A numerical study of the forces affecting the movement of carbon nanotubes in the solution during dielectrophoresis

Dielectrophoresis (DEP) is one of the most popular methods for fabricating devices based on nanotubes and nanowires. During a typical dielectrophoretic deposition experiment, several forces other than the DEP force itself could play important roles; however, their effects have often been neglected. Here, a particle tracing approach is used to follow the path of carbon nanotubes (CNTs) from suspension in the solution to deposition on the substrate surface, taking into account several influential factors: the DEP force, the movement of the solution itself, and the Brownian movement of the CNTs. The mechanisms involved in the deposition of metallic and semiconducting nanotubes, as well as the extent of effectiveness of each force in various scenarios during deposition, are explored. We show that the Brownian and electrothermal forces are by no means negligible in many cases and, in fact, can be of primary importance in the final results.