Development of Micro-Gas Valve Driven by Magnetic Field

Giant magnetostrictive Fe-Pd and Fe-Ga alloys are promising as actuator/sensor materials with high respective velocity and stress created by magnetostriction. To apply them to a micro valve, we developed magnetostrictive actuators, that is, Fe80Ga20/Ni and Fe70.4Pd29.6/Ni bimorph layers. These cantilever-type actuators can be bent by applying magnetic field parallel to length. An actuator point displaced about 270 μm under a low magnetic field of 37 kAm-1. Large (20 mm×18 mm×0.2 mm) and small (17.5 mm×5 mm×0.2 mm), (10 mm×3 mm×0.2 mm) actuators were applied to a micro-gas valves. The opening and closing action of a valve consisting of magnetostrictive bimorph layers can be controlled remotely by magnetic fields. Gas flow rate can be driven from 43 to 0 ml min-1 by increasing the magnetic field to 20 kAm-1. The response time to the applied magnetic field is below 0.12 s. Moreover, the magnetostrictive actuator is excellent in durability.