Designs for miniaturization of bending actuator utilizing hydrogen storage alloy

Bending behavior of a miniature actuator utilizing Pd–Ni hydrogen storage alloy (HSA) has been investigated on hydriding and dehydriding process. The actuator has a bimorph structure consisting of the HSA thin sheet and copper plating on one side of the sheet. Palladium sputtering on the back surface of the HSA significantly improves bending characteristics due to the catalytic action of palladium. The maximum bending velocity is obtained in the HSA with 10 μm thick Cu-plating. The bending actuators having the same aspect ratio (length to width) and different dimensions show the same bending velocity and the critical aspect ratio of the actuator free from the constraint by deformation in width direction is around five. The bending behavior can be controlled by adjusting the surrounding hydrogen pressure.

► Actuator using hydrogen storage alloy (HSA) shows a reversible bending motion. ► Pd sputtering on the HSA surface remarkably improves the bending characteristics. ► Optimal thickness of Cu plating on HSA 20 μm thick is around 10 μm. ► Critical aspect ratio of actuator free of constraint by width deformation is five. ► Bending behavior can be controlled by adjusting hydrogen pressure.