1. What are the types of sensors?
There are many ways to classify sensors, usually the following four methods.
1. According to the input physical quantity, it is divided into: displacement sensor, pressure sensor, speed sensor, temperature sensor and gas sensor, etc.
2. According to the working principle, it is divided into: resistive type, inductive type, capacitive type and potential type, etc.
3. According to the nature of the output signal, it is divided into: analog sensors and digital sensors.
4. According to the principle of energy conversion, it is divided into: active sensors and passive sensors. Active sensors convert non-electrical quantities into electrical energy, such as electromotive force, charge sensors, etc.; passive sensors do not have an energy conversion function, but only convert the measured non-electrical quantities into electrical parameters, such as resistive and inductive sensors
2. Complete list of sensor types and characteristics
1. According to purpose
Pressure-sensitive and force-sensitive sensors, position sensors, liquid level sensors, energy consumption sensors, speed sensors, acceleration sensors, radiation sensors, thermal sensors.
2. According to principle:
Vibration sensor, humidity sensor, magnetic sensor, gas sensor, vacuum sensor, biosensor, etc.
3. According to its manufacturing process
Integrated sensors: They are manufactured using standard process technology for producing silicon-based semiconductor integrated circuits. Usually some circuits used for preliminary processing of the measured signal are also integrated on the same chip.
Thin film sensor: It is formed by depositing a thin film of corresponding sensitive material on a dielectric substrate (substrate). When using a hybrid process, part of the circuit can also be fabricated on this substrate.
Thick film sensor: It is made by coating the slurry of the corresponding material on a ceramic substrate. The substrate is usually made of Al2O3, and then heat treated to form a thick film.
Ceramic sensors: produced using standard ceramic technology or some variant thereof (sol, gel, etc.).
4. According to the purpose of measurement
Physical sensor: It is made by utilizing the characteristics of certain physical properties of the measured substance that change significantly.
Chemical sensor: It is a sensor that can convert the composition, concentration and other chemical quantities of chemical substances intoIt is made of sensitive components that form electrical quantities.
Biological sensors: Sensors made by utilizing the characteristics of various organisms or biological substances to detect and identify chemical components in organisms.
5. According to its components
Basic sensor: It is the most basic single conversion device.
Combined sensor: It is a sensor composed of a combination of different individual transformation devices.
Application sensor: It is a sensor composed of a basic sensor or a combined sensor and other mechanisms.
6. According to the mode of action
According to the mode of action, it can be divided into active and passive sensors.
Active sensors: There are also action and reaction types. This type of sensor can emit a certain detection signal to the object being measured, and can detect the changes in the detection signal produced in the object being measured, or by the detection signal. Produce a certain effect in the measured object to form a signal. The method of detecting signal changes is called the action type, and the method of detecting and responding to form a signal is called the reaction type. Radar and radio frequency range detectors are examples of the action type, while photoacoustic effects analyzers and laser analyzers are examples of the reaction type.
Passive sensors: only receive signals generated by the object being measured, such as infrared radiation thermometers, infrared camera devices, etc.
3. Types of commonly used sensors
Usually according to their basic sensing functions, they can be divided into thermal sensors, light sensors, gas sensors, and force sensors. , magnetic sensitive components, moisture sensitive components, sound sensitive components, radiation sensitive components, color sensitive components and taste sensitive components.
1. Thermal sensor
Thermal sensor is a conversion device that converts temperature into an electrical signal. It can be divided into two categories: active and passive. kind. The working principle of the former is pyroelectric effect, thermoelectric effect and semiconductor junction effect. The latter works on the thermal property of resistors, which accounts for about 55% of thermal sensors. This kind of sensor is more suitable in situations where temperature detection accuracy is required to be relatively high. The more widely used thermal resistance materials are platinum, copper, nickel, etc. They have the characteristics of large temperature coefficient of resistance, good linearity, stable performance, wide operating temperature range, and easy processing. Used to measure temperatures in the range of -200℃~+500℃.
2. Photosensitive sensor
Photosensitive sensor is one of the most common sensors. It has many types, mainly including: photoelectric tube, photomultiplier tube, Photoresistor, phototransistor, solar cell, infrared sensor, ultraviolet sensor, optical fiber photoelectric sensor, color sensor, CCD and CMOS image sensor, etc. Major domestic manufacturers include the OTRON brand. Light sensor is one of the most produced and widely used sensors. It is used in automatic control and non-electricalIt plays a very important role in electrical measurement technology. The simplest light sensor is a photoresistor, which generates an electric current when photons strike the joint.
3. Gas-sensitive sensor
Gas-sensitive sensor is a sensor used to detect gas concentration and composition. It plays an important role in environmental protection and safety supervision. extremely important role. Gas-sensitive sensors are used when exposed to gases of various components. Due to the large changes in temperature and humidity at the detection site, as well as the presence of a large amount of dust and oil mist, the working conditions are relatively harsh, and the gas affects the materials of the sensing elements. Chemical reactants will be produced and adhere to the surface of the component, often deteriorating its performance. Therefore, the gas sensor has the following requirements: it can detect the allowable concentration of alarm gas and the gas concentration of other standard values, it can work stably for a long time, it has good repeatability, it has fast response speed, and it has little influence from coexisting substances.
4. Force-sensitive sensor
Force-sensitive sensor is a conversion device that converts mechanical quantities such as stress and pressure into electrical signals. Force-sensitive sensors come in various forms, including resistive, capacitive, inductive, piezoelectric and galvanic types, each with their own advantages and disadvantages. It is widely used in various industrial automatic control environments, involving water conservancy and hydropower, railway transportation, intelligent buildings, production automation, aerospace, military industry, petrochemicals, oil wells, electric power, ships, machine tools, pipelines and many other industries.
5. Magnetic sensor
The Hall sensor is a magnetic field sensor based on the Hall effect. It is widely used in industrial automation technology and detection. Technology and information processing, etc. The Hall effect is a basic method for studying the properties of semiconductor materials. The Hall coefficient measured through the Hall effect experiment can determine important parameters such as the conductivity type, carrier concentration, and carrier mobility of the semiconductor material. The Hall effect sensor is a passive sensor that requires an external power supply to work. This feature enables it to detect low-speed operation.
6. Humidity-sensitive sensor
The humidity-sensitive sensor is able to sense changes in external humidity and convert the humidity into A device that generates useful signals. The characteristics of an ideal humidity sensor are: suitable for use in a wide temperature and humidity range, high measurement accuracy; long service life, good stability; fast response, small hysteresis, good reproducibility; sensitivity High, good linear shape, small temperature coefficient; simple manufacturing process, easy for mass production, simple conversion circuit, low cost; corrosion resistance, low temperature and high temperature resistance, etc.
7. Sound-sensitive sensor
The sound-sensitive sensor is a sensor used for flow detection. The sensor can be set with electricity when wiring. /Operate in low sensitivity range mode. The high sensitivity range is suitable for high frequency signals fluctuating at 40db. The low sensitivity range is used inHigh frequency signal fluctuating from 28db to 68db. The sensor can operate independently of the control device by providing external power. Acoustic sensors are mainly used for solid flow detection. At the same time, the device can also be used to detect water pump cavitation and liquid leakage, and then generate sufficient sound alarms.
8. Radiation sensor
After the material is irradiated by radiation. The phenomenon of changes in some of its properties (such as refractive index). Collectively called the radiation effect. For example, the refractive index of optical fibers (germanium-doped optical fibers) made of certain special components changes when exposed to radiation. The received light intensity changes, so it can be made into an optical fiber radiation sensor. The interaction between radiation and matter is the basis of all nuclear radiation sensors.
9. Vision sensor
A vision sensor has thousands of pixels that capture light from an entire image. The clarity and detail of an image is usually measured by resolution, expressed in the number of pixels. The low cost and ease of use of vision sensors has attracted machine designers and process engineers to integrate them into a variety of applications that once relied on humans, multiple photoelectric sensors, or no inspection at all. Industrial applications for vision sensors include inspection, metrology, measurement, orientation, defect detection and sorting.
10. Taste-sensitive sensor (electronic tongue)
The electronic tongue simulates the human tongue to analyze, identify and judge the sample to be tested, using multivariate statistics The method processes the obtained data, quickly reflects the overall quality information of the sample, and realizes the identification and classification of the sample. It is a detection technology that uses a multi-sensor array as a basis to perceive the overall characteristic response signal of the sample, and conducts simulated identification and quantitative and qualitative analysis of the sample. It is mainly composed of three parts: taste sensor array, signal acquisition system and pattern recognition system.
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