Fiber-based Surface Plasmon Resonance Sensor Research Articles

Multianalyte sensing analysis with multilayer photonic crystal fiber-based surface plasmon resonance sensor

In this work, we proposed multianalyte multichannel Photonic Crystal Fiber (PCF)-based Surface Plasmon Resonance sensor with gold- and silver-doped plasmonic layers. The Full Vectorial Finite Element Method (FV-FEM) with perfectly matched layers (PML) are employed for numerical analysis of the proposed sensor. The key propagation features, such as confinement loss, resonance condition, resolution, and sensitivity of the proposed sensor, have been reported for all possible refractive index variations. According to the spectral sensitivity analyses, the average sensitivities for fixed RI values are obtained as 4100 nm/RIU and 3820 nm/RIU for Ch1 and Ch2, respectively. On the other hand, results for varying RI values are obtained as 3600 nm/RIU and 3700 nm/RIU for Ch1 and Ch2, respectively. Moreover, the maximum average sensitivity of proposed sensor reaches to 4250 nm/RIU for varying RI at Ch2 and 4200 nm/RIU for varying RI at Ch1.

Air-hole attributed performance of photonic crystal fiber-based SPR sensors

Photonic crystal fiber (PCF) based surface plasmon resonance (SPR) sensors show great promise in different fields due to their flexibility, remote accessibility, and remarkable sensing capability. To improve the performance (e.g. sensitivity) of PCF-based SPR sensors, two strategies are generally employed: (i) use of new plasmonic materials, and (ii) engineering the air-hole geometry. In particular, air-holes geometry plays a crucial role in maintaining both core and surface plasmon polariton (SPP) modes in SPR sensors. This work aims at investigating the effect of air-holes geometry on the performance of PCF-based SPR sensors. Here, three PCF models namely A, B, and C have been built with different air-hole geometries, and their effect on refractive index (RI) sensitivity is explored systematically through design, numerical simulation, data acquisition, and interpretation. Performance parameters such as confinement loss (CL), sensitivity, and sensing range of analytes (i.e. RI) have also been evaluated. Model A and B exhibit same maximum wavelength sensitivity and resolution of 5000 nm/RIU and 2 × 10−5 RIU−1 respectively, where model B's air holes are rotated 90° compared to model A. Otherwise, model C introduces a small air hole at the middle of PCF, where the maximum wavelength sensitivity and resolution are found to be 8000 nm/RIU and 1.25 × 10−5 RIU−1, respectively. Moreover, model C exhibits CL much higher than model A and B. In addition, model C shows larger detection ranges of analyte's RI. This analysis would be helpful in designing highly sensitive PCF-based SPR sensors for detecting a wide range of analyte's RI.

Highly sensitive fiber optic surface plasmon resonance sensor employing 2D nanomaterials

Optical fiber-based surface plasmon resonance sensors using, silver layer (Ag), platinum (Pt), and indium tin oxide in addition to 2D nanomaterials such as graphene are presented in this research. In terms of sensitivity (S) and figure of merit (FoM), the performance analysis of the proposed and configured sensor has been demonstrated. The proposed sensors are based on the scheme of Kretschmann for obtaining the transmitted power using the transfer matrix method and the equations of Fresnel. With theoretical and numerical studies, the reported sensor exhibits a good wavelength sensitivity which is improved to the maximum value of 4150 nm/RIU. Full width half maximum values are minimized to be 59 nm and the FoM is optimized to be 70 RIU−1 which gives better sensing properties in comparison with other published articles.

Fabrication of a Chemical Sensor Based on Surface Plasmon Resonance via Plastic Optical Fiber

In this work, a chemical optical fiber sensor based on Surface Plasmon Resonance (SPR) was designed and implemented using plastic optical fiber. The sensor is used for estimating refractive indices and concentrations of various chemical materials (methanol, distilled water, ethanol, kerosene) as well as for evaluating the performance parameters such as sensitivity, signal to noise ratio, resolution and the figure of merit of the fabricated sensor. It was found that the value of the sensitivity of the optical fiber-based SPR sensor, with 40 nm thick and 10 mm long Au metal film of exposed sensing region, was 3μm/RIU, while the SNR was 0.24, the figure of merit was 20, and the resolution was 0.00066. The sort of optical fiber utilized in this work is plastic optical fiber with a core diameter of 980 μm, a fluorinated polymer cladding of 20μm and a numerical aperture of 0.51.

Fiber-based Surface Plasmon Resonance Sensor for Lead Ion Detection in Aqueous Solution

Maghemite/reduced graphene oxide nanocomposite has been successfully deposited onto the surface of a gold-coated D-shaped optical fiber. The synergetic combination of gold, graphene, and iron oxide nanoparticles has shown enhancement of the resonance field and sensitivity of the fiber-based plasmonic sensor. In particular, the sensor exhibited its capability to detect lead ions (Pb2+) in aqueous solution via monitoring the spectral response of the sensor probe to different concentrations of Pb2+. A sensor sensitivity of 1.2 nm per μg/L was attained at the lowest detected Pb2+ concentration, which is 0.001 ppm (limit of detection). This robust, compact, and highly sensitive fiber-based plasmonic sensor will be of a great interest for an in situ and real-time water safety environmental monitoring.

SPR studies on optical fiber coated with different plasmonic metals for fabrication of efficient biosensors

In the recent years, there have been numerous reports on study of Surface Plasmon Resonance (SPR) in different Plasmonic metals. Optical – fiber based SPR sensors have gained much attention over the years because of their copious advantages over conventional Prism coupled SPR sensors, including miniaturization, ability to perform remote sensing etc. In the present work, Optical – fiber based Surface Plasmon studies are performed on metal – air interface with different Plasmonic metals. Four different metals chosen for the current work are as follows: Gold (Au), Silver (Ag), Aluminum (Al) and Copper (Cu). Thermal Evaporation technique is utilized to deposit the Au, Ag, Al and Cu metal thin films. XRD, AFM and UV–Visible spectroscopy are used for the determination of the structural, morphological and optical characteristics of the deposited metal thin films. SPR transmittance curve is obtained for different metals and their observed SPR wavelength (λspr) matches very well with the reported values. The performance of these metals for their application in SPR based biosensors, was assessed in terms of the Full Width at Half Maxima (FWHM) and minimum transmitted intensity (Tmin) of their SPR transmittance curves and it was found that Ag (50 nm thickness) possesses the least FWHM whereas Au (40 nm thickness) has the lowest Tmin. Suitability of both Ag and Au is discussed for sensing applications and it was concluded that Au (40 nm thickness) is a better candidate for the realization of efficient biosensors.

Surface plasmon resonance sensor based on D-shaped optical fiber using fiberbench rotating wave plate for sensing pb ions

In this paper, a D-shaped optical fiber is presented in terms of sensor application using FiberBench rotating wave plate. The designed sensor was adopted to detect plumbum ions in aqueous medium using surface plasmon resonance (SPR). The fiber-based SPR sensor was designed using a bilayer sensor chip. The polished area of the D-shaped optical fiber was coated by reduced graphene-based maghemite nanocomposite+1-ethyl-3-(3-dimethylaminopropyl)-carbodiimidehydrochloride/N-hydroxysuccinimide as a sensing layer. The transmission response curves were investigated according to the wavelength and intensity shifts at different concentrations. By incorporating the sensing layer, Pb2+ can be easily detected by wavelength and intensity interrogation methods. The sensor exhibited a recognizable intensity shift at 0.3 ppb Pb ion concentration. The limit of detection due to wavelength shift was 1 ppm. The sensitivity of the Pb ion concentration was 0.116 nm/ppm, and the accuracy was 19.1×10−4. FiberBench rotating wave plate was used to control the depth and the width of the transmission curve using SPR. The outcome of the developed sensor revealed a high accuracy, high sensitivity, and real-time sensor in a static water environment.

Fluoride Fiber-Based Plasmonic Biosensor with Two-Dimensional Material Heterostructures: Enhancement of Overall Figure-of-Merit via Optimization of Radiation Damping in Near Infrared Region.

Two-dimensional (2D) heterostructure materials show captivating properties for application in surface plasmon resonance (SPR) sensors. A fluoride fiber-based SPR sensor is proposed and simulated with the inclusion of a 2D heterostructure as the analyte interacting layer. The monolayers of two 2D heterostructures (BlueP/MoS2 and BlueP/WS2, respectively) are considered in near infrared (NIR). In NIR, an HBL (62HfF4-33BaF2-5LaF3) fluoride glass core and NaF clad are considered. The emphasis is placed on figure of merit (FOM) enhancement via optimization of radiation damping through simultaneous tuning of Ag thickness (dm) and NIR wavelength (λ) at the Ag-2D heterostructure–analyte interfaces. Field distribution analysis is performed in order to understand the interaction of NIR signal with analyte at optimum radiation damping (ORD) condition. While the ORD leads to significantly larger FOM for both, the BlueP/MoS2 (FOM = 19179.69 RIU−1 (RIU: refractive index unit) at dm = 38.2 nm and λ = 813.4 nm)-based sensor shows massively larger FOM compared with the BlueP/WS2 (FOM = 7371.30 RIU−1 at dm = 38.2 nm and λ = 811.2 nm)-based sensor. The overall sensing performance was more methodically evaluated in terms of the low degree of photodamage of the analyte, low signal scattering, high power loss, and large field variation. The BlueP/MoS2-based fiber SPR sensor under ORD conditions opens up new paths for biosensing with highly enhanced overall performance.

Modeling of a fiber-optic surface plasmon resonance biosensor employing phosphorene for sensing applications

An enhanced optical fiber-based surface plasmon resonance (SPR) biosensor is proposed utilizing a two-dimensional phosphorene heterostructure as an interacting layer with the analyte. This is the first model so far of a phosphorene-based fiber-optic SPR biosensor. High sensitivity and figure of merit (FOM), the two desirable parameters, are analyzed to investigate sensor performance. The analysis indicates that the proposed sensor provides significantly higher sensitivity in comparison to conventional fiber-optic SPR sensors. Numerical study shows that on using 10 layers of phosphorene on the Ag layer, the fiber-optic biosensor exhibits extremely high sensitivity of 3725 nm / RIU with a FOM of 61 RIU − 1. FOM reaches its maximum value of 64 RIU − 1 with six layers of phosphorene. Effects of the number of heterostructure layers and light wavelength on sensitivity are also analyzed. The results will open a new way for using phosphorene heterostructure in an optical fiber-based SPR sensor for biosensing applications.

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.

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.

Geometrical comparison of photonic crystal fiber-based surface plasmon resonance sensors

Numerical analysis and comparison of surface plasmon resonance (SPR)-based photonic crystal fiber (PCF) structures are presented. Full vectorial finite-element method (FEM) is employed to model and compare circular, elliptical, and square air hole-based PCF structures. The key propagation features, such as phase matching, sensitivity, resolution, and confinement loss behaviors of proposed structures, are reported. The effects of geometrical and design parameters are discussed and compared thoroughly. It is found that the sensitivity of circular air hole-based structure can reach up to 4200 nm/RIU, and the sensor resolution is 2.4 × 10 − 5 RIU.

Hollow-fiber-based surface plasmon resonance sensor with large refractive index detection range and high linearity

A surface plasmon resonance (SPR) sensor based on the gold-coated hollow fiber (HF) is proposed to realize the detection of refractive index (RI). The large hollow core of the HF is utilized as the microfluidic channel of the analyte, and gold is coated inside the air holes surrounding the core to generate surface plasmons. Benefitting from the unique structure of HF and liquid filling into the core, the sensor can work in a large RI range from 1.27 to 1.45 at the near-infrared region, overcoming the limitation of 1.42, as other side-hole-filled photonic crystal fiber-based SPR sensors reported. Moreover, the relations between the resonance wavelength and RI are highly linear and more suitable for standardization, while almost all similar works show higher sensitivity for the high RI change than for the low. The average spectral sensitivity 5653.57 nm/RIU is obtained. Other structure parameters, such as gold-coated air hole numbers and gold layer thicknesses, are also investigated.

Indium Tin Oxide Coated Two-Mode Fiber for Enhanced SPR Sensor in Near-Infrared Region

A surface plasmon resonance (SPR) sensor based on side-polished two-mode fiber (TMF) coated with indium tin oxide (ITO) film is proposed. ITO enables tuning of resonance wavelength of the sensor through changing its carrier concentration. The advantages of the TMF and ITO are combined in the sensor, which can achieve high sensitivity and plasma frequencies in the near-infrared region. The impact of ITO film thickness and residual fiber thickness on the sensing performance are numerically investigated with LP01 and LP11a modes coupled to specific surface plasmon modes. The results show that the resonance wavelength locates in 1500–2200 nm and an average sensitivity of ∼10149 and ∼10400 nm/RIU can be achieved for LP01 and LP11a modes, respectively, when the environmental refractive index varies between 1.33 and 1.39. The penetration depths of evanescent wave for the LP01 and LP11a modes are 460 and 502 nm, respectively. Both the sensitivity and penetration depth of the sensor are larger than those of single-mode fiber and multimode fiber based SPR sensors. The proposed sensor can play an important role in various applications, including environment, medicine, and security.

Cascaded distributed multichannel fiber SPR sensor based on gold film thickness adjustment approach

We propose and demonstrate a cascaded distributed multichannel fiber surface plasmon resonance (SPR) refractive index (RI) sensor by using a gold film coating thickness adjustment approach. For a multimode fiber-based SPR sensor, different gold film thicknesses produce different resonance wavelengths, different dynamic ranges, and even different testing sensitivities. Therefore, we design and fabricate a cascaded distributed two–channel multimode fiber SPR sensor with the gold film thickness of 30nm in #1 sub–channel and 60nm in #2 sub–channel. The corresponding testing sensitivities are 1712nm/RIU and 3038nm/RIU with the RI range of 1.333–1.385. The experimental results indicate that, in the range of 20nm–60nm, the smaller is the gold film thickness, the larger is the RI testing range, and the lower is the testing sensitivity, and the deeper is the resonance dip. In addition, it is worthy to say that, the testing sensitivity and the dynamic range of the cascaded distributed multichannel fiber SPR sensor keep unchanged after multiple sensing sub-channels being cascaded–connected. By using the gold film thickness adjustment approach, we overcome the limit of adjusting and separating the dynamic ranges of the multichannel fiber SPR sensors effectively.

A Hollow-Core Photonic Crystal Fiber-Based SPR Sensor With Large Detection Range

We propose a large detection range surface plasmon resonance (SPR) sensor based on hollow-core photonic crystal fiber in this paper. The sensor consists of an analyte channel in the core hole and a silver nanowire in the cladding holes. We investigate the resonance properties between the core modes and the surface plasmon polariton (SPP) modes excited on the nanowire surface in a large refractive index (RI) range from 1.33 to 1.5. Numerical results show that the resonance between the core mode and the higher order SPP modes can occur at particular wavelengths, thus exciting resonance peaks that shift to short wavelengths as RI increases. By tracking most sensitive peak, which is formed by the resonance combination of the x -polarized core mode and the second-order SPP mode, our sensor can measure large RI ranges of the analyte either higher or lower than that of the fiber material.

Simulation of the Sensing Performance of a Plasmonic Biosensor Based on Birefringent Solid-Core Microstructured Optical Fiber

A finite element method is used to analyze the performance of a microstructured optical fiber-based surface plasmon resonance sensors aimed for biomedical applications, such as the detection of blood carried species. Birefringence obtained by removing of a row of holes in a two-ring hexagonal lattice of holes in a gold covered silica fiber leads to a relatively high sensitivity of the fiber optical response to a refractive index of the analyte surrounding the fiber. This fiber structure supports two types (I and II) of resonant modes. In these modes, there is an opposite variation of some sensing parameters with the increase of the refractive index of the analyte between 1.36 and 1.39. Thus, for a smaller value (1.36) of the refractive index of the analyte n a, the resonance spectral width δλ 0.5 is large for the core mode I and small for the core mode II but for a larger value (1.39) of n a, δλ 0.5 is small for the core mode I and large for the core mode II. Also, for n a = 1.36, the amplitude sensitivity S A is small for the core mode I and large for the core mode II but for n a = 1.39, S A is large for the core mode I and small for the core mode II. By adjusting the radius of the gold layer, the proposed sensor shows high spectral sensitivity S λ and narrow δλ 0.5 at the same resonance wavelength and n a (1.39) where the figure of merit (FOM) is very large in comparison with the most recently published values.

Highly sensitive multi-core flat fiber surface plasmon resonance refractive index sensor.

A simple multi-core flat fiber (MCFF) based surface plasmon resonance (SPR) sensor operating in telecommunication wavelengths is proposed for refractive index sensing. Chemically stable gold (Au) and titanium dioxide (TiO(2)) layers are used outside the fiber structure to realize a simple detection mechanism. The modeled sensor shows average wavelength interrogation sensitivity of 9,600 nm/RIU (Refractive Index Unit) and maximum sensitivity of 23,000 nm/RIU in the sensing range of 1.46-1.485 and 1.47-1.475, respectively. Moreover, the refractive index resolution of 4.35 × 10(-6) is demonstrated. Additionally, proposed sensor had shown the maximum amplitude interrogation sensitivity of 820 RIU(-1), with the sensor resolution of 1.22 × 10(-5) RIU. To the best of our knowledge, the proposed sensor achieved the highest wavelength interrogation sensitivity among the reported fiber based SPR sensors. Finally we anticipate that, this novel and highly sensitive MCFF SPR sensor will find the potential applications in real time remote sensing and monitoring, ultimately enabling inexpensive and accurate chemical and biochemical analytes detection.

A multi-channel fiber SPR sensor based on TDM technology

Surface plasmon resonance (SPR) sensor has been widely used in biochemical reaction detection. With the development of SPR sensing, multi-channel SPR sensors have attracted attention owing to their potential application in multi-analyte detection. For fiber-based SPR sensor, due to the small size of the fiber core, it is hard to realize the multi-channel fiber SPR sensor based on the time division multiplexing (TDM) technology. Here we propose and demonstrate a multi-channel fiber SPR sensor based on the TDM technology by using the multi-core fiber. The multiple cores are multiple sensing zones, which equals to subdividing the traditional single fiber core into multiple independent sensing zones, realizing the multi-channel SPR sensing. This multi-channel SPR sensor has some advantages: it can realize multi-analyte detection simultaneously; it can compensate the ambient temperature variation, nonspecific binding and physical absorption and others; it can adjust working resonance wavelength shift range by adjusting the fiber grinding angle; it can work without resonance wavelength shift range overlapping by switching independent sensing channels. Besides that, we can add a sensing zone on the receiving fiber to construct the wavelength division multiplexing (WDM) sensing for each fiber core channel. By combining TDM and WDM technology, we can double the sensing channels.

Photonic crystal fiber-based surface plasmon resonance sensor with selective analyte channels and graphene-silver deposited core.

We propose a surface plasmon resonance (SPR) sensor based on photonic crystal fiber (PCF) with selectively filled analyte channels. Silver is used as the plasmonic material to accurately detect the analytes and is coated with a thin graphene layer to prevent oxidation. The liquid-filled cores are placed near to the metallic channel for easy excitation of free electrons to produce surface plasmon waves (SPWs). Surface plasmons along the metal surface are excited with a leaky Gaussian-like core guided mode. Numerical investigations of the fiber’s properties and sensing performance are performed using the finite element method (FEM). The proposed sensor shows maximum amplitude sensitivity of 418 Refractive Index Units (RIU−1) with resolution as high as 2.4 × 10−5 RIU. Using the wavelength interrogation method, a maximum refractive index (RI) sensitivity of 3000 nm/RIU in the sensing range of 1.46–1.49 is achieved. The proposed sensor is suitable for detecting various high RI chemicals, biochemical and organic chemical analytes. Additionally, the effects of fiber structural parameters on the properties of plasmonic excitation are investigated and optimized for sensing performance as well as reducing the sensor’s footprint.