Fiber Surface Plasmon Resonance Research Articles

Experimental and theoretical investigation for surface plasmon resonance biosensor based on graphene/Au film/D-POF.

A D-shape plastic optical fiber (D-POF) surface plasmon resonance (SPR) biosensor based on the graphene/Au film (G/Au) was proposed and experimentally demonstrated for detection of DNA hybridization process. To improve the detection performance of SPR sensors, the Physical Vapor Deposition (PVD) method was used to evaporate the Au film directly onto the graphene grown on copper foil, and the Au film acted as a role of traditional Polymethyl Methacrylate (PMMA). The process made graphene and Au film form seamless contact. Next, the G/Au was transferred onto the D-shape fiber together. We explored the G/Au SPR sensor by using the finite element method (FEM) and obtained the optimum materials thickness to form configuration. Compared to other plastic optical fiber experiments, the proposed sensor's sensitivity was improved effectively and calculated as 1227 nm/RIU in a range of glucose solution. Meanwhile, our proposed sensor successfully distinguishes hybridization and single nucleotide polymorphisms (SNP) by observing the resonance wavelength change. It also exhibits a satisfactory linear response (R2 = 0.996) to the target DNA liquids with respective concentrations of 0.1nM to1µM, which shows this method's wide potential in medical diagnostics.

A high sensitivity D-type surface plasmon resonance optical fiber refractive index sensor with graphene coated silver nano-columns

A high sensitivity surface plasmon resonance (SPR) fiber sensor with graphene coated silver nano-columns on the surface of the D-type single mode fiber has been proposed and simulated in this paper. The sensor uses evanescent wave on the surface of the fiber to excite free electrons on the metal surface to generate surface plasmon waves (SPW), and the change of refractive index (RI) is measured by monitoring the variation of the resonance absorption peak. The COMSOL Multiphysics software is used to optimize the diameter of sliver nano-column, the width of air gap between sliver columns, and to study the effect of graphene sensing layer thickness on sensor sensitivity. The simulation results show that the sensitivity of the sensor can be greatly improved with graphene coated sliver nano-columns. The maximum external RI response sensitivity of the sensor proposed in this paper can reach 8860.93 nm/RIU in the RI range of 1.33–1.39 when the diameter of silver nano-column is 90 nm, the graphene is 23 layers and the width of air gap between columns is 53.82 nm. When the RI is 1.39, the sensitivity of the sensor with 23 layers of graphene can be increased by 28% compared with the sensor without the graphene layer. The simulation results will be helpful for design and fabrication of optical fiber SPR refractive index sensor.

Theoretical study on negative permittivity of the material producing sharp surface plasmon resonance dips

Using theoretical simulations for optical fiber surface plasmon resonance (SPR) sensors and prism-based SPR sensors coated with negative permittivity material (NPM), we investigated the effect of the permittivity of NPM on the transmitted spectrum of optical fiber SPR sensors and the reflected spectrum of prism-based SPR sensors and then obtained optimum permittivity of the NPM, which can excite the sharpest SPR spectrum in the white light region (400–900 nm).

Side-polished flexible SPR sensor modified by graphene with in situ temperature self-compensation.

Fiber-based techniques make it possible to implant a miniaturized and flexible surface plasmon resonance (SPR) sensor into the human body. However, for implantable applications, the miniaturization of fiber SPR sensors results in low sensitivity compared with traditional prism-type SPR sensors due to limited space and the effects of temperature fluctuations. Therefore, it is necessary to compensate for temperature drift in the measurements, such as the case of the quantification of the relationship between glucose concentration and SPR resonance wavelength. In this report, we proposed a highly sensitive fiber SPR sensor based on a side-polished structure modified by graphene for implantable continuous glucose monitoring with in situ temperature self-compensation using a long-period fiber grating (LPFG). The results demonstrate that the sensor with monolayer graphene achieved the best sensitivity of 3058.22 nm/RIU, and the LPFG achieves a maximum resolution of 0.042 nm/°C. The proposed SPR sensor enabled the detection of hypoglycemia, which is still a significant challenge for continuous glucose monitoring in a clinical setting.

Research on the performance of a novel SPR sensor based on graded index multimode fiber

PurposeThis paper aims to propose and demonstrate a novel surface plasmon resonance (SPR)-sensing approach by using the fundamental mode beam based on a graded index multimode fiber (GIF). The proposed SPR sensor has high sensitivity and controllable working dynamic range, which expects to solve the two bottlenecks of fiber SPR sensor, including low sensitivity and the difficulty in multichannel detection.Design/methodology/approachThe low-order mode of the GIF to SPR sense, which keeps the sensitivity advantage of the single-mode fiber SPR sensor, is used. By using this new SPR sensor, the effect of light incident angle and gold film thickness on working dynamic range was studied. According to the study results, the smaller is the incident angle, the larger is the SPR working dynamic range and the longer is the resonance wavelength with a fixed gold film thickness; the larger is the gold film thickness, the longer is the resonance wavelength with a fixed grinding angle. After the parameter optimization, the sensitivity of these two parameter-adjusting methods reach 4,442 and 3031 nm/RIU.Originality/valueWhen the grinding angle of the GIF increases, the dynamic range of the resonance wavelength increases and has a redshift, sensitivity increases, and the resonance valley becomes more unobvious with a fixed gold film thickness. Similarly, when gold film thickness increases, the dynamic range of the resonance wavelength increases and has a redshift, sensitivity increases, and the resonance valley becomes more unobvious with a fixed grinding angle. These adjusting performance aforementioned lay the foundation for solving of the fiber-based SPR multichannel detection and increasing of the fiber-based SPR sensor sensitivity, which has a good application value.

A new application of optical fiber surface plasmon resonance for micro-displacement measurement

We provided an effective method that optical fiber surface plasmon resonance (SPR) can be used to displacement measurement. By fabricating a Kretschmann configuration on a micro-structure fiber which is produced by splicing a short segment of graded-index fiber (GIF) with a plastic-clad silica (PCS), we made a novel micro-displacement sensor. We employed a single-mode fiber (SMF) to change the radial position of the incident beam as the displacement. In the GIF, the angle between light beam and fiber axis, which is changed by the displacement, will lead to changes of resonance angle in the PCS. Thus the resonance wavelength shifts. The detection range of the proposed sensor is 0–25 μm; and its sensitivity is related to the refractive index (RI) of liquid surrounding in which the sensing zone is immersed (named cladding liquid). The higher the cladding liquid RI, the higher the sensitivity. Under cladding liquid RI of 1.41, the resonance wavelength redshifts from 801 nm to 839 nm when the displacement changes from 0 μm to 25 μm. When the displacement is close to 25 μm, the sensitivity reaches a maximum of 2.43 nm/μm, which transcends almost all of other optical-fiber micro-displacement sensors. The proposed micro-displacement sensor will have potential applications in high precision instruments.

Three-core photonic crystal fiber surface plasmon resonance sensor

Abstract A three-core photonic crystal fiber (PCF) surface plasmon resonance (SPR) biosensor with high performance is presented. The structure of the biosensor is easy to implement and has good repetition. The outer layer of the fiber structure is gold film. The analyte is placed on the surface of the gold film. The Full vector finite element method is used to numerical simulation and analysis the transmission mode and characteristics of the three-core PCF-SPR biosensor. The influence of sensor structure parameters on sensing performance is investigated. The structure parameters are optimized. The optimum structure parameters are given. The refractive index (RI) sensitivity of the sensor is discussed there. The results show that the average refractive index sensitivity of the sensor is 3435 nm/RIU in the sensing range of 1.33–1.40, and the resolution is 2.91 × 10−6 RIU. The sensor has the advantages of high sensitivity and high resolution. And it can be applied to real-time detection of the biomolecules and small drug-molecules.

A Novel Two-Dimensional Material Based Optical Fiber Surface Plasmon Resonance Sensor for Sensing of Organic Compounds in Infrared Spectrum Window

Glucose, sucrose and fructose are typical organic compounds having carbon-hydrogen-oxygen atoms. Their sensing is important in many bio-medical applications. In this paper we present a 2D material-based fiber optic surface plasmon resonance sensor for refractive index sensing of some typical organic compounds. 2D material graphene in combination with active metal gold is used in the sensing region. Fiber core is covered with gold and graphene layer. The sensor is simulated using COMSOL Multiphysics simulation software. To measure the sensing performance of sensor we see the effect of two physical parameters of the sensor, thickness of the Au-metal and graphene layer on the sensing performance. The use of graphene layer enhances the sensitivity of SPR sensor. The angular interrogation method of SPR excitation is used for sensor simulation in COMSOL Multiphysics.

Design and Optimization of Surface Plasmon Resonance Sensor Based on Polymer-Tipped Optical Fiber

In this study, a novel surface plasmon resonance (SPR) sensor based on a single-mode polymer-tipped optical fiber (PTOF) is designed and optimized. The refractive index (RI) measurement is achieved by exciting SPR at the interface between gold film and TiO2 layer coated on the polymer-tip. Finite-difference time-domain (FDTD) method based commercial optiFDTD software is used to optimize the design of the proposed sensor for a better performance related to the materials of the metal film, the shape of polymer-tips, and the thickness of TiO2 layer. The results show that the sensitivity of optimal single-mode PTOF SPR sensor reaches 3798 nm/RIU when analyte RI is 1.333, and reaches 5708 nm/RIU when analyte RI is 1.383. Compared with conventional optical fiber SPR sensors, the single-mode PTOF SPR sensor proposed in the paper is simpler in fabrication, smaller in size, and higher in sensitivity, which has broad application prospect in biomedical sensing.

An Optical Fiber Refractive Index Sensor Based on the Hybrid Mode of Tamm and Surface Plasmon Polaritons.

A novel high performance optical fiber refractive index (RI) sensor based on the hybrid transverse magnetic (TM) mode of Tamm plasmon polariton (TPP) and surface plasmon polariton (SPP) is proposed. The structure of the sensor is a multi-mode optical fiber with a one dimensional photonic crystal (1 DPC)/metal multi-films outer coated on its fiber core. A simulation study of the proposed sensor is carried out with the geometrical optical model to investigate the performance of the designed sensor with respect to the center wavelength, bilayer period and the thickness of silver layer. Because the lights transmitted in the fiber sensor have much larger incident angles than those in the prism based sensors, the center wavelength of the 1 DPC should shift to longer wavelength. When the coupling between TM-TPP and SPP is stronger, the sensor exhibits better performance because the electromagnetic field of the TPP-SPP hybrid mode is enhanced more in the analyte. Compared to most conventional fiber surface plasmon resonance sensors, the figure of merit of the proposed sensor is much higher while the sensitivity is comparable. The idea of utilizing TPP-SPP hybrid mode for RI sensing in the solid-core optical fiber structure presented in this paper could contribute to the study of the fiber RI sensor based on TPP.

SiO2-doping Films Effects on Optical Properties of Optical Fiber Surface Plasmon Resonance Hydrogen Sensor

SiO2-doping WO3 films were obtained by magnetron sputtering. Experiments indicated more obvious optical phenomenon with SiO2-doping films. Different thickness of the SiO2 film was discussed for better optical properties, according to the resonance peak width, the resonance depth and the sensitivity. This work can provide theory support for the design of optical fiber surface plasmon resonance hydrogen sensor.

D-shaped photonic crystal fiber plasmonic refractive index sensor based on gold grating.

In this work, we proposed a high-resolution D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor based on gold grating. Gold grating is introduced to modulate the resonance wavelength and enhance the refractive index (RI) sensitivity. Structure parameters of PCF and gold grating are analyzed by the finite element method for optimizing the SPR sensor. The simulation results indicate that air hole pitch, air hole diameter, and gold thickness and grating constant have little influence on the sensitivity of the refractive index, which reduces the requirement of precise processing. For improving the resolution of RI sensing, a two-feature (2F) interrogation method, which combines wavelength interrogation and amplitude interrogation, is used. The maximum theoretical resolution of the SPR sensor reaches to 5.98×10-6 RIU in the range of 1.36-1.38, and the wavelength sensitivity reaches to 3340nm/RIU. The proposed SPR sensor shows potential applications for developing a high-sensitivity, real-time, and fast-response SPR-RI sensor.

Mechanism and Characteristics of Humidity Sensing with Polyvinyl Alcohol-Coated Fiber Surface Plasmon Resonance Sensor.

A surface plasmon resonance (SPR) sensor based on a side-polished single mode fiber coated with polyvinyl alcohol (PVA) is demonstrated for relative humidity (RH) sensing. The SPR sensor exhibits a resonant dip in the transmission spectrum in ambient air after PVA film coating, and the resonant wavelength shifts to longer wavelengths as the thickness of the PVA film increases. When RH changes, the resonant dip of the sensor with different film-thicknesses exhibits interesting characteristics for optical spectrum evolution. For sensors with initial wavelengths between 550 nm and 750 nm, the resonant dip shifts to longer wavelengths with increasing RH. The averaged sensitivity increases firstly and then drops, and shows a maximal sensitivity of 1.01 nm/RH%. Once the initial wavelength of the SPR sensor exceeds 850 nm, an inflection point of the resonant wavelength shift can be observed with RH increasing, and the resonant dip shifts to shorter wavelengths for RH values exceeding this point, and sensitivity as high as −4.97 nm/RH% can be obtained in the experiment. The sensor is expected to have potential applications in highly sensitive and cost effective humidity sensing.

Numerical analysis of side-hole fiber surface plasmon resonance sensor for simultaneous magnetic field and temperature measurement

A side-hole fiber surface plasmon resonance (SPR) sensor is proposed and numerically analyzed to solve the cross-sensitivity problem of temperature and magnetic field. In the side-hole fiber SPR sensor, the side-holes I and II are filled with magnetic fluid and a mixture of ethanol–glycerin, respectively, resulting in a loss spectrum with two channels. Each channel has different sensing characteristics. When the external magnetic field intensity increases, the magnetic field sensitivities of channels I and II are 1.098 and −0.018 nm / Oe, respectively. Moreover, with the increasing temperature, the temperature sensitivities of channels I and II are −5.909 and −4.211 nm / ° C, respectively. Therefore, the variations of magnetic field intensity and temperature can be simultaneously measured by detecting resonant wavelengths of channels I and II of side-hole fiber SPR effects, resulting in the influence of temperature in a side-hole fiber SPR magnetic field sensor being eliminated. The side-hole fiber SPR sensor has obvious advantages of compact structure and high sensitivity, and it also has solved the problem of liquid storage glassware to compact the structure of the fiber SPR sensor further.

Refractive index sensing characteristics of carbon nanotube-deposited photonic crystal fiber SPR sensor

Abstract In this paper, the carbon nanotubes (CNTs)-deposited Au film photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor (CNTs/Au-PCF sensor) and CNTs-deposited Ag film PCF SPR sensor (CNTs/Ag-PCF sensor) were developed and utilized to conduct a series of experiments for the refractive index sensing characteristics study of the CNTs-deposited SPR sensors. The PCF, spliced between two sections of multimode fibers (MMFs), was coated with a metal (Au or Ag) film and then deposited with CNTs for further sensing. CNTs coating can enhance the confined electric field intensity surrounding the sensing layer, making the SPR sensor more sensitive to the changes in the ambient medium. Compared with conventional Au film PCF SPR sensor (Au-PCF sensor), the sensitivity of CNTs/Au-PCF sensor increases by 1016.09 nm/RIU. Compared with conventional Ag film PCF SPR sensor (Ag-PCF sensor), the sensitivity of CNTs/Ag-PCF sensor increases by 709.22 nm/RIU. Therefore, we find that CNTs have a more significant effect on the Au-PCF sensor than the Ag-PCF sensor. The experimental measurements results agreed well with the simulation results. Furthermore, CNTs have high surface-to-volume ratio and extremely excellent biocompatibility. Bovine serum albumin (BSA) was employed as the target analyte to evaluate the feasibility of the CNTs/Au-PCF sensor for the detection of biomolecules, and the sensor exhibits higher sensitivity (8.18 nm/(mg/mL)), lower limit of detection (LOD) (2.5 µg/mL), and faster response time (8 s) than the Au-PCF sensor. Such CNTs-deposited SPR sensors with high sensitivities and fast response present highly promising potential for application in the field of biochemistry.

Graphene enhanced optical fiber SPR sensor for liquid concentration measurement

Abstract A high sensitivity optical fiber Surface Plasmon Resonance (SPR) sensor which based on coreless optical fiber, silver film and graphene, has been designed and implemented for liquid concentration detection. In this paper, Graphene is firstly verified that it can be used to enhance the evanescent field of traditional optical fiber and thus increasing sensitivity in experiment. The sensitivity of proposed sensor is 6.417 nm/%, which is higher than that of the traditional optical fiber SPR sensor according to the comparative experiments. In addition, the proposed sensor is extremely easy to make and the silver film could be protected from oxidation and damage due to the existence of graphene. Moreover, the sensor has pretty small size, immunity to electromagnetic interference, quick response speed and thus can suitable a variety of severe environments and real-time measurement.

Signal processing in SPR fiber sensors: Some remarks and a new method

The importance of Surface Plasmon Resonance (SPR)-based devices in the field of chemical and biological sensing and the expectations created in terms of sensitivity and resolution impose the necessity of developing an adequate methodology for the processing of the signals obtained and for the evaluation of the performance of the sensing systems. We discuss in depth and clarify the problem of the analysis of data acquiring and processing in SPR fiber sensors, show how in many cases this analysis could and must be improved and propose a new method of SPR curve shaping, apt for sensors encapsulated or inaccesible. We illustrate the use of the method with real experimental examples.

D-Shaped photonic crystal fiber biosensor based on silver-graphene

A D-shaped photonic crystal fiber surface plasmon resonance biosensor is presented with high sensitivity. Determinand are used outside the fiber structure to realize a simple detection mechanism. The sensor consists of photonic crystal fiber, graphene and metal. The sensitivity of the sensor is enhanced by graphene between the silver layer and D-shaped photonic crystal fiber. The two small air holes in the center of the photonic crystal fiber are beneficial to the phase matching of the core and the plasmon polaritons. The two large air holes are beneficial to the birefringence and the coupling of polarized light with metal. The Full vector finite element method is used to numerical simulation and analysis the transmission mode and characteristics of the photonic crystal fiber surface plasmon resonance biosensor. In the range of refractive index is 1.34–1.40, the average sensitivity of the sensor is 4850 nm/RIU with a high resolution of 2 × 10−5RIU. The minimum full width at half maximum is 10 nm. The proposed sensor can be applied to real-time detection of the biomolecules and small drug-molecules due to the advantages of long distance transmission, high sensitivity and high resolution.

Design and Optimization of an Opened Suspended Core Fiber-Based SPR Sensor with Gold Cylinder Structures

In this study, an opened three-hole suspended core fiber surface plasmon resonance sensor structure based on the combination of photonic crystal fiber and surface plasmon resonance (SPR) mechanism was proposed and analyzed. One hole in the clad layer was exposed to the outside, and a lay of gold cylinders with the same size and gap was placed along the inside of the opened hole. The existence of the gold cylinders could stimulate the SPR effect and selecting the suitable gaps between the cylinders could enhance the SPR effect and increase its sensitivity. Then COMSOL software was used to simulate how the cylinder diameter, the gaps between the cylinders, and the fluid refractive index variation affect the sensor’s transmission loss spectrum, field enhancement effect, and the sensitivity. The optimized results show that the sensitivity of this proposed SPR sensor could be high, up to 1 × 10−5 RIU/nm, and it was much higher than the sensitivity of the existing photonic crystal fiber SPR sensor (1 × 10−4 RIU/nm), which was an order of magnitude improvement. This study could provide a reliable theoretical basis for future research and design of real-time and high-sensitivity opened fiber SPR sensors.

Hollow fiber SPR sensor available for microfluidic chip

We propose and demonstrate a dual-channel surface plasmon resonance (SPR) sensor based on a microstructured hollow fiber (MHF), which is available for microfluidic chips. Two channels contain an internal sensing channel inside of the MHF due to the hollow structure, and an external sensing channel outside of the MHF. We employ a fiber grinding-polishing & butt-jointing technology to configure the hollow fiber SPR sensing probe. We plate the gold coatings on the internal and external sensing channels with the thickness of 50 nm, respectively. When the refractive index of the testing samples is in the range of 1.333–1.385, the range of resonance wavelengths in the internal sensing channel is 712nm–1010 nm, and the range of resonance wavelengths in the external sensing channel is 618nm–700 nm. The testing sensitivity of the internal sensing channel is 5645 nm/RIU and testing sensitivity of the external sensing channel is 1576 nm/RIU. Due to the special structure of the MHF, where an air hole in the MHF, the hollow fiber SPR sensor has the superiority of being easy to be multiplexed in a microfluidic chip system.