A Magnetic Field Sensor Based on SPR-POF Platforms and Ferrofluids

Abstract

We present a novel methodology for magnetic field sensing by exploiting surface plasmon resonance (SPR) sensors based on D-shaped plastic optical fiber (POF) and magnetic fluids (MFs). The proposed methodology adopts a multimode POF patch covered with ferrofluid placed between the light source and the SPR-POF platform. The working principle exploits the changing of the SPR spectra due to variations of the SPR resonance conditions generated by the changing in the input light in the SPR-POF sensor due to the attractive force exerted by the target magnetic field on the POF covered with ferrofluid. A model showing a good fitting between the simulated and measured values of the magnetic field is also presented. A proof of concept for this novel sensing approach has been obtained exploiting a prototype of a sensor that has been characterized in the range of values between 0.15 and 1.2 mT. Particularly, we have estimated, in the linear range of the sensor response, sensitivity equal to about 6800 pm/mT and resolution equal to about 0.029 mT. Moreover, the comparison between the expected and the experimental behavior has shown a very good match with a mean squared error of about 5%.