What is an oxygen sensor?

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What is an oxygen sensor?

The function of the oxygen sensor is to monitor whether the combustion of the mixture in the engine is complete effectively regulating the fuel system. The main purpose 

is to enable the car to better comply with emission regulations, therefore the oxygen sensor is widely used in electronic control fuel injection systems mainly applied to the ECU.

Type of oxygen sensor

lambda sensor

Titanium dioxide (TiO2) type oxygen sensor

Thin mixed ratio sensor

Zirconia Oxygen Sensor

Oxygen sensors are typically installed on the exhaust pipe. A thin layer of platinum is coated on both the inner and outer surfaces of the zirconia tube, which serves as both an 

electrode and a catalyst. The inner side of the zirconia tube is exposed to atmospheric air and maintains a constant oxygen concentration, while the outer side directly interfaces 

with the exhaust gas, which has a lower oxygen concentration. During operation, the high temperature of the exhaust pipe causes oxygen separation. Due to the difference in 

oxygen concentration between the two surfaces of the outer electrode, oxygen ions flow from the side of higher concentration to the side of lower concentration, generating an 

electromotive force. In a sense, it functions more like a chemical cell with a smaller capacity, also known as an oxygen concentration difference cell.

Titanium dioxide oxygen sensor

The titanium dioxide oxygen sensor utilizes the characteristic of the resistivity of semiconductor material titanium dioxide which changes with variations in oxygen content in the 

exhaust pipe. It is known as a resistive oxygen sensor. This type of sensor has a high resistance value; when titanium dioxide is deficient in oxygen on its surface, the resistance value 

decreases.

Thin mixed ratio sensor

The generation of rare mixed ratio sensors is based on the fundamental control principle of being expanded upon the zirconia-type oxygen sensor. As mentioned earlier, the zirconia-type 

oxygen sensor has a characteristic that when oxygen ions move, it causes the generation of an electromotive force. If a reverse procedure is applied, applying voltage to the zirconia 

component will cause the movement of oxygen ions. According to this step, the desired ratio value can be controlled by a computer.

Titanium dioxide (TiO2) oxygen sensor

Titanium dioxide oxygen sensor is a type of sensor made by utilizing the characteristic that the conductivity of porous conductor TiO2 changes with variations in oxygen content in the 

exhaust gas. The working principle of titanium dioxide oxygen sensor differs significantly from that of zirconia oxygen sensor, as it employs the characteristic that the conductivity of 

porous conductor TiO2 varies with changes in oxygen content in the exhaust gas.