Properties of homogeneous ER fluid comprised of liquid crystalline polysiloxane (LCS) were described. The fluid shows Newtonian flow in an electric field and far larger ER effect than heterogeneous ER fluids of particles dispersion in oil. ER brake employed the LCS ER fluid was accomplished with many contrivances in the design and set up process for preventing a fluid leak and filling the fluid completely into a narrow electrode gap. The brake showed a large torque (brake power) with very small electric consumption. A caster walker with intelligent ER brake was developed for a practical use.