Acoustofluidic on-chip platform for blood cell medium exchange

Efficient blood cell medium exchange is essential for eliminating plasma interference and providing a stable microenvironment in applications such as drug screening and flow cytometry. The widely used centrifugation method is limited by high sample consumption, discontinuous processing, and poor integration potential. Here, we present a high-frequency acoustofluidic platform that enables continuous, on-chip medium exchange by directing blood cells from the sample stream into a buffer stream by acoustic manipulation. By systematically optimizing platform parameters through numerical simulations and experimental validation, we achieve continuous and stable operation with a cell recovery rate of 92.9%. Notably, the unique helical trajectories of motion induced in cells by high-frequency acoustics, when combined with the well-engineered microchannel geometry and laminar interfaces, enable effective cell washing during transfer, removing up to 96% of the original medium. Additionally, owing to the universality and biocompatibility of acoustic manipulation, the proposed platform shows strong potential for medium exchange in a variety of cells and particles.