Microfluidics and Nanofluidics

, Volume 17, Issue 5, pp 879–890 | Cite as

Separation of particles using acoustic streaming and radiation forces in an open microfluidic channel

  • Citsabehsan Devendran
  • Ian Gralinski
  • Adrian NeildEmail author
Research Paper


In this study, a method to separate particles, within a small sample, based on size is demonstrated using ultrasonic actuation. This is achieved in a fluid, which has been deposited on a flat surface and is contained by a channel, such that it has a rectangular wetted area. The system utilises acoustic radiation forces (ARFs) and acoustic streaming. The force field generates two types of stable collection locations, a lower one within the liquid suspension medium and an upper one at the liquid–air interface. Acoustic streaming selectively delivers smaller particles from the lower locations to the upper ones. Experimental data demonstrate the ability to separate two sets of polystyrene microparticles, with diameters of 3 and 10 μm, into different stable locations. Methods to reduce migration of larger particles to the free surface are also investigated, thereby maximising the efficiency of the separation. Extraction of one set of 99 % pure particles at the liquid–air interface from the initial particle mixture using a manual pipette is demonstrated here. In addition, computational modelling performed suggests the critical separation size can be tuned by scaling the size of the system to alter which of ARFs and acoustic streaming-induced drag forces is dominant for given particle sizes, therefore presenting an approach to tunable particle separation system based on size.


Acoustic radiation force Particle manipulation Ultrasonic standing wave Open fluid Sorting 



The authors gratefully acknowledge the support of the Australian Research Council in the form of Grant No. DP110104010.

Supplementary material

Supplementary material 1 (WMV 13484 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Citsabehsan Devendran
    • 1
  • Ian Gralinski
    • 1
  • Adrian Neild
    • 1
    Email author
  1. 1.Laboratory for Micro Systems, Department of Mechanical and Aerospace EngineeringMonash UniversityClaytonAustralia

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