Micro nanofibers have a large aspect ratio with a length of micron and a width of nanometer. The existing static characterization methods can only describe the morphology of a limited number of samples and can’t be counted automatically, which is cumbersome, time-consuming and poor representativeness, while the existing dynamic characterization methods of micro/ nanofibers have low accuracy. The application of micro /nanofibers in various industries has attracted extensive attention，so it is urgent to develop instruments that can conveniently, quickly and accurately characterize micro /nanofibers. In this project, large aspect ratio and cross-scale micro/ nanofibers are selected as the main research object. In order to overcome its characteristics of easy aggregation and high light transmittance, micro/ nanofibers were pretreated by dilution, fluorescent staining and dispersion. The sheath flow focusing channel, fluorescence inverted microscope, optical system, electron multiplying charge coupled device （EMCCD） and other hardware are applied to construct the 3D-stochastic optical reconstruction microscopy (3D-STROM )environment for photographing the large aspect ratio and cross-scale micro /nanofibers circulating in the microfluidic channel in total internal reflection fluorescence (TIRF) mode. At the same time, fluorescence single molecule localization, background denoising, identification tracking, object association and three-dimensional reconstruction processing on the captured multi-frame consecutive pictures are performed to analyze and describe the morphology, scale and flow field of micro nanofibers in static, liquid and fluid states. The static, liquid and dynamic measurement of scanning electron microscope (SEM), atomic force microscopy (AFM), inverted microscope and Micro-PIV are combined to establish a database of the correspondence among morphology, scale and flow field of nanomaterials under static, liquid and dynamic conditions, constructing and modifying the mathematical model of the scale and flow field of nanomaterials, now the instrument developed in this project has been manufactured and placed in State Key Lab of Pulp and Paper Engineering. The characterization method and developed instruments provided by this project enable efficient, comprehensive and accurate characterization of thousands of large high aspect ratio and cross-scale nanofibers. In addition, static, liquid and dynamic characterization of other nanomaterials can also be achieved. The project plays a good leading and pioneering role in the characterization of micro /nanofibers, which will promote the development of micro/ nanofibers industry.
 

micro /nanofibers; dynamic characterization; microfluidic technology.