Miniaturized two stage aerosol impactor with chip-scale stages for airborne particulate size separation

This work presents integration of two chip-scale real-time aerosol impactor stages within a miniaturized cascade assembly for airborne particulate size segregation and mass concentration measurement. Impaction stages, each comprised of a MEMS resonant microbalance, an impaction micro-chamber and a number of micro-nozzles, all integrated on a single chip, are fabricated using a three mask micromachining process on SOI substrates. Tests were performed in different environments with different particle mass concentrations ranging from 0.012 to 0.13 μg/m³ (particles larger than ~ 9 nm) show a clear correlation between the resonator response and the expected particle concentrations. SEM images of the deposited particles clearly show a size difference between particles collected in the two stages.