Date of Award
Master of Science (MS)
Millions of counterfeit products are produced every year, which negatively impacts the global economy, public health, and human safety. Current anti-counterfeiting methods include holograms, watermarks, microprinting, and QR codes. QR codes are a two-dimensional version of a barcode, thus they can store more information. Different types of inks such as thermochromic ink and invisible UV ink are widely used in making anti-counterfeiting labels. Most of these inks have specific changes in optical properties with external stimulations, and these changes are usually associated with broad bands in the visible region. Such broad bands result in a low information capacity that can be vulnerable to counterfeiting. Raman spectra have narrow Stokes lines as well as the potential for high information capacity. Thus, security inks with surface-enhanced Raman scattering (SERS) properties are becoming more prevalent in anti-counterfeiting research. In this study, a new approach for SERS-based anti-counterfeiting labels is presented. A silver ink was synthesized according to literature methods, and then printed using a commercial inkjet printer. This proof-of-concept study focuses on typical Raman probes such as 4-aminothiophenol and 4-mercaptobenozic acid. SERS spectra with unique peaks were obtained from printed security labels and QR codes, which contain probe molecules and silver nanoparticles. The Raman maps analyzed from SERS spectra can be used to visualize covert patterns of the printed labels. Such Raman maps add additional layers of protection to these labels, which makes it difficult for counterfeiters to replicate. Multilayered QR codes were also printed using the SERS-based security inks containing different Raman probe molecules. With further exploration, this approach can be used to produce anti-counterfeiting labels easily and conveniently, ultimately contributing to the global anti-counterfeiting effort.
mesoporous silica nanoparticles, colorectal cancer, veratridine, Anti-Counterfeiting Labels, SERS-based Inks
Number of Pages
University of South Dakota
Schnetzer, Erin E., "Inkjet Printing of SERS-based Inks for Covert Anti-Counterfeiting Labels" (2023). Dissertations and Theses. 171.
Available for download on Friday, September 13, 2024