波长调制型表面等离子体共振的传感特性研究

表面等离子体共振(SPR)光学传感器能实现生物医学的快速、 无标记、 高精度检测,是生物化学分析的重要方法。 研制了基于波长调制型的Kretschmann结构表面等离子体共振(SPR)生物传感系统,研究了在体溶液传感方式下的传感性能。 利用不同浓度的乙醇和乙二醇溶液进行体溶液传感测试。 实验结果表明,在折射率低时共振波长对折射率变化响应的灵敏度低,但响应的线性度高;随着折射率增大,共振波长对折射率的响应变化的灵敏度提高。 在1.407 0～1.430 RIU折射率范围内,灵敏度高达11 487 nm·RIU-1。 传感器的共振波长的稳定性为0.213 8 nm,可分辨最小折射率趋近10-6 RIU。 所研制的波长调制型表面等离子共振传感器操作简单、 灵敏度高、 检测范围大,可实现浓度极低生物标记物的有效检测,在化学、 生物传感领域有重要的应用。     

反射式光纤表面等离子体波共振传感器特性研究

研究了一种基于表面等离子体波共振(SPR)光谱分析的折射率检测新方法。研究发现,表面等离子体波共振效应光谱特征的折射率灵敏度会随着液体性质变化而发生改变。根据折射率测量范围不同,分别选择共振波长和共振强度作为检测参量,实现理论折射率分辨力达到10~(-5)数量级以上。在理论分析和实验基础上,设计出一种基于共振光强检测的终端反射式光纤表面等离子体波共振效应传感系统,采用将传感信号和基准光信号的比值作为液体折射率变化的度量值。在1．3325～1．3991的折射率测量范围内,度量值与折射率之间呈现单调递减关系,线性相关系数为0．9983。通过定义耦合系数,还可实现对表面等离子体波共振效应效应强弱和变化趋势的评估。     

表面等离子体共振成像生物芯片检测系统

根据表面等离子体共振(Surface Plasmon Resonance, SPR)原理,提出基于表面等离子体共振成像(Surface Plasmon Resonance imaging, SPRI)的生物芯片检测系统构建方法.介绍了SPRI生物芯片检测系统的原理、自行组建的SPRI生物芯片检测系统的结构.采用Kretschmann型棱镜耦合结构激励SPR,偏振的平行光经棱镜投射到生物芯片上,发生表面等离子体共振,由CCD摄像机采集反射光芯片图像.以巯基修饰淋病奈瑟氏菌探针为例验证该系统,利用自组装单分子层技术(Self-Assembled Monolayer,SAM)固定探针.应用该检测系统采集了探针共振、非探针处共振、探针和非探针处都不共振时的生物芯片图像.     

基于表面等离子体共振的新型超宽带微结构光纤传感器研究

基于表面等离子体共振的微结构光纤传感器具有高灵敏、免标记和实时监控等优点.如今,由于此类传感器广泛应用于食品安全控制、环境检测、生物分子分析物检测等诸多领域而受到大量研究.然而,目前所报道的绝大多数此类传感器只能应用于可见光或近中红外传感.因此,对可应用于中红外传感的表面等离子体共振微结构光纤传感器的研究是一项极具挑战性的工作.基于此,本文设计了一种可以工作在近红外和中红外区域的新型高灵敏表面等离子体共振微结构光纤传感器.传感器采用双芯单样品通道结构,该结构不仅可以消除相邻样品通道间的相互干扰和提高传感器的信噪比,还可以在超宽带波长范围内实现高灵敏检测.采用全矢量有限元法对其传感特性进行了系统的研究,研究结果表明:当待测样品折射率分布在1.423—1.513范围内时,传感器不仅可以在1.548—2.796μm的超宽带波长范围内进行工作,而且其平均灵敏度高达13964 nm/RIU.此外,传感器的最高波长灵敏度和折射率分辨率分别为17900 nm/RIU,5.59×10^–7 RIU.     

高精度表面等离子体共振传感中的信号处理方法

表面等离子体共振传感技术是一种简单可行并广为应用的光学高精度表面检测方法,能够对折射率的变化(10-8)进行检测。若要实现高灵敏度、高稳定性、高可靠性的检测,除了光电系统硬件外,信号的数据处理方法也是关键技术之一。运用合适的数据处理方法可有效地降低实验中的随机噪声以及系统不理想性所带来的影响,可大大提高测量精度、准确性和测量范围。从信号处理方法的角度,根据国内外近年来的研究成果,利用表面等离子体共振实现了在微量检测和薄膜分析时进行数据处理的算法。     

基于分光计的表面等离子体共振实验

在分光计的基础上,利用激光二极管作为光源,自制硅光电池放大电路作为检测元件,自行组装了角度指示型表面等离子体共振传感器综合实验装置.使用该装置可以在分光计上观察表面等离子体共振现象,测量电解质折射率与共振角的关系.     

基于表面等离子体共振和定向耦合的D形光子晶体光纤折射率和温度传感器

利用光子晶体光纤结构的灵活性和性能的优越性, 设计了一种基于D形光子晶体光纤的折射率和温度传感器. 在D形光子晶体光纤表面抛磨并镀上金纳米薄膜, 作为表面等离子体共振传感通道用来测量液体折射率; 在包层的一个空气孔中填充温敏液体甲苯, 作为定向耦合通道实现对温度的测量. 进一步的数值计算发现, 基于定向耦合效应的温度传感和基于表面等离子体共振的折射率传感相互独立, D形光子晶体光纤同时进行折射率和温度传感检测. 在各向异性的完美匹配层边界条件下利用全矢量有限元法对该传感器特性进行了数值研究, 发现D形光子晶体光纤的空气孔直径决定了定向耦合吸收峰的中心波长和温度传感的灵敏度, 金薄膜的厚度和D形结构的抛磨深度仅影响表面等离子体共振峰的相对强度. 结果表明: 该传感器在-10–80 ℃的温度范围内具有11.6 nm/℃的温度灵敏度, 在1.34–1.44折射率范围内折射率灵敏度最高可达26000 nm/RIU.     

侧边抛磨光纤的光谱调制型表面等离子体共振传感研究

表面等离子体共振传感是基于光学消逝波与金属表面等离子体波共振的一种高灵敏度、快速、无标记的测量方式。光纤的表面等离子体共振传感具有在线测量、体积小、抗电磁干扰等优点。为提高折射率传感灵敏度,采用轮式侧边抛磨法抛磨掉多模光纤的全部包层和部分纤芯,并采用溅射法在光纤抛磨区先镀高折射率的铬层然后镀金膜,制作了侧边抛磨光纤表面等离子体共振传感器。研究结果表明:该传感器可实现液体折射率在1.333~1.431RIU范围的测试,平均光谱灵敏度为4.11×103 nm·RIU-1,在1.417~1.431RIU折射率范围内光谱灵敏度达1.09×104 nm·RIU-1,折射率测量范围和光谱灵敏度均优于已报道的结果。此外,该传感器具有良好的稳定性与重复性实验测试,最小分辨率约为3.6×10-5 RIU。该传感器光谱灵敏度高、检测范围大、尺寸小及良好的稳定性与重复性等优点,可被用于食品检测、环境监测、生物医学检测等相关领域。     

光纤表面等离子体共振传感检测系统共振波长的红移

介绍了光纤表面等离子体共振传感器的制造工艺和系统组成,针对光纤传感检测系统在一定的条件下进行了多次测试,试验表明该系统在测试过程中存在红移现象.分析了发生红移的主要原因是金属薄膜内部和表层吸附了空气中的杂质.为此提出了改进镀膜工艺、测试条件和建立修正数据库已有效地减弱了系统测试中的红移现象.     

氧化石墨烯快速修饰表面等离子体共振传感芯片的研究

表面等离子体共振(SPR)是近年来兴起的一种光学检测技术。其主要利用光波经全反射后产生的倏逝场与金属相互作用而感知外界介质的折射率变化。理论上任何介质折射率变化现象的发生都能被SPR技术检测到。在实际应用中，SPR传感器存在灵敏度不高，检测信号不强等缺点，因此对提高SPR传感器检测灵敏度的研究一直备受关注。氧化石墨烯又被看成是石墨烯的氧化物，它有着与石墨烯相近似的光电学特性，但又比石墨烯更容易进行化学修饰，因此被广泛用作SPR传感芯片的表面镀层来提高灵敏度。将氧化石墨烯用于修饰SPR芯片以提高灵敏度的报道很多，但对氧化石墨烯的使用量说法不一，并且在制备氧化石墨烯修饰传感芯片时需要浸泡很长一段时间，大大影响了芯片制备效率。该研究中使用长直链功能化聚乙二醇(polyethylene glycol, PEG)对SPR金芯片表面进行化学改性，用流动冲刷的方法使氧化石墨烯溶液对芯片进行修饰。通过对折射率变化响应信号的对比，最终确定氧化石墨烯最佳使用浓度为0.5 mg·mL^-1,并且将修饰时间降到20 min以内。研究了不同波长入射光对氧化石墨烯修饰后芯片共振峰的影响，并对芯...     

Sensitivity enhancement of surface plasmon resonance sensor using continuous film metallic gratings

A surface plasmon resonance (SPR) sensor based on continuous film metallic gratings is numerically investigated for enhance sensitivity. The results calculated by rigorous coupled-wave analysis (RCWA) present that interplays between localized surface plasmons and surface plasmons polaritons contribute to sensitivity enhancement. The sensitivity enhancement factor (SEF), which represents the influence of metallic grating, increased as the grating period decreased. In addition, several reflection dips can be achieved as the period of metallic grating increased. By double-dips method, the sensitivity SPR sensor based on continuous film grating-based is improved into 153.23°/RIU, which is more sensitive than conventional thin film-based SPR sensor in the same condition. The SPR sensor based on continuous film metallic gratings exhibits good linearity.     

光纤SPR湿敏传感器及其共振光谱特性研究

提出并研制了基于光纤SPR传感探针的新型湿敏传感器。首先研究了光纤SPR传感探针对环境湿度变化的敏感特性,在此基础上提出在光纤SPR传感探针表面增覆不同厚度且具有水分子吸附功能的PVA薄膜来实现环境相对湿度的监测。研究结果表明,增覆双层PVA薄膜的光纤SPR传感探针在高湿区具有较好监测效果,其共振强度对应的相对湿度测量灵敏度达到1.59%/%RH,较光纤SPR探针呈现显著提高。而增覆单层PVA薄膜的光纤SPR传感探针在高湿区共振波长对应的相对湿度监测灵敏度达到2.411nm/%RH。此外所提出的新型光纤SPR湿敏探针在PVA薄膜失效后经过特殊工艺处理仍可重复镀膜使用。     

Surface plasmon optical sensor with enhanced sensitivity using top ZnO thin film

Surface plasmon resonance (SPR) is one of the most sensitive label-free detection methods and has been used in a wide range of chemical and biochemical sensing. Upon using a 200 nm top layer of dielectric film with a high value of the real part ε′ of the dielectric function, on top of an SPR sensor in the Kretschmann configuration, the sensitivity is improved. The refractive index effect of dielectric film on sensitivity is usually ignored. Dielectric films with different refractive indices were prepared by radio frequency magnetron (RF) sputtering and measured with spectroscopic ellipsometry (SE). The imaginary part ε′′ of the top nanolayer permittivity needs to be small enough in order to reduce the losses and get sharper dips. The stability of the sensor is also improved because the nanolayer is protecting the Ag film from interacting with the environment. The response curves of the Ag/ZnO chips were obtained by using SPR sensor. Theoretical analysis of the sensitivity of the SPR sensors with different ZnO film refractive indices is presented and studied. Both experimental and simulation results show that the Ag/ZnO films exhibit an enhanced SPR over the pure Ag film with a narrower full width at half maximum (FWHM). It shows that the top ZnO layer is effective in enhancing the surface plasmon resonance and thus its sensitivity.     

Design of a silicon-based plasmonic optical sensor for magnetic field monitoring in the infrared

Surface plasmon resonance (SPR) sensor chip is proposed for magnetic field monitoring in the infrared wavelength region. The structure is based on silicon substrate and gold as SPR-active metal used with an appropriate magnetic fluid film. The angular interrogation method has been used to study the sensor’s performance in terms of large shift and small width of the SPR curve for a wide range of magnetic field between 30 and 220 Oe. The effect of field incidence angle is also studied on the proposed sensor’s performance, and it is observed that the field should be incident as parallel to the magnetic fluid surface as possible. Any possibility of oxidation problem to the proposed SPR sensor is addressed by using a stable buffer layer. All the performance parameters were found to be significantly large for the above field incidence condition. The proposed sensor is able to achieve a resolution of the order as high as 0.18 Oe for magnetic field detection.     

Investigation of dual-channel fiber-optic surface plasmon resonance sensing for biological applications

A dual-channel fiber-optic sensor based on surface plasmon resonance (SPR) for self-referencing refractive-index measurements has been proposed. Most applications of fiber-optic SPR sensors are designed to measure the refractive index of a liquid or gas sample by measuring the signal from a single surface, the sensitivity and stability of which is easily affected by the fluctuation of external environmental conditions. We have designed a dual-channel fiber-optic surface sensor with two independent SPR signals from two areas of the same probe. A prototype sensor was fabricated and characterized. The preliminary experimental results demonstrate the characteristic responses of both SPR signals from two channels that independently correspond to the refractive index changes in the liquid samples with which they are in contact. The design could be extended to a multichannel sensor with further developments. The experimental results confirmed that one channel can be used as a reference sensor that could compensate for unexpected changes in bulk refraction or temperature and develop this sensor as a practicable high-sensitivity biosensing device.     

Design of a highly sensitive surface plasmon resonance sensor using aluminum-based diffraction grating

A highly-sensitive grating-based surface plasmon resonance (SPR) sensor is proposed. The angular interrogation method has been used to study the performance of the sensor, and high sensitivity is obtained if the ?1st diffraction order is used to excite surface plasmon (SP). The sensitivity as well as the width of the SPR curves and reflective amplitude is considered for designing the sensor. Compared with the conventional gold (Au)-based or silver (Ag)-based SPR sensor, it is found that the aluminum (Al)-based sensor has the best performance. The oxidation problem of an Al-based SPR sensor has been addressed by coating it with an ultrathin gold film on the surface. Numerical simulations based on rigorous coupled wave analysis (RCWA) show that the sensitivity of the optimized sensor is 245°/RIU (degree per refractive index unit).     

Performances of different metals in optical fibre-based surface plasmon resonance sensor

The capability of various metals used in optical fibre-based surface plasmon resonance (SPR) sensing is studied theoretically. Four metals, gold (Au), silver (Ag), copper (Cu) and aluminium (Al) are considered for the present study. The performance of the optical fibre-based SPR sensor with four different metals is obtained numerically and compared in detail. The performance of optical fibre-based SPR sensor has been analysed in terms of sensitivity, signal-to-noise (SNR) ratio and quality parameter. It is found that the performance of optical fibre-based SPR sensor with Au metal is better than that of the other three metals. The sensitivity of the optical fibre-based SPR sensor with 50 nm thick and 10 mm long Au metal film of exposed sensing region is 2.373 μm/RIU with good linearity, SNR is 0.724 and quality parameter is 48.281 RIU^− 1. The thickness of the metal film and the length of the exposed sensing region of the optical fibre-based SPR sensor for each metal are also optimized.     

Bimetallic Silver-Gold Film Waveguide Surface Plasmon Resonance Sensor

It is desirable that a surface plasmon resonance (SPR) sensor is highly sensitive to binding interactions within the sensing region, generate evanescent fields with long penetration depths, and utilize a metal film that is very stable even in extreme environmental conditions. In this study, we present the first example of a wavelength-modulated waveguide SPR sensor with a bimetallic silver-gold film for surface plasmon excitation. The underlying silver yields better evanescent field enhancement of the sensing surface, while the overlying gold ensures that the stability of the metallic film is not compromised. It is shown experimentally that in terms of dλ/dn, the bimetallic film waveguide SPR configuration has a sensitivity of 1232 nm/RIU, greater than two times improvement from the 594 nm/RIU achievable with single gold film waveguide SPR sensor. The higher sensitivity, compact nature, and better evanescent field enhancement of this configuration provides the potential to biosensing applications.     

内置调制层型光纤表面等离子体波共振传感器研究

研究了一种基于内置调制层结构的光纤表面等离子体波共振(SPR)传感器。通过在金膜与纤芯的内侧增覆具有不同厚度和属性的光学透明薄膜作为内调制层,构成了性能独特的光电复合薄膜,起到调节倏逝波矢量和金膜表面等离子体振荡波矢量的双重作用,进而控制共振效应,为调节灵敏度提供依据。采用时域有限差分方法对内置调制层结构光纤SPR共振激励模型属性进行数值仿真。在此基础上,研制了用于液体折射率测量的内置调制层型光纤SPR传感探针。实验结果表明,该传感器在1.335～1.392折射率范围内,随着待测液体折射率的增大,SPR共振光谱向长波方向偏移,且灵敏度达到2263.1nm/RIU,与基于纤芯-金膜-环境介质三层结构的常规光纤SPR传感器相比提高一倍,能够更好地满足环境折射率检测的需求。     

High-Sensitivity Sensor Based on Surface Plasmon Resonance Enhanced Lateral Optical Beam Displacements

We present a new optical sensor based on surface plasmon resonance （SPIt） enhanced lateral optical beam displacements. Compared with the traditional SPIt methods, the new method provides higher sensitivity to the sensor system. Theoretical simulations show that the refractive index （RI） detection sensitivity of the SPR sensor based on the displacement measurement has a strong dependence on the thickness of the metal film. When the optimal thickness of the metal film is selected, the RI resolutlon of the SPIt sensor is predicted to be 2.2 × 10^-7 refractive index units （RIU）. Furthermore, it is found that the incidence angle can be used as a parameter to adjust the operating range of the sensor to different refractive index ranges.