Abstract
An instrument capable of performing multi-angle light scattering measurements on single particles in suspension has been developed. The system uses an ellipsoidal flow chamber and a polar coordinate photodetector with 32 concentric ring detector elements. The flow system was primarily designed for medical research problems, but it may be used in other research areas involving rapid analysis of single particles as, for example, in microbiology and environmental biology. Since intensities of light scattered at different angles are measured as a cell traverses a focused laser beam no staining of the cells has to be performed and viable specimens can be used. The flow system has the unique capability of sorting individual particles and separating a subset from the parent population based on lightscatter intensities from a number of discrete scattering angles.The instrument's mechanical, electronic, fluidic, and optical design aspects are discussed in detail. Software relating to data acquisition, storage, display, and analysis is presented.Application examples for system performance evaluation and calibration with plastic particles are given. The sorting capability was successfully demonstrated with plastic microspheres. The analysis of unicellular microalgae shows the instrument's capabilities for applications to biological samples.