::: Application Flash
How an Optical Oxygen Sensor works
How is it possible that the oxygen concentration in beverages
can be quantified by means of light?
Just read and learn the basics!
Photo: Application image
Few components provide a lot of information
Did you know ...
An optical oxygen (O2) sensor quickly and reliably detects the amount of
O2 in liquid or gaseous media. Generally, the O2 measurement remains
unaffected by other gases. An optical O2 sensor consists of
... that different polymer matrices and
different dyes influence the properties
of the sensor, for example its sensitivity
in certain ranges?
• a light-emitting diode (LED),
• an inert carrier holding the light-sensitive layer where dye molecules are
embedded in a polymer matrix and protected by an optical insulation
layer,
• and a photodiode plus filter to quantify the emitted light.
What happens in the absence or presence of oxygen?
If no O2 is present in the sample, the
dye absorbs excitation light, emitted
by the LED, gets transferred to a
higher energy level and emits light
again. The emission light is
time-delayed and has a different
wave length. The filter in front of the
photodiode ensures that only
emitted light is detected.
Is O2 present in the sample, the dye
absorbs excitation light, but in its
excited state the energy is taken
over by O2 molecules. The dye has
now less energy left to emit. The
more O2, the less emitted light gets
to the photodiode.
The sensor’s characteristics speak for themselves:
How to quantify the O2
concentration ?
The emission light is time-delayed with
respect to the excitation light. The time
shift between excitation and emission
light is independent from the intensity.
It is proportional to the partial pressure
of O2 and acts as a measure for the O2
concentration.
LED
Photodiode
Filter only
lets emitted
light pass
Inert carrier
Light-sensitive layer
Photo: The instrument
Optical insulation
O2 O O
O2 O2
layer
O2 O2 O2 2 2
Do you have any questions?
Contact Anton Paar directly: 
[email protected]
• Non-destructive: no oxygen consumed during measurement
• User-friendly: no electrolyte needed, no polarization time required
• Ecologically friendly: no chemicals required
XDLIA021EN-A
www.anton-paar.com