An Overview of Security Materials in Banknotes and Analytical Techniques in Detecting Counterfeits.

Counterfeiting or forged imitation of banknotes is a perpetual practice engulfing global economies. This not only poses challenges for the material scientists to come forth with advanced security materials but also demands veracious forensic examination to detect counterfeits. The present article pursues novel efforts in summarizing a study that lays focus on the recent optical and analytical examinations being used for the characterization and detection of chemical profiles of authentic and counterfeited banknotes. The article briefs the trends in banknote materials, security paper manufacturing process, security inks used for printing, and types of the security printing process in banknote practices. Reported literature shows the introduction of new anti-counterfeiting materials viz. magnetically-responsive photonic anti-counterfeiting watermarks, and fluorescent nanoparticles that can be used as anti-counterfeiting inks, anti-stokes inks, metameric inks, etc. Analytical techniques such as IR spectroscopy, Raman spectroscopy, Mossbauer spectroscopy, X-ray diffraction, X-ray fluorescence, LIBS, XRF, ELDI-MS, EASI/DESI-MS, HPLC, VSC, AFM, etc. in conjunction with different chemometrics approaches have been critically discussed. The study also presents the future scope in banknote examination like the use of hyper spectral imaging and sensor-based counterfeit detection systems.