Dual-modal measurements of suspended particles combining polarization and fluorescence analysis

This study focuses on the precise online extraction of bioaerosol content and accurate classification of multi-class suspended aerosols in the atmospheric environment. The polarization state is sensitive to the physical properties of micro-particles, such as size and shape. Fluorescence is a measurement method suitable for the identification of bacteria, fungi, viruses and other bioaerosols. If the micro-physical characteristics of some bioaerosols are similar to different kinds of non-biological aerosols, polarization detection assisted with fluorescence analysis can increase the extracted information related to aerosol molecular features, effectively enhancing the identification of biological particles. This paper combines multi-angle polarization vector detection and fluorescence analysis to propose a dual-modal aerosol online optical analysis system. An optical signal processing mechanism based on a support vector machine (SVM) has also been established to identify multi-class suspended aerosols, especially the biological components, accurately. The validity and recognition accuracy of the online aerosol optical analysis using two-modal techniques are confirmed by experimental results. The study of biological samples also shows that the detected aerosols' in situ characteristics and active status can be extracted from microscopic size, morphological structure and molecular properties by combining polarization scattering and fluorescence signals.