基于波导型光流体芯片的有序微结构制备及其SERS应用研究

Surface enhanced Raman spectroscopy is widely applied in various fields including biomedicine, molecular recognition, trace detection, material science and etc. SERS mainly relies on the drastic enhancement of the Raman signal at the metallic surface, especially those so-called "hot spot" structure. The hot spots usually refer to the junction of adjacent particles or nano-meter scale gaps; their instability, low repetition rate and inhomogeneity greatly hinder the preparation of high-quality SERS substrates. Based on the waveguide theory and mature fabrication technology, this project proposes a novel method to obtain SERS substrates with high "hot spot" density and high activity. Optical waveguide modes are excited to interact with metallic nanoparticles in the colloid, and pattern structures can be obtain via self-assembly of the captured particles. This project focuses on the following points: (1) The design of the metallic planar optical waveguide and the distribution model of the mode field; (2) The mechanism of the capture of colloidal particle via waveguide mode; (3) Modulation on the SERS substrate pattern and "hot spot" density via waveguide mode; (4) Raman effect enhancement via both the SERS substrate and waveguide structure. This project presents a new approach for the assembly of the colloidal nanoparticles, and provide deep understanding on the optical-particle interaction in the colloidal enviroment, and may be of great importance to the development of the SERS technology.

表面增强拉曼（SERS）技术在生物医学、分子识别、痕量检测、材料科学等众多领域广泛应用，目前已经达到单分子检测水平。它主要是基于金属表面，尤其是“热点”结构的超强拉曼增强效应。热点结构通常位于粒子的结合点或纳米间隙处，它们的不稳定性，低重复率和不均匀性极大限制了高品质SERS基底的制备。本研究基于平板型金属光波导的成熟工艺和理论，拟激发波导模式来俘获并组装胶体中的金属纳米颗粒，并由此来制备具有高热点密度、高活性的SERS基底。重点解决：（1）平板金属光波导的设计和模场的空间分布模型；（2）波导模场俘获并组装胶体颗粒机制；（3）波导模场对SERS基底图样和热点密度的调制作用；（4）SERS基底与波导模场共同增强拉曼信号的机理。该研究提出一种新的纳米颗粒微结构的新组装方法，更加深入理解胶体环境中的光-粒子相互作用，并推动SERS技术的发展。

本项目针对表面增强拉曼散射（SERS）基底中普遍存在的因热点结构分布不均匀而导致检测可靠性差的问题，基于电子束刻蚀成本昂贵、受分辨率限制的现状，设计和制备了一种液芯双面金属光波导。通过激发波导模式来俘获并组装胶体中的金属纳米颗粒，并由此来制备具有高热点密度、高活性的SERS基底。本项目中实时监测了组装二氧化硅微球的过程，同时也组装了金银纳米颗粒，并且制备成SERS芯片用于检测化学和生物材料。此外拓展了光波导器件在光刻蚀中的应用，进一步降低刻蚀SERS芯片的成本。