Conventional cell sorters feature 'drop in air' sorting, where cells are encapsulated inside a droplet that falls between electrically charged plates which deflect the droplet into the desired container. This process is highly stressful to cells and can kill many of the sorted cells. We re-imagine fluorescence cell sorting using acoustic waves inside a microfluidic cartridge. An acoustic wave is focused to the size of a single cell to gently isolate target cells. CellWaveTM is a gentle alternative to drop in air cell sorters that ensures the viability of even the most fragile cell types.