Flow cytometry is a widely used laser- or impedance-based method for CAR T Characterization by analyzing the expression of cell surface and intracellular molecules, characterizing and defining different cell types in a heterogeneous cell population, assessing the purity of isolated subpopulations and analyzing cell size and volume.  https://www.creative-biolabs.com/car-t/flow-cytometry-application-in-car-t-system.htm