Recent Progress in SERS-Based Anti-counterfeit Labels

Anti-counterfeit labels protect many commercial goods, drugs, and currencies from counterfeiting activities. Recently, the designs of anti-counterfeit labels have emerged utilizing surface-enhanced Raman scattering (SERS) as a powerful technique, in which SERS-active materials provide strong Raman signals of probe molecules. These signals are unique and, so far, have rarely been used in practical anti-counterfeit labels applications. In this review, the general methodology of using Raman and SERS in designing anti-counterfeit labels is first introduced. Then, two types of secret information in SERS labels, spectroscopic information and graphical information, are detailed and discussed with a focus on how the molecular information is encoded with SERS labels. Later, several advanced SERS labels are presented which combine existing security features such as barcode, quick response code, fluorescence, and unclonable features. Finally, the challenges in building usable SERS anti-counterfeit labels are discussed and possible research directions are described.