Advances in a developed surface acoustic wave based particulate matter 2.5 monitor

This paper presented a surface acoustic wave (SAW) based particulate matter (PM) 2.5 monitor, which consisted of a SAW dual-resonator oscillator, a thermophoresis unit and a virtual impactor. The structure optimization for improving the performance of the sensor by considering the particle distribution deposited by thermophoresis on the SAW detector was analyzed and verified in experiments. The size of thermophoresis micro-channel was obtained by Talbot formula and the movement of particles to the surface of the SAW detector was simulated by using the finite element method (FEM). Based on the theoretical results, the micro-channel was fabricated and the thermophoresis distribution was observed under an optical microscope. The optimal monsitoring structure of the SAW based PM2.5 monitor was established theoretically.