Characterization of a magnetic fluid exposed to a shear flow and external magnetic field using small angle laser scattering

Abstract The paper demonstrates a possibility to use Small Angle Light Scattering (SALS) method realized in a conventional laboratory to investigate structuring processes in a magnetic fluid simultaneously exposed to a shear flow and an external magnetic field. We have used a custom made SALS-setup with a laser source combined with a microfluidic chip, an electromagnet and a magnetic circuit to obtain scattering images of a low concentrated biocompatible magnetic fluid with clustered iron oxide nanoparticles. The application of an external magnetic field drastically influences the physical behaviour of the fluid and this effect is directly related to aggregation of particles resulting in chains with a dimension of several micrometers. These chains lead to an anisotropy of the scattering patterns. We have observed an influence of the field and flow on the intensity gradient of the obtained scattering patterns. The presented method opens broad perspectives to obtain microstructural information as well to evaluate structuring kinetics of the diluted magnetic suspensions using conventional laboratory conditions. The SALS measurements are accomplished with a full characterization of the fluid using magneto-rheometry, vibrating sample magnetometry, microscopy as well as dynamic light scattering.