Intrinsic position sensing of a Ni–Mn–Ga microactuator

This paper presents an investigation of the intrinsic magnetoresistance of a ferromagnetic shape memory alloy microactuator for position sensing. The microactuator is designed as a double-beam cantilever made of a polycrystalline Ni–Mn–Ga thin film, which exhibits both a martensitic transformation in the temperature range 333–359 K and a ferromagnetic transition at about 370 K. The microactuator is placed in the inhomogeneous magnetic field of a miniature Nd–Fe–B magnet causing a mixed thermo-magnetoresistance effect upon actuation. The maximum in-plane magnetic field is about 0.38 T. In this case, the maximum magnetoresistance is 0.19%. Under these conditions, a maximum positioning accuracy of 18 µm can be reached within the deflection system presented