Cell sorting

Question
Herber et al. (2010) “A low-pressure sort was performed on the BD FACSAria cell sorter with a 100 iμm nozzle.”

What does this mean? What is the significance of “low-pressure” and of this particular nozzle?

Answer
The FACSAria has two nozzle sizes, 70 um and 100 um. For good stream stability, it is important that the cells being sorted are 1/4 to 1/5 the size of the nozzle. This gives the FACSAria an effective limit on sorting cells below 50 um in diameter.

Furthermore, the stability of the stream is related to the nozzle size. Using the 70 um nozzle, the instrument is stable at 70 PSI (high pressure sort), and for most cell types this is the best setting. If the cells are small and fragile, the pressure can be reduced to 35 PSI (medium pressure sort). For larger cells, such as adherent cell lines, the use of the 100 um nozzle at 20 PSI (low pressure sort) is best.

(From the FACSaria sorting guidlines listed below)