The working principle of ER fluids is based on the polarization of suspended particles under an electric field. In the absence of an electric field, the particles are randomly distributed within the insulating liquid. Once an electric field is applied, the particles become polarized and align themselves along the direction of the field, forming chain-like structures. This alignment restricts the movement of the liquid, drastically increasing its viscosity. When the electric field is removed, the particles return to their random distribution, and the fluid regains its original viscosity.
