Investigation of the dynamics of carbon nanotube deposition in dielectrophoresis

Dielectrophoresis is one of the popular methods in making carbon nanotube (CNT) devices using CNT solutions on pre-patterned electrodes. The interaction between the deposited and suspended nanotubes during deposition, together with the type of solution (containing surfactants or not) and electrode geometries have a significant effect in the dynamics and the results of the deposition. Here, we report the results of experiments and simulations investigating these effects. The formation of semi-periodic patterns made of stripes of nanotubes bridging the electrodes is related to the mutual effects of CNTs on each other during deposition. The periodicity of these structures depends on the geometry of the electrodes. Simulations show that the reason is changes in the electric field as a result of deposition of CNTs. These changes affect the DEP force and, therefore, the CNTs are guided toward certain spots based on their initial location.