Measuring cell density in a acoustofluidic microcavity

Detecting changes in the density of biological cells is of paramount importance as it may reveal the cell status in processes such as differentiation and disease. Several methods have been devised to measure cell density in microfluidic devices. Here, we introduce a 3D printed microfluidic wherein cells are levitated by means of the acoustic forces of ultrasonic waves. The density can be inferred by measuring the height versus time of a single cell in free fall. We determine the density of $10\mu$m-polystyrene beads and macrophage cells (line j774.A1) with high accuracy.