Temperature compensated polarographic oxygen gas sensor and sensing system, particularly for automotive application

TLDR: In this paper, the output of a polarographic sensor is rendered independent of aging of electrodes and temperature effects of the solid electrolyte body, within the operating ranges of the sensor to measure the oxygen composition of exhaust gases.

Abstract: To render output of a polarographic sensor essentially independent of aging of electrodes and temperature effects of the solid electrolyte body, within the operating ranges of the sensor to measure the oxygen composition of exhaust gases, the solid electrolyte plate of, for example, 50 mm length, 8 mm width and 1 mm thickness has a sensing electrode system including a cathode (2), and an anode (3) applied thereto, connected to a voltage source (7) of controllable output voltage. An oxygen molecule diffusion barrier (6) is applied to the cathode electrode. Additionally, a further electrode pair (5,4) is applied to the solid electrolyte body (1), serially connected in the current limiting circuit including the control voltage source. The voltage across one (2,3) of the electrode pairs is measured and compared with the voltage across the other electrode pair (4,5) voltage source, since the resistance of the zirconium solid electrolyte body drops with increasing temperature at roughly the same rate as the increase in limit current flow with increasing temperature. Both electrode pairs (2,3; 4,5) on the solid electrolyte body (1) are exposed to the gases, the oxygen content of which is to be analyzed.