Trajectory analysis of single-walled carbon nanotubes during the dielectrophoretic separation

Abstract

One of the emerging methods in the application area of microfluidic device is the dielectrophoresis (DEP)-induced separation technique. For the purpose of manipulating and separating the particles, this method has advantages such as non-destructive and scalable. Thus, there have been a growing number of investigations about the application of this method. Recently, noticeable research in this area was to separate metallic single-walled carbon nanotubes (m-SWCNTs) from semiconducting sing-walled carbon nanotubes (s-SWCNTs). During the separation there is no need of chemical modification of the SWCNTs. However, separation efficiency obtained from this method is not comparable to other methods which utilize modification of SWCNTs with chemicals. One of the reasons for the low efficiency may be poor microfluidic channel design in view of electrical properties of SWCNTs. Therefore, it is necessary to analyze the motion of SWCNTs under the DEP force. In this study, calculations of trajectory of SWCNTs, fluid velocity and electric field in the 3-dimensional domain have been performed. Fluid velocity field and electric field in a channel domain were solved from the Navier-Stokes equation and the Poisson’s equation, respectively, by COMSOL Multiphysics(R)software based on the finite element method. Then, they were used to obtain drag force and DEP force which determine different movement of m-SWCNTs and s-SWCNTs. Finally, trajectories of SWCNTs have been predicted using these forces. It is expected that this study can be helpful in achieving more effective separation of SWCNTs and realizing novel design of electrodes on microfluidic device.