The Fabrication of Directional Carbon Nanotube Networks by Dielectrophoresis With Layer-by-Layer Deposition

A carbon nanotube (CNT) has been used as electronic materials for functional electronic devices such as transistors, transparent electrodes, sensors, and Joule heating devices owing to their unique properties and high aspect ratios. However, the CNT network is randomly aligned on sheets fabricated by the spreading of a CNT suspension. In order to fabricate directional CNT network, we demonstrate the large scale alignment and assembly of CNTs by a dielectrophoretic external force, which is applied by an alternating current (AC). The alignment of the CNT network was monitored to have 2.6-17.5 times lower resistance values in the direction of the applied electrical field than in the vertical directions of the electrical field. We demonstrated that the resistance values were increased in the vertical direction by the multiple AC alignment process with layer-by-layer. Furthermore, the directionally aligned CNT network was transferred onto a nitrocellulose sheet via solvent evaporation and the electrical properties were measured. Even though we demonstrated only the limited MAAP process with CNT, the directional MAAP including transfer process could be used for diverse applications such as Joule heating transparent electrodes and flexible sensor devices.