Magnetorheological fluid

Magnetorheological (MR) fluid is a type of smart fluid whose rheological (flow) properties can be altered by the application of a magnetic field. These fluids typically consist of a base fluid, such as oil or water, containing micron-sized ferromagnetic particles. When exposed to a magnetic field, the particles align along the field lines, which increases the fluid's viscosity and causes it to behave more like a solid.