Optic SPR Sensor Research Articles

Theoretical study of distance-dependent optical fiber SPR sensor based on MoS2 nanosheets

Sandwich assay employing gold nanoparticles and DNA is a common signal amplification strategy designed for surface plasmon resonance sensor. To further improve the sensitivity employing sandwich assay, sandwich-structured optical fiber surface plasmon resonance sensors based on AuNPs and MoS2 nanosheets has been theoretically studied. Au film deposited on fiber core is the bottom nanomaterial of sandwich structure while AuNPs and MoS2 nanosheets are optional used as top nanomaterials. Top and bottom nanomaterials are separated by double stranded DNA, which allows solvent to perform as a spacer. The thickness of spacer is able to be tuned by the number of base pairs of double stranded DNA. Spacer thickness and nanomaterials play important roles to regulate the performance of optical fiber surface plasmon resonance sensor. The refractive index sensitivity has been found to be enhanced by the presence of MoS2 nanosheets compared to AuNPs. Large spacer thickness supported by long double stranded DNA further improves the performance of sensor. This study yields new insight into the structural design of optical fiber surface plasmon resonance sensor enhanced by sandwich structure and will open exciting avenues to apply sandwich-like assay for biosensing.

Orthogonal-Sided Polished Microstructured Optical Fiber-Based SPR Sensor for Simultaneous Measurement of Temperature and Refractive Index

We propose a concept of orthogonal-side polished microstructured optical fiber (MOF)-based surface plasmon resonance (SPR) sensor to implement the simultaneous sensing for two parameters. Two feasible structures, L-shaped MOF based and rectangular MOF based SPR sensors are investigated theoretically, which can support <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> -polarized resonance peaks that can be used to measure and separate variations of the temperature and refractive index (RI). Our results show that the temperature coefficients (K <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_Tx</i> and K <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_Ty</i> ) are 8 pm/°C and 6 pm/°C, and the RI coefficients (K <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_nx</i> and K <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_ny</i> ) are 1470 nm/RIU and 1570 nm/RIU, for the L-shaped MOF-SPR sensor, while the K <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_Tx</i> and the K <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_Ty</i> are 10 pm/°C and 8 pm/°C, the K <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_nx</i> and K <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_ny</i> are 1460 nm/RIU and 1500 nm/RIU, for the rectangular MOF-based SPR sensor. Moreover, these coefficients can be further improved by choosing the appropriate structure parameters. The proposed SPR sensors with the advantages of simultaneously measuring two parameters and no need to be filled with the sensing media are expected to be more competitive in the MOF-based SPR sensor field.

Study of LSPR Spectral Analysis Techniques on SPR Optical Fiber Sensors

Nanoparticles create localized surface plasmonic resonances (LSPR) with lower surrounding refractive index (SRI) sensitivities than their propagating SPR counterpart, originated in thin films. Historically, LSPR SRI sensitivities enhancements were achieved through spectral analysis methods that focus on unique spectral features. Herein, a study using that methodology was applied on SPR devices resulting in an increased sensitivity to SRI. It was found that by applying the inflection point method on optical fiber SPR sensors resulted in both sensitivity and resolution increments up to 44 and 35 %, respectively, in the SRI range from 1.3333 to 1.4150. Thus, successfully improving sensing capabilities of SPR based optical fiber sensors.

Optical fiber SPR sensor for the detection of fluoride contamination in drinking water

Optical fiber SPR sensor for the detection of fluoride contamination in drinking water

Tapered Optical Fiber Spr Sensor for Salinity Measurement with High Sensitivity

Tapered Optical Fiber Spr Sensor for Salinity Measurement with High Sensitivity

Highly Sensitive U-Shaped Optical Fiber Refractometer Based on Bi2O2Se-Assisted Surface Plasmon Resonance

In this work, we firstly used a new two-dimensional (2D) semiconductor material Bi2O2Se for optical-fiber SPR sensor sensitization, proposed and validated a U-shaped optical-fiber SPR sensor with Au film- Bi2O2Se Sandwich structure. The finite element simulation results illustrate that the electric field strength on the surface is 2.08 times higher than that of the pure Au film, which excites a stronger SPR phenomenon thus leading to a high sensitivity of the sensor. The effect of the Radius on the sensor performance was investigated, and the optimal structural parameters were derived to fabricate the sensing probes. The RI sensitivity of the presented sensor is 6827.41 nm/RIU, 1.98 times superior to that of the pure Au film U-shaped optical SPR sensor. The sensor is insensitive to temperature fluctuations and has good repetitive and environmental stability. The proposed sensor has good potential for future applications in biomass detection, which also indicates that Bi2O2Se has good prospects for future applications in optoelectronic devices.

Numerical Analyses of Liquid-Core Fiber Optic SPR Sensor with Nano-Porous Sio2 as Inner Coating

In this paper, a novel type of liquid-core fiber optic SPR sensor with a nano-porous SiO2 inner coating is proposed. The nano-porous SiO2 is deposited on the inner wall of the quartz tube. Due to the flexible and adjustable refractive index of the deposited material, the RI detection range of the sensor is expanded. The simulation results show that the proposed sensor owns good responses in both low and high refractive index regions, with the corresponding RI sensitivities of 1043.71 nm/RIU and 1234.86 nm/RIU respectively, while the FWHM is only about 20 nm. There are some potential applications for the proposed sensor in environmental monitoring, biochemical detection, food safety etc.

Metallic Grating-Assisted Fiber Optic SPR Sensor with Extreme Sensitivity in IR Region

Metallic Grating-Assisted Fiber Optic SPR Sensor with Extreme Sensitivity in IR Region

Structure optimization of gold-sputtered side-polished U-shaped plastic optical fiber SPR sensor

PurposeThis study aims to optimize the structure of gold-sputtered U-shaped plastic fiber sensors.Design/methodology/approachA group of U-shaped Au-sputtered plastic optical fiber sensing probes with polishing angles of 45°, 90° and 135° is prepared.FindingsThe experimental results show that the spectral response and sensitivity of the sensor at 45°polishing angle is twice that of the sensor at 90°.Research limitations/implicationsDue to the limitations of laboratory temperature and equipment, the overall effect has not reached the ideal, but the expected effect has been obvious. Experiments also optimize the sensor.Practical implicationsOptical fiber sensing has always been an indispensable part of various fields.Social implicationsSensor optimization is of great help to the progress of technology and the development of science and technology.Originality/valueThe authors have no conflicts of interest to disclose.

Fiber optic SPR sensing of liquids using copper and zinc oxide

Refractive index sensing of liquids by fiber optic SPR sensor using bi-layers of copper-zinc oxide has been experimentally demonstrated. Thicknesses of copper and zinc oxide layers are shown to affect the sensitivity of the sensor. Sensitivity is found to increase with increase in zinc oxide layer thickness till 15 nm and keeps reducing with additional augmentation in zinc oxide layer thickness beyond 15 nm. Optimized thickness of zinc oxide layer is ensured to be 15 nm. Sensor developed using 40 nm thick copper-15 nm thick zinc oxide bi-layers manifests good sensing action.

On the application of few layer $$\hbox {Ti}_{3}\hbox {C}_{2}$$ MXene on fiber optic SPR sensor for performance enhancement

On the application of few layer $$\hbox {Ti}_{3}\hbox {C}_{2}$$ MXene on fiber optic SPR sensor for performance enhancement

Optical Fiber Biomedical Sensor Based on Surface Plasmon Resonance

Optical fiber biomedical sensor based on surface plasmon resonance for measuring and sensing the concentration and the refractive index of sugar in blood serum is designed and implemented during this work. Performance properties such as signal to noise ratio (SNR), sensitivity, resolution and the figure of merit were evaluated for the fabricated sensor. It was found that the sensitivity of the optical fiber-based SPR sensor with 40 nm thick and 10 mm long Au metal film of the exposed sensing region is 7.5µm/RIU, SNR is 0.697, figure of merit is 87.2 and resolution is 0.00026. The sort of optical fiber utilized in this work is plastic optical fiber with a core diameter of 980 µm, a cladding of 20μm, and a numerical aperture of 0.51.

Performance Analysis of SPR Sensor Based on Polymer-tipped Optical Fiber Coated with Barium Titanate Layer

In this paper, an optical fiber SPR sensor based on polymer-tipped optical fiber (PTOF) coated with a gold film and a Barium Titanate (BaTiO3) layer has been designed and analyzed by finite difference time-domain (FDTD) method. Three SPR dips are observed and the sensitivity is proved to be higher than the structure without BaTiO3. A novel measurement method based on sum-value and difference-value of two SPR dips is proposed. Compared with conventional measurement method based on single dip, the measurement based on sum-value can significantly improve the sensitivity and the measurement based on difference-value can effectively reduce the environmental influence.

Study of Surface Plasmon Resonance Sensor Based on Polymer-Tipped Optical Fiber With Barium Titanate Layer

In this article, an optical fiber SPR sensor based on polymer-tipped optical fiber (PTOF) coated with a gold film and a Barium Titanate (BaTiO3) layer has been designed and optimized by finite difference time-domain (FDTD) method. Three SPR dips are observed and the optimal sensitivity of single-mode PTOF SPR sensor coated with an additional BaTiO3 layer reaches 6710 nm/RIU when refractive index (RI) of analyte is 1.333–1.343. A novel measurement method based on sum-value and difference-value of two SPR dips is proposed. Compared with conventional measurement method based on single dip, the measurement based on sum-value can significantly improve the sensitivity and the measurement based on difference-value can effectively reduce the environmental influence.

Simultaneous measurement of salinity, temperature and pressure in seawater using optical fiber SPR sensor

A new fiber optic reflective probe is designed for simultaneous detection of salinity, temperature, and pressure in seawater. As far as we know, it is the first time that these three parameters are measured by an integrated reflex optical fiber sensor. Surface Plasmon Resonance effect inspire by an Au film coated on the fiber’s surface. Photonic crystal fiber (PCF) is chosen as an ideal mode-excitation field. Slow spreading cladding pattern provide a possibility for simultaneous existence of multiple SPR resonance dips. Two kinds of sensitive films (PDMS, SU-8) are coated outside the Au film at different sections. This design makes it possible to form three different sensitive areas, and then three distinct SPR resonance dips appear by optimizing the structure’s parameters. In calibration experiments of an optimized probe, the maximum sensitivity of 0.560 nm/ g/kg, −1.802 nm/°C, and 2.838 nm/MPa are obtained respectively for salinity, temperature, and pressure measurement. Meanwhile, transmission matrix coefficients are determined for cross-sensitive demodulation. This design will have great practical potential if more optimization and process treatments are carried out in the future.

The effect of the TiO2 film on the performance of the optical fiber SPR sensor

We studied the effect of the Titanium Oxide (TiO2) film on the performance of the optical fiber SPR with two kinds of probes. The light guiding properties and sensing performance of the D-type optical fiber SPR sensor coated with TiO2 was studied numerically by finite element method (FEM) and the sensing performance of the multimode-single mode-multimode (MSM) hetero-core optical fiber SPR sensor coated with TiO2 was investigated experimentally. The simulation and experimental results for two kinds of probes consistently show that the absence of TiO2 film layer on the gold film can enhance the refractive index sensitivity and tune the resonance curve of the sensor from visible light to near-infrared.

A D-type fiber based symmetrical long-range surface plasmon resonance sensor with high quality factor

A D-type fiber based symmetrical long-range surface plasmon resonance (sLRSPR) sensor with high quality factor (Q-F) as high as 107.52 RIU−1 was proposed and experimentally demonstrated. The sensing structure of the proposed sensor consisted of fiber/dielectric buffer layer (DBL)/Au film/DBL/analyte, and the DBLs on both sides of the Au film in the sLRSPR sensor were identical, which greatly increased the permittivity matching degree between the analyte and the DBL near the D-type fiber, and reduced the loss of long-range surface plasmon polaritons. For LRSPR sensor, the closer the permittivities of DBL and analyte on both sides of metal film are, the easier the LRSPR is to stimulate, and thus the proposed sensor possessed higher sensitivity and higher detection accuracy. The transfer matrix method supported by the finite-difference beam propagation method and the finite element analysis was employed to optimize the sensor parameters for the first time. The refractive index sensing performance of the conventional SPR (cSPR) sensor, the conventional LRSPR (cLRSPR) sensor, and the sLRSPR sensor with optimal parameters were systematically researched by simulation and in-depth experiment. The results suggested that the sensing performance of the sLRSPR sensor was better than that of the other two sensors. This paper provided a meaningful advancement for designing an optical fiber SPR sensor with remarkable performance to measure biomass.

Indium tin oxide and silver based fiber optic SPR sensor: an experimental study

Fabrication and characterization of SPR based fiber optic sensor utilizing bi-layers of ITO-Ag is presented. Effects of thicknesses of ITO and Ag layers on the sensitivity of sensor are studied experimentally. Sensitivity ascends as the thickness of Ag layer is enhanced till 30 nm and it starts decreasing as the thickness of Ag layers is further increased beyond 30 nm. SPR sensor based on 40 nm thick ITO layer-30 nm thick Ag layer demonstrates highest sensitivity.

Effect of zinc oxide overlayer on the sensitivity of fiber optic SPR sensor with indium tin oxide layer

Experimental analysis of surface plasmon resonance based fiber optic refractive index sensor using bi-layers of ITO-ZnO is presented. Outcomes of thicknesses of ITO and ZnO layers on the sensitivity of SPR sensor are experimentally studied. Sensitivity is found to be enhanced with increase in thickness of ZnO layer up to a certain thickness. 40 nm ITO-15 nm ZnO based fiber optic SPR sensor exhibits largest value of sensitivity.

Fluoride fiber optic SPR sensor with enhanced performance: Simulation and analysis within the framework of Kubo formulation for graphene

Abstract The performance of a fiber optic SPR sensor with ZBLAN fluoride glass core, NaF clad, Ag layer, and graphene monolayer is simulated and analyzed under the synchronized tuning of temperature, near infrared (NIR) wavelength, and graphene’s chemical potential. The simulation is carried out by considering the graphene’s conductivity variations as per Kubo formulation. For other constituent media, the thermo-optic effect is considered. The simulation results suggest a general outcome that a combination of shorter NIR wavelength, higher temperature, and larger chemical potential can provide considerably enhanced performance. A finer analysis predicts that 1310 nm wavelength, 0.61 eV chemical potential, and 332.4 K temperature can be used as a pragmatic combination in order to achieve significantly enhanced sensing performance. The proposed sensor provides higher figure-of-merit than most recent works reported on SPR-based sensors.