Wide-range magnetic field sensor based on magnetic fluid coated polymer optical fiber: The influence of concentration

A simple design of a wide-range magnetic field sensor is proposed employing a tapered polymer optical fiber (POF) coated with magnetic fluid (MF). This sensor operates based on intensity modulation of the evanescent field technique. In order to expose the evanescent field to the surrounding environment, the middle segment of POF was tapered to the diameter of 0.5 mm and surrounded with MF. Output light intensity is modulated through magnetic field owing to the refractive index variation of MF as new cladding of the POF. In order to evaluate the effect of concentration on the sensing performance, experimental comparative studies were performed with incorporating different concentrated synthesized MF as well as the one provided by a commercial MF. The prepared nanoparticles were characterized by X-Ray diffraction pattern (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and atomic force microscopy (AFM). Characteristic results confirm the formation of Fe3O4 crystallite nanoparticles size of less than 10 nm and cubic spinel structure with high saturation magnetization of 68.34 emu/gr. Results reveal that the proposed sensor is capable of detecting magnetic field with linear response of more than 99% in the wide range of 2.5-125 mT measurements.