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5 – Applications
The main inconveniences are
2 the properties of conduction evolve with age of the sensor and
2 the non-specificity of the response.
Solution 5.11 – Amperometric oxygen sensor
1. The operation of an amperometric oxygen sensor is based on determining
the diffusion limited current due to the limitation in the oxygen supply at
the cathode of a solid-oxide-electrolyte electrochemical cell. The limitation
is enforced by a diffusion barrier. The measured limiting current manifests
itself in the form of a plateau in the current-voltage curve of the cell. It is
related to the oxygen partial pressure in the gas being analyzed.
The form of the current-voltage curve in the case of a gaseous O 2 -Ar mixture
is shown in figure 109 and reveals the limiting current I ℓ .
Figure 109 – Form of current-voltage
curve of an amperometric oxygen sensor
in the case of a gaseous O 2 -Ar mixture.
2. Figure 110 shows a schematic of an amperometric sensor in which the
oxygen supply is limited by a small-diameter hole.
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Figure 110 – Schematic of an amperometric sensor
in which the oxygen supply is limited by a small-diameter hole.
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