Density-dependent separation of encapsulated cells in a microfluidic channel by using a standing surface acoustic wave

Jeonghun Nam, Hyunjung Lim, Choong Kim, Ji Yoon Kang, Sehyun Shin

Research output: Contribution to journalArticlepeer-review

105 Citations (Scopus)


This study presents a method for density-based separation of monodisperse encapsulated cells using a standing surface acoustic wave (SSAW) in a microchannel. Even though monodisperse polymer beads can be generated by the state-of-the-art technology in microfluidics, the quantity of encapsulated cells cannot be controlled precisely. In the present study, mono-disperse alginate beads in a laminar flow can be separated based on their density using acoustophoresis. A mixture of beads of equal sizes but dissimilar densities was hydrodynamically focused at the entrance and then actively driven toward the sidewalls by a SSAW. The lateral displacement of a bead is proportional to the density of the bead, i.e., the number of encapsulated cells in an alginate bead. Under optimized conditions, the recovery rate of a target bead group (large-cell-quantity alginate beads) reached up to 97% at a rate of 2300 beads per minute. A cell viability test also confirmed that the encapsulated cells were hardly damaged by the acoustic force. Moreover, cell-encapsulating beads that were cultured for 1 day were separated in a similar manner. In conclusion, this study demonstrated that a SSAW can successfully separate monodisperse particles by their density. With the present technique for separating cell-encapsulating beads, the current cell engineering technology can be significantly advanced.

Original languageEnglish
Article number024120
Issue number2
Publication statusPublished - 2012 Apr 26

ASJC Scopus subject areas

  • Biomedical Engineering
  • General Materials Science
  • Condensed Matter Physics
  • Fluid Flow and Transfer Processes
  • Colloid and Surface Chemistry


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