Methods of Automated Cell Counting
& Differentiation
Hematology Review 330
METHOD PRINCIPLE APPLICATION
Electrical impedance
(Coulter principle)
Radio frequency (RF)
Optical light scattering
(flow cytometry)
Low-voltage direct current (DC) resistance. ↑resistance (impedance)
when nonconductive particles suspended in electrically conductive diluent
pass through aperture. Height of pulses indicates cell volume, # pulses
indicates count.
High-frequency electromagnetic probe measures conductivity. Change in
RF signal provides information about nucleus-to-cytoplasm ratio, nuclear
density, granularity.
Hydrodynamically focused stream of cells passes through quartz flow cell
past light source (tungsten halogen lamp or laser light). Scattered light is
measured at different angles. Provides information about cell volume &
complexity, e.g., granularity.
Cell counting & sizing
WBC differential
Cell counting & sizing,
WBC differential
