Surface-Enhanced Raman Scattering: A Promising Nanotechnology for Anti-Counterfeiting and Tracking Systems

Surface-enhanced Raman Scattering (SERS) is a sensing method based on inelastic scattering of a laser beam by a reporter molecule absorbed on a plasmonic substrate. The incident laser beam induces a localized-surface plasmon resonance in the substrate, which generates an oscillating electromagnetic field on the substrate dielectric surface. Under the influence of this field, the reporter molecule absorbed on the plasmonic substrate starts to vibrate, causing inelastic scattering of the laser beam. The laser-induced electromagnetic field is also the main contributor to the enhancement observed in the intensity of the scattered light. Plasmonic substrates are nanostructured surfaces often made of noble metals. The surface enhancement of a plasmonic substrate is determined primarily by factors related to the substrate’s nano-architecture and its composition. SERS-based labeling has emerged as a reliable and sophisticated anti-counterfeiting technology with potential applications in a wide range of industries. This technology is based on detecting the SERS signals produced by SERS tags using Raman spectroscopy. SERS tags are generally made of a plasmonic substrate, a Raman reporter, and a protective coating shell. They can be engineered using a wide variety of materials and methods. Several SERS-based anticounterfeiting labels have been developed in the past two decades. Some of these labels have been successfully combined with identification systems based on artificial intelligence. The purpose of this review is to shed light on the SERS technology and the progress that has been achieved in the SERS-based tracking systems.