Enhanced three-dimensional light scattering sensor (3D-LSS) for online characterization of aerosol particle shape: Development and validation with test aerosols

The accurate characterization of aerosol particle shape and size is essential for understanding and controlling processes in aerosol science and may also be relevant to pharmaceutical manufacturing and process monitoring. However, existing measurement techniques often lack the capability for real-time, high-throughput shape analysis under process conditions. This work presents an enhanced 3D Light Scattering Sensor (3D-LSS) for the online characterization of aerosol particle shape and size. The sensor system operates by measuring the elastic scattering of circularly polarized incident light from aerosol particles. Here, this sensor has been extended by integrating FPGA-based signal processing. This implementation enables fully online data acquisition, high-throughput signal handling, and rapid morphological evaluation of individual particles. A series of validation experiments was conducted using aerosols generated from polystyrene monospheres, disaccharides (sucrose and α -lactose monohydrate), and inorganic salts (sodium chloride and potassium sulfate). The sphericity index (SPX), calculated from multi-angle scattering measurements, served as a quantitative shape descriptor. The results showed high SPX values (mean up to ≈ 0.95) for spherical particles such as monospheres and spray-dried sugars, whereas lower SPX values (0.8–0.83) were observed for cubic or irregular particles such as sodium chloride and potassium sulfate. The formation of agglomerates and concentration-dependent morphological changes during particle generation were reliably identified through systematic shifts in the SPX distribution. The system’s capability for accurate, high-throughput, real-time morphological characterization highlights its potential for future process-monitoring applications.