Principle Of The Design Of An Oxygen Electrode - Mettler Toledo InPro 6950 Série Instructions D'utilisation

InPro 6950 Series O
termined not only by the oxygen partial pressure
but by many other electrode parameters. The elec-
trode currents of different electrode types may differ
by several powers of ten. For this reason oxygen
electrodes and amplifiers cannot be freely inter-
changed.
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 advan-
tages:
– Oxygen measurement in gases and solutions
– No mutual contamination of electrode and solu-
tion
– No or little dependency on flow
In the case of the Clark electrode, geometrical config-
uration 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.
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Printed in Switzerland
Sensor 12 mm
2
Meas uring Soluti
A
on
33
Polariza ion
Vol t age
Anode
Elec trolyt e
Insul ator
Cathode
Membrane
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