The working principle of PM2.5 sensors is based on light scattering. When being exposed to light, particles and molecules will absorb part of the energy, and scatter part of the light. When a light beam goes parallel into the particle field to be measured, the light is affected by scattering and absorption, and its intensity attenuates.
By this method, we can obtain the relative attenuation rate of incident light in the concentration field to be measured. The relative attenuation rate basically reflects the relative dust concentration linearly, and the intensity of light is proportional to the intensity of electric signal transferred from photovoltaic signals. By measuring electric signals, we can obtain the relative attenuation rate, so that dust concentration can be calculated. Herein ISWeek would like to make a comparison between several types of popular PM sensors, so as to help our users to make ideal selection for their applications.
PDSM010 is a type of IR dust sensor producted by Syhitech (KR). It is capable of detecting particles of about 1㎛, including indoor dust, pollen, microorganism, dust mites and cigarette smoke. It can measure concentration of floating particles in a room within 30㎥. With PWM output, PDSM010 is factory calibrated, easy to maintain, noise resisting and its service life can be as long as 5years. It is an ideal option for applications which requires low cost and low accuracy, like air purifiers, air-conditioning, ventilation system, IAQ monitors and IoT equipment.
PSM series are newly updated types of IR dust sensors developed by syhitech. They can measure PM1.0 or PM2.5 respectively and output in UART or optional PWM. It is capable of detecting particles as small as 0.3μm, while its price is lower than that of laser sensors. Its measurement range is 0~900 ug/m³, and its accuracy has been enhanced (±2.5 ug/m³@0~100 ug/m³; ±25@100~500 ug/m³). With its size of 59x45x17mm, the sensor can responses in 1s, and serve for 5 years. It is suitable for air quality solutions (air purifiers and air conditioning), HAVC control systems, smart IAQ devices, outdoor particle sensing equipment and so on.
TF-LP01 is a laser PM2.5 sensor produced by Figaro (JP) for civil use. It can measure values of PM1.0, PM2.5 and PM10 and output in USART. It features compact size of 51x33x22mm, high accuracy(±10 ug/m³ @0~99 ug/m³, ±10@100~999 ug/m³), repeatablity and consistency, and strong resistance against interference. It adopts ultra-silent fan, and is able to response in real-time and collect data continuously. The sensors are 100% tested and calibrated in factory. With its moderate cost, the sensor covers a measurement range between 0~999 ug/m³ with its resolution of 1 ug/m³, and has a service life of 5 years. This type of sensors are often applied in air purifiers, portable air quality monitoring equipment and smart homes.
ISWeek is distributing industrial grade laser PM2.5 sensor OPC-N3 produced by Alphasense (UK), which is capable of measuring values of PM1.0, PM2.5 and PM10, whose particle size is between 0.38~40μm, up to 2000 ug/m³. Its number of paths is extended to 24, and it has temperature and humidity sensors mounted on its board. OPC-N3 adopts SPI and USB output and is of relatively high price. This type of sensors is often used in highly-polluted cities for environment monitoring.