As one of intelligent material candidates, electrorheological (ER) fluid changes from liquid to solid-like under an applied electric field. The ER fluid particles from a chain structure induced by a dipole under a uniform electric field and polymerize into an opaque columnar fringe at macro level. Under certain conditions, the opaque forms a periodic arrangement, similar to the structure of a grating. We design the corresponding experiment to study the grating diffraction phenomenon based on the ER fluid structure under uniform electric field. The results show that the concentration of ER fluid is the main factor affecting the clarify of fringe structure, grating constant, slit width, the diffraction principal spacing, and determining whether the diffraction pattern is obvious or not.

In this paper, based on the macro performance of calcium titanium oxalate positive and negative electrorheological fluids, through the design of optical imaging contrast experiment, the change process of internal structure of positive and negative electrorheological fluids under direct current electric field was observed directly, which intuitively verified the principle of chain formation of positive electrorheological fluid. On the one hand, the experimental observations explain some optical properties of positive and negative electrorheological fluids, on the other hand, the formation mechanism of corresponding positive and negative electrorheological fluid samples is explored. In the meanwhile, an unique dendritic structure and formation process of negative rheological fluid was photographed. It was found that the structure shape was related to the direction of electric field. At the end, some possible explanations for these phenomena are given.