MEMS-based particle detection system for measuring airborne ultrafine particles

A MEMS-based particle detection system which includes a particle processing chip and electronic circuits was developed for low-cost and ubiquitous monitoring of airborne ultrafine particles. The detection system consists of particle classification, charging, precipitation, and sensing sections. Particles with different sizes enter the ultrafine particle processing chip and are separated according to their sizes in the classification section. Size-classified particles are charged in the charging section. Then, the mean size and particle concentrations are determined in the precipitation and sensing sections. The particle classification, charging, and precipitation sections were integrated on a single chip using MEMS and microfluidic technologies. The particle sensing section was realized using a metal filter connected to a high-precision electrometer. The characteristics of each section were first analyzed, and the proposed particle detection system was then compared with standard commercially available instruments. The calculated particle number concentrations correspond to the results measured by commercially available instruments. The proposed particle detection system can be applied for monitoring of ultrafine particles with size range of 20–300 nm (20–130 nm particle mean diameter) and concentration range of 320–10⁶ particles/cm³.