Teledyne 3290 - OEM percent oxygen analyzer - Manual (Page 18)

Operational Theory Model 3290
Teledyne Analytical Instruments 8
therefore a hybrid between a battery and a true fuel cell; where in a true
fuel cell all of the reactants are stored externally.
2.2.2 Anatomy of the Oxygen Sensor
The oxygen sensor is made of extremely inert plastic (which can be
placed confidently in practically any environment or sample stream). It
is effectively sealed, though one end is permeable to oxygen in the
sample gas. At the permeable end a screen retains a diffusion membrane
through which the oxygen passes into the cell. At the other end of the
cell is a connector. The connector mates with a miniature phone jack
that provides electrical connection to the Control Unit.
Refer to Figure 2-1, Basic Elements of a Oxygen Sensor, which
illustrates the following internal description.
Figure 2-1: Basic Elements of the Oxygen Sensor (not to scale)
At the sensing end of the cell is a diffusion membrane, whose
thickness is very accurately controlled. Near the diffusion membrane lies
the oxygen sensing element—the cathode.