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Working Principle of PM2.5 (PM10) Sensor

Working Principle of PM2.5 (PM10) Sensor

2020-03-02
The working principle of the pm2.5 sensor is developed based on the principle of light scattering. Particles and molecules will produce light scattering under the irradiation of light, while also absorbing part of the energy of the irradiated light. When a beam of parallel monochromatic light is incident on the measured particle field, it will be affected by scattering and absorption around the particle, and the light intensity will be attenuated. In this way, the relative attenuation rate of the incident light through the concentration field to be measured can be obtained. The relative attenuation rate can basically linearly reflect the relative concentration of dust in the field to be measured. The magnitude of the light intensity is directly proportional to the strength of the electrical signal converted by the photoelectric conversion. The relative attenuation rate can be obtained by measuring the electrical signal, and the concentration of dust in the field to be measured can be determined.
 
PM2.5 sensor is also called dust sensor, dust sensor, which can be used to detect the dust concentration in the air around us, that is, the value of PM2.5. Aerodynamic dust that can enter the alveolar region with a diameter of less than 10 μm is also commonly referred to as respiratory dust. Most of the dust particles with a diameter of more than 10 μm are deposited by impact, and most of them are deposited in the nasopharynx when the human body inhales, and the dust below 10 μm can enter the deep part of the respiratory tract. The majority of the dust deposited in the alveoli is less than 5 μm.

The PM2.5 sensor is designed to sense dust particles in the air. The infrared light emitting diodes and phototransistors are placed diagonally inside. Their optical axes intersect. When the air flow with dust passes through the intersection area where the optical axes intersect, the dust on the infrared Light reflection. The intensity of the reflected light is proportional to the dust concentration. The phototransistor makes it possible to detect the reflected light from the dust in the air, even very small particles such as tobacco smoke can be detected. The infrared light emitting diode emits light that encounters dust to generate reflected light. The receiving sensor detects the light intensity output of the reflected light. Signal, the concentration of dust is judged according to the intensity of the output signal light, and the concentration of different dust particles is distinguished by outputting two different pulse width modulation signals (PWM).
 
PM10 refers to particles with an aerodynamic equivalent diameter of 10 μm or less in ambient air. PM2.5 fine particles have a small diameter, a long suspension time in the atmosphere, a long distance of propagation and diffusion, and usually contain a large amount of toxic and harmful substances, so they have a greater impact on human health. PM2.5 can enter the lungs and blood. Carrying germs can be very harmful to the human body, including our respiratory system, cardiovascular system, and even the reproductive system.
 
Rika's Dust Sensor features:
 
1.High Sensitivity
 
2.Fast response
 
3.Low power consumption
 
4.Excellent stability
 

5.Long service life



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