The temperature sensor is the earliest developed and most widely used type of sensor. The market share of temperature sensors greatly exceeds that of other sensors. From the beginning of the 17th century, people began to use temperature for measurement. With the support of semiconductor technology, semiconductor thermocouple sensors, PN junction temperature sensors and integrated temperature sensors have been developed this century.
If two conductors of different materials are connected to each other at a certain point, heating the connection point will cause a potential difference in the parts where they are not heated. The value of this potential difference is related to the temperature of the measuring point at the unheated part, and is related to the materials of the two conductors. This phenomenon can occur in a wide temperature range. If you accurately measure this potential difference, and then measure the ambient temperature of the unheated part, you can accurately know the temperature of the heating point. Since it must have conductors of two different materials, it is called a "thermocouple". Thermocouples made of different materials are used in different temperature ranges, and their sensitivity is also different.
Thermocouple sensor has its own advantages and disadvantages. Its sensitivity is relatively low, and it is easily affected by environmental interference signals, and it is also easily affected by the temperature drift of the preamplifier, so it is not suitable for measuring small temperature changes. Because the sensitivity of the thermocouple temperature sensor has nothing to do with the thickness of the material