BD FACSCelesta Flow Cytometer - About fluidics

BD FACSCelesta Flow Cytometer User’s Guide100
About fluidics
Introduction This topic describes the BD FACSCelesta flow cytometer fluidics
system.
Pressure-driven
fluidics system
The fluidics system in the BD FACSCelesta flow cytometer
operates at a pressure of 5.5 psi. After passing through the sheath
filter, sheath fluid is introduced into the lower chamber of the
quartz flow cell.
Hydrodynamic
focusing
The sample to be analyzed arrives in a separate pressurized stream.
When a sample tube is placed on the SIP, the sample is forced up
and injected into the lower chamber of the flow cell by a slight
overpressure relative to the sheath fluid. The conical shape of the
lower chamber creates a laminar sheath flow that carries the
sample core upward through the center of the flow cell, where the
particles to be measured are intercepted by the laser beam. This
process is known as hydrodynamic focusing.
The objective in flow cytometric analysis is to have at most one cell
or particle moving through a laser beam at a given time. The
difference in pressure between the sample stream and sheath fluid
stream can be used to vary the diameter of the sample core.
Low sample
pressure
(12 µL/min)
High sample
pressure
(60 µL/min)
Laser beam Laser beam
Sheath
fluid
Sheath
fluid
Sheath
fluid
Sheath
fluid
Sample Sample