Model Optimization And Process Simulation Of Carbon Nanotube Assembly By Dielectrophoresis

Carbon nanotubes(CNTs) have excellent properties due to their special structure. They have found wide application in the electronics, sensors, and mechanics, among others. However, CNTs produced with existing techniques are the mixture of metallic and semiconducting CNTs. As well, they are not easy to be assembled due to their tiny sizes. And this greatly limits the application of CNTs. Therefore, it is necessary to separate CNTs firstly, and then assemble them into designed devices.Mathematical model of dielectrophoresis(DEP) based on microfluidics for separating CNTs with different electrical properties is established, and the separation process is simulated. The combination of values of feasible velocity and voltage has been found for successful separation. The results can be used to separate CNTs for reduced separation time. CNTs with different sizes can also be successfully separated using DEP based on microfluidics.DEP model for CNT assembly is established, which satisfies "dipole approximation". The motion of CNTs during DEP is studied by simulation. Three-dimensional trajectories and a distribution region of initial positions from where CNTs can be successfully assembled onto the electrode gap are obtained. The DEP force, translational velocity, and assembly time have been examined. Results show that the nearer the CNT to the electrode gap, the greater the DEP force and the faster the velocity, and the shorter the assembly time. If only one side of a CNT contacts with one electrode between a pair of electrodes, the maximum electric field appears at the other side of the CNT without contacting the other electrode, easily leading to a chain assembly of CNTs between the electrode gap. The results of simulation will provide guidance for DEP assembly of CNTs.