High concentration measurement of mixed particle suspensions using simple multi-angle light scattering system

A simple multiple-angle light scattering system was developed for the differential measurement of particle concentrations in suspension even in high concentration where multiple scattering effects are significant based on size. The system combines multiple-angle detection to collect scattered angle dependent light intensities, and Partial Least Square Regression method (PLS-R) to compose the predictive models for analyzing scattered signal obtain concentrations of samples under investigation. The system was designed to be simple, portable and inexpensive. It employs a diode lasers (red AlGaInP-based) as a light source and a silicon photodiode as a detector and optical components, all of which are readily available. The technique was validated using 1.1 μm and 3.0μm polystyrene latex beads in both mono-dispersed and poly-dispersed suspensions. The measurement results showed good agreement between the measured results and reference values. Their deviations from the reference values are 2.4% and 1.5% relating to references' concentrations of 1.3×108 and 1.2times;107 particles/ml for 1.1 m and 3.0 μm in mono-dispersed solutions and 2.3 % and 3.5% relating to references' concentrations of 1.1times;108 and 4.4 times;105 particles/ml for 1.1 μm and 3.0 μm in mixed solutions, respectively. This system is a compact but high performance system allowing multiple particle sizes in high concentration to be measured simultaneously.