There are four main types of temperature sensors used in industrial and electronic applications — Thermocouples, RTDs (Resistance Temperature Detectors), Thermistors, and Semiconductor sensors. Each of these sensors works in a different way, and their selection depends on the accuracy, temperature range, and environment where they are used.
The first and most common type is the Thermocouple. It is made of two different metal wires joined at one end. When the junction experiences a change in temperature, it generates a small voltage, which is then converted into a temperature reading. Thermocouples are widely used in furnaces, kilns, and process industries because they can measure very high temperatures, sometimes up to 1800°C. They are fast, durable, and inexpensive but slightly less accurate than other sensors.
The second type is the RTD (Resistance Temperature Detector). This sensor works on the principle that the electrical resistance of metals changes with temperature. As the temperature increases, the resistance of the metal wire (usually platinum) also increases in a known way. RTDs are known for their high accuracy, stability, and repeatability. They are used in applications where precise temperature control is required, such as food processing, chemical plants, and laboratory equipment. However, they are more expensive and slower to respond than thermocouples.
The third type is the Thermistor, which is a type of resistor whose resistance changes significantly with temperature. It is made from ceramic materials and is highly sensitive to small temperature changes. Thermistors are ideal for applications that require precise temperature monitoring over a limited range, such as HVAC systems, medical equipment, and battery management systems. However, they are not suitable for very high-temperature environments.
The fourth type is the Semiconductor temperature sensor, also called an integrated circuit (IC) sensor. These sensors produce a voltage or current output proportional to temperature and are often used in electronic devices, microcontrollers, and consumer appliances. They are compact, affordable, and easy to interface with digital systems, but they can only measure moderate temperature ranges.
Each of these four temperature sensors — Thermocouple, RTD, Thermistor, and Semiconductor sensor — has its strengths. The right one is chosen based on the temperature range, accuracy needs, response time, and the specific industrial or electronic application.