Design of Resonant Magnetic Field Sensor Based on Magnetostrictive Optical Fiber Micro-cantilever

In this paper, a magnetostrictive-based optical fiber micro-cantilever resonant magnetic field sensor is proposed. The magnetic field sensor is based on the optical fiber end face design of the optical fiber micro-cantilever beam. The surface of the optical fiber micro-cantilever beam is plated with a magnetostrictive film, and the two form a double layer micro-cantilever beam structure. The magnetostrictive film generates a magnetostrictive effect under a magnetic field, which causes the double-layer cantilever structure to deflect and change its resonant frequency. The magnetic field can be determined by detecting the change in resonant frequency. Then use ANSYS simulation software to simulate the resonance frequency of the double-layer micro-cantilever structure under the magnetic field, and obtain the relationship between the magnetic field and the resonance frequency, in order to optimize the size of the double-layer cantilever structure, and then obtain the best sensitivity of the magnetic field sensor. The simulation results show that: when the double-layer micro-cantilever structure is 90 μm long, the thickness of the fiber-optic micro-cantilever is 2 μm, and the thickness of the magnetostrictive film is 3⁄5 of the thickness of the fiber-micro-cantilever, the magnetic field sensor can reach the maximum sensitivity of 40,760 \({\text{Hz}}/{\text{Gs}}\).