This is a range of accurate oxygen sensors, designed for HVAC, Combustion and aerospace applications and now available as Commercial Oxygen Sensors, Medical Oxygen Sensors and Industrial Oxygen Sensors.

At temperatures above 650 deg C Zirconium Dioxide (ZrO2 ) exhibits two mechanisms:

AND Firstly, it partly dissociates, producing mobile oxygen ions within the material. Normally moving at random, these ions can be transported through the piece of ZrO2 when a DC voltage is applied across the material. This liberates an amount of oxygen at the anode proportional to the charge transported (electrochemical pumping action).

Secondly, when there is an oxygen pressure difference across a piece of ZrO2 a voltage (the Nernst voltage) is generated across it. This voltage is proportional to the natural logarithm of the ratio of the oxygen pressure on each side of the material.

These mechanisms are used in a number of oxygen sensors but our sensor makes use of both simultaneously. This removes the need for a reference pressure which simplifies the sensor operation.

Our sensor contains 2 pieces of ZrO2 with a small hermetically sealed chamber between them. One of the discs functions as a reversible oxygen pump, which is used to successively fill and empty the chamber. The second disc measures the ratio of the oxygen partial pressure difference and generates a corresponding sense voltage. A heater surrounding the sensing element produces the 650 deg C required for the ZrO2 to act as a pump.

The time taken for the pump to achieve specific minimum and maximum pressures within the chamber is a measure of the partial pressure of oxygen in the environment. Al2O3 discs filter particulate matter and neutralize un-burnt gasses to avoid contamination, which might lead to unstable readings.