Noncontact Manipulations of a Single Nanowire Using an Ultrasonic Microbeak

In this paper, we have put forward and demonstrated a noncontact manipulation strategy that uses an ultrasonic microbeak to suck, align, trap and transfer a single nanowire in a film of water on the surface of a glass substrate. The sucking and trapping force is generated by symmetric acoustic streaming eddies flowing into the microbeak tip in ultrasonic vibration, from the front of the microbeak and along the direction perpendicular to the microbeak vibration. A nanowire in front of the microbeak can be sucked to and trapped under the microbeak, and aligned perpendicularly to the vibration direction approximately. Sucking range of the microbeak becomes larger as its vibration increases, and the transfer speed of a sucked nanowire depends on its relative position to the microbeak. During the sucking process, a nanowire rotates to the direction perpendicular to the microbeak vibration, and the angular speed depends on the orientation angle of the nanowire. A trapped nanowire, which is not in contact with the microbeak, can be dragged on the substrate surface by moving the microbeak, along an arbitrary 2-D path in the water film. The driving force on a transferred nanowire is estimated to have an order of magnitude of 10^-14 N.