An ultrasonic sweeper with micro-/nano-concentration, decorating, transmedium extraction, and localized cleaning functions.

The strategies that allow one single device to possess multiple controlled micro-/nano-manipulation functions are demanded by various fields. In this work, we have developed a probe-type ultrasonic sweeper with rich micro-/nano-manipulation functions, including concentration, decorating, transmedium extraction, and removal of micro-/nanoscale materials at the interface between a suspension film and a non-vibration substrate. The functions are implemented with a micro-manipulation probe (MMP) in contact with the substrate, which vibrates approximately linearly and perpendicularly to the substrate. Silver nanowires on the substrate can be sucked onto the vibrating MMP's tip and accumulate to form a microsheet. By moving the MMP horizontally, nanowires on its motional path can be sucked onto the MMP's tip, and controlled cleaning can be realized. If nanoparticles are mixed into the AgNW suspension uniformly, AgNWs in the accumulated microsheet can be decorated with the nanoparticles. More importantly, the accumulated nanomaterials on the MMP's tip can be transported freely in the suspension film and even extracted into air from the liquid film. To the best of our knowledge, the ultrasonic sweeper in this work possesses the richest micro-/nano-manipulation functions than any other existing acoustic manipulators. The finite element analyses indicate that the multiple manipulation functions achieved are caused by the acoustic radiation force generated by the ultrasonic field in the suspension film.