What is the working principle of Thermocouple Sensor?

1. Basic Principle
Thermocouple sensor is composed of two different metal or alloy materials, which form a thermocouple at the junction. When there is a temperature difference between the two ends of the thermocouple (hot end and cold end), an electromotive force, namely thermoelectric potential, will be generated in the circuit. This thermoelectric potential is related to the temperature difference between the two ends of the thermocouple and is the basis for the thermocouple sensor to measure temperature.

2. Measurement principle of thermocouple sensor
In a thermocouple sensor, the hot end (measuring end) is usually in contact with the object to be measured, while the cold end (reference end) is maintained at a relatively constant temperature (such as ambient temperature or temperature maintained by a temperature compensation device). When the temperature of the hot end changes, a thermoelectric potential will be generated in the thermocouple circuit, which is proportional to the temperature difference between the hot end and the cold end. By measuring this thermoelectric potential, the temperature of the hot end can be inferred.