Dual-channel fiber-optic surface plasmon resonance sensor with cascaded coaxial dual-waveguide D-type structure and microsphere structure

To address the restriction of fiber-optic surface plasmon resonance(SPR) sensors in the field of multi-sample detection, a novel dual-channel fiber-optic SPR sensor based on the cascade of coaxial dual-waveguide D-type structure and microsphere structure is proposed in this paper. The fiber sidepolishing technique converts the coaxial dual-waveguide fiber into a D-type one, and the evanescent wave in the ring core leaks, generating a D-type sensing region;the fiber optic fused ball push technology converts the coaxial dual waveguides into microspheres, and the stimulated cladding mode evanescent wave leaks, producing the microsphere sensing region. By injecting light into the coaxial dual-waveguide middle core alone, the sensor can realize single-stage sensing in the microsphere sensing area;it can also realize dual-channel sensing in the D-type sensing area and microsphere sensing area by injecting light into the ring core. The refractive index measurement ranges for the two channels are 1.333–1.365 and 1.375–1.405, respectively, with detection sensitivities of 981.56 nm/RIU and 4138 nm/RIU. The sensor combines wavelength division multiplexing and space division multiplexing technologies, presenting a novel research concept for multi-channel fiber SPR sensors.

Fiber cladding dual channel surface plasmon resonance sensor based on S-type fiber

Fiber cladding surface plasmon resonance(SPR)sensors have few structures,and a clad SPR sensor based on S-type fiber is proposed in this paper.This new type of fiber cladding SPR sensor was formed by electrofusing an S-shaped structure on the fiber to couple the light in the fiber core to the cladding.In this paper,the effects of fiber parameters on the performance of the sensor were studied by simulation and experiment.Based on the conclusion that the smaller the core diameter is,the closer the working band of the SPR resonance is to long wavelengths,and that the geometric characteristics mean that a multimode fiber can receive the fiber cladding light from a small core diameter few-mode fiber,a dual channel SPR sensor with a double S-type fiber cascade was proposed.In the refractive index detection range of 1.333–1.385refractive index units(RIU),the resonant working band of channel I is 627.66 nm–759.78 nm,with an average sensitivity of 2540.77 nm/RIU,and the resonant working band of channel II is 518.24 nm–658.2 nm,with an average sensitivity of2691.54 nm/RIU.The processing method for the S-type fiber cladding SPR sensor is simple,effectively solving the problem of this type of SPR sensor structure and the difficult realization of a dual channel.The sensor is expected to be used in the fields of medical treatment and biological analysis.

Design of a coated thinly clad chalcogenide long-period fiber grating refractive index sensor based on dual-peak resonance near the phase matching turning point

A novel method for designing chalcogenide long-period fiber grating(LPFG) sensors based on the dual-peak resonance effect of the LPFG near the phase matching turning point(PMTP) is presented. Refractive index sensing in a high-refractive-index chalcogenide fiber is achieved with a coated thinly clad film. The dual-peak resonant characteristics near the PMTP and the refractive index sensing properties of the LPFG are analyzed first by the phase-matching condition of the LPFG. The effects of film parameters and cladding radius on the sensitivity of refractive index sensing are further discussed. The sensor is optimized by selecting the appropriate film parameters and cladding radius. Simulation results show that the ambient refractive index sensitivity of a dual-peak coated thinly clad chalcogenide LPFG at the PMTP can be 2400 nm/RIU, which is significantly higher than that of non-optimized gratings. It has great application potential in the field of chemical sensing and biosensors.

Numerical simulation of a truncated cladding negative curvature fiber sensor based on the surface plasmon resonance effect

A refractive index(RI)sensor based on the surface plasmon resonance effect is proposed using a truncated cladding negative curvature fiber(TC-NCF).The influences of the TC-NCF structure parameters on the sensing performances are investigated and compared with the traditional NCF.The simulation results show that the proposed TC-NCF RI sensor has an ultra-wide detection range from 1.16 to 1.43.The maximum wavelength sensitivity reaches 12400 nm/RIU,and the corresponding R^(2)of the polynomial fitting equation is 0.9999.The maximum and minimum resolutions are 2.56×10^(-5)and 8.06×10^(-6),respectively.In addition,the maximum amplitude sensitivity can reach-379.1 RIU^(-1)when the RI is chosen as 1.43.The proposed TC-NCF RI sensor could be useful in biochemical medicine,environmental monitoring,and food safety.

High sensitivity SPR sensor for liquid phase sample with Ag/PbS/Graphene hybrid nanostructure

A surface plasmon resonance(SPR)sensor with Ag/PbS/GR hybrid nanostructure has been proposed for the diagnostics of liquid phase samples.Here Ag/PbS/GR hybrid nanostructure is designed as an asymmetric MIM waveguide for surface plasmon.Due to the guided wave SPR(GWSPR)modes,the index of the liquid phase samples can be measured more accurately than the conventional SPR sensors.Numerical simulation results show that the sensitivity of the sensor is about 5 times higher than the conventional SPR sensors.The origin of the enhancement mechanism is the combination of GWSPR in the Ag/PbS/GR hybrid nanostructure which enables the surface plasmon to spread along the PbS layer.In Ag/PbS/GR hybrid nanostructure,the electric field is concentrated mostly in the PbS layer,and the enhancement of the field intensity is nearly30%.

Advances in Phase Detection Technique of Surface Plasmon Resonance Biosensor

Surface plasmon resonance (SPR) sensing is an optical method based on evanescent wave.SPR biosensor can detect interaction of label-free biomolecules in real-time.With further development,it can become a research instrument in proteomics.SPR biosensor can be divided intensity measurement and phase measurement,and the latter possesses higher sensitivity than the former one.This paper attempts to summarize the SPR phase detection theory,discuss the major developments,compare the merits and deficiencies of various methods,and look forward to future prospects.

Sensitivity Dependence of Surface Plasmon Resonance Based Sensors on Prism Refractive Index

We theoretically and experimentally demonstrate that refractive index of the prism used to load metal film has significant influence on sensitivity of surface plasmon resonance based sensors. The prism with lower refractive index gives the sensors a higher sensitivity in detecting refractive index variations of a sample. We attribute this effect to the fact that a prism with low refractive index will increase coupling distance between surface plasmons and the medium under investigation.

Detection of Penicillin via Surface Plasmon Resonance Biosensor

A method of using Au colloid to capture the decomposed product of penicillin, penicillamine, on a surface plasmon resonance（SPR） biosensor for the quantitative determination of penicillin was developed. Based on the de-composition of penicillin to generate penicillamine and penilloaldehyde, a high sensitive biosensor for detecting penicillin was also developed. In our experiment, it was penicillamine rather than penicillin that has been measured. This is because penicillamine contains a functional group that makes it self-assembling on Au colloid to increase the molecular weight so as to improve the surface plasmon resonance signal. On a UV-Vis spectrophotometer, a high concentration of penicilliamine-Au complex was determined, indicating that penicillamine was already well combined with Au colloid. The method, using the combination of Au colloid with penicillamine, proved to detect penicillin.

Refractive Plasmonic Sensor Based on Fano Resonances in an Optical System

A symmetric plasmonie structure consisting of metal-insulator metal waveguide, groove studied, which supports double Fano resonances deriving from two different mechanisms and slot cavities is One of the Fano resonances originates from the interference between the resonances of groove and slot cavities, and the other comes from the interference between slot cavities. The spectral line shapes and the peaks of the double Fano resonances can be modulated by changing the length of the slot cavities and the height of the groove. Furthermore, the wavelength of the resonance peak has a linear relationship with the length of the slot cavities. The proposed plasmonic nanosensor possesses a sensitivity of 800nm/RIU and a figure of merit of 3150, which may have important applications in switches, sensors, and nonlinear devices.

Refractive index sensor based on high-order surface plasmon resonance in gold nanofilm coated photonic crystal fiber

We propose a novel kind of wide-range refractive index optical sensor based on photonic crystal fiber(PCF) covered with nano-ring gold film.The refractive index sensing performance of the PCF sensor is analyzed and simulated by the finite element method(FEM).The refractive index liquid is infiltrated into the cladding air hole of the PCF.By comparing the sensing performance of two kinds of photonic crystal fiber structures, a wide range and high sensitivity structure is optimized.The surface plasmon resonance(SPR) excitation material is chose as gold, and large gold nanorings are embedded around the first cladding air hole of the PCF.The higher order surface plasmon modes are generated in this designed optical fiber structure.The resonance coupling between the fundamental mode and the 5 th order surface plasmon polariton(SPP)modes is excited when the phase matching condition is matched.Therefore, the 3 rd loss peaks appear obvious red-shift with the increase of the analyte refractive index, which shows a remarkable polynomial fitting law.The fitnesses of two structures are 0.99 and 0.98, respectively.When the range of refractive indices is from 1.40 to 1.43, the two kinds of sensors have high linear sensitivities of 1604 nm/RIU and 3978 nm/RIU, respectively.

Polydopamine-Assisted Fabrication of Fiber-Optic Localized Surface Plasmon Resonance Sensor Based on Gold Nanoparticles

A fast and facile method of fabricating fiber-optic localized surface plasmon resonance sensors based on spherical gold nanoparticles was introduced in this study. The gold nanoparticles with an average diameter of 55 nm were synthesized via the Turkevich method and were then immobilized onto the surface of an uncladded sensor probe using a polydopamine layer. To obtain a sensor probe with high sensitivity to changes in the refractive index, a set of key optimization parameters, including the sensing length, coating time of the polydopamine layer, and coating time of the gold nanoparticles, were investigated. The sensitivity of the optimized sensor probe was 522.80 nm per refractive index unit, and the probe showed distinctive wavelength shifts when the refractive index was changed from 1.328 6 to 1.398,7. When stored in deionized water at 4 ℃, the sensor probe proved to be stable over a period of two weeks. The sensor also exhibited advantages, such as low cost, fast fabrication, and simple optical setup, which indicated its potential application in remote sensing and real-time detection.

Cascaded dual-channel fiber SPR temperature sensor based on liquid and solid encapsulations

In order to control the working wavelength range of the fiber surface plasmon resonance(SPR)temperature sensor and realize the wavelength division multiplexing type multi-channel fiber SPR temperature sensor,by comprehensively investigating the influence of liquids with different thermal-optical coefficients and solid packaging materials on the performance of fiber SPR temperature sensor,a dual-channel fiber SPR temperature sensor based on liquid-solid cascade encapsulation was designed and fabricated.The liquid temperature sensing stage encapsulated in capillary worked in 616.03 nm-639.05 nm band,the solid sensing stage coated with pouring sealant worked in 719.37 nm-825.27 nm band,and the two stages were cascaded to form a fiber dual-channel temperature sensor.The testing results indicated that when the temperature range was 35℃-95℃,the sensitivity of two-stage temperature detection was−0.384 nm/℃and−1.765 nm/℃respectively.The proposed fiber sensor has simple fabrication and excellent performance which can be widely used in various fields of dual-channel temperature measurement and temperature compensation.

Fiber cladding SPR bending sensor characterized by two parameters

A fiber cladding surface plasmon resonance(SPR)bending sensor is realized by the cladding of the fiber structure.By employing coating film,the sensing zone is protected and the toughness of the sensor increases.Three different sensing probes are tested,the experiment results indicate that the two parameters(wavelength sensitivity and light intensity sensitivity)sensing performances of the eccentric butt joint structures are superior to that of hetero-core structure,and the SPR bending sensor based on hetero-core structure is stable and uneasy to damage.By employing hetero-core fiber and silver film,a fiber cladding SPR bending sensor with better stabilization and sensing performance is realized.The proposed fabricating method of sensing probe with coating film provides a new approach for fiber SPR-distributed bending sensor.

Surface plasmon resonance sensor based on molecularly imprinted films for the detection of pentaerythritol tetranitrate （PETN）

A novel surface plasmon resonance （SPR） sensor based on molecularly imprinted films （MIFs） was developed for the detection of pentaerythritol tetranitrate （PETN）. In this work, the thin MIFs were formed on a gold sensor chip through thermal co-polymerization of functional mono- mers （methacrylic acid, MAA） and crosslinking monomers （ethylene glycol dimethacrylate, EGD- MA） in the presence of template molecules PETN. The template molecules PETN were subsequently removed from the MIFs simply by rinsing the MIFs with a mixture of acetonitrile and acetic acid 9：1 （ v/v）, thus the recognition sites were formed for specific detection of PETN. According to the mass coverage equation, the surface coverage of removed PETN from MIFs was about 10. 8 ng/mm~. The developed SPR sensor allowed for the detection of PETN at concentration down to 10-~~ mol/L. A control experiment utilizing an analogue cyclotrimethylenetrinitramine （RDX） showed MIFs＇ good selectivity to PETN.

Performance analysis of surface plasmon resonance sensor with high-order absentee layer

A surface plasmon resonance （SPR） sensor with a high-order absentee layer on the top of metallic film is proposed. The performance of the SPR sensor with NaCl, MgO, TiO2 or AlAs high-order absentee layer is analyzed theoretically. The results indicate that the sensitivity and the full width at half maximum of those SPR sensors decrease with the increasing of the order of absentee layer, but the variation of the figure of merit （FOM） depends on the refractive index of absentee layer. By improving the order of absentee layer with high-refractive-index, the FOM of the SPR sensor can be enhanced. The maximum value of FOM for the SPR sensor with high-order TiO2 （or AlAs） absentee layer is 1.059% （or 2.587%） higher than the one with one-order absentee layer. It is believed the proposed SPR sensor with high-order absentee layer will be helpful for developing the high-performance SPR sensors.

基于新型拼接光子晶体光纤的SPR葡萄糖浓度传感器

针对人体血糖的稳定高效检测问题,本文提出了一种基于表面等离子体共振(SPR)技术的光纤传感器并成功应用于葡萄糖浓度检测。采用光纤熔接机级联拼接多模光纤–光子晶体光纤–光子晶体光纤–多模光纤(MPPM),利用磁控溅射仪在光纤结构表面沉积金膜。随后,使用巯基乙胺对传感区的金膜进行修饰,采用戊二醛固定葡萄糖氧化酶(GOD)的技术路线,使传感器具备葡萄糖特异性识别功能,并实现对低浓度葡萄糖溶液的传感。针对SPR传感器的折射率灵敏度,本文设计两组对比实验,分别是相同结构不同传感区长度的传感器对比,以及相同长度不同结构的传感器对比。研究结果表明:传感区长度对传感器的折射率灵敏度的影响较小;MPPM传感结构的折射率灵敏度优于MPM传感结构(提高了约101.84 nm/RIU),且MPPM结构的传感器具有更深的SPR共振峰,意味着检测精度更高。对于制备的葡萄糖传感器,设计了一套葡萄糖浓度、特异性识别及稳定性的检测方案。实验结果表明:在0~0.8 mg/mL的浓度范围的葡萄糖溶液中,MPPM传感器的葡萄糖灵敏度约为29.61nm/(mg·mL^(–1)),且表现出良好的线性关系,拟合系数达到了0.954;具有良好的特异性识别能力及稳定性能。相比于传统的葡萄糖传感器,本文提出的葡萄糖传感器结构紧凑、生物相容性好、灵敏度高。

Sensitivity improvement of aluminum-based far-ultraviolet nearly guided-wave surface plasmon resonance sensor

An aluminum(Al)based nearly guided-wave surface plasmon resonance(NGWSPR)sensor is investigated in the far-ultraviolet(FUV)region.By simultaneously optimizing the thickness of Al and dielectric films,the sensitivity of the optimized Al-based FUV-NGWSPR sensor increases from 183/RIU to 309/RIU,and its figure of merit rises from 26.47 RIU^(-1)to 32.59 RIU^(-1)when the refractive index of dielectric increases from 2 to 5.Compared with a traditional FUV-SPR sensor without dielectric,the optimized FUV-NGWSPR sensor can realize simultaneous improvement of sensitivity and figure of merit.In addition,the FUV-NGWSPR sensor with realistic materials(diamond,Ta_(2)O_(5),and GaN)is also investigated,and 137.84%,52.70%,and 41.89%sensitivity improvements are achieved respectively.This work proposes a method for performance improvement of FUV-SPR sensors by exciting nearly guided-wave,and could be helpful for the high-performance SPR sensor in the short-wavelength region.

Numerical study of a highly sensitive surface plasmon resonance sensor based on circular-lattice holey fiber

A new design of surface plasmon resonance(SPR)sensor employing circular-lattice holey fiber to achieve highsensitivity detection is proposed.The sensing performance of the proposed sensor is numerically investigated and the results indicate that our proposed SPR sensor can be applied to the near-mid infrared detection.Moreover,the maximum wavelength sensitivity of our proposed sensor can reach as high as 1.76×10^(4)nm/refractive index unit(RIU)and the maximum wavelength interrogation resolution can be up to 5.68×10^(-6)RIU when the refractive index(RI)of analyte lies in(1.31,1.36).Thanks to its excellent sensing performance,our proposed SPR sensor will have great potential applications for biological analytes detection,food safety control,bio-molecules detection and so on.

纳米金用于SPR传感器检测小分子的研究进展

近年来,表面等离子体共振(Surface Plasmon Resonance,SPR)技术因具有可实时、动态监测SPR芯片上分子间相互作用的优点,而广泛应用于小分子传感检测领域。信号放大是小分子SPR传感器的重要研究内容,它决定小分子能否被检出及传感器灵敏度,因此信号放大技术对其发展非常重要。纳米金因其高电子密度、介电特性及易修饰等特性而用于多种传感器的信号放大。重点介绍近5年来纳米金在小分子SPR传感器方面的应用情况,旨在为小分子SPR传感器的进一步发展提供参考依据。

A saccharides sensor developed by symmetrical optical waveguide-based surface plasmon resonance

We proposed a new saccharides sensor developed by symmetrical optical waveguide(SOW)-based surface plasmon resonance(SPR).This unique MgF_(2)/Au/MgF_(2)/Analyte film structure results in longer suface plasmon wave(SPW)propagation lengths and depths,leading to an increment of resolution.In this paper,we managed to decorate the dielectric interface(MgF_(2) layer)by depositing a thin polydopamine film as surface adherent that provides a platform for secondary reactions with the probe molecule.3-Aminophenylboronic acid(3-PBA)is chosen to be the saccharides sense probe molecule in the present work.The aqueous huumnor of Diabetes and Cataract patient whose blood glucose level is normal are analyzed and the results dermonstrated that this sensor shows great potential in monitoring the blood siugar and can be adapted in the field of biological monitoring in the future.