Aluminum-Based Deep-Ultraviolet Surface Plasmon Resonance Sensor

Plasmonics - An aluminum-based deep-ultraviolet surface plasmon resonance (DUV-SPR) sensor is promising for biological applications. Design aspects of a DUV-SPR sensor are here considered by using...     

Novel Detection of Diesel Adulteration Using Silver-Coated Surface Plasmon Resonance Sensor

Plasmonics - In this study, we propose a silver-coated (SPR—surface plasmon resonance)-based biosensor for the detection of diesel adulteration for the first time in the field of biosensing....     

基于波长寻址的表面等离子体共振传感技术

本文提出了基于光谱扫描技术的非机械扫描的表面等离子体共振(SPR)传感技术,采用白光为SPR激发光源,通过单色仪控制入射光的波长实现光谱寻址,在保证灵敏度和动态范围的同时,使系统在整个动态范围内具有较好的线性,简化了传感器结构。理论分析了光谱扫描SPR传感技术的灵敏度和动态范围,搭建了实验系统,并测量了不同浓度的酒精水混合溶液的SPR信号变化。结果表明:系统折射率测量范围为1.30-1.38,灵敏度可达3.1×105RIU。     

A Waveguide-Coupled Surface Plasmon Resonance Sensor Using an Au-MgF2-Au Structure

Plasmonics - We describe an Au-MgF2-Au trilayered waveguide-coupled surface plasmon resonance (WCSPR) sensor in this article. The characteristics of this sensing structure are compared with those...     

偏振干涉角度调制SPR传感技术研究及应用进展

针对一种新兴生物检测方法——表面等离子体波共振(SPR)技术,文中SPR传感系统采用偏振干涉和角度调制方案,使SPR传感灵敏度与光复反射系数的模和相位都相关,从而实现较大线形范围内的高灵敏测量。同时开展了该SPR传感系统在环保领域的应用研究,SPR共振信号可实时随甲烷含量线性改变,气体检测灵敏度达到1 070ppm,实验结果验证了这种SPR传感技术的检测性能并显示了其在环保监测领域的应用潜力。     

Electrically Tunable Fiber Optic Sensor Based on Surface Plasmon Resonance

The response of optical fiber surface plasmon resonance (SPR) sensor to potential is monitored in real time. The potential-induced reflectance of a gold-coated optical fiber SPR probe is dependent on potential step width and ionic strength. Wider potential step and stronger ionic strength are generally able to enhance the reflectance and accelerate the response time. The specifically adsorptive anion Cl^? provides a pronounced effect on a potential-dependent SPR probe. The exclusive contact of the SPR probe with anion Cl^? could significantly slow down the optical response. The work offers opportunities for optical fiber SPR probes to characterize the electrochemical application.     

A Novel Strategy for Analyzing RNA-Protein Interactions by Surface Plasmon Resonance Biosensor

Surface plasmon resonance (SPR) biosensor is a promising technology for its various advantages including the real-time measurement of biomolecular interactions without labeling. A method of hybridizing RNAs on the surface of the streptavidin-coated (SA) sensor chip to study RNA-protein interactions was described in this paper. In our study, it has been shown that the nucleocapsid (N) protein of severe acute respiratory syndrome coronavirus (SARS-CoV) has a high binding affinity for the leader sequence of SARS-CoV genome. Effect of temperature on the RNA-DNA hybridization was also examined. This method can provide the affinity of interactions with high sensitivity. Therefore, it will be useful in screening binding candidates for a given RNA target motif with one chip.     

Waveguide-Coupled Surface Plasmon Resonance Sensor for Both Liquid and Gas Detections

Plasmonics - In this paper, we propose a novel surface plasmon resonance sensor for both liquid and gas detections, which is based on the two dielectric planar waveguide (PWG)-coupled plasmonic...     

Novel and Sensitive Core-Shell Nanoparticles Based on Surface Plasmon Resonance

In this paper, a rough silver core-shell nanoparticle with strong electric field enhancement in the vicinity of a bumpy structure on the silver core-shell surface is reported. A dipolar plasmonic mode of the silver nanoshell is investigated by using the quasi-static approach and plasmon hybridization theory, which analytical results identify the electric field enhancement spectra in which the enhancement is optimized. As the silver shell thickness is small, the hot spots play an important role in the plasmonic field enhancement. In addition, the deposition of a rough silver shell can generate a stronger near-field enhancement near the silver surface which is more desirable than that of a smooth silver shell for sensitive detection based on SPR and surface enhanced Raman scattering (SERS). The plasmonic field enhancement of a bumpy silver core-shell nanoparticle permits the detection and characterization of bovine serum albumin (BSA) protein molecule and hemoglobin solution with a high sensitivity.     

High-Performance Magneto-Optic Surface Plasmon Resonance Sensor Design: An Optimization Approach

High-performance intensity-interrogated magneto-optic surface plasmon resonance (MOSPR) sensors are designed by a multi-objective optimization approach. Designed devices show bulk refractive index sensitivity 1 order of magnitude larger than the current state of the art, while the design procedure allows to chose an appropriate trade-off between sensor performance and ease of fabrication. Straightforward guidelines for the sensor design and fabrication emerge from the optimization process, indicating that minimization of the optical losses takes precedence on the maximization of the magneto-optical modulation.     

Light Humidity Sensor of Surface Plasmon Resonance by Symmetric Metal Film

The field of plasmonics has experienced a renaissance in recent years by providing a large variety of new physical effects and applications. Here, we demonstrate a light humidity sensor of surface plasmon resonance (SPR) by a symmetric metal film, which uses P polarised light of emergent He–Ne laser to stimulate SPR. Resonance angle change received by the spectrum detector can determine humidity via the relationship between humidity and effective refractive index. When the relatively short wavelengths are shown in the model, the evanescent wave penetration depth is shallow, resonance state is weak and energy loss is low. The opposite results are obtained, when the wavelength is long. Also, with increasing thickness, the resonance peak becomes acute, thereby indicating the improvement in detection accuracy. When the metal thickness of our model is 50 nm, the resonance peak of the reflection spectrum is narrower, accuracy is high and reflectivity is close to 0. By analysing the experimental results, the SPR resonance phenomenon is shown. The electromagnetic field energy is highly concentrated near the interface between the metal and SiO₂, which appears highly localized. The resolution of the structure can reach 0.37% RH (relative humidity), which is significantly more than the resolution of capacitive humidity sensor, i.e., resolution is usually 1% RH to 2% RH. The optical sensor of our development can provide a key device for long-distance transmission sensing, in special conditions such as low temperature.

     

Graphene-MoS2 Hybrid Structure Enhanced Fiber Optic Surface Plasmon Resonance Sensor

Plasmonics - In this paper, a fiber optic surface plasmon resonance sensor based on graphene-MoS2 hybrid structure is presented. The wavelength interrogation method is employed to analyze the...     

Refractive Index Sensor Using Long-Range Surface Plasmon Resonance with Prism Coupler

Plasmonics - Long-range surface plasmon resonance (LRSPR)-based sensors exhibit high sensitivity as compared to the conventional SPR sensors due to low losses. A high refractive index prism and low...     

Surface Plasmon Resonance Based Fiber Optic Ammonia Sensor Utilizing Bromocresol Purple

In this paper, a surface plasmon resonance (SPR) based fiber optic ammonia gas sensor has been designed and fabricated using bromocresol purple (BCP) as sensing element. The sensor works under wavelength modulation scheme. The detection of ammonia gas has been carried out at room temperature. Three different kinds of film coating configurations, namely silver + BCP, gold + BCP, and silver + silicon + BCP on the unclad portion of the fiber have been used for studying the role of each layer. Further, to optimize the performance of the sensor, the films of varying thicknesses were coated using thermal evaporation technique. Experiments have been performed for the ammonia concentrations ranging from 0 to 150 ppm around the probe. To record the SPR spectrum, light from a polychromatic source is launched in the fiber and the spectrum is recorded at the other end of the fiber. The spectrum has a peak at lower wavelength while a dip at the higher wavelength. The dip corresponds to SPR while the peak appears to be due to fluorescence properties of the dye. It has been observed that as the ammonia gas comes in contact of the BCP layer, it changes the refractive index of the BCP dye which, in turn, changes the resonance wavelength. Further, the change in refractive index increases as the concentration of ammonia gas increases up to certain concentration of ammonia after that it saturates. Silicon layer has been shown as a protection layer for silver and gold from oxidation and acts as a tuner of wavelength. The proposed ammonia sensor has small response as well as recovery time.     

Influence of Dielectric Coating on Performance of Surface Plasmon Resonance Sensor

Plasmonics - In the present study, the nature of dielectric layer above metal layer in surface plasmon resonance sensor is investigated. The performance-defining parameters, i.e., shift in...     

Nano-gap-Enhanced Surface Plasmon Resonance Sensors

This paper analyzes how dual-mode surface plasmon resonance sensors can be further improved if one were to introduce small (∼20 nm) gaps in the film surface. First, a figure of merit, the sensor’s limit of detection (LOD), is defined in order to optimize the design of the nano-gap sensor. Secondly, the LOD of this design is compared with that of an optimized planar dual-mode design. Through this analysis, it is shown that the LOD of the planar sensor can be improved upon by around a factor of 7 when compared with the nano-gap-enhanced design. Furthermore, with the nano-gap design, the lower wavelength plasmon mode demonstrates remarkably improved selectivity when compared with the conventional sensor. In order to explain these results, the dispersion of each plasmon mode along with the electromagnetic field profiles are modeled and analyzed.     

Extra-broad Photonic Crystal Fiber Refractive Index Sensor Based on Surface Plasmon Resonance

Plasmonics - We propose and investigate a photonic crystal fiber (PCF) refractive index sensor with triangular lattice and four large-size channels based on surface plasmon resonance. In such...     

Graphene/Au-Enhanced Plastic Clad Silica Fiber Optic Surface Plasmon Resonance Sensor

Owing to its large surface-to-volume ratio and good biocompatibility, graphene has been identified as a highly promising candidate as the sensing layer for fiber optic sensors. In this paper, a graphene/Au-enhanced plastic clad silica (PCS) fiber optic surface plasmon resonance (SPR) sensor is presented. A sheet of graphene is employed as a sensing layer coated around the Au film on the PCS fiber surface. The PCS fiber is chosen to overcome the shortcomings of the structured microfibers and construct a more stable and reliable device. It is demonstrated that the introduction of graphene can enhance the intensity of the confined electric field surrounding the sensing layer, which results in a stronger light-matter interaction and thereby the improved sensitivity. The sensitivity of graphene-based fiber optic SPR sensor exhibits more than two times larger than that of the conventional gold film SPR fiber optic sensor. Furthermore, the dynamic response analyses reveal that the graphene/Au fiber optic SPR sensor exhibits a fast response (5 s response time) and excellent reusability (3.5% fluctuation) to the protein biomolecules. Such a graphene/Au fiber optic SPR sensor with high sensitivity and fast response shows a great promise for the future biochemical application.     

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

Plasmonics - 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,...     

Surface Plasmon Resonance Imaging Sensors: A Review

Surface plasmon resonance (SPR) imaging sensors realize label-free, real-time, highly sensitive, quantitative, high-throughput biological interaction monitoring and the binding profiles from multi-analytes further provide the binding kinetic parameters between different biomolecules. In the past two decades, SPR imaging sensors found rapid increasing applications in fundamental biological studies, medical diagnostics, drug discovery, food safety, precision measurement, and environmental monitoring. In this paper, we review the recent advances of SPR imaging sensor technology towards high-throughput multi-analyte screening. Finally, we describe our multiplex spectral-phase SPR imaging biosensor for high-throughput biosensing applications.