotubes (MWCNTs) have led to frequent suggestions of a new class of nanoscale devices, with carbon nanotubes (CNTs) as the fundamental building block [1]?[4]. Unfortunately, the aligned CNTs can be difficult to realize, and the majority of commercially available CNTs are sold in the form of entangled bundles, which impedes their straightforward transformation into devices since almost all of the excellent properties of CNTs are highly anisotropic. For example, the thermal conductivity of CNTs is only high in the longitudinal and not the lateral direction of the nanotubes. Thus, to exploit CNTs? properties in a device, they must be first disentangled and then aligned or oriented in a preferential direction. Nanotube disentanglement can usually be achieved via the use of surfactant in a fluid medium containing the CNTs, while a variety of techniques have been developed to align the longitudinal axes of the nanotubes.