Study of size-related sensitivity of surface acoustic wave sensor towards particulate matter sized particles using finite element and experimental methods

摘要

To investigate the potential of using a surface acoustic wave sensor to measure both particulate matter (PM) concentration and size distribution, a forced-vibration model of a coupled particle–SAW system with interfacial excitation was built using the finite element method. The model shows different behaviors of the coupled vibration between mass loading and elastic loading regimes. The calculation of the frequency change of a 260 MHz SAW perturbed by different sized starch particles in the elastic regime is in agreement with our previous experiment, proving the validity of the model. The impact of different parameters, including the particle size, contact size, and material, on the particle–SAW interaction was investigated for understanding the perturbation mechanism of real particles. Wheat flour and talcum powder particles were measured by SAW experimentally, resulting in positive and negative frequency change, respectively. The experiment shows that SAW has different sensitivities toward particles with different size distributions and morphologies. The size-related sensitivity property of SAW could be used for building an instrument that is capable of monitoring both PM concentration and size distribution.