Mitsubishi Electric has developed an air quality sensor, which detects PM2.5 particles, pollens & dust.
The air quality sensor takes in air that potentially contains fine particles such as PM2.5 particles and identifies the kinds of particles by applying laser light to the air and receiving the scattered light. It uses two kinds of photodetectors placed at a right angle to the emitted laser light.
When there is no particle, there is no scattered light. If the particle size is large, so is the intensity of the scattered light. This light intensity is measured by one kind of photodetectors.
Moreover, the polarization properties of the scattered light change depending on particle shape, enabling to distinguish between spherical and nonspherical particles. The other kind of photodetectors is equipped with two detectors, each of which has a polarizing filter with a different vibration direction, enabling to estimate polarization properties based on the ratio between the light intensities measured by the two detectors.
As a result, the existence, size and shape of fine particles can be detected by the intensity and polarization properties of the scattered light, enabling to identify particles such as PM2.5 particles and pollens.
This time, Mitsubishi Electric used the air quality sensor to suck in fine particles and show the distribution of each kind of particle and operated an air cleaner in conjunction with the sensor.