No abstract

The wide utilization of nanomanipulation as a promising approach in microorganisms, nanoelectromechanical systems, and assembly of nanostructures remarks the importance of nanostructures' motion in electric fields. Here, we study the rotational dynamics of metallic and non-metallic nanowires (NWs) in a static uniform electric field in viscous dielectric liquids. For metallic NWs, it has been theoretically shown that the electric field-induced rotation is practically independent of the geometrical dimensions and the electrical properties of NWs. Our experimental results for suspended silver (Ag) NWs in microscope oil are perfectly in agreement with this model. However, in the case of TiO2 NWs, as an example of non-metallic NWs, we surprisingly observe the exact same electromechanical torque as metallic Ag NWs under the same experimental conditions. This is mainly explained by NWs' high aspect-ratio which allows one to ignore the non-axial component of the electric field inside the NWs. Therefore, all high-aspect-ratio metallic Ag and non-metallic TiO2 NWs demonstrate an identical rotational speed in the same dielectric liquid and electric field. This result can be used for the controllable alignment or synchronous rotation of an ensemble of different types of NWs for hybrid and advanced devices.

We report an approach for collecting, charging, and exceedingly fast motion of silver nanowires (Ag NWs) using an external static electric field. With a proper choice of suspension medium, dispersed Ag NWs can be efficiently driven to align and accumulate vertically on the edges of two parallel gold microelectrodes on a glass substrate surface by dielectrophoresis. Then, at sufficiently high electric fields (>2.0×105 V/m), these NWs break at the electrode contact point while carrying some net charge. Afterwards, they immediately accelerate in the field direction and, despite an extremely low Reynolds number for the motion of NWs in viscous liquids, move with high speeds (>25  mm/s) toward the counter electrode. By solving the appropriate equation of motion, the amount of the net charge on the NWs in the beginning of the motion is estimated as ∼1×10−14 C. The described NW-shooting mechanism can be employed to construct a NW “gun” for piercing soft thin membranes at nanoscale. Furthermore, we show that the interplay of the competing dielectrophoretic and electric field forces leads to interesting dynamics for the NWs.