Resonant magnetic sensor using concentration of magnetic field gradient by asymmetric permalloy plates

摘要: This paper demonstrates a novel resonant magnetic sensor that utilizes concentrator to obtain large magnetic-field gradient. A silicon-cantilevered resonator, with 10-µm-diameter particle on the tip, is placed between two asymmetric permalloy plates, which function as concentrator; one of plates has narrow whereas other wide one. asymmetric-plate pair generates gradient, considerable force particle. The resonant-frequency varies, depending applied extremal field can be determined by monitoring changes in frequency. gradient generated theoretically calculated using finite element method, obtaining 5.4 × 104 T/m for 1 T. fabricated conventional microfabrication techniques, and force-dependent change observed. experimental sensitivity estimated 5.1 × 10−7 T, considering minimum noise level (3.29 ppm).