Directed transport and location-designated rotation of nanowires using ac electric fields

The motion control of individual nanowires is essential for effective nanowire manipulation strategies. In this paper, we demonstrate a simple and general method to dynamically control the motion of a chemically untreated nanowire in a quadrupole electrode structure. The motion of single nanowires was determined by positive dielectrophoresis and orientational torque, which were induced by optionally exerting ac signals onto specific electrodes for regulating the electric field distribution in real time. A silver nanowire was guided to transform postures and transport directionally in a working regime of about 115 mu m x 115 mu m. The selected nanowire was then transported to a region of weak gradients and forced to rotate at the designated location subsequently. The behavior of the nanowires, including their posture, cornering time, linear displacement and location-designated rotation, was dynamically monitored and regulated. A simple analytical model was developed to derive the driving forces and torques on the nanowire.