Comprehensive study of magnetostriction-based MEMS magnetic sensor of a FeGa/PZT cantilever

Abstract

This research comprehensively studies a magnetostriction-based cantilever resonator magnetic sensor of Iron Gallium (FeGa) coupled to a piezoelectric material of lead zirconate titanate (PZT) is performed. The study is meant to explore its magnetic sensing mechanism, reaction to magnetic field direction, the separate effect of magnetic force, and the advantage of miniaturization. The FeGa/PZT cantilever is sensitive to magnetic field direction when objected to a static DC magnetic field in the perpendicular direction with 5.47 Hz/mT sensitivity. It is also concluded that the FeGa/PZT cantilever is also sensitive to magnetic force with a different reaction to a static magnetic field. The sensitivity to magnetic force is in the value of 1.77 Hz/mT. Both sensitivities are calculated from the slope of the resonance frequency shift and magnetic field graph divided by its resonance frequency. The Allan variance method's minimum detectable magnetic field is determined with a frequency noise of 0.02 Hz, equal to 3.66 μT. The minimum detectable magnetic field can be improved by reducing the thermal noise through structure modification by designing a narrow, thin, and long cantilever with a high Q factor with complementary material. The magnetostriction-based magnetic sensor can be applied in either direct magnetic field measurement or a magnetic resonance system such as micro NMR or micro ESR.