Principle Of The Design Of An Oxygen Electrode; Parameters Determining Current - Mettler Toledo InPro 6800 Serie Bedienungsanleitung

36

10.2 Principle of the design of an oxygen electrode

There are two main types of oxygen electrodes:
– Electrodes without membrane
– Electrodes with gas-permeable membrane
(Clark Principle)
The membrane electrode according to Clark is today
most widely used. As compared to the electrode with-
out membrane it possesses the following advantages:
– Oxygen measurement in gases and solutions
– No mutual contamination of electrode and solution
– No or little dependency on flow
In the case of the Clark electrode, geometrical con-
figuration is very important. In particular, the thickness
of the electrolyte film between the cathode and the
membrane must be within narrow tolerances so as to
ensure good linearity and a low zero current (current
in a nitrogen atmosphere). The figure above exempli-
fies the principle of the design of a Clark-type oxygen
electrode.

10.3 Parameters determining current

The quantity of oxygen diffused in and the magnitude
of the electrode current are influenced by the following
parameters:
– Oxygen partial pressure of the solution
– Membrane material and thickness
– Size of cathode
– Polarization voltage
– Temperature
– Flow conditions in the solution
InPro 6800
52 200 953 C
Measuring solution
InPro 6800 O
A
© 02 / 2023 METTLER TOLEDO
Printed in Switzerland
Sensor 12/25 mm
2
Polarization
voltage
Anode
Electrolyte
Insulator
Cathode
Membrane