A micro ER valve fabricated by micromachining

As an advanced control component for practical micromachines using fluid power in millimeter size, the authors have proposed a micro ER valve using homogeneous ER fluids and verified the validity through basic experiments using several micro ER valves fabricated by conventional machining. In this paper, to control micro grippers mounted on micromachines, further miniaturized ER valves are realized by using micromachining. Firstly, to investigate an ER effect in micro size, several 2-port micro ER valves with different electrode gap lengths are fabricated and investigated. It is ascertained that the viscosity change rate is 4.5 constant with miniaturization. Secondly, a 3-port micro ER valve is fabricated and basic characteristics are experimentally investigated. It is ascertained that the controllable pressure change rate is 60% of supply pressure and the rise time is 0.2 s. Finally, the validity of the micro ER valve is confirmed by applying to position control of a bellows microactuator.