The Investigations On Several Flexible SSERS Substrates

Surface-enhanced Raman scattering (SERS) has been widely applied as a powerful tool for analytical chemistry, catalysis, biology, medicine science, environment science and food safety, which can provide non-destructive and ultra-sensitive characterization down to single molecular level. To flexible substrates, they offer advantages over traditional rigid substrates in their flexibility to sense with non-planar geometries in terms of flexible or wearable labels. Moreover, they possess excellent mechanical strain resistance and can be easily tailored into any desired shapes and sizes. It is of great significance to bring the SERS technology from the laboratory to real-world applications.In this thesis, we designed four novel flexible SERS substrates and investigated the performances of them in detail. These novel substrates have remarkable SERS performance and flexibility. The SERS intensity acquired from these substrates remains almost constant after100～200bending cycles. Compared with the traditional SERS substrates, the obtained substrates have a lot of advantages, such as being highly lightweight, foldable, and portable. More importantly, it can be scaled up for high-throughput production with low cost.In this paper, we propose a facile and efficient way to fabricate a highly flexible and transparent SERS-active substrate, in which Au nanoparticles were embedded into the polymeric nanopillars via3D NIL (Nanoimprinting Lithography) method and porous anodic aluminum oxide (AAO) template. The obtained substrate displays a high SERS sensitivity to Rhodamine6G (R6G) that a concentration as low as10-12M can still be identified and the enhancement factor (EF) was calculated to be about8.2×107. This substrate exhibits prominent reproducibility and relative standard deviation (RSD) values corresponding to the six major SERS peaks of R6G were all below10%. Moreover, the polymer based SERS substrate possesses excellent transparency and flexibility. It can also be used as SERS substrate for the in situ detection of pesticides on food and fruit, in situ water pollutant detection, microbiological monitoring and spot fast analysis for chemical reactions.By using conical AAO template and NIL technology, we successfully fabricated another highly flexible, transparent and efficient SERS-active substrate, that is, polymer nanocone array with gold nanoparticle inlays. Using this substrate, the detection limit of R6G was below10"12M and the EF was calculated to be about1.3×108. The substrate shows distinguished reproducibility and RSD values corresponding to the six main SERS peaks of R6G were below11%.We designed and successfully fabricated the nanocone-shaped Si arrays, which is in submicron level, via NIL and Inductively Coupled Plasma (ICP) technology. By using this template and NIL technology, the cone-shaped polymer nanohole array with gold nanoparticle inlays was obtained for the first time, that is another different flexible and transparent substrate. The obtained substrate can make the detection limit of R6G lower than10’12M and EF was calculated to be about9.2x107. Additionally, the substrate demonstrates brilliant reproducibility and RSD values corresponding to the six major SERS peaks of R6G were all below13%.A flexible and sensitive SERS substrate was fabricated via electroless plating of Ag nanoparticles on the surface of carbon cloth which is uniformly woven by carbon fibers. By controlling the reaction time, the optimal substrate was obtained, which exhibits remarkable reproducibility. Using the substrate, Raman peaks of R6G still can be identified clearly even at a concentration as low as10-14M. This novel substrate offers a great deal of unique advantages, such as being highly lightweight, portable, easily handled and cost-effective. What is more, it is highly suited for mass production.