Temperature is a basic physical quantity, and all processes in nature are closely related to temperature. The temperature sensor is the earliest developed, the most widely used sensor. The market share of temperature sensors greatly exceeds that of other sensors. The temperature has been used for measurements since the early 17th century. With the support of semiconductor technology, semiconductor thermocouple sensors, PN junction temperature sensors, and integrated temperature sensors have been developed successively in this century. Correspondingly, according to the interaction law between wave and matter, acoustic temperature sensors, infrared sensors, and microwave sensors are developed successively.

Thermocouple sensor has its own advantages and disadvantages, it is relatively low sensitivity, easy to be affected by environmental interference signals, and susceptible to preamplifier temperature drift, so it is not suitable for measuring small temperature changes. Because the sensitivity of the thermocouple temperature sensor is independent of the thickness of the material, the temperature sensor can be made of very fine materials. Also due to the ductility of the metal from which the thermocouple is made, the tiny temperature measuring element has a very high response rate and can measure rapid changes.