Banknote Surfaces Research Articles

Improving a method for determining the level of wear of the mark for people with visual impairments on Ukrainian hryvnia banknotes

The object of this study is the wear resistance of marks for people with visual impairments, which are printed by the intaglio printing method on Ukrainian hryvnia banknotes to identify the banknote denominations. The subject of the study is to determine the impact of wear on the recognizability of marks for people with visual impairments and the identification of banknote denominations by people with visual impairments. The paper considers the problem of inadequate assessment of the level of banknote wear by the systems of control and rejection of protected products from the point of view of banknote accessibility for people with visual impairments. An improved methodology for determining the level of wear of the mark for people with visual impairments on Ukrainian hryvnia banknotes is given, taking into account the indicator of its accessibility for all population groups, in particular for people with absolute vision loss, throughout the entire period of circulation. According to the developed methodology, artificial wear of banknotes was carried out according to three test options. The results of changes in the mass of banknotes, the microstructure of the surface of banknotes, the compressibility of marks for people with visual impairments (elasticity level), and the level of tactile identification of the denomination of banknotes by people with total vision loss were obtained. It was determined that during the artificial wear of banknotes, the main destruction of the mark takes place in the first cycle. After the second cycle of wear, there is an increase in the elasticity of the mark for people with visual impairments, a decrease in the level of its tactile sensation and the identification of the denomination of the banknote. Therefore, the properties of banknotes after the second cycle of wear have been determined to be critical for withdrawing such banknotes from circulation. The revealed regularities make it possible to adjust the parameters of intaglio printing during the production of banknotes and to adjust the sorting equipment to determine the suitability of banknotes for further circulation, taking into account the criterion of accessibility of banknotes for all groups of people.

Prolific shedding of magnetite nanoparticles from banknote surfaces

Here, we use magnetic methods first to quantify the content of strongly magnetic particles of banknotes (US dollars, USD, and British pounds sterling, GBP), and then examine the possibility of their release from handled banknote surfaces. The content of magnetic particles, from magnetic remanence measurements, for the USD and paper GBP banknotes is high; greater, for example, than that in vehicle engine-exhaust emissions, and similar to that for airborne roadside particulate matter (PM). Our magnetic analyses of USD and GBP banknotes, and of the ink pigment widely used in their printing, reveal not only that the banknotes are highly magnetic, but also that strongly magnetic, nano-sized particles are readily and prolifically shed from their surfaces (especially from the USD banknotes). A common practice, prior to increased automation, was for bank tellers to count banknotes by licking a finger to adhere to each successive counted note, and thus speed up the manual counting process. Given the rate of particle shedding reported here, this traditional manual counting procedure must have resulted in prolific transfer of iron-rich nanoparticles both to the fingers and thence to the tongue. We hypothesise that, pre-automation, magnetite and other metal-bearing nanoparticles were repetitively and frequently ingested by bank tellers, and subsequently entered the brain directly via the taste nerve pathway, and/or indirectly via the systemic circulation and the neuroenteric system. This hypothesis may plausibly account for the reported and currently unexplained association between elevated neurodegeneration-related mortality odds ratios and this specific occupation.

Advantages and disadvantages of Raman spectroscopy in testing paper banknotes

This paper presents advantages and disadvantages of Raman spectroscopy when used for testing banknotes, i.e. in case study I, 1 and 5 dinars banknotes from a private collection dating from 1876 of numismatic value were analyzed, and in case study II, 1000 dinars banknote from circulation together with its counterfeit. In both cases banknotes were analyzed by using Raman spectrometer DXR Raman microscope at the Faculty of Physical Chemistry, with a laser of wave-length 780 nm at 12 mW of power. Specters were recorded under microscope using 50X lens in a range 1800-60 cm-1. Analyses from case study I on both specimens showed spectrum characteristic for fluorescence appearance, therefore intensive signal of fluorescence covered Raman signal. In case study II, it was established that Raman spectroscopy can reliably detect a counterfeit banknote. Research, comparisons and analyses regarding original and counterfeit 1000 dinars note were performed on red banknote surfaces.

Direct detection of label-free blood fingermarks by SECM imaging

A label-free strategy for imaging blood fingermarks (BFMs) on a hydrophobic poly(vinylidene difluoride) (PVDF) membrane has been developed using scanning electrochemical microscopy (SECM) in the surface interrogation (SI) mode. In this approach, hexaammineruthenium chloride ([Ru(NH3)6]Cl3) was chosen as a redox mediator to react chemically with the electroactive hemichrome (HC) present in the BFM ridge deposits but not in the furrow regions. This provides a sharp contrast of the current response at the tip of the electrode between ridges and furrows and results in an electrochemical image of the BFM with the high resolution required for personal identification. In addition, this approach has high sensitivity, with the ability to directly image latent BFMs deposited with 1000-fold diluted blood on PVDF membranes. Such marks cannot be detected by optical microscopy. Moreover, for the first time a commercial PVDF membrane was used instead of adhesive forensic tape to lift the BFMs from common glass and multicolored banknote surfaces, and the lifted BFMs could also be efficiently imaged by this electrochemical method.

Improved antifungal activity and stability of chitosan nanofibers using cellulose nanocrystal on banknote papers

Microorganisms can spread on the surface of banknotes and cause many infectious diseases. Chitosan nanofibers (CNFs) and cellulose nanocrystals (CNCs) are nanomaterials, which can affect the antimicrobial properties. In this study, the fungal species that grew on the surfaces of collected banknotes from different places were identified. To examine the antifungal effect of the both nanomaterials on the banknotes, the stable coatings using CNFs and CNCs emulsions were prepared by roller coating. The results revealed that the most colonies in the banknotes obtained from the bakeries and butcheries were Aspergillus sp., whereas the colonies in bus terminals and the hospitals were Aspergillus niger and Penicillium, respectively. The results showed that the CNCs had no antifungal effect alone on the aforementioned species, but it could improve the antifungal effect, adhesion, and stability of CNFs on the banknote surfaces. This study suggested a new approach to decrease the infection spreads through banknotes.

Location-specific immunodetection of cocaine on banknotes.

A novel in-gel bioanalytical immunodetection method has been developed to determine both the presence and the location of cocaine on the surface of banknotes. The cocaine was 'fixed' to the surface of the banknote via a coating of a polyacrylamide gel matrix. Immunostaining of the immobilised cocaine on the banknote surface was performed using an anti-cocaine primary antibody, either pre-labelled with horse radish peroxidase (HRP) or in conjunction with a HRP-labelled secondary antibody. Visualisation of the location of the cocaine was achieved through chemiluminescence imaging of the banknote following application of a chemiluminescent substrate. The novel method was applied to the detection of cocaine on partial and whole banknote samples obtained from general circulation. Newly minted banknotes, with or without spiked cocaine, were used as positive and negative controls, respectively. The results obtained, for the first time, demonstrate the successful location-specific immunostaining of cocaine on banknotes. A preliminary analysis of six UK banknotes, obtained from general circulation, suggests that cocaine can be present at variable locations across the whole of the banknote.

Characterization of anti-theft devices directly from the surface of banknotes via easy ambient sonic spray ionization mass spectrometry

Using Brazilian banknotes as a test case, forensic examination and identification of Rhodamine B dye anti-theft device (ATD) staining on banknotes were performed. Easy ambient sonic spray ionization mass spectrometry (EASI–MS) was used since it allows fast and simple analysis with no sample preparation providing molecular screening of the surface with direct desorption and ionization of the security dye. For a more accurate molecular characterization of the ATD dye, Q Exactive Orbitrap™ Fourier transform (tandem) mass spectrometry using eletrospray ionization (ESI–HRMS/MS) was also applied.

Characterization of ANFO explosive by high accuracy ESI(±)–FTMS with forensic identification on real samples by EASI(−)–MS

Ammonium nitrate fuel oil (ANFO) is an explosive used in many civil applications. In Brazil, ANFO has unfortunately also been used in criminal attacks, mainly in automated teller machine (ATM) explosions. In this paper, we describe a detailed characterization of the ANFO composition and its two main constituents (diesel and a nitrate explosive) using high resolution and accuracy mass spectrometry performed on an FT-ICR-mass spectrometer with electrospray ionization (ESI(±)–FTMS) in both the positive and negative ion modes. Via ESI(−)–MS, an ion marker for ANFO was characterized. Using a direct and simple ambient desorption/ionization technique, i.e., easy ambient sonic-spray ionization mass spectrometry (EASI–MS), in a simpler, lower accuracy but robust single quadrupole mass spectrometer, the ANFO ion marker was directly detected from the surface of banknotes collected from ATM explosion theft.

Detection of explosives on the surface of banknotes by Raman hyperspectral imaging and independent component analysis

The aim of this study was to develop a methodology using Raman hyperspectral imaging and chemometric methods for identification of pre- and post-blast explosive residues on banknote surfaces. The explosives studied were of military, commercial and propellant uses. After the acquisition of the hyperspectral imaging, independent component analysis (ICA) was applied to extract the pure spectra and the distribution of the corresponding image constituents. The performance of the methodology was evaluated by the explained variance and the lack of fit of the models, by comparing the ICA recovered spectra with the reference spectra using correlation coefficients and by the presence of rotational ambiguity in the ICA solutions. The methodology was applied to forensic samples to solve an automated teller machine explosion case. Independent component analysis proved to be a suitable method of resolving curves, achieving equivalent performance with the multivariate curve resolution with alternating least squares (MCR-ALS) method. At low concentrations, MCR-ALS presents some limitations, as it did not provide the correct solution. The detection limit of the methodology presented in this study was 50μgcm−2.

Organic Electronics on Banknotes: Organic Electronics on Banknotes (Adv. Mater. 5/2011)

Organic thin-film transistors and organic integrated circuits can be fabricated directly onto the surface of banknotes, report Ute Zschieschang and co-workers on p. 654. The transistors have a field-effect mobility of about 0.2 cm2 V−1 s−1 and operate with voltages of 3 V. For an array of 100 transistors fabricated on a 5 Euro note, a yield of 92% working devices has been obtained, pre-senting organic electronics as a possible route to improved anti-counterfeiting strategies.

Organic Electronics on Banknotes

Organic transistors and circuits are fabricated directly on the surface of banknotes. The transistors operate with voltages of 3 V and have a field-effect mobility of about 0.2 cm2 V−1s−1. For an array of 100 transistors a yield of 92% is obtained.