A Simple Optical Aerosol Sensing Method of Sauter Mean Diameter for Particulate Matter Monitoring

Abstract

Mass concentration is a commonly used but insufficient metric to evaluate the particulate matter (PM) exposure hazard. Recent studies have declared that small particles have more serious impacts on human health than big particles given the same mass concentration. However, state-of-the-art PM sensors cannot provide explicit information of the particle size for further analysis. In this work, we adopt Sauter mean diameter (SMD) as a key metric to reflect the particle size besides the mass concentration. To measure SMD, an effective optical sensing method and a proof-of-concept prototype sensor are proposed by using dual wavelengths technology. In the proposed method, a non-linear conversion model is developed to improve the SMD measurement accuracy for aerosol samples of different particle size distributions and reflective indices based on multiple scattering channels. In the experiment of Di-Ethyl-Hexyl-Sebacate (DEHS) aerosols, the outputs of our prototype sensor demonstrated a good agreement with existing laboratory reference instruments with maximum SMD measurement error down to 7.04%. Furthermore, the simplicity, feasibility and low-cost features of this new method present great potential for distributed PM monitoring, to support sophisticated human exposure hazard assessment.

Simulation and design research on improving MPASS based on dual-wavelength detection technology

“…According to Mie theory, the scattering intensity of aerosol particles depends not only on wavelength, observation angle, particle size, and refractive index but also on the polarization direction of incident light 21,22,23 . Previous research and detector designs have not taken into account the impact of polarization on scattering characteristics.…”

System Integration of an Optimally Designed Virtual Impactor with a QCM Sensor as a One-Stop PM2.5 Classification and Detection Platform

“…However, it requires a long time for sampling, and the PM mass is hard to detect in real time. The light scattering method is the most widely used method − and can provide real-time measurement. However, as this method does not directly provide the mass concentration of PM, accurate measurement is impossible.…”

Experimental Study on Particle Size Distribution Characteristics of Aerosol for Fire Detection

“…According to the Mie theory, the particle size distribution of aerosols is one of the most important influencing factors of their optical characteristics [19][20][21][22][23]. Therefore, it is essential to study the particle size distributions and the differences of typical fire smokes and non-fire aerosols for developing fire detectors with higher alarm accuracy.…”