Actuators Based on Electro-Rheological Fluid
Electro-Rheological (ER) fluids are special fluids made of base hydraulic fluids with chargeable particles suspended in the fluids. The important properties of ER fluid is that when it is put between two plates with gap h (typical of less than 1 mm) and a voltage is applied on the two plates, the fluid becomes stiffer with shear stress of typical 2 kN/m2 has been reported. This is shown in Fig. 8.1. The range of the applied voltage is 4 kV/mm. The current drawn is very small and it is the range of a few milliamps.