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What are the physical sensors? How does the physical sensor work?

Author: Release time:2019-08-12 Source: Font: Big Middle Small View count:28

What are the physical sensors?

According to its purpose

Pressure sensitive and force sensitive sensor position sensor liquid level sensor energy sensor speed sensor

Acceleration sensor ray radiation sensor thermal sensor 24 GHz radar sensor

According to its principle

Vibration sensor humidity sensor magnetic sensor gas sensor vacuum sensor biosensor.

Press output signal

Analog Sensor - Converts the measured non-electrical quantities into analog electrical signals. Digital Sensor - Converts the measured non-electrical quantities into digital output signals (both direct and indirect).膺 Digital Sensor - Converts the measured semaphore into the output of a frequency signal or short-cycle signal (including direct or indirect conversion). Switch Sensor - When a measured signal reaches a certain threshold, the sensor outputs a set low or high signal accordingly.

According to its material

Under the influence of external factors, all materials will have a corresponding and characteristic response. The materials that are most sensitive to external influences, that is, those with functional properties, are used to make sensitive components of the sensor. Sensors can be divided into the following categories from the point of view of the applied materials:

(1) According to the type of materials used: metal polymer ceramic mixture

(2) According to the physical properties of the material: conductor insulator semiconductor magnetic material

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

Sensor development work closely related to the adoption of new materials can be summarized into the following three directions:

(1) Explore new phenomena, effects, and reactions in known materials and then make them practical for use in sensor technology.

(2) Explore new materials and apply known phenomena, effects, and reactions to improve sensor technology.

(3) Explore new phenomena, new effects and reactions on the basis of researching new materials, and implement them in sensor technology. Advances in modern sensor manufacturing depend on the development of new materials and sensitive components for sensor technology. The basic trend in sensor development is closely related to the application of semiconductors and dielectric materials.

According to its manufacturing process

Integrated sensor, film sensor, thick film sensor, ceramic sensor. Integrated sensors are fabricated using standard process technology for the production of silicon-based semiconductor integrated circuits. Part of the circuitry used to initially process the signal under test is also typically integrated on the same chip. The thin film sensor is formed by a film of a corresponding sensitive material deposited on a dielectric substrate (substrate). When a mixing process is used, part of the circuit can also be fabricated on this substrate. The thick film sensor is made by coating a slurry of a corresponding material on a ceramic substrate, which is usually made of Al2O3, and then heat-treated to form a thick film. Ceramic sensors are produced using standard ceramic processes or some variation thereof (sol-gel, etc.). After the appropriate preparatory operation is completed, the formed component is sintered at a high temperature. There are many common characteristics between the two processes of thick film and ceramic sensors. In some respects, the thick film process can be considered as a variant of the ceramic process. Each process technology has its own advantages and disadvantages. Ceramic and thick film sensors are more reasonable due to lower capital investment required for research, development and production, and high stability of sensor parameters. (Air Monk HVAC experts provide)

According to its measurement

Physical sensors are made using properties that significantly change certain physical properties of the substance being measured. Chemical sensors are made of sensitive components that convert chemical quantities such as chemical composition and concentration into electrical quantities. Biosensors are sensors that use the properties of various biological or biological materials to detect and identify chemical components in living organisms.

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How physical sensors work

A physical sensor is a sensor that detects physical quantities. It is a device that uses certain physical effects to convert the measured physical quantity into a signal in the form of energy that is easy to process. The signal it outputs has a definite relationship with the input signal. The main physical sensors are photoelectric sensors, piezoelectric sensors, piezoresistive sensors, electromagnetic sensors, pyroelectric sensors, optical fiber sensors, and the like.

As an example, let's take a look at the more commonly used photoelectric sensors. Such a sensor converts an optical signal into an electrical signal, which directly detects radiation information from an object, and can also convert other physical quantities into an optical signal. The main principle is the photoelectric effect: when light is irradiated onto a substance, the electrical effect on the substance changes, and the electrical effects here include electron emission, conductivity, and potential current. Obviously, a device that can easily produce such an effect becomes a major component of a photoelectric sensor, such as a photoresistor. In this way, we know that the main working process of the photoelectric sensor is to receive the corresponding light, convert the light energy into electrical energy through a device like a photoresistor, and then obtain the desired output through the amplification and denoising processing. electric signal. The output electrical signal here has a certain relationship with the original optical signal, usually a nearly linear relationship, so that the calculation of the original optical signal is not very complicated. The principles of other physical sensors can be analogized to photoelectric sensors.

How to distinguish physical sensors

There are many types of sensors, and the same sensors can be classified in different ways. One type is to distinguish sensors from measurement purposes. Such sensors can be classified into physical sensors, chemical sensors, and the like. The following is a brief analysis of physical sensors. Physical sensors can be divided into structural sensors and physical sensors.

Structured sensors are based on structures (such as shape, size, etc.) that are sensed (sensitive) by certain physical laws and converted to electrical signals for measurement. For example, a capacitive pressure sensor must have a capacitive sensing component designed according to specified parameters. When the measured pressure acts on the moving plate of the capacitive sensing component, a change in the capacitance gap causes a change in the capacitance value, thereby achieving Measurement of pressure. Another example is a resonant pressure sensor, which must be designed to produce a suitable resonant sensitive component that senses the measured pressure. When the measured pressure changes, the equivalent stiffness of the resonant sensitive structure is changed, resulting in a change in the natural frequency of the resonant sensitive component. Measurement of pressure.

A physical sensor is a sensor that is measured and converted into an available electrical signal by utilizing the intrinsic properties and effect perception (sensitivity) of certain functional materials. For example, a piezoelectric sensor made of a quartz crystal material having piezoelectric characteristics is obtained by using a positive piezoelectric effect of a quartz crystal material to realize pressure measurement; and a semiconductor material is used to induce internal stress under a measured pressure. A piezoresistive sensor made by a change in its resistance value is a pressure measurement using a piezoresistive effect of a semiconductor material.

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In general, physical sensors have certain requirements for physical effects and sensitive structures, but the focus is different. Structured sensors emphasize the need to rely on precision-designed structures to ensure their normal operation; while physical-type sensors rely primarily on the physical and physical effects of the material to achieve the measured inductance. In recent years, due to the rapid development and advancement of materials science and technology, physical sensor applications have become more and more widespread. This is closely related to the convenience of such sensors for mass production, low cost and ease of miniaturization.

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