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How to solve the long-term stability problem of PM2.5 sensor?

Update: 2019-12-19 15:32 Source: LUFTMY Reading: ↻ News

From the global distribution of air pollution, North America and Europe have better air quality, India and China are the worst, while in China, the north is worse than the south. In recent years, China's situation is not very good, which is greatly affected by PM2.5. Therefore, it is necessary for us to improve the environment, which should be measured first.

The air pollution
The air pollution

Now, PM2.5 (particulate matter) sensors have been widely used, and many companies have launched such sensors. LUFTMY, a global sensor supplier, has also launched LD series PM2.5 sensors. It solves a big problem that PM2.5 sensor customers complain about, namely, long-term stability. What "black technology" is used in it?

How to solve the long-term stability problem of PM2.5 sensor
How to solve the long-term stability problem of PM2.5 sensor

What is particulate matter?

Particulate matter is a mixture of solid particles and droplets in the air. Inhalation of particulate matter can cause serious health problems. The smaller the particles are, the easier it is for them to penetrate the respiratory system and enter the blood through respiration. Historically, the value of particulate matter was measured in μ g / m3.

Particles: local distribution considerations

In indoor environments, particles are common, such as spray and smoke (cigarettes, candles, incense). The concentration difference of these suspended particles can be up to 50% or higher within a few centimeters. In outdoor environment, even in stable environment, local difference (such as only one street apart) may be very large.

LUFTMY developed an innovative anti pollution technology with long-term stability, which is one of the most complained problems by customers. Many competitors' products may be able to meet some requirements in the short term, but in the long term, they will not be able to meet customer requirements. For example, after three or four years, the signal will drop by half or even more. Customers have to clean or change products, which is time consuming and the user experience is not good.

However, due to this innovative technology, the life span of lejmay's products can exceed eight years under the condition of continuous operation 24 hours a day. In addition, it does not require cleaning or maintenance to avoid sensor drift or fault problems.

The product is developed according to the principle of laser scattering and can achieve high resolution and granularity classification (determined by algorithm). It's small package, so it's also suitable for integration into small consumer devices. In addition, it provides fully calibrated digital output, as well as UART and PWM interfaces, which are easy to use.

Advanced measurement principle based on laser

There are two kinds of light sources used in PM2.5 sensor in the market: laser and LED laser are more expensive than led, but their accuracy is much higher. Because the laser beam is focused in a small range (so that all particles can be hit and all scattering can be achieved), and the light spot of LED greatly exceeds the size of particles (all scattering can not be achieved), the signal-to-noise ratio of laser will be much higher than that of LED, and LED can not achieve the accurate measurement of PM2.5.

Life considerations

Why can LUFTMY LD series work for 8 years, while competitors can't? There are two main factors that affect working life: component life and dust. In PM2.5 sensor, the two components with the shortest life and the most easily damaged are fan and laser. The accumulation of dust on the optical elements can cause light attenuation.

So how to solve these problems? First of all, we should choose a good quality fan and laser. When the life span of the fan and laser is more than eight years, then consider how to prevent dust.

From the profile of PM2.5 sensor which has been used for a while, it is very dirty. But this part of LUFTMY LD series laser channel is very clean (competing products are also dirty). How does this technology work? To put it simply, use clean air to protect the laser head.

In addition, the aging of the equipment. The attenuation of luftmy LD series relative competitive products over time is much smaller. The attenuation of laser head is inevitable, but the attenuation of LD series is controllable. Competitor's products may be relatively good if the measurement is 20% different from the previous one. If the air quality gets worse, the sensor will trigger the ventilation system, so we will feel a lot better.

LD09 Laser dust sensor
LD09 Laser dust sensor

LUFTMY PM2.5 air cleanliness sensor LD09 can continuously collect and calculate the number of suspended particles with different particle sizes in the air per unit volume, i.e. particle concentration distribution, and then convert it into mass concentration, and output it in the form of general digital interface.The air cleanliness sensor LD09 has the characteristics of small volume, high precision, strong anti-interference, low power consumption, long service life, short response time of zero error alarm rate, etc. the air cleanliness sensor can be embedded in a variety of instruments related to the concentration of suspended particles in the air, such as air purifier or environmental improvement equipment, providing timely and accurate concentration data.

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