A Universal Measurement Method for Nanoparticle Number Concentration Based On Atomic Force Microscope

The concentration of nanoparticles in liquid suspensions is a fundamental indicator, which plays an important role in the applications using nanoparticles. Researchers are devoted to developing efficient and accurate methods for measuring nanoparticle concentration based on different principles, such as optical-based methods, liquid nebulization-based methods, transmission electron microscopy-based (TEM) methods, etc. In this paper, a new measurement method based on atomic force microscope (AFM) integrated with the newly discovered distribution characteristics of completely evaporated nanoparticles on silicon wafers is proposed. A theory for predicting the number of nanoparticles based on limited AFM sampling points is established, thus enabling accurate and fast measurement of nanoparticle concentration. The number concentrations of several kinds of nanoparticle suspensions were measured by the proposed method, and the results were compared with the estimated concentrations obtained by mass fraction. Finally, a qualitative uncertainty analysis was performed.