Particle-size-dependent acoustophoretic motion and depletion of micro- and nano-particles at long timescales

Wei Qiu*, Henrik Bruus, Per Augustsson

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

61 Downloads (Pure)


We present three-dimensional measurements of particle-size-dependent acoustophoretic motion of microparticles with diameters from 4.8 mu m down to 0.5 mu m suspended in either homogeneous or inhomogeneous fluids inside a glass-silicon microchannel and exposed to a standing ultrasound wave. To study the crossover from radiation force dominated to streaming dominated motion as the particle size is decreased, we extend previous studies to long timescales, where the particles smaller than the crossover size move over distances comparable to the channel width. We observe a particle-size-dependent particle depletion at late times for the particles smaller than the crossover size. The mechanisms behind this depletion in homogeneous fluids are rationalized by numerical simulations which take the Brownian motion into account. Experimentally, the particle trajectories in inhomogeneous fluids show focusing in the bulk of the microchannel at early times, even for the particles below the critical size, which clearly demonstrates the potential to manipulate submicrometer particles.
Original languageEnglish
Article number013108
JournalPhysical Review E
Issue number1
Number of pages11
Publication statusPublished - 2020


Dive into the research topics of 'Particle-size-dependent acoustophoretic motion and depletion of micro- and nano-particles at long timescales'. Together they form a unique fingerprint.

Cite this