How Does a Zirconia Oxygen Sensor Work?

Zirconia Oxygen Sensor

Zirconia oxygen sensors are used in a variety of applications and industries to measure the air-to-fuel ratio in combustion, automotive, oil, gas, and bio-mass environments.

How does a Zirconia Oxygen Sensor Work?

Zirconia Oxygen Sensor System

The Zirconia Oxygen Sensor utilizes a core containing two porous electrodes which are made of Zirconia ceramic elements combined with a thin layer of platinum. This element is what gives the sensor the ability to control the air-fuel ratio.

In order to control this ratio, one side of the electrode is exposed to the air and the opposite side is exposed to an exhaust gas.

The results provide a precise voltage which is accumulated in response to the difference in overall oxygen concentration.

Another fascinating feature

The small zirconium dioxide based element at the heart of the Zirconia Oxygen Sensor does NOT require a reference gas. 

This unique capability creates the innovative sensor we have today, and further removes limitations in the environment which the sensor can be operated in.

Regardless of high temperatures, humidity and oxygen pressures, the possible applications are nearly endless, making the sensor a highly valued product for integration applications. 

Let's Discuss the Zirconia Oxygen Sensor Core

Taking a look at the actual core of the Zirconia Oxygen Sensor you will notice the "heart" of the sensor, called the "sensing cell".

This unique cell is what contains the two zirconium Dioxide (ZrO2) electrodes.

The dual electrodes provide stability and consistency which enables the electrodes to separate the O2 and the oxygen ions to then be carried in and out of the ZrO2.

CO2Meter Sensor Cell Construction

The two ZrO2 squares are separated by a platinum ring which forms an airtight, sealed sensing chamber. At the outer surfaces, there are two further platinum rings which along with the center platinum ring, provide the electrical connections to the actual cell.

Two outer alumina (Al2O3) discs filter and prevent any ambient particulate matter from entering the sensor and also remove any "un-burned" gas concentrations.

This prevents contamination of the cell which may lead to unstable measurement readings.

In Figure 3-2 below, it shows a cross-section of the sensing cell with all the major components highlighted.

CO2Meter Cross Section of Sensing Cell

Overall, the Zirconia Oxygen Sensor System's cell assembly is surrounded by a heater coil which produces the necessary 700°C required for operation.

The cell and heater are then housed within a porous stainless steel cap to filter larger particles and dust and also to protect the sensor from mechanical damages.

In Figure 3-3 below, it also shows the complete sensor assembly which you will notice on the Zirconia Oxygen Sensor System.

CO2Meter Complete Sensor Assembly

There are a variety of things to consider prior to choosing any Zirconium Dioxide Oxygen (O2) Sensor or interface, such as cap, housing, sensor type and overall  application.

Sensors such as the Zirconium Oxygen Sensor System encompass a majority of these overall behaviors, are rich in conditions, and provide easy integration into a variety of environments.

Unique Main Features:

-Zirconium dioxide technology, Measuring 0.1-25% or 0.1-100% O2

-Interface electronics included

-Integral heating element

-Linear output signal

-Heat resistant, allowing severe high temperature environments

-Rugged stainless steel construction, for use in aggressive environments

-Pre-calibrated directly from the facility, does not require further calibration

-Suitable for applications in combustion control, automotive, small engines, agricultural, industrial and many others.


References:

http://co2meters.com/Documentation/Other/Zirconia_Sensors_3.pdf

https://www.sstsensing.com/what-is-a-zirconium-dioxide-oxygen-sensor/

https://en.wikipedia.org/wiki/Oxygen_sensor


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