Plasmonic Crystal Based Biosensors And Their Applications

Plasmonic crystal is a kind of novel nano-optical devices based on ordered plasmonic structure, can realize the manipulation of light at the nanoscale, and complete the process of biological sensing and transduction. Because plasmonic crystal possesses the physical properties of photonic crystal and metal plasmon simultaneously, it can produce the phenomenon of localized surface plasmon resonance when the light interacts with plasmonic crystal in the certain conditions, which makes plsmonic crystal have the strong modulating ability of electromagnetic wave. This property makes plasmonic crystal as the optimal selection of transduction components in biosensor system, and the plasmonic crystal has a good application prospect in biochemical domain, such as the Raman signal enhancement, fluorescence enhancement, the label-free detection, environmental monitoring, and so on.At present, the fabrication of plasmonic crystal is mainly by the combination of electron beam etching, reactive ion etching, nano-imprinting, electroplating, sputtering, and other methods. The process of preparation is time-consuming and high costing. Plasmonic crystal cannot be achieved in large by these factors, thereby limiting the development of its application. A large scaled plasmonic crystal was prepared with the photonic crystal as template in this thesis, combined with electroless plating, or magnetron sputtering technology. The specific study contents are as follows:(1) The fabrication of photonic crystal monolayer. In the thesis, a large area and hexagonal closely packed monolayer was prepared by the method that nanoparticles with different diameters and materials (such as SiO2, or PS nanoparticles) will be self-assembled on the air/water interface. Then the crystals were spontaneously transferred from the water surface to the different substrates by Marangoni flow effect.(2) The fabrication of plasmonic crystal structures. Three kinds of plasmonic crystal structures were prepared by electroless plating, magnetron sputtering, and wet etching. These structures were hybrid plasmonic crystal monolayer based on metal and silicon dioxide, honeycomb plasmonic crystal based on pure metal, and gold nano-capping structure with the tunable resonator.(3) The optical performance analysis of the plasmonic crystal structure. The optical property, the distribution and enhancement of local electromagnetic field of these three plasmonic crystal structures were analyzed in the thesis, according to the reflection spectra of samples and the simulation result of electromagnetic field based on the finite difference time domain method.(4) According to the optical properties of plasmonic crystal, three kinds of plasmonic crystal were used as SERS substrate for the raman preliminary detection of 4-ATP molecule. And when these kinds of plasmonic crystal were used as SERS substrates, the Raman enhanced performance of the structures was analyzed in the thesis.