Mitsubishi Electric has developed a new air quality sensor that is the first of its sort to be able to detect not only pollen and dust, but also extremely fine particulate matter just 2.5 µm in diameter (designated as PM2.5). Airborne PM2.5 particles cause serious pollution and health issues, particularly in China, India and Japan.
 
To enable it to detect such small particles, the new sensor is equipped with a unique double-sided mirror system that collects 1.8 times as much scattered light from the particles as conventional single-sided systems. Pollen and dust particles are distinguished by a shape discrimination algorithm developed by Mitsubishi, based on the optical characteristics of the scattered light.
The new sensor consists of a laser diode, an aspherical lens, a mirror that collects the light, a photodetector and an airflow controller. The sensor can detect particles as small as 0.3 µm.