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What are the PM2.5 sensors?

Update: 2019-12-19 15:19 Source: LUFTMY Reading: ↻ News

With people's attention to air quality, PM2.5, as a hot word, is frequently seen in various media. Many companies have seen the huge business opportunities contained in PM2.5 governance. Therefore, many sensors or modules that can measure PM2.5 appear on the market. From the product name, they are all linked with PM2.5 to attract attention. However, as a product developer, they should carefully select according to their product positioning and demand No, choose the right sensor / module for your product.

Vector image of laser PM2.5 sensor
Vector image of laser PM2.5 sensor

According to the World Health Organization's global assessment of disease exposure and burden in 2016, up to now, air pollution - environment (outdoor) and family (indoor) - is the biggest environmental risk to health, and about one ninth of deaths are caused each year. Only one tenth of people live in cities that meet the who air quality guidelines.

1. Particles, also known as fine particles, PM2.5

Particulate matter refers to the particles with an equivalent aerodynamic diameter of less than or equal to 2.5 microns in the ambient air. It can be suspended in the air for a long time. The higher the concentration in the air, the more serious the air pollution.

Although PM2.5 is only a small component of the earth's atmosphere, it has an important impact on air quality and visibility. Compared with the coarser atmospheric particles, PM2.5 has the advantages of small particle size, large area, strong activity, easy to attach toxic and harmful substances, such as heavy metals, microorganisms, etc., and has a long stay time in the atmosphere and a long transport distance, so it has a greater impact on human health and atmospheric environment quality.

2. PM2.5 sensor is also called dust sensor and dust sensor

PM2.5 sensor can be used to detect the concentration of dust in the air around us, i.e. the value of PM2.5. The working principle is developed according to the light scattering principle: particles and molecules will scatter light under the light irradiation, and absorb part of the light energy at the same time. When a beam of parallel monochromatic light is incident on the particle field to be measured, it is affected by the scattering and absorption around the particle, and the light intensity is attenuated.

In this way, the relative attenuation rate of the incident light passing through the concentration field to be measured can be obtained. The relative attenuation rate basically reflects the relative concentration of the dust to be measured. The intensity of the light is proportional to the intensity of the electrical signal converted by photoelectric. By measuring the electric signal, the relative attenuation rate can be obtained, and then the dust concentration in the field to be measured can be determined.

3. Difference between laser PM2.5 sensor and infrared PM2.5 sensor

The principle of ordinary infrared dust sensor is to use visible infrared light, which is difficult to produce accurate scattering judgment for particles under 1 μ m, especially when the concentration is low. However, the accurate concentration of 0.3-2.5 μ m diameter particles in air per unit volume can be obtained. Generally, the wavelength of ordinary red laser is 630-650 μ m, half wave diffraction is 630-650 nm, and particles higher than 300 nm (0.3 μ m) can be detected accurately.

HPD05 Infrared dust sensor
HPD05 Infrared dust sensor

The particle sensor HPD05 has a built-in infrared light-emitting diode and a highly sensitive photoelectric receiving sensor. When the infrared light-emitting diode sends out light, it will produce reflected light when encountering dust. The photoelectric sensor reflects the concentration of dust in the air by detecting the intensity of the reflected light. The sensor directly outputs PWM signal, and the PWM width is the current concentration value.HPD05 air detection instrument has stable detection capacity, high production efficiency and double advantages. The particulate matter sensor HPD05 has the characteristics of small volume, high precision, low power consumption, short response time, stable operation under high dust concentration, etc. the indoor air quality sensor can be used in air purifier, etc.

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