A Magnetic Field SPR Sensor Based on Temperature Self-Reference.

Xinwei Mo,Qiang Liu,Xiaoxiao Jiang,Guangyuan Si,Jiangtao Lv

doi:10.3390/s21186130

Abstract

In this paper, a novel D-shaped photonic crystal fiber sensor for simultaneous measurements of magnetic field and temperature is proposed and characterized. Based on the surface plasmon resonance theory, the D-shaped flat surface coated with a gold layer is in direct contact with magnetic fluid to detect magnetic field, and one of the relatively small air holes near the fiber core is filled with polydimethylsiloxane (PDMS) to sense temperature. The realization of measuring the magnetic field and temperature separately through two channels depends on the fact that the magnetic field only changes the refractive index of the magnetic fluid, but has no effect on the refractive index of PDMS. The refractive index of the magnetic fluid and PDMS can be affected by temperature at the same time. The sensor designed in this work can separate the variations of the magnetic field and temperature simultaneously, therefore solving the cross-sensitivity problem to further improve the magnetic field sensitivity. When the thickness of the gold film is 50 nm and the radius of the filling hole is 0.52 µm, the magnetic field sensitivity and the temperature sensitivity of magnetic field sensor based on temperature self-reference can reach 0.14274 nm/Oe and −0.229 nm/°C, respectively.

Highlights

Surface plasmon resonance (SPR) is a kind of physical optical phenomenon occurring at metal–dielectric interfaces [1,2,3]
When an interface of negative and positive dielectric constant materials is irradiated with light, there are both evanescent waves and plasmon waves on the surface of the metallic material
Because the SPR phenomenon is extremely sensitive to small changes of the dielectric constant on the surrounding media of the metal film, high sensitivity sensing [5] is enabled, which can be widely used for biochemical applications

Summary

Introduction

Surface plasmon resonance (SPR) is a kind of physical optical phenomenon occurring at metal–dielectric interfaces [1,2,3]. In order to obtain high fidelity outputs, sensitivity and selectivity are two key characteristics for magnetic field sensors [13]. Optical fiber magnetic field sensors possess many to obtain high fidelity outputs, sensitivity and selectivity two key and characteristics for advantages, such as small volume, anti-interference, highare sensitivity accuracy, cormagnetic field sensors [13]. D-shaped micro-structured optical fiber (MOF) to realize the simultaneous measurements thickness is 40 nm, the sensitivities of temperature and RI reach the maximum value of 2 of refractive index (RI) and temperature. The measuring for magnetic field and temperature detection with a high sensitivity of 99.68 pm/Oe and range of the magnetic field of the sensor is only 0~21 Oe, and the cross-sensitivity com−77.49 pm/◦ C, respectively.

Working

Results

Conclusions