For determination of average particle size and its distribution in a solution. Can be used for any solution appropriate for polystyrene cuvette, that is based on solvent which does not dissolve the polymer (e.g water, alcohols). If a user has their own glass cuvette with 4 transparent walls, it can be used for all other solvents. With appropriate cuvette (not available as a lab consumable, to be purchased separately on a grant budget) it can be also used for determination of Zeta potential of the material. The measurement is based on scattering of the 633 nm laser beam, what means that the solution used cannot absorb light of this wavelength. Therefore, as it was checked experimentally, the ZS90 we have, cannot be used for PEDOT-containing solution no matter of their concentration.