Particle Generators can be designed with a polydisperse or monodisperse aerosol generator, such as an atomizor or nebulizer to create a particle aerosol. Typically one is looking for a monodisperse particle aerosol, but there may also be a need for a polydisperse aerosol particle output. Particle sizing can be achieved thru the use of a laser particle counter, spectrometer; but aerosol research generally needs a less expensive, more accurate capability to size particles, such as a differential mobility analyzer, DMA. The Differential Mobility Analyzer is designed to sample a particle aerosol from an airflow, pick out a particle size peak of interest within the sampled airflow with very high size accuracy, or to sample the entire particle size range. Particle Counting can be achieved through the implementation of a laser particle counter, but less expensively using versions of a condensation particle counter (CPC). The CPC could be a N-Butanol based CPC, a water based CPC or a condensation nucleus counter.
The aerosol generator needs to create a monodisperse or polydisperse particle aerosol, using a solution of polystyrene latex spheres, silica in DI Water, or perhaps NaCl solution in DI water. As the particle aerosol is generated, it also creates charged particles which affect particle counting downstream. Unwanted particles such as agglomerates would be filtered out of the particle air stream, usually thru some form of filter or impactor. Airflow control thru the Differential mobility analyzer during a size scan needs to be quite accurate, thus mass flow controllers are typically incorporated. Prior to a DMA or CPC, a particle ionizer would be useful to remove unwanted electrical charges to particles before sizing and counting, often accomplished thru use of a PO210 ion source or similar electrical ion device. Electrical ionizers are more advantageous to minimize radiation concerns, which can be difficult for control in some countries.