Ultrasonic Micro-cages: a New Approach for Manipulation and Monitoring of Individual Cells and for Fluid Mixing

Four designs of ultrasonic microcages are presented together with force field simulations and experimental verification. The microcages enable three-dimensional ultrasonic manipulation of individual microparticles combined with on-line monitoring using high-resolution optical microscopy. The microcages can also be employed as acoustic-streaming-based micromixers. We investigate and compare the force field distributions and streaming patterns in the cages, and we demonstrate concentration, aggregation and positioning of individual particles. The cages can be used for, e.g., studies of interactions between single cells and functionalized particles or pairs of cells in contact only with each other.