Simulation study on trajectory of dielectrophoretic force controlled nanowires

Nanoscale manipulation is of tremendous importance in the application of nanowire-based devices like chemical and biological sensors, light-emitting diodes, and field effect transistors. In order to fabricate nanodevices with high throughput, nanowires need to be manipulated towards pre-defined electrodes with high efficiency. Dielectrophoresis (DEP) provides a noninvasive, nondestructive method to effectively align nanowires. In this paper, the trajectory of single nanowire manipulated by DEP force in liquid is analyzed and simulated. Because the electrode gap is usually shorter than the nanowire, the electric field generated by the electrode pair is highly nonuniform along the nanowire. Using an approach similar to finite element, the DEP force applied to the nanowire as well as the torque induced by DEP can be precisely calculated by dividing the nanowire into small segments. By assuming the electric field is uniform along each segment, the total force and torque on the nanowire induced by DEP can be obtained. By considering the drag force from the surrounding liquid, the overall force on the nanowire is calculated, thus the trajectory of nanowire manipulated by DEP force is obtained. The simulation results show that the DEP force is able to attract the nanowire to electrodes and to force it bridge the gap between electrodes.