temperature sensor

Since the early 17th century, people have been using temperature for measurement. With the support of semiconductor technology, semiconductors have been developed successively in this centuryThermocouple sensorCorrespondingly, based on the interaction law between waves and matter, acoustic temperature sensors have been developed successivelyinfrared sensorandmicrowave sensor.

There are four main types: thermocouples, thermistors, resistance temperature detectors (RTDs), and IC temperature sensors. IC includes two types: analog output and digital output.^[2]

When two conductors of different materials are connected to each other at a certain point, heating the connection point will result in a potential difference in the areas where they are not heated. The value of this potential difference is related to the temperature of the measurement point in the unheated area and the materials of these two conductors. This phenomenon can occur over a wide temperature range. If the potential difference is accurately measured and the ambient temperature of the unheated area is also measured, the temperature of the heating point can be accurately determined. Due to the need for two different materials of conductors, it is called a "thermocouple". Thermocouples made of different materials are used in different temperature ranges, and their sensitivity also varies. The sensitivity of a thermocouple refers to the change in output potential difference when the heating point temperature changes by 1 ℃. For most metal supported thermocouples, this value is approximately between 5-40 microvolts/℃.

Thermocouple sensors have their own advantages and disadvantages. They have low sensitivity, are easily affected by environmental interference signals, and are also susceptible to temperature drift from preamplifiers. Therefore, they are not suitable for measuring small temperature changes. Due to the sensitivity of thermocouples being independent of the thickness of the material, they can also be made with very fine materials. Also, due to the excellent ductility of the metal materials used to make thermocouples, this subtle temperature measuring element has a fast response speed and can measure rapidly changing processes.