Hybrid Plasmonic Fiber-Optic Sensors

Abstract

With the increasing demand of achieving comprehensive perception in every aspect of life, optical fibers have shown great potential in various applications due to their highly-sensitive, highly-integrated, flexible and real-time sensing capabilities. Among various sensing mechanisms, plasmonics based fiber-optic sensors provide remarkable sensitivity benefiting from their outstanding plasmon–matter interaction. Therefore, surface plasmon resonance (SPR) and localized SPR (LSPR)-based hybrid fiber-optic sensors have captured intensive research attention. Conventionally, SPR- or LSPR-based hybrid fiber-optic sensors rely on the resonant electron oscillations of thin metallic films or metallic nanoparticles functionalized on fiber surfaces. Coupled with the new advances in functional nanomaterials as well as fiber structure design and fabrication in recent years, new solutions continue to emerge to further improve the fiber-optic plasmonic sensors’ performances in terms of sensitivity, specificity and biocompatibility. For instance, 2D materials like graphene can enhance the surface plasmon intensity at the metallic film surface due to the plasmon–matter interaction. Two-dimensional (2D) morphology of transition metal oxides can be doped with abundant free electrons to facilitate intrinsic plasmonics in visible or near-infrared frequencies, realizing exceptional field confinement and high sensitivity detection of analyte molecules. Gold nanoparticles capped with macrocyclic supramolecules show excellent selectivity to target biomolecules and ultralow limits of detection. Moreover, specially designed microstructured optical fibers are able to achieve high birefringence that can suppress the output inaccuracy induced by polarization crosstalk and meanwhile deliver promising sensitivity. This review aims to reveal and explore the frontiers of such hybrid plasmonic fiber-optic platforms in various sensing applications.

Immunosensing Based on Optical Fiber Technology: Recent Advances

“…Nevertheless, these prism-based sensors are expensive and bulky, which hinders in situ biosensing, particularly in locations of difficult access [7,8]. For these reasons, vast research has been devoted to optical fiber technology as it provides a highly-integrated and miniaturized structure compared to their bulky counterparts, with greater flexibility in terms of design, materials and performance, along with the capacity for in vivo measurement [8,37].…”

“…Similarly to SPR, the excitation of localized SPs (LSPs) arises from the interaction of the incident light and the electrons in the conduction band of the metals, inducing strong localized oscillations of surface electrons [24,36]. Despite having the same excitation mechanism, contrary to SPR, which involves lossy propagation along the intersection between metal and dielectric nanofilm, LSPs are non-propagating and oscillate locally in the nanostructure as a result of particle size restriction [7,8,37]. For LSPR, detection relies on monitoring the change of the absorbed wavelength of the light propagating through NPs dispersed in liquids or deposited on solid substrates.…”

“…Micro-structured optical fibers (MOFs), structures that have air holes or micro-capillaries inside the fiber, have been used owing to their higher degree of integration, longer interaction distance between light and analyte, which occurs along the entire length of the fiber, and improved robustness. Furthermore, in MOFs, the fabrication of the sensing region happens inside of the fiber instead of on the exterior, which allows effective interaction between the analyte of interest and the evanescent field of the core mode [ 37 , 76 ].…”

Special Issue “Fiber Optic Sensors and Applications”: An Overview

“…In "Hybrid Plasmonic Fiber-Optic Sensors" [13], the development of plasmonics-based fiber-optic sensors was reviewed to reveal and explore the frontiers of such hybrid plasmonic fiber-optic platforms in various sensing applications. Coupled with the new advances in functional nanomaterials as well as fiber structure design and fabrication in recent years, new solutions continue to emerge to further improve the fiber-optic plasmonic sensors' performances in terms of sensitivity, specificity, and biocompatibility.…”

Biosensing Applications Using Nanostructure-Based Localized Surface Plasmon Resonance Sensors

“…Further, plasmonic sensors, a type of optical sensors, offer high sensitivity and multiplexing capability and do not require relatively expensive proprietary instruments. Therefore, several types of plasmonic sensors have been developed to date, including surface plasmon resonance (SPR) [ 2 ], long-range surface plasmon polariton (LRSPP) [ 3 ], surface-enhanced Raman scattering (SERS) [ 4 , 5 ], and localized surface plasmon resonance (LSPR) [ 1 , 6 , 7 ] sensors. LSPR biosensors offer several advantages over other plasmonic sensors, including their inherent label-free nature, portability, low cost, and real-time sensing capacity.…”