Development of a new surface acoustic wave based PM2.5 monitor

This paper presents a novel approach for PM_2.5 monitoring by using the Surface Acoustic Wave (SAW) based sensor. To analyze the response mechanism of SAW sensor, the mass loading effect from the PM_2.5 layer to SAW propagation was described by solving the coupled electromechanical field equation in layered structure and surface effective permittivity (SEP). The dispersion curve of the SAW propagation along the layered structure of fused silicon dioxide settled layer and ST-X quartz substrate was calculated. Accordingly, when the operation frequency was 500 MHz, the threshold detection limit of the PM_2.5 sensor estimated by three times the noise detection principle was 0.17 ng. It indicates that the PM_2.5 detection by using the SAW technology is entirely possible according to the "National ambient air quality standards for particulate matter: final rule, U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, 2006".