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Cytometers differ in number of technical specifications. Some of them predetermine basic aspects of data generated by the instrument. They include:


Number of detectors determines number of analysed parameters per each cell. Specifically it is number of fluorescence detectors so forward and side scatter parameters need to be added to the list of parameters (i.e. 6 colour flow cytometry produces at least 8 parameter data). On top of this, each parameter is usually detected as area, height and width of the signal pulse.


Dynamic range of detection is referred in number of channels. It also determines how many decades can be seen on log scale of flow graph. For example 262144 (2.6105) channels give 5 log decades plots.


Analog vs. digital signal processing. In analog cytometers compensation is "hard-coded" in the data and can't be changed. Also the data (most often log scaled) have any value below 0 set to 0. Newer cytometers are digital.


The ability of acquisition software to export data in correct fcs files. Sticking to standards helps with data processing :-)


Note: There is number of other instrument specifications important for experimental design (spectra of detected light, minimal particle size detected, etc.). They are not as important for the nature of the data generated and so not mentioned here.


Examples of cytometers


Cytometer (company) Detectors DR [channels] Signal
FACSCalibur (BD biosciences) 4 1024 Analog
FACS Canto II (BD biosciences) 6 - 8 2.6105 (18-bit) Digital
BD LSR II (BD biosciences) 6 - 18 2.6105 (18-bit) Digital
CyAn ADP (Beckman Coulter) 7 or 9 4096 Semi-digital





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