How an Optical Oxygen Sensor works

An optical oxygen 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 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:

• Non-destructive:no oxygen consumed during measurement

• User-friendly:no electrolyte needed, no polarization time required

• Ecologically friendly:no chemicals required

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