【作者】 罗吉；

【导师】 罗先刚； 邱传凯；

【作者基本信息】 中国科学院研究生院（光电技术研究所） ， 光学工程， 2014， 博士

【摘要】 本文从满足微型高灵敏度生化分析仪在环境监测及食品卫生安全检测等方面的实际需求出发，结合局域表面等离子体共振与光纤消逝场传感技术，提出一种基于金属微纳结构的光纤消逝场传感器。论文的主要工作是从理论分析和实验检测两个方面展开的:(1)在理论分析方面，阐明了传感机理并且分析了金属微纳结构的表面等离子体特性。(2)在实验上利用基于金属微纳结构修饰的光纤消逝场传感器实现对多种待测样品的传感检测。首先，明确了光纤消逝场传感的基本原理并建立了传感理论模型，分析并优化了影响传感灵敏度的几个关键参数。其次，对金属微纳结构的表面等离子体特性进行了研究，利用时域有限差分方法对金属纳米粒子的形状、大小等尺寸参数对消光特性的影响进行了分析讨论，并且研究了纳米粒子之间的耦合以及纳米粒子与基底间的耦合作用。同时，提出了Ag/SiO2/Ag新月复合纳米柱结构作为LSPR传感的活性基底，仿真分析了不同偏振方向的激励对消光特性的影响，研究了尖端热点效应和中间介质层的厚度对共振峰的影响。此外，为了进一步提高金属纳米结构的传感性能提出一种具有30度尖角的Ag/SiO2/Ag三角星形复合纳米柱结构，这种纳米结构对环境折射率的传感灵敏度较高，呈现出大的局域场增强效果和较好的等离子体共振可调谐性。根据实际加工工艺的限制，分析了包含不同尖角抹去程度的三角星形复合纳米柱结构对消光谱和环境折射率灵敏度的影响。在实验上，采用微细加工技术制作了高精度的微通道传感芯片，利用湿法腐蚀工艺制备了含有两个锥形过渡区的组合锥形传感光纤，并完成了光纤消逝场传感实验平台的搭建。利用银纳米溶胶颗粒修饰的光纤消逝场传感器对100nmol/mL的亚甲基蓝溶液的传感灵敏度达到0.402dB/(umol·mL-1)，相比于无修饰的光纤消逝场传感器对其的检测灵敏度提高了约3倍。最后为了完善传感的整体性能，提出了银核金壳复合纳米结构来增强消逝场能量，通过调整银核和金壳尺寸，可以实现对整个核壳结构的吸收性能的调控，并利用表面等离子体杂化理论模型对其进行解释。实验上利用晶种生长法制备了银核金壳复合纳米球结构，利用核壳结构修饰的消逝场增强型光纤传感器实现了对微量三聚氰胺的高灵敏度传感检测，灵敏度为2.869dB/(ug·mL-1)，检测极限为1ug/mL。研究结果表明，基于微纳结构的光纤消逝场传感器具有体积小，响应速度快，抗电磁干扰强等优点，能够实现对微量待测物质快速、实时、高灵敏度检测，在生化传感领域具有广泛的应用前景。更多还原

【Abstract】 Biochemical sensors for the diagnosis of diseases, food, and environmentaldetection of biological agents have been increasingly in demand over the past fewdecades. Combined evanescent field optical fiber sensing with localized surfaceplasmon resonance technologies, this work presents an evanescent field enhancementoptical fiber sensor based on metal micro/nano-structures.This thesis is mainly carried out from these two parts:(1) as for the theoreticalsection, the sensing mechanism and the optical properties of the metalmicro/nano-structures have been both analyzed and optimized;(2) in the experimentalpart, a variety of analytes with fractional content have been tested by the evanescentfield optical fiber sensor decorated with metal nanostructures.Firstly, the sensing principle of the evanescent optical fiber is defined and theimpacts of several key parameters on the sensor sensitivity are also analyzed. Thesurface plasmon properties of the metal nanoparticles depend on the geometry,material, and dielectric environments, etc. and have been carefully studied. Besides,the interactions which occur between nanoparticle and the sensing optical fibersubstrate and among particles have been studied using the FDTD method. Secondly,combining both the sharp tips and the metal/dielectric/metal multilayer structurestogether, an Ag/SiO2/Ag sandwich nanocrescent has been proposed. The extinctionefficiency and LSPR property below different incident polarizations are studied byvarying the thickness of the SiO2layer. Furthermore, for better sensing ability, a novelsandwich delta nanostar that features an Ag/SiO2/Ag sandwich delta star nanoplatewith three sharp angles of30degree is introduced. The structure is shown to producea high local field enhancement as well as wide plasmon resonance tunabilities.Moreover, the influence of the vertex truncation on the refractive index sensitivity andthe extinction spectra has also been analyzed based on the existing fabricationcondition.In this work, the evanescent field optical fiber sensor modified with silvernanoparticles based on a MEMS micro-channel chip has been successfully fabricatedand experiment with different concentrations of the detecting analytes is performed.The concentration of the methylene blue solution varying per100nmol/mL can causethe absorbance change0.402dB, which is about three times higher than the same sensing without any decoration.Finally, the Ag-Au core-shell composite nanostructure is adopted for enhancingevanescent field energy. And by adjusting the size parameters can achieve the tuningof absorption properties, which is explained by the hybridization model theory for theplasmon response of complex nanostructures. Experimentally, the evanescent fieldenhanced optical fiber sensor based on the core-shell composite nanostructures isprepared and applied to the melamine detection. The sensing sensitivity is2.869dB/(ug·mL-1) with the detection limit of1ug/mL.From above studies, it shows that the evanescent field optical sensor decoratedwith metal nanostructure is of low cost, high sensitivity and convenience, which willpotentially operate on rapid, real-time and continuous detection in biochemical analytedetecting applications.更多还原