Flowing cells stability test and evaluation for fast flow cytometry

Cell sorting requires a stable flowing speed, especially for a fast flow cytometry like the optical time-stretch imaging. The flowing speed fluctuation of Euglena cells and Nile red particles is tested and evaluated by a home-built flowing speed testing system. Higher flowing speeds have better stability. Flowing microchannels with controlling steps also improve the speed stability. The time fluctuation is ~ 1 ms under a flowing speed of ~ 1.4 m/s. Cell sorting can be realized by either using an ultra-short delay time between the sorting point and imaging point, which is suitable for relative lower cells counting speed (~ 5000 cells/s), or developing effective fluctuation controlling methods for higher counting speed, like using step glass microchannels.