nPSize

While size can be accurately measured for simple (ideal) nanoparticles, i.e. spherical, mono-dispersed, non-agglomerated/aggregated, the characterization of non-spherical nanoparticles with broader size distributions is much more difficult and less accurate.

The nPSize project (Improved traceability chain of nanoparticle size measurements), funded between 2018 and 2021 by the EMPIR European metrology research program, aimed to assess the performance of several nanoparticle measurement systems, including in particular Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Small Angle X-ray Diffusion (SAXS), and to deliver improved calibration methods to users. Reference materials with various characteristics (shape, chemical composition, polydispersity, concentration) were used to compare the different techniques (notably within the VAMAS framework), including an assessment of the associated measurement uncertainties. These results will make it possible to propose in standardization (ISO) an approach combining several of these techniques (hybrid metrology) to take advantage of the benefits of each and thus improve the metrological traceability of size measurements and the assessment of errors that can be made in this type of characterization.