Low-cost Fabrication Of High-performance Surface-enhanced Raman Scattering Substrates:Tuning The Intensity And Molecular Accessibility Of Hot Spots

Surface-enhanced Raman Scattering(SERS) spectroscopy is of great significance in scientific researches and practical applications. According to the electromagnetic theory of SERS, the key issue for improving the performances of substrates is to enhance the intensity and the molecular accessibility of hot spots. As the development of the precise fabrication techniques in recent years, it has been possible to tune the hot spots for fabricating high-performance SERS substrates. However, the high-precision techniques always depend on the large-sized instruments, which are high-cost and low-yield. For the purpose of the real-life uses of SERS, it is still needed to fabricate high-performance SERS substrates using facile and inexpensive methods.The main topic of this paper is how to improve the performance of low-cost SERS substrate.1. Improving the SERS sensitivity by adjusting the hot spot intensity. Bowtie nanoantenna is a typical structure serving as the SERS substrate. The usual way to optimize its performance is by means of more precise and expensive fabrication of the subtle features. We present a new strategy to further enhance the hot spot intensity, which is the evolution of the bowtie configuration based on the large-area and low-cost nanosphere lithography.2. We present a low-cost substrate which conducts the enrichment and detection of trace amounts of analytes. The substrate is of excellent low-friction super-hydrophobicity, which induces the delivery of femto-/subfemtomolar analytes and their Raman response.3. We fabricate a highly reproducible SERS substrate only using chemical methods. The fabrication does not need for any large-size instruments. The yield is high and the cost is very low. The reproducibility of the substrate is attributed to the high density of the hot spots and the confined deposition of analytes.To sum up, we present three methods to fabricate and optimize the low-cost SERS substrates, which respectively realize the high-sensitivity, the low-concentration, and the high-reproducibility SERS detection. These methods may be applied for the fabrication of SERS substrates of high performance, which is of significance for promoting the practical applications of SERS.