**Abstract**

The technology of electro-rheological fluids is old, but now it is being used in market at high speed. In the near future, ER fluids may be used for structure design where accuracy, density and power density are primarily the main criteria. For minimizing the costs and maximizing the functionality of the products, like where the viscosity of the fluid is varied to design, solid structure ER fluids are used. Features like fast response and easy interface between electrical and mechanical input–output makes the ER fluid attractive to various technology fields. In this study, ER fluids' working principle, various low-cost ER fluids working procedures and ER fluid applications in multiple areas are explained.

**Keywords:** ER clutch, mechatronics, ER fluids, ER damper
