New Measuring Technique for Multi-Dimensional Characterization of Nanoparticles

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Existing particle characterization methods typically measure the distribution of one specific physical property of the particles. However, for non-spherical particles this is often not sufficient to describe their complex properties to the required extent. The SPP 2045 aims for a multi-dimensional fractionation according to different particle characteristics. Therefore, it is essential to be able to characterize the disperse properties of the involved particle systems comprehensively and regarding multiple properties in order to quantify the fractionation results. The aim of this research proposal is the development of a novel measuring principle for the direct 2D characterization of submicron particle systems, which allows to determine the complete, two-dimensional frequency distribution of the mass as well as the mobility equivalent diameter with the help of one compact device. From this multidimensional distribution, further information can be derived, e.g. on the distribution of shape and structural properties of the particles. The measurement method is based on an already existing method for the analytical separation of particles in a rotating cylindrical gap, which is now extended by a superimposed electric field. A laboratory set-up is built in order to characterize its transfer function thoroughly. A detailed simulation of all relevant effects during the classification shall allow a precise prediction of the transfer behaviour. This model is in turn necessary in order to obtain the desired distribution with regard to mass and mobility diameter from the directly determined 2D distribution with regard to speed and voltage. However, since this is a mathematically ill-posed problem, a suitable inversion algorithm is required. Therefore, this research project also addresses the application of novel data inversion strategies to reconstruct the desired two-dimensional distributions. The method is to be successively tested using model particles and complex particle systems with defined properties. The method will then be used in various projects of the SPP 2045 to demonstrate its ability to evaluate the respective fractionation and thus make an important contribution to these projects. It is expected that this research project will also contribute beyond the SPP to significantly improve the characterization of complex particle systems and will make an important contribution to a better fundamental understanding of the disperse properties of complex particle systems.