Detecting the magnetic field direction by a cantilever operating in different vibration modes

This paper presents a new method of measuring magnetic direction by a cantilever driven in different modes. The magnetic field is detected by measuring the vibration amplitude of the mechanical structure. The vibration mode is activated by an AC current which is driven into the coil on the cantilever. When the structure works at the 1st or 2nd resonant frequency, it will resonant at the modes of the rotation about an axis or the out-of-plane vibration. The structure has been designed, fabricated and tested. The experimental results are compared with the finite element analysis. The displacements of the structure, which differ with the different modes, are shown to be a sine and cosine function of the angle of the magnetic field, respectively. The experiment agrees well with the predicted. The structure can be used to measure the magnetic field direction easily while it is integrated with the function of measuring the vibration amplitudes of the cantilever, exhibiting a resolution of 10 degrees.