In-Line Enrichment of Cancer Cells from Whole Blood by Cell Self-Organization in Acoustic Fields

We present a novel method for in-line acoustofluidic separation of cancer cells directly from whole blood. We report for the first time the observation that blood cells can self-organize when packed closely together in an acoustic field. We utilize this effect to enrich K-562 cancer cells and white blood cell subpopulations from whole blood at normal hematocrit levels. Further, we investigate the effect of self-organization of particles and cells with different sizes and acoustic properties. We propose that the mechanism for the phenomenon is based on the change of sign of the acoustic contrast of cancer cells relative to the densely packed red blood cells such that they are pushed to the RBC-plasma interface. This method may be useful as a rapid and gentle initial refinement stage for accessing rare cells, potentially enhancing point-of-care diagnostics and advancing treatments like immunotherapy.