It is crucial to have knowledge about the different types of oxygen sensors because they play a significant role in modern engine management systems. Oxygen sensors are used to measure the amount of oxygen in the exhaust gas, which is essential for maintaining the correct air-to-fuel ratio in the engine’s combustion process. A faulty oxygen sensor can cause several problems, such as reduced fuel economy, increased emissions, and decreased engine performance. By understanding the various types of oxygen sensors, including their advantages and disadvantages, one can select the appropriate sensor for a particular application, ensuring optimal engine performance and reducing harmful emissions. Therefore, knowledge of oxygen sensors is essential for proper engine maintenance, repair, and operation.

There is no “single” universal oxygen sensor type

• Ambient temperature electrochemical oxygen sensors
• Paramagnetic oxygen sensors
• Polarographic oxygen sensors
• Zirconium oxide oxygen sensors

Below is a quick review of the various gas phase oxygen sensors.  Use this information to help you select the right oxygen sensor type for your application:

AMBIENT TEMPERATURE ELECTROCHEMICAL SENSOR

• Often referred to as a galvanic sensor, is typically a small, partially sealed, cylindrical device (1-1/4” diameter by 0.75” height) that contains two dissimilar electrodes immersed in an aqueous electrolyte, commonly potassium hydroxide.
• Refinements in electrode materials, and enhanced electrolyte formulations, the galvanic oxygen sensor provides extended life over earlier versions and are recognized for their accuracy in both the percent and traces oxygen ranges.
• Response times have also been improved.
• They are easy to damage when used with samples containing acid gas species such as hydrogen sulfide, hydrogen chloride, sulfur dioxide, etc.

PARAMAGNETIC OXYGEN SENSORS

• This is the magnetodynamic or `dumbbell’ type of design and is the predominate sensor type.
• The paramagnetic oxygen sensor consists of a cylindrical shaped container inside of which is placed a small glass dumbbell.  The dumbbell is filled with an inert gas such as nitrogen and suspended on a taut platinum wire within a non-uniform magnetic field.
• A precision optical system consisting of a light source, photodiode, and amplifier circuit is used to measure the degree of rotation of the dumbbell.
• Some paramagnetic oxygen sensor designs, have an opposing current is applied to restore the dumbbell to its normal position.
• In general, paramagnetic oxygen sensors offer very good response time characteristics and use no consumable parts, making sensor life, under normal conditions, quite good.
• Offers excellent precision over a range of 1% to 100% oxygen.
• They are quite delicate and sensitive to vibration and/or position.
• Due to the loss in measurement sensitivity, in general, the paramagnetic oxygen sensor is not recommended for trace oxygen measurements.