Shooting at the nanoscale: Collection and acceleration of nanowires with an external electric field

Abstract

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.