A sensor is a detection device that can sense the measured information, and can transform the sensed information into electrical signals or other required forms of information output according to certain rules, so as to meet the requirements of information transmission, processing, storage, Display, record and control requirements. It is the first link to realize automatic detection and automatic control. The national standard GB7665-87 defines a sensor as: "a device or device that can sense the specified measured and convert it into a usable signal according to a certain law, usually composed of sensitive elements and conversion elements".

Sensors can be classified with different viewpoints: their conversion principle (basic physical or chemical effects under which the sensor works); their purpose; the type of their output signal and the materials and processes from which they are made, etc.

According to the working principle of the sensor, the sensor classification can be divided into two categories: physical sensor and chemical sensor:

Classification of sensor working principle Physical sensors apply physical effects, such as piezoelectric effect, magnetostriction, ionization, polarization, pyroelectric, photoelectric, magnetoelectric and other effects. Small changes in the measured signal quantity will be converted into electrical signals.

Chemical sensors include those with chemical adsorption, electrochemical reaction and other phenomena as causal relationship, and small changes in the measured signal quantity will also be converted into electrical signals.

Some sensors cannot be classified into either physical or chemical classes. Most sensors operate on the basis of physical principles. There are many technical problems of chemical sensors, such as reliability problems, the possibility of mass production, price problems, etc. If these problems are solved, the application of chemical sensors will have a huge growth.

Sensor classification

Sensor classification 1: Sensors can be classified according to their use

Pressure-sensitive and force-sensitive sensors Position sensors

Liquid level sensor Energy consumption sensor

Speed sensor Accelerometer 

Radiation Radiation Sensor Thermal Sensor

Sensor classification 2: According to its principle, sensors can be classified

Vibration sensor Humidity sensor

Magnetic sensor Gas sensor

Vacuum sensor, biosensor, etc. 

Sensor classification 3: The sensor can be divided into:

Analog Sensors - Convert a measured non-electrical quantity into an analog electrical signal. 

Digital Sensor - Converts measured non-electrical quantities into digital output signals (both direct and indirect).



Pseudo-digital sensor - converts the measured signal quantity into a frequency signal or a short-period signal output (including direct or indirect conversion).



Switching Sensors - When a measured signal reaches a certain threshold, the sensor outputs a set low or high signal accordingly.

Sensor classification 4: Classification by material



Under the action of external factors, all materials will make corresponding and characteristic responses. Among them, those materials that are more sensitive to external effects, that is, those with functional properties, are used to make the sensitive elements of the sensor. Sensors can be divided into the following categories from the point of view of the materials used:

(1) According to the categories of materials used: metals, polymers, ceramics, mixtures



(2) According to the physical properties of materials: conductors, insulators, semiconductors, magnetic materials

(3) According to the crystal structure of the material: single crystal, polycrystalline, amorphous material

Sensor classification 5: According to its manufacturing process, sensors can be divided into:

Integrated Sensors, Thin Film Sensors, Thick Film Sensors, Ceramic Sensors