Optical hygroscopic growth characterization of pollen aerosol particles based on FDTD

The complex relationship between the hygroscopicity of pollen particles and their optical properties is of great significance for atmospheric monitoring and bioaerosol research. In this study, the hygroscopic structural model of petunia, Artemisia annua and ragweed pollen was constructed by Cinema 4D modeling technique, and the scattering field of pollen particles at 10%-89% RH humidity was simulated by combining with Finite-Difference Time-Domain (FDTD) system. The results show that the microstructure of pollen surface and the changes caused by hygroscopicity significantly regulate the light scattering field distribution, and the differences in the optical response of pollen of different species are closely related to their morphological features, which provides a potential basis for the identification of pollen species and inversion of humidity state based on optical features. This study provides a modeling and analytical method for understanding the optical-hygroscopic coupling mechanism of biological particles, which can be further validated with experiments in the future to promote its application in environmental monitoring and optical sensing.