PM2 5 dust sensor working principle

Introduction of PM2 5 dust sensor

PM2 5 dust sensor is a general-purpose, miniaturized Laser Dust Sensor used to detect PM2.5, PM10 and other parameters. The Mie scattering particle concentration analysis technology is used to detect the dust particles in the air. Through professional algorithm and calibration detection process, the sensor has good consistency and stability. Particulate matter PM2.5\PM10 sensors are widely used in environmental monitoring of air purifiers, air quality detectors, fresh air ventilation systems, agricultural greenhouses, outdoor breeding places, and smart home equipment.

PM2 5 dust sensor function

PM2.5 sensor is also called dust sensor. The pm2 5 dust sensor can be used to detect the dust concentration in the air around us, which is the value of PM2.5. Dust with a diameter of less than 10 μm is generally called respirable dust. Most dust particles larger than 10 μm in diameter are deposited by impact.

When inhaled by the human body, most of the dust is deposited in the nasopharynx, and dust below 10 μm can enter the deep part of the respiratory tract. Most of the dust deposited in the alveoli is smaller than 5 μm.

PM10 refers to particulate matter in the ambient air with an aerodynamic diameter less than or equal to 10 μm. PM2.5 fine particles have a small diameter, a long suspension time in the atmosphere, and a long transmission distance. They usually contain a large amount of toxic and harmful substances, which have a great impact on human health.

PM2.5 can enter the lungs and blood. If it contains bacteria, it will cause great harm to the human body, including the respiratory system, cardiovascular system, and even the reproductive system.

PM2 5 dust sensor working principle

PM2 5 dust sensor working principle is developed according to the principle of light scattering. Particles and molecules will produce light scattering phenomenon under the irradiation of light, and also absorb some light energy at the same time. When parallel monochromatic light enters the particle field to be measured, it will be affected by scattering and absorption around the particle, and the light intensity will attenuate.


In this way, the relative attenuation rate of incident light can be obtained by measuring the concentration field. The relative attenuation rate can basically reflect the relative concentration of the measured dust linearly. The intensity of light is proportional to the intensity of the photoelectrically converted electrical signal. By measuring the electrical signal, the relative attenuation rate can be obtained, and then the concentration of the measured dust can be measured.

The PM2 5 dust sensor is designed to sense dust particles in the air. Infrared light-emitting diodes and phototransistors are placed in the inner corners. Their optical axes intersect. When the dust stream passes through the intersection region where the optical axis intersects, the dust will reflect infrared light, and the intensity of the reflected light is proportional to the dust concentration. Phototransistors enable it to detect the reflected light of dust in the air. Even very small smoke particles, such as tobacco, can be detected. The light emitted by the infrared LED will produce reflected light when it meets dust. The sensor receives the light intensity of the reflected light and the output signal, determines the dust concentration according to the light intensity of the output signal, and outputs two different pulse width modulation (PWM) signals to distinguish the concentration of different dust particles.