A sensor is a detection device that can sense the information being measured and can convert the sensed information into electrical signals or other required forms of information output according to certain rules to meet the requirements of information transmission, processing, storage, display, recording and control. It is the primary link in realizing automatic detection and automatic control. The national standard GB7665-87 defines sensors as: "devices or devices that can sense the specified measured quantity and convert it into usable signals according to certain rules, usually composed of sensitive elements and conversion elements."
Sensors can be classified from different perspectives: their conversion principles (the basic physical or chemical effects of sensor operation); their uses; their output signal types and the materials and processes used to make them.
According to the working principle of sensors, sensors can be divided into two categories: physical sensors and chemical sensors:
Classification of sensor working principles Physical sensors use physical effects, such as piezoelectric effect, magnetostriction, ionization, polarization, thermoelectric, photoelectric, magnetoelectric and other effects. Slight changes in the measured signal will be converted into electrical signals.
Chemical sensors include those sensors that are causally related to phenomena such as chemical adsorption and electrochemical reactions. Slight changes in the measured signal quantity will also be converted into electrical signals.
Some sensors cannot be classified into either physical or chemical categories. Most sensors operate based on physical principles. Chemical sensors have many technical problems, such as reliability, the possibility of large-scale production, price issues, etc. Once these problems are solved, the application of chemical sensors will grow tremendously.
Sensor classification
Sensor classification 1: According to their use, sensors can be classified
Pressure-sensitive and force-sensitive sensors Position sensors
Liquid level sensors Energy consumption sensors
Speed sensors Acceleration sensors
Radiation sensors Thermal sensors
Sensor classification 2: According to their principles, sensors can be classified
Vibration sensors Humidity sensors
Magnetic sensors Gas sensors
Vacuum sensors Biosensors, etc.
Sensor classification 3: Sensors can be classified based on their output signals:
Analog sensors - convert the measured non-electrical quantity into analog electrical signals.
Digital sensor - converts the measured non-electrical quantity into a digital output signal (including direct and indirect conversion).
Pseudo-digital sensor - converts the measured signal quantity into a frequency signal or a short-period signal output (including direct or indirect conversion).
Switch sensor - when a measured signal reaches a certain threshold, the sensor outputs a set low-level or high-level signal accordingly.
Sensor classification 4: Classification by material
Under the influence of external factors, all materials will make corresponding and characteristic reactions. Among them, those materials that are more sensitive to external effects, that is, those with functional characteristics, are used to make sensitive elements of sensors. From the perspective of the materials used, sensors can be divided into the following categories:
(1) According to the type of materials used: metals, polymers, ceramics, and mixtures
(2) According to the physical properties of the materials: conductors, insulators, semiconductors, and magnetic materials
(3) According to the crystal structure of the materials: single crystals, polycrystalline, and amorphous materials
Sensor classification 5: According to their manufacturing process, sensors can be divided into:
Integrated sensors, thin film sensors, thick film sensors, and ceramic sensors
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