Laser Nanostructuring for SERS Application

Abstract

Surface-enhanced Raman scattering (SERS) is an advanced detecting method, permitting the identification of molecules by their unique vibrational fingerprints presenting in the enhanced Raman spectra. Due to its advantages on rapid detection, label-free, nondestructive, specificity, and excellent sensitivity, SERS is widely used in the fields of food detection, pollutant monitoring, and disease early diagnosis. Correlated to its two enhancement mechanisms - electromagnetic enhancement (EM) and chemical enhancement (CM) - the sensitivity of SERS highly depends on the substrates with well-designed nanostructures. Laser nanostructuring is a promising approach for fabricating versatile functional nanostructures for the SERS substrate needs. It is a one-step, maskless, and no-contact process with sufficient high processing efficiency, uniformity, and stability, which overpasses the available conventional processes for fabricating the nanostructures of SERS substrates. In addition, laser micro-nano structuring is able to fabricate specific wetting surfaces including patterned superhydrophilic center with superhydrophobic surroundings, by which the tested liquids can be concentrated up to 105 times by evaporation. Integrated with the hot spot nanostructures and the evaporation enrichment, the nanostructured SERS substrates via ultrafast laser are able to achieve 10−18 mol/L detection sensitivity, the highest available detection limit. This chapter reviews the development and the state of the art on laser nanostructuring for SERS applications, including but not limited to the nanostructures for SERS substrates, the versatile nanostructures formed via ultrafast lasers on metals, the efforts to increase the sensibility of SERS substrates, the laser fabricated patterned superhydrophilic-superhydrophobic surfaces for evaporation concentration, the ultrasensitive SERS detection with patterned platform via evaporation enrichment, and the application cases on laser-nanostructured SERS substrates for cancer diagnosis, food safety evaluation, and others. This chapter ends with a summery and prospective section.