Air Quality Monitor Working Principle
Nowadays, more and more people have paid attention to health and environmental protection. After decorating the new houses, in addition to the basic ventilation, placing formaldehyde plants, charcoal, and other measures, many people will also use air quality monitors to comprehensively detect the air quality status, thereby comprehensively protecting the health of the pregnant women, children, the elderly and family personnel. Indoor air pollutants mainly come from decoration, decorative materials, boards, paints, wall paints, glues, new furniture, adhesives and other pollutants widely used in decoration which will harm human health.
Working principle of air quality monitor
The air quality monitor is used to detect formaldehyde (HCHO), PM2.5, TVOC and temperature and humidity in real time. It is small and exquisite, easy to carry. Through the inner sensors, the monitor can accurately measure the concentration of pollutants, and calculate the air quality index AQI, and give an alarm when the concentration exceeds the standard.
The principle of the air quality monitor is to detect the signals of the front-end formaldehyde sensor, PM2.5 sensor, TVOC sensor and temperature and humidity sensor, amplify the weak signal of the sensors through an operational amplifier, remove the noise interference through the filter circuit, collect the signal through AD, use a high-precision CPU to process, and then convert it into a concentration value and display it on the LCD screen.
Working principles of air quality sensors
The air quality monitor is equipped with a variety of gas sensors, including formaldehyde sensor, PM2.5 sensor, TVOC sensor and temperature and humidity sensor, thus it can detect different varaibles. The below introduce the basic principle of these sensors.
1. Formaldehyde sensor
The air quality detector adopts a high-sensitivity electrochemical sensor. The HCHO sensor uses the scientific and effective electrochemical principles to sensitively and accurately detect the formaldehyde concentration in the air. When there is indeed formaldehyde existing, a low DC current will be generated. Combined with a high-precision amplifier circuit and AD sampling, the formaldehyde concentration will be measured.
2. PM2.5 sensor
The air quality monitor uses a high-precision laser sensor for PM2.5 detection. The laser sensor calculates the number and diameter of particles through laser scattering method, and finally accurately calculates the PM2.5 concentration of the measured environment, with a detection accuracy of 1 microgram/cubic meter.
3. Temperature and humidity sensor
In addition to formaldehyde and PM2.5 detection, the detector also has a built-in temperature and humidity sensor. When the temperature and humidity in the air change, the detector can immediately sense it and display the indoor environmental indicators more comprehensively.
4. TVOC sensor
The air quality monitor usually uses a semiconductor sensor to provide real-time monitoring of indoor TVOC concentrations for 24 hours a day, and provides warning alerts if the value exceeds the standards. Then, it is very suitable for home, office, and car applications.