text: These cells are lead/oxygen galvanic cells where oxygen molecules are dissociated and reduced to hydroxyl ions at the cathode. The ions diffuse through the electrolyte and oxidize the lead anode. A current proportional to the rate of oxygen consumption is generated when the cathode and anode are electrically connected through a resistor
  Function
  The cell reaction for a lead/oxygen cell is: 2Pb + O2 → 2PbO, made up of the cathode reaction: O2 + 2H2O + 4e− → 4OH−, and anode reaction: 2Pb + 4OH− → 2PbO + 2H2O + 4e−.
  The cell current is proportional to the rate of oxygen reduction at the cathode, but this is not linearly dependent on the partial pressure of oxygen in the gas to which the cell is exposed: Linearity is achieved by placing a diffusion barrier between the gas and the cathode, which limits the amount of gas reaching the cathode to an amount that can be fully reduced without significant delay, making the partial pressure in the immediate vicinity of the electrode close to zero. As a result of this the amount of oxygen reaching the electrode follows Fick's laws of diffusion and is proportional to the partial pressure in the gas beyond the membrane. This makes the current proportional to PO2.
  The load resistor over the cell allows the electronics to measure a voltage rather than a current. This voltage depends on the construction and age of the sensor, and typically varies between 7 and 28 mV for a PO2 of 0.21 bar