Micromachined magnetoflexoelastic resonator based magnetometer

In this paper, we demonstrate the performance of a magnetoflexoelastic magnetometer consisting of a micromachined ultra-thin (7.5 mu m) quartz bulk acoustic resonator on which 500 nm thick magnetostrictive Metglas (R) (Fe85B5Si10) film is deposited. The resonance frequency of the unimorph resonator structure is sensitively affected by the magnetostrictively induced flexoelastic effect in quartz and is exploited to detect low frequency (< 100 Hz) and nanoTesla magnetic fields. The resonance frequency shift is measured by tracking the at-resonance admittance of the resonator as a function of the applied magnetic field. The frequency shifts are linearly correlated to the magnetic field strength. A minimum detectable magnetic flux density of similar to 79 nT has been measured for 10 Hz modulated magnetic field input signals which corresponds to a frequency sensitivity of 0.883 Hz/mu T. (C) 2015 AIP Publishing LLC.