【作者】 杨天夫；

【导师】 张大明；

【作者基本信息】 吉林大学 ， 微电子学与固体电子学， 2014， 博士

【摘要】 为了应对日益严峻的生化恐怖袭击威胁和在医疗诊断、环境监测领域的大量需求，光学生化传感器吸引着越来越多的关注。平面光波导传感器兼具光纤传感器灵敏度高、响应迅速、抗电磁干扰能力强等特点，还可以通过灵活设计与不同结构、不同功能的波导器件构成集成光子传感芯片，符合光学生化传感器多功能化、集成化和便携化的未来发展方向。但是使用无机材料制备的波导器件因其生长工艺复杂、设备昂贵，不易实现大规模的生产与应用。目前针对应用于光通信领域的有机聚合物材料研究已较为成熟，材料成本较低、合成工艺简单、对加工设备要求不高、结构种类丰富。在生化传感领域与离子、蛋白质、细胞等待测物的生物化学兼容性更强。因此使用聚合物材料制备波导传感器能弥补无机材料在这方面的不足。本论文结合目前存在的技术难题与未来发展趋势，对几种不同波导结构的聚合物平面光波导生化传感器进行改进优化，主要工作如下：1.以光波导模式理论为基础，在一定边界条件下求得非对称三层平板波导的特征方程，再利用有效折射率法推导矩形波导导模特征方程，确定了波导传感器件的单模传输条件；阐述光波导传感器的工作原理—消逝场原理及两种传感检测模型：均匀传感与表面传感；详细介绍传感器的性能参数，包括灵敏度、检测极限、分辨率、量程和线性度。列举本论文完成过程中制备器件所主要使用的实验药品及仪器设备。2.针对基于MZI结构的波导生化传感器输出信号具有周期性，提出不借助电光、热光等外部调制手段，仅通过精确控制传感窗口长度来调节器件的静态工作点，同时能在较大折射率测量范围内实现较高线性度的理论设想；首先根据波导材料SU-8和P(MMA-GMA)的折射率，综合考虑器件尺寸与插入损耗等因素，使用Matlab软件编程计算和Rsoft光学仿真软件模拟后得到优化后的传感窗口长度为11515μm；其次优化制备传感窗口的ICP刻蚀工艺，深入研究各参数对波导形貌和表面亲水性的影响，包括天线功率、偏置功率、气体流量及配比、腔室压强、刻蚀时间；刻蚀后的波导表面水接触角测试发现接触角从130°降低到35°；光学性能测试证明传感芯片的插入损耗没有因刻蚀而明显增大；传感测试结果表明优化后的聚合物波导生化传感芯片可检测的液体折射率测量范围是1.31~1.42，灵敏度为225.4dB/RIU，检测极限约为10-6RIU；最后制备传感窗口长度为10000μm和15000μm的聚合物MZI波导传感芯片与优化器件进行对比实验后发现，优化后的传感器灵敏度比二者分别提升141%和139%，并考察波导传感芯片的长期工作稳定性，发现在30天内器件性能未出现明显衰减。3.进一步优化了基于MZI结构的聚合物波导生化传感器器件性能及制备工艺。通过编程计算和软件模拟，将Y型分束器与合束器在横向上设计成不同长度来控制两分支波导的相位差，使非对称的MZI波导传感器件始终处于静态工作点；尝试了聚合物波导生化传感器在表面传感模型上的应用，利用溶胶-凝胶法合成了基于硅烷偶联剂KH590的亲水性敏感层，利用Comsol仿真软件模拟后证明将折射率高于芯层，厚度为500nm的敏感层固定在波导表面后，传输光场在敏感层的占比分布增大至12%；将修饰后的传感芯片用于检测溶液中的铜离子浓度，传感芯片对于铜离子的可分辨浓度为20μg/ml。4.探索了聚合物材料体系下的微环型波导结构在传感检测方面的应用；编程计算了微环半径、波导间距等结构尺寸参数并分析器件的输出功率与输出光谱，根据其线性度确定了待测物折射率的检测范围，得到了以聚合物为波导材料的微环传感器性能参数。本论文从优化理论设计和改进制备工艺等方面针对基于有机聚合物材料的平面光波导生化传感器件进行了一系列的研究。发挥有机聚合物材料在波导器件功能集成、个数集成方面的优势，有望制备出高性能、小尺寸、低成本的生化传感芯片并实现规模化生产，从而服务于反恐预警、医疗卫生、食品安全等关键领域。更多还原

【Abstract】 To withstand the growing threat of terror attacks and great demands of medicaldiagnosis and environmental monitoring, optical bio-chemical sensor is attractingmore and more attention. Same as fiber sensor, planar optical waveguide sensorbenefits from high sensitivity, fast response and resistance to electromagneticinterference etc. Moreover, flexible design in structure and function makeswaveguide sensor a promising solution for future optical bio-chemical sensor.However, the waveguide devices based on inorganic materials fail to meet therequirements of mass production due to the complicated fabrication process andexpensive equipments.Organic polymers for optical communication are not only cost-effective insynthesis and processing, but also highly compatible with samples as metal ions,proteins and virus. Polymers include a wide range of structures, which offer lots ofchoices. Therefore, it is more profitable to use polymers to fabricate opticalbio-chemical sensors than inorganic materials. This dissertation combines withexisting technical problems and the trend of developments to optimize severaldifferent structures of polymeric waveguide bio-chemical sensor, includingtheoretical design and fabrication technology. The main work is as follows:1. On the basis of the theory of optical waveguide mode, taking certainboundary conditions into account, we solved the characteristic equations ofasymmetric three-layer slab waveguide. Then using effective index method, wededuced the equations of guiding mode of rectangular waveguide. This dissertationexplained the working principle of optical waveguide sensors, which was the theoryof evanescent field and two kinds of sensing model: uniform sensing and surfacesensing. We also introduced the parameters of waveguide sensor, includingsensitivity, detection limit, resolution, range and linearity in detail. And we enumerated the experimental drugs and instruments for the fabrication of polymericwaveguide sensors in this dissertation.2. Aiming at the bio-chemical sensor based on Mach-Zehnder interferometer(MZI) structure, whose output signal is periodic, we presumed to set the workingpoint of the device and achieve high linearity in a large measuring rang bycontrolling the length of sensor window. First, according to the refractive index ofwaveguide materials and dimension and insertion loss of the device, using thecalculation of Matlab software and simulation of Rsoft software, we obtained thatthe optimum length of sensing window was11515μm. At the same time, weimproved the fabrication technology of Inductively Coupled Plasma (ICP) etchingprocess for sensing window by deeply investigating etching parameters, includingantenna power, bias power, gas ratio, chamber pressure and etching time. Due to theprecise control of etching, the water contact angle on the waveguide surface wasdecreased from130°to30°, and no additional insertion loss was brought in afteretching. The results of sensing test demonstrated that the refractive index measuringrange for liquid, sensitivity and detection limit of the optimized waveguide sensorwere from1.31to1.42,225.4dB/RIU and10-6RIU, respectively. Waveguidesensors based on MZI structure with sensing window lengths of10000μm and15000μm were fabricated to compare with the optimized sensor. The sensitivitieswere93.3dB/RIU and94.2dB/RIU, which were much lower than225.4dB/RIU.Finally we evaluated the long-term stability of the waveguide sensor chip.3. The MZI-structure waveguide bio-chemical sensor was further improved indesign and fabrication. Through calculation and simulation, the Y-shape splitter andcombiner were designed as different lengths in horizontal direction to form anasymmetric MZI structure, which kept the sensor at the working point. Then weprepared the sensing layer based on silane coupling agent KH590with sol-gelmethod. This layer was deposited on the waveguide core, which greatly enhance theevanescent field. The simulation results showed that12%of the optical field in thesensing layer distributed in the sensing layer. After the modification on thewaveguide core, detection for copper ions was conducted and the minimum detectable concentration was20μg/ml.4. The advantages of micro-ring waveguide in sensing applications wereanalyzed. The working principles of waveguide coupling and polymeric microringresonators were detailedly introduced. Then we calculated the radius of micro-ring,the distance of coupling gap and structure parameters. The output power andspectrum of the micro-ring sensor were studied in consideration of linearity andmeasuring range.This dissertation has carried out the research on the optimization of theoreticaldesign and fabrication technology for polymeric planar optical waveguidebio-chemical sensor. Due to the advantages of function and quantity integration, it islikely to fabricate high-performance, small-size and low-cost sensor chip withpolymeric waveguide devices of and realize large-scale production, which serves inhealth care, food security and other important areas.更多还原