6.1
6. Technical Information and Notes
Measuring principle
For measurement, the test strip is fixed to a movable carriage, the
transporter. When the flap of the measuring chamber is closed this
transporter moves the test strip into the measuring position with the
help of a motor. After a certain individual waiting time depending on
the test, the so-called Ulbricht sphere is lowered onto the test strip.
This brings the reagents contained in the test strip into contact with
the sample (if blood is used the erythrocytes have been separated
from the plasma during the waiting time) and starts the reaction.
Depending on the test, the colour reaction is measured in different
ways (end point or kinetic analysis) and at different times.
The Ulbricht sphere contains LEDs of different wavelengths and
detectors. The opto-electronic determination is performed as shown
in the following schema:
A light-emitting diode (1) flashes light of a defined wavelength onto
the surface of the test area (2). The light that strikes the strip is
reflected by the surface with varying intensity depending on the
colour of the test area.
Ulbricht sphere
Detector Microprocessor
Analog-to-digital converter
Result
Surface of test area
LED
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