The optochemical oxygen measurment system offers outstanding features:
The measurement principle is described here:
A luminescent (often named fluorescent) dye molecule (indicator substance) is irradiated with light of a characteristic wavelength (e.g., 520 nm), which then emits light at a longer wavelength. This shift is called „Stoke’s“ shift, the whole phenomenon fluorescence or luminescence.
This luminescence light „lights up“, which means that it is still lit for a while after switching off the excitation light. This time is referred to as the „lifetime of the luminescence process“; it is between nano seconds and a few seconds, depending on the used dye.
Excitation of luminescence by energy absorption at a specific wavelength.
Emission is shifted to longer wavelength (Stoke’s shift)
Excitation (left side of the maximum) and decay (right side of the maximum) of the luminescence indicating the luminescence life time.
Principle setup of an opto-chemical device: Luminescence excitation and detection using a LED respectively a photodiode. The oxygen sensitive dye is embedded into a polymer layer (sensitive layer).
Luminescence life time as a function of oxygen concentration. The curve is fitted with a 3 component “False light” model.