Controlled Aggregation And Transportation Of Nanoparticles Using Ultrasonic Needle Probe

Efficient and reproducible aggregation of nanoscale materials and controlled transportation of the aggregated nano materials has huge potential applications in nano fabrication. Here we report an ultrasound based strategy to aggregate nanoparticles at an arbitrary location at the interface between a non-vibrating substrate and water film, and to transport the aggregated spot freely at the interface. The strategy employs the acoustic streaming, which is generated by an ultrasonic needle probe in vibration. In the experiments, the Si nanoparticles are aggregated under the ultrasonic needle probe at a desired location, forming a round spot of nano materials, and the round spot can be transported through an arbitrary path at the interface by moving the device. The dependencies of the acoustic streaming field around the ultrasonic needle probe on the parameters are clarified by numerical simulations.