ABX Pentra 80 RAB108BA, User Manual, Page: 205 / 306

Description & Technology
Measuring principles
Pentra 80 - User Manual - RAB108EA
6–11
3.2. CBC detection principles
3.2.1. RBC/PLT
The RBC’s and PLT’s are measured by an
electronic impedance variation princi-
ple. This means that an electronic field
is generated around the micro-aperture
within the chamber in which the blood
cells are pulled through.
The sample is diluted with an electroly-
tic Diluent (electronic current
conducting fluid), mixed then pulled
through a calibrated micro-aperture. Two
electrodes are placed on either side of
the aperture and electric current conti-
nuously passes between the two
electrodes.
As the blood cells pass through the aper-
ture, they create resistance (Impedance)
in the electronic field between the two
electrodes. The voltage, which measures
the cells, is proportional to the size of
the cell. Since the current is constant
and remains unchanged, the larger the
cell is, the «more» resistance it has. The
smaller the cell is, the «less» resistance
it has.
These electronic voltages vary in pulse
size as the cells pass through the aper-
ture. The pulses are amplified,
channeled according to size and thres-
hold, grouped and then mathematically
calculated along with the calibration
coefficients to give a final numerical va-
lue for both RBC’s and PLT’s.
▼ Results
Number of cells counted per volume unit
x calibration coefficient
▼ Histograms
RBC : Distribution curves on 256 coun-
ting channels from 30fl to 300fl.
PLT : Distribution curves on 256 channels
from 2fl to a mobile threshold. This
threshold moves according to the micro-
cyte population present in the analysis
area.
Fig. 6–13 Impedance Principles
Fig. 6–14 RBC distribution curve
Fig. 6–15 PLT Distribution curve
Time
Time
Analogue conversion
Number of cells
Data integration and plotting
of RBC distribution curve
RBC
Plt Pulse
RBC pulse
Pulse height
Cell size
Number of cells
Cell size
Analogue conversion
PLT
Data integration and plotting
of PLT distribution curve
Cell size
Cell size
Number of cells
Number of cells