Temperature Sensor Overview
Publish Time: 2026-08-11
Temperature Sensor Overview
A sensor is a device or apparatus that can sense a specified measurand and convert it into a usable output signal according to a certain rule. In modern industrial production, especially in automated production processes, various sensors are needed to monitor and control various parameters in the production process, so that the equipment operates in a normal or optimal state and the products achieve the best quality.
Sensor Classification
1. Resistive sensor
2. Variable frequency power sensor
3. Weighing sensor
4. Resistance strain gauge sensor
5. Piezoresistive sensor
6. Resistance Temperature Detector (RTD) Sensor
7. Laser sensor
8. Hall effect sensor
9. Temperature sensor
10. Wireless Temperature Sensor
11. Smart Sensors
12. Photosensitive sensor
13. Vision sensor
14. Displacement sensor
15. Grating sensor
16. Infrared sensor
17. Vacuum sensor
18. Pressure sensor
19. Ultrasonic distance sensor
20. Capacitive level sensor
21. Antimony Electrode Acidity Sensor
22. Conductivity sensor
Temperature sensor definition
A temperature transducer is a sensor that can sense temperature and convert it into a usable output signal.
Classification of temperature sensors
Temperature sensors are the core component of temperature measuring instruments, and there are many different types.
According to the measurement method, it can be divided into:
• Contact
• Non -contact
Based on the characteristics of sensor materials and electronic components, they can be classified as follows:
• Resistance temperature detector
• Thermocouple
NTC temperature sensor
NTC temperature sensors are sensitive devices composed of resistive elements, connecting wires, and one or more other materials, primarily used for temperature measurement and control.
Since NTC temperature sensors use NTC thermistors as their core component, their basic terminology remains consistent with that of NTC thermistors, including:
• Resistance
• B value
• Dissipation coefficient
• Thermal time constant
• RT characteristics, etc.
In addition, due to insulation requirements, parameters such as insulation resistance and withstand voltage (insulation) need to be added.
Basic selection requirements
1. Purpose: The basic requirements for actual use must be clearly defined.
2. Rated resistance value or B value: If not specified, please provide your usage requirements, and AMPRON will recommend applicable specifications.
3. Environmental conditions for use: Temperature, humidity, installation requirements, etc. must be specified.
4. Temperature measurement and control range: including the normal operating temperature range, control range, and maximum operating temperature of the product.
5. External dimensions: Installation requirements and desired appearance must be clearly defined.
6. Multi-point control: If multi-point control is required, the temperature requirements for each control point should be provided.
Selection principle one: Determine the operating ambient temperature range
As a temperature-sensitive component, the selection of different materials for NTC temperature sensors based on their operating temperature range is crucial.
NTC temperature sensors typically consist of a sensing head (metal or plastic housing), wiring, terminals and connectors, epoxy resin or other filler materials. Appropriate materials must be selected based on the ambient temperature.
• Operating temperature ≤ 105℃: Select PVC wire with a temperature resistance of 105℃.
• Operating temperature ≤ 125℃: Select an irradiation line with a temperature resistance of approximately 125℃.
• Operating temperature ≥ 200℃: Use Teflon or silicone wire.
Note: The selection of wire must be matched with the actual use environment, and cannot be based solely on basic temperature and pressure resistance parameters.
In addition, when the temperature is above 125°C, the epoxy resin used for encapsulation also needs to be replaced accordingly.
Selection Principle Two: Determine the Temperature Measurement Accuracy
The appropriate model must be selected based on the accuracy requirements of the temperature measurement application. Accuracy is a crucial performance indicator for NTC temperature sensors, directly impacting the overall accuracy of the measurement system.
Higher precision comes at a higher cost, so it is sufficient to meet the overall precision requirements of the system.
Two factors affecting accuracy:
1. The inherent error of the thermistor
• The higher the resistance accuracy and B-value accuracy, the higher the measurement accuracy.
2. Contact method between the temperature sensor and the object being measured
Direct contact offers higher precision than indirect contact.
Furthermore, the RT curve of NTC thermistors is non-linear, making it impossible to maintain the same accuracy over a wide temperature range. Typically, the accuracy is highest at the center operating temperature, and the accuracy error increases with distance from this point.
Application examples:
• Human body temperature measurement: Select a center point around 37℃
Kettle : Set the center point to around 100℃.
• Refrigerator/Freezer: Set the center temperature to around 5℃ or -18℃.
Beer dispenser: Select center point around 4℃.
Selection Principle Three: Sensitivity required by the working environment
The appropriate model should be selected based on the required response speed for the application. Different materials have different thermal conductivity, and factors affecting response speed include:
1. Thermal time constant of the thermistor chip: The smaller the constant, the faster the response.
2. Thermal conductivity of the temperature sensor housing material: The higher the coefficient, the better the thermal conductivity.
3. Temperature sensor size: The smaller the size, the shorter the heat conduction time and the faster the response.
Thermally conductive adhesive filling the inside of the temperature sensor:
• Applying high thermal conductivity silicone grease results in a faster response than applying no grease or low thermal conductivity silicone grease.
For even faster response, ceramic temperature-sensitive adhesive can be used.
To achieve a faster response time, all of the above factors need to be considered.
Common application scenarios
Water treatment equipment: water heaters, boilers, solar energy systems, warm water bidet toilets, water purifiers, bathtubs, washbasins, etc., used for water supply or hot water temperature control.
• Kitchen appliances: microwave ovens, induction cookers, electric/gas ovens, rice cookers, IH rice cookers, electric kettles, bread makers, electric stoves, gas stoves, coffee makers, electric heating plates, electric frying pans, porridge cookers, deep fryers, etc., for temperature sensing and control; microwave ovens and electric stoves can also achieve automatic cooking based on humidity.
• Household refrigeration and washing equipment: refrigerators (internal temperature measurement and cooling, defrosting, and preservation control), washing machines/dryers (ejection temperature measurement).
