Temperature sensor types: a comprehensive guide from principle to application

1. What is a temperature sensor? ​​

A temperature sensor is a device that can convert temperature changes into electrical or digital signals, which is equivalent to the "temperature antenna" of an object. It is widely used in:

● ​Industry: furnace temperature control, pipeline leakage monitoring;

● ​Life: refrigerator preservation, air conditioning automatic temperature adjustment;

● ​Medical: forehead thermometer temperature measurement, surgical instrument disinfection monitoring;

● Technology: Battery overheat protection, automotive engine management.

​Why is it important? ​​

Temperature is a core parameter in industrial production and daily life. According to statistics, about 50% of the global sensor market is occupied by temperature sensors. Without it, smart devices cannot operate, factories may explode due to high temperatures, and hospitals cannot quickly diagnose illnesses.

2. Two core types: contact vs non-contact​

​1. Contact sensor: direct “touch” temperature measurement​

Thermocouple​

​Principle: Temperature difference voltage is generated at the junction of two different metals (such as copper and nickel).

Applicable scenarios: Steel plant furnace (-200℃~2300℃), automobile exhaust pipe temperature measurement.

​Features: Durable, but requires regular calibration.

Thermal resistor​

​Principle: The resistance of metals (such as platinum and copper) changes with temperature.

​Applicable scenarios: laboratory constant temperature box (-200℃~600℃), refrigerator temperature control.

​Features: Extremely high accuracy (±0.1℃), but slow response, low absolute resistance, expensive.

Thermistor (NTC)​

Principle: The resistance of semiconductor materials is sensitive to temperature (NTC temperature drops and the resistance value increases).

Applicable scenarios: high-precision temperature measurement, surge suppression, liquid level detection.

​Features: fast response speed, non-wire diameter, power supply required.

​2. Non-contact sensor: remote temperature measurement

​Infrared sensor

Principle: Capture infrared radiation emitted by objects (all objects>0℃ will radiate heat energy).

​Applicable scenarios: Overheat warning of power equipment (such as transformers), human body temperature screening (forehead temperature gun).

​Features: No contact is required, but the surface color and material of the object must be considered (such as glass will reflect infrared rays).

​Radiation Thermometer​

​Principle: Determine the temperature by analyzing the thermal radiation spectrum of the object.

​Applicable scenarios: Molten steel temperature measurement in the metallurgical industry (up to 3000℃).

III. Other important types and innovative technologies​

Integrated temperature sensor​

Principle​: Integrate the temperature sensing element with the circuit and directly output a digital signal (such as DS18B20).

Applications: Smart home (temperature and humidity monitoring), wearable devices (sports bracelets).

Advantages: Small size, strong anti-interference ability, high precision. ​