Working Principle of Temperature Sensor

Working principle of temperature sensor - thermistor

Thermistors are usually made of ceramic materials, such as nickel, manganese, or cobalt oxides plated in glass, which makes them easily damaged. Compared to the quick acting type, their main advantage lies in their response speed to any changes in temperature, accuracy, and repeatability.

Working principle of temperature sensors - Resistance Temperature Detectors (RTDs)

RTD is an accurate temperature sensor made by winding high-purity conductive metals (such as platinum, copper, or nickel) into coils. The resistance variation of an RTD is similar to that of a thermistor. Thin film RTDs can also be provided. These devices have a thin layer of platinum paste deposited on a white ceramic substrate.

Resistance temperature detectors have a positive temperature coefficient (PTC), but unlike thermistors, their output is very linear and can produce very accurate temperature measurements.

Working principle of temperature sensor - thermocouple

One of the most common temperature sensors includes thermocouples because they have a wide temperature operating range, reliability, accuracy, simplicity, and sensitivity. Mainly due to its small volume. Thermocouples also have the widest temperature range among all temperature sensors, ranging from below -200 ℃ to far above 2000 ℃.

Thermocouples are typically composed of two joints of different metals (such as copper and constantan) welded or pressed together. One of them is called the cold end, which is maintained at a specific temperature, while the other is the measuring end, which is called the hot end.