In a paper published in the ACS Nano journal, "Enriching Nanoparticles via Acoustofluidics", they describe an acoustofluidic nanoparticle-enrichment device able to generate single vortex acoustic streaming inside a glass capillary through the use of low-power acoustic waves.
Operating at down to 5V, the low-power set up consists of a piezoelectric substrate (LiNbO3) with chirped interdigital transducers (IDTs) fabricated on top and a square glass capillary bonded on the substrate through a thin UV epoxy layer. By applying a radio frequency signal to the transducers (in the megahertz range), a SAW (surface acoustic wave) is generated and travels perpendicular to the glass capillary, actuating a torsional vibration mode and generating a type of acoustic streaming with a single vortex.
This seemingly simple setup was first proven and understood with mechanical simulation tools. Based on these results, the researchers were able to optimize and develop a working prototype, combining single vortex acoustic streaming with an acoustic radiation force to enrich submicrometer- and nanometer-sized particles within the small capillary volume.