Several different technological approaches have been proposed to promptly identify counterfeit products. This article discusses the use of thin film sensors in anti-counterfeit efforts.
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The Impact of Counterfeit Items
According to the United States Organization for Economic Cooperation and Development (OECD), counterfeit items account for 3.3% of global trade. In fact, recent estimates indicate that the global economy loses over $500 billion United States dollars (USD) each year to the sale of counterfeit products.
Although counterfeit products may not initially appear to be a serious threat, these items, which are often of much lesser quality than the original, are considered significant dangers to public health and safety, as well as the economic growth of legitimate businesses.
For example, counterfeit makeup and skincare products that closely resemble authentic brands may consist of harmful chemicals and heavy metals that, when applied to the skin, can cause skin infections and rashes.
Counterfeit electronic devices, such as automotive parts, smartphones, tablets, and even vapes, can significantly impact the user's health. In addition to the sale of counterfeit products, currency counterfeiting is a persistent issue in many countries worldwide, as it threatens their national economies, financial institutions, and consumers.
Commercial Technologies to Prevent Counterfeiting
Red Points, for example, utilizes automated image recognition software to confirm whether the advertised product is actually inside the image and compares these images to ‘known bad images’ to confirm an infringement. This company also offers clustering technology to match seller information from different marketplaces and social media sites to identify counterfeiters who may be trying to sell their products on various platforms.
Systech Solutions is another company that aims to protect legitimate brands by creating unique e-Fingerprints® on products that cannot be duplicated. This label can then be used by both supply chain partners and consumers to confirm the authenticity of the product.
Due to the widespread availability of high-quality scanning and printing devices, counterfeit banknotes and other forms of currency have become increasingly sophisticated. Thus, law enforcement officials have turned to spectroscopy to obtain a full chemical profile of the potential counterfeit within seconds.
More specifically, this analytical tool determines whether the banknote has an uneven distribution of mass spectrum ions across its surface, thus indicating it is likely a fake bill. Spectrometers may also identify counterfeit currency by revealing the presence of fluorescence, which has been embedded into many large bills to prevent criminals from bleaching and reprinting paper money.
What are Thin Film Sensors?
Thin films are material layers that are constructed on substrates through the condensation of atoms, molecules, and ions. In addition to the substrate and material, the construction of thin film sensors also requires the incorporation of various conductive mediums, the most common of which include metallic nanoparticle inks.
This process, which can be achieved through physical, chemical, or electrochemical reactions, creates thin film layers several nanometers (nm) or micrometers (µm) in thickness. Some of the different methods that can be used to prepare thin film sensors are chemical vapor deposition (CVD), sputtering, physical vapor deposition (PVD), pulsed laser deposition, electro-deposition, sol-gel technique, nanoparticle-based techniques, as well as various printing and coating techniques.
The utilization of thin films within the sensor industry has led to the creation of devices capable of sensing gases, temperature, humidity, pressure, material ions, forces, and chemicals. Depending on their application, thin film sensors can be built on various types of substrates, including synthetic and biological polymers, as well as paper and inorganic chemicals.
Thin Film Sensors to Prevent Counterfeiting
In a recent Advanced Materials study, researchers describe novel wavelength-sensitive thin film sensors that offer numerous advantages as compared to commercial spectrometers, including reduced weight, cost, and exceptional sensitivity. Some of the proposed applications of this sensor include programmable luminescent tags, oxygen sensors, moisture sensors, light-emitting diodes (LEDs), solar cells, and transistors.
This single host-guest system consists of organic room temperature phosphors and colloidal quantum dots (QDs). Upon excitation by light of an unknown wavelength, the system mixes both excited single and triplet states into one active film.
With the ability to scan light within the wavelength range of 300 to 410 nanometers (nm), the system subsequently produces a monotonously falling afterglow intensity monitored by a simple photodetector. The photodetector allows users to determine the excitation wavelengths for material identification.
Although the sensitivity of the sensor is dependent upon excitation intensity and averages, the researchers report that it can achieve a resolution of 1 nm or below.
This acute sensitivity to minor wavelength changes of light sources indicates that this sensor may also be useful in detecting counterfeit products. More specifically, the authors of the study propose that their sensor can reliably and quickly confirm the authenticity of banknotes, documents, and other highly sensitive materials.
Despite the promising results described in this study, the sensor design remains in its early conceptual phase and must be further investigated before it can be brought to market. Furthermore, although it cannot be used to completely replace modern spectrometers, it can facilitate wavelength measurements in a single compact system.
References and Further Reading
Counterfeit Goods [Online]. Available at: https://www.ice.gov/features/dangers-counterfeit-items.
The Counterfeit Problem and How Retailers Can Fight Back in 2020 [Online]. Available at: https://www.forbes.com/sites/forbestechcouncil/2020/03/17/the-counterfeit-problem-and-how-retailers-can-fight-back-in-2020/?sh=6382a8af1f32.
3 ways technology can tackle the global counterfeiting problem [Online]. Available at: https://www.redpoints.com/blog/ways-technology-can-tackle-the-counterfeiting-problem/.
Identifying Counterfeit Currency Through Spectroscopy [Online]. Available at: https://sensing.konicaminolta.us/us/blog/identifying-counterfeit-currency-through-spectroscopy/.
Elanjeitsenni, V. P., et al. (2022). A review won thin films, conducting polymers as sensors. Materials Research Express 9(2). doi:10.1088/2053-1591/ac4aa1.
Kirch, A., et al. (2022). Accurate Wavelength Tracking by Exciton Spin Mixing. Advanced Materials. doi:10.1002/adma.202205015.