Smart Labels Research Articles

3D Printing of smart labels with curcumin-loaded soy protein isolate

A two-step method for preparing smart labels that can monitor food freshness through color change is presented. The conventional casting method for such labels is not cost-effective, as it uses organic solvents and requires additional cutting processes. Our method is more eco-friendly and customizable, as it uses water as the sole solvent and 3D printing as the fabrication technique. First, curcumin was encapsulated with soy protein isolate (SPI) by a pH-driven method involving hydrogen bonding and hydrophobic interactions. Subsequently, the SPI-curcumin complex was blended with gelatin to create a printable ink. The ink has suitable rheological properties for extrusion, with a yield stress of 400–600 Pa and a viscosity of 122.93–142.82 Pa·s at the optimal printing temperature. The complex modulus of the ink increases to above 2 × 103 Pa when cooled to 25 °C, indicating rapid gel formation. The application of these smart labels to minced meat demonstrated their ability to reflect its freshness by transitioning from yellow to red. Furthermore, the printability and mechanical properties of the labels can be adjusted by changing the glycerol/water ratio. This innovative approach is a promising solution for producing environmentally friendly and customizable smart labels for food freshness monitoring.

A colorimetric sensor array based on transparent photographic film (triacetyl cellulose polymer) as a smart label for naked eye detection of chicken meat spoilage

A new transparent colorimetric sensor array is presented for naked eye monitoring of the chicken meat freshness. This sensor array consists of four sensors fabricated by using pH indicators, immobilized on triacetyl cellulose (TAC) membrane. The sensor array represented obvious color change when it was exposed to the volatile organic compounds emitted from the chicken meat after 20 h keeping at room temperature or after four days of storage in the refrigerator. Therefore, it could easily identify spoiled meat from the fresh one assisted by chemometrics data analysis. Also, the color change of sensors due to the spoilage was sharp enough that could be read even by untrained people, providing naked eye monitoring the chicken meat freshness. The TAC polymer represented high physical stability for industrial scale-up. In addition, the immobilized indicators represented good stability against color change in humid condition. This offered the potential for continuous monitoring of the meat spoilage as smart labeling in the markets.

Effects of glycerol and PVA on gelatin/Gum Arabic aerogels: Microstructure, mechanical properties, and applications for food monitoring

Smart labels are a hot research topic in the field of food science, but the low sensitivity of film smart labels limits the on-site and visual detection of seafood freshness. To address these challenges, betacyanin (BET) as a response signal and an aerogel smart label based on gelatin/gum arabic (Gel/GA) were designed. The labels produced a visually observable color change in the presence of volatile ammonia (2500 ppm) and displayed an immediate colorimetric response to food spoilage when packaged shrimp was used as an example. The results showed that the smart aerogel labels were better than the film smart labels in the response sensitivity test of volatile ammonia. In addition, the addition of a small amount of plasticizers (glycerol) or hardeners (polyvinyl alcohol, PVA) further enhanced the responsiveness of the aerogel to volatile ammonia. Notably, the addition of a small amount of PVA further increased the hardness of the aerogels. The scanning electron microscopy (SEM), infrared spectroscopy, and X-ray diffraction (XRD) results showed that these results may be caused by the interpenetration of the PVA network and the Gel/GA network to form a new type of interpenetrating polymer network structure. Therefore, the developed smart aerogel labels play an important role in ensuring food quality and reducing food waste and inspire new ideas for the development of additional functional smart labels.

Employing polyaniline/viologen complementarity to enhance coloration and charge dissipation in multicolor electrochromic display with wide modulation range

Multicolor electrochromic devices have gained attention widely. To support the development of multicolor electrochromic devices, we studied complementary combinations of a multicolor switchable polyaniline (PANI) electrode and 1-methyl-4,4′-bipyridyl iodide (MBI). In particular, MBI acting as an electrolyte and cathodic electrochromic layer can not only simplify the architecture of a device, but also support the color richness of the device simultaneously. Wide band optical modulation in visible light (58.1% at 550 nm) and near-infrared light (35% at 800 nm) confirms the advantageous optical properties of the combination, possessing a wide color gamut range over a range of working voltages adjustable for red, yellow, green, blue, and purple, each having a high color contrast of up to 73.8. This is accompanied by the excellent electrochemical performances of the mentioned combination, such as a fast response time of 1 s/1.9 s (modulating 77%-colored/bleached) with good cycle stability, and high coloration efficiency of 140.63 cm2/C. In addition, utilizing a screen-printed polyvinyl alcohol (PVA) as a masking barrier layer, it is possible to display patterned anti-counterfeit information within the application. Given these electrochromic performance properties, it is considered a readily feasible strategy to utilize PANI and MBI combination to develop novel electrochromic devices, which can be used widely in the areas of smart packaging, smart labels, and flexible smart windows associated with specific application scenarios.

Colorimetric Properties of Bombyx mori Silk Fibroin.

Recent reports highlighted several novel applications for the Bombyx mori silk fibroin (SF), as edible coatings for the preservation of food freshness, smart labels, or packaging materials. This study complements these reports and additionally describes the colorimetric sensing properties of the natural protein that could be explored to enhance the practical value of such applications. Our data show that in response to pH changes, reconstituted SF is able to undergo visible color changes that correlate with the intensity of the stimuli, regardless of its physical format or physical cross-linking state. The intensity of the developed color was proportional to the extent of the protein's hydrolytic degradation. We also found that these pH-driven color changes were reversible and interchangeable, with colorless samples at neutral pH, purple in acidic environments, and yellow under basic conditions. Our mechanistic studies identified tryptophan as being responsible for these colorimetric responses, which could be further intensified by the presence of ionized tyrosine functionalities. In addition, we determined that SF's sensing properties also applied to ultraviolet light exposure. Finally, we showed that the innate sensing capabilities of activated SF can be enhanced via the covalent incorporation of additional tryptophan into the protein. Overall, our results further support the utility of SF for sensing applications.

Overcoming Downscaling Limitations in Organic Semiconductors: Strategies and Progress.

Organic semiconductors have great potential to revolutionize electronics by enabling flexible and eco-friendly manufacturing of electronic devices on plastic film substrates. Recent research and development led to the creation of printed displays, radio-frequency identification tags, smart labels, and sensors based on organic electronics. Over the last 3 decades, significant progress has been made in realizing electronic devices with unprecedented features, such as wearable sensors, disposable electronics, and foldable displays, through the exploitation of desirable characteristics in organic electronics. Neverthless, the down-scalability of organic electronic devices remains a crucial consideration. To address this, efforts are extensively explored. It is of utmost importance to further develop these alternative patterning methods to overcome the downscaling challenge. This review comprehensively discusses the efforts and strategies aimed at overcoming the limitations of downscaling in organic semiconductors, with a particular focus on four main areas: 1) lithography-compatible organic semiconductors, 2) fine patterning of printing methods, 3) organic material deposition on pre-fabricated devices, and 4) vertical-channeled organic electronics. By discussing these areas, the full potential of organic semiconductors can be unlocked, and the field of flexible and sustainable electronics can be advanced.

Development and application of multifunctional films based on modified chitosan/gelatin polyelectrolyte complex for preservation and monitoring

Green and sustainable natural macromolecular-based multifunctional packaging has received widespread attention due to its excellent fresh-keeping effect and sensitive monitoring function. Herein, water-soluble modified chitosan (GCS) as the film substrate and emulsifier was synthesized first. Based on gelatin and GCS, a composite film (GF/GCS) and an emulsion film containing garlic essential oil (GF/GCSE2) were fabricated and compared. The interactions mainly included intermolecular hydrogen bonds and electrostatic interactions. The incorporation of GCS and the emulsion enhanced the hydrophobicity (water contact angle >100°) of films and also endowed the films with antioxidant activity and antibacterial activity (up to 100% for S. aureus and 97% for E. coli). Moreover, anthocyanins extracted from purple cabbage were added to the above two films as indicators to form pH-responsive smart labels GF/GCS/A and GF/GCSE/A. The gelatin/GCS polyelectrolyte complex improved the stability of anthocyanins in labels. Compared to commercial PE film, GF/GCS and GF/GCSE2 displayed better preservation effects on cherry tomatoes and fish. GF/GCSE2 exhibited the best preservation effect on cherry tomatoes, significantly reducing the decrease in total phenolic content and titratable acids. The integrated packaging composed of GF/GCS and GF/GCS/A could effectively prevent fish spoilage (TVB-N<15 mg/100 g) and sensitively reflected the freshness of fish during storage at 4 °C.

An attack resistant physical unclonable function smart optical sensors for internet of things for secure remote sensing

COVID-19 pandemic scenario makes extensive use of remote temperature sensors, using IoT devices and communications. Earlier, flexible organic-inorganic luminous inks were used to design and print univocal smart labels based on QRCs (quick response codes) on medical substrates (protective masks and adhesive). Through simultaneous combination of luminescence thermometry and PUFs (physical unclonable functions), temperature measurements in non-contacts, identifications, and connections with IoTs. PUFs are extremely helpful for hardware security, but are open to attacks from MLTs (machine learning techniques) that mimic the behaviours of CRPs (controvert-response pairs). The study suggests ARPUFs architecture that implements two-round controverts to randomise the mapping of CRPs in order to satisfy the unpredictability requirements for resistances, intriguing examples on the usages of organic/inorganic hybrids luminous inks changed by lanthanide ions for creating smart labels with the ability of sensing temperatures including maximal thermal sensitivities up to 1.46%K and uncertainties of 0.2 K, along with authentications like methodology accuracies (98.4%), precisions (99.6%), and recalls (87.7%). Proposed methodology of univocal identifications and monitoring of mobile optical temperatures in individuals, enable control of accesses to restricted areas and medical information transfers for post-medical evaluation results in opening the door to new generations of mobile-assisted eHealths (mHealth-mobile-assisted eHealths).

A Colorimetric Label‐Free Sensor Array of Metal–Organic‐Framework‐Based Fabry–Pérot Films for Detecting Volatile Organic Compounds and Food Spoilage

AbstractThe unambiguous detection and classification of volatile organic compounds (VOCs) are crucial in many fields. For using VOC‐sensing to explore the alteration and spoilage of food, very inexpensive sensors are desired. Simple colorimetric sensors seem highly attractive for these applications. Here, a label‐free, colorimetric sensor array made of metal‐organic‐framework‐based (MOF‐based) Fabry‐Pérot (FP) films is presented where the signal read‐out is performed either by their optical spectra or by pictures taken with a smartphone camera. Exposing the FP‐MOF‐films to various VOCs causes a reversible shift of the photonic pattern, where the magnitude of the shift depends on the VOC type, its concentration, and the MOF structure. The application of machine‐ learning‐ algorithms on the sensor data allows to identify the VOCs with a high classification accuracy (92% at 100 ppm). It is shown that the sensor array read‐out can also be performed with a common smartphone camera, also precisely classifying the VOC analytes. Moreover, fresh and spoiled food, like milk and meat, is distinguished by its head space. Thus, the study presents a very inexpensive platform of small colorimetric sensors that allow determining the quality, alteration, and spoilage of food, and it may contribute to realizing smart labels and intelligent packaging.

Portable and reversible smart labels for non-destructive detection of seafood freshness via amine-response fluorescent ionic liquids

Herein, a functionalized ionic liquid (IL) 7-HDCP (7-hydroxycoumarin-quaternary phosphorus) was developed as NH3 trapping agents and fluorescent indicators to achieve in-time and on-site detection of seafood freshness. Interestingly, the IL displayed remarkable blue fluorescence “turn-on” enhancement to gaseous amine due to excellent amine solubility. By FTIR and 1H NMR spectrogram, this fluorescence “turn-on” phenomenon originated from the weak hydrogen bonding between the ester group of the coumarin functional group and the ammonia molecule. Moreover, the IL exhibited a rapid response (<11 s), prominent sensitivity (0.12 ppm), excellent selectivity (10 interfering substances) and outstanding reversibility (>22 cycles). Benefiting from ion characters, 7-HDCP obtained advantages of easy-to-fabricate and easy-to-use, which was fabricated by one-step simple immersion without aggregation-caused quenching phenomenon. This portable and sensitive smart label made of ion probes facilitates the timely and on-site NH3 detection in the early deterioration stages of aquatic products, enabling “early detection, early warning, and early treatment”.

Consumer willingness to pay for shelf life of high-temperature, short-time-pasteurized fluid milk: Implications for smart labeling and food waste reduction

Food waste in the United States was valued at $285 billion in 2019, representing 70% of all food surplus; dairy and eggs alone represented 15.90% of food surplus. Milk is the fifth most consumed beverage in the United States, and therefore its contribution to food waste has significant economic and environmental ramifications. Smart labels that provide precise spoilage information for fluid milk may help reduce food waste in fluid milk, but it is unclear if consumers will accept or pay for this novel technology. This paper examines consumer preferences for high temperature, short time pasteurized fluid milk shelf life and smart date labels and tests how information about the environmental impact of fluid milk food waste affects consumers' acceptance and willingness to pay. We used a choice-based conjoint study administered in an online survey, along with a between-subject experiment to measure preferences under different information treatments about the environmental impact of food waste. Our results suggest that consumers' valuations of extended shelf life and an ecolabel is positive; however, using the smart label creates disutility for consumers, thereby hindering acceptance of new labeling technology that may facilitate food waste reduction in the milk industry. These findings imply that retailers should find alternative means to enhance the communication of precise shelf life information and its role in reducing food waste.

Development of a Qualitative Tool for Sustainability Assessment and Application of the Tool to Benchmark Electronic Smart Labels

This paper presents a sustainability benchmarking tool, the GreenTool, to compare different electronic product concepts, specifically printed ones, with each other from the sustainability perspective. The purpose is to increase awareness of different aspects of sustainability and support the design of more sustainable electronics. This tool is built on European and global sustainability regulations and recommendations, and it considers environmental, economic, and social sustainability aspects in seven different criteria, each with several sub-criteria that are the actual categories used in the comparison. The tool uses scientific and industrial information as input, as well as a technical understanding of the new and baseline concepts to be compared to properly support sustainability benchmarking. In this paper, we further present an example comparison of four smart label product concepts, one of which is the commercial baseline concept, and the other three are developmental concepts. The biggest differences among the product concepts were found in the categories of ‘raw materials’, ‘manufacturing’, and ‘logistics’ criteria, where the developmental concepts based on manufacturing by printing and bio-based materials gave environmental benefits over the baseline. In the other criteria, the differences were smaller, but the developmental concepts also provided slight improvements in sustainability. The GreenTool can be considered suitable for qualitative sustainability comparisons in product concept design.

Optimization of a Power Management Process in a Printed Electronics Smart Label System

The topic of this research was to investigate and optimize power management of a printed electronics prototype device used for quality assurance of Ready-to-Eat food products. Printed electronics enables the manufacturing of thin, lightweight products and components, which can be part of a functional system. In order to maintain the lightweight and thin nature of the products, a small and thin battery is integrated in these types of autonomous systems. Power consumption of the system should be kept at low level to enable the use of printed batteries.The optimization of power consumption was done at software level. The goal was to reach so low power consumption that the printed prototype device can operate on a food package long enough using a small sized printed battery. Another goal was to study the effects of different operating modes to the power consumption and how much is it possible to affect to them.The research started by studying power management in embedded systems and finding out what was the device’s power consumption at the start. After that, a plan for optimization procedures was done. The optimization procedures were executed one by one and effects to power consumption was measured. This revealed exactly how much each procedure was affecting to power consumption. Usability also played a key role in finding the optimal solution. As a result, the device’s current consumption was optimized to the desired level where it can reach the targeted operating time. All functionalities and usability were maintained in the power optimization process.

Light Delivery, Acoustic Read‐Out, and Optical Thermometry Using Ultrasound‐Induced Mechanoluminescence and the Near‐Infrared Persistent Luminescence of CaZnOS:Nd3+

AbstractLight emission from CaZnOS:Nd3+ by high‐intensity ultrasound excitation is demonstrated. Acoustic power and duty ratio enable simultaneous control of the degree of (local) thermo‐acoustic heating in isothermal or nonisothermal conditions. The Nd‐related photoemission provides direct thermometric feedback at an absolute sensitivity on the order of 10−4 K−1, within the physiological temperature range. From the individual temperature dependence of persistent luminescence and mechanoluminescence, both effects are attributed to a heterologous de‐trapping mechanism. In addition to acoustic heating and optical thermometry, this enables optical information storage and smart labeling with optoacoustic read‐out.

Smart Labels as Indicators of Tomato Freshness Using Mangosteen Peel Extract

Tomato is one of the most popular tropical fruits because it tastes fresh and can be consumed directly or processed as a seasoning, garnish, and industrial raw material. Tomato cultivation is increasing with the increasing demand for tomatoes in the market. As a perishable product, many efforts have been made to maintain the quality of fresh tomatoes, one of which is by packing fresh tomatoes using innovative packaging. Smart packaging is packaging with an additional label to provide information to consumers without touching the product, so that product cleanliness is maintained. Several studies have added synthetic substances as smart labels, which will certainly have a negative impact on fresh products that are consumed directly. For this reason, smart labels were developed on packaging with natural ingredients taken from plant extracts. One that can be used as an indicator on a smart label is the rind of the mangosteen fruit. Mangosteen rind contains high anthocyanin substances, which are very sensitive to changes in pH. This situation can be used as an indicator of changes in pH that accompany a decrease in the quality of tomatoes during storage. This study aimed to determine the action of anthocyanin substances from mangosteen rind as a smart label indicator that detects the freshness of packaged tomatoes during storage, both at room temperature and cold storage.

Smart tag packaging technologies: A qualitative investigation of consumers' needs and expectations

AbstractIn this paper, we attempt to better understand concerns, needs and expectations of European consumers towards the use of intelligent packaging technologies as this topic appears to need further investigation from a marketing point of view. Thus, this study contributes to the currently limited body of research on the application of smart tag technologies on food packaging by exploring information benefits to consumers and by providing insights for marketers on how these technologies could be further employed to create value for consumers, manufacturers and regulatory bodies.A qualitative user‐centred approach was employed to get insights about consumers' shared views on future packaging solutions that could be introduced by European stakeholders of the food industry using different smart labels. Focus group discussions (FGDs) were conducted online in five European countries: United Kingdom, Finland, Spain, Poland and Iceland.Respondents indicated that food safety and quality were the most important issues connected to the food value chain. Participants also identified and expressed their preferences for information that stakeholders of the food industry should deliver with smart tag labels. Smart tag labels should inform consumers about ingredients, food storage, food preparation, shelf life, health, real‐time freshness, recycling and personalised deals. In terms of preferences for different smart labels, participants indicated quick response (QR) codes and freshness indicators to be the technologies of the future for stakeholders of the food industry.

Micro perforation based smart label to guide freshness of pasteurized milk packet

A colour code-based Time Temperature Indicator (TTI) is a consumer-friendly option to monitor the freshness of packaged milk. This study aimed to develop a micro-perforation-based external TTI label that is cost-effective, efficient and on-time activation. To understand the spoilage of milk, various quality parameters at storage conditions, 4 ± 1, 27 ± 2 and 37 ± 4 °C, were evaluated. The Ea of the developed TTI was co-related with the Ea of spoiled packaged milk. An activated TTI label was sticked on the milk packet to check its applicability. The TTI changes colour from green to red, indicating spoilage of packaged milk.

Reversible thermochromic systems based on a new library of flavylium spirolactone leuco dyes

The aim of this work was the design, synthesis, and characterization of new chromogenic spirolactone dyes based on a 2-phenyl-1-benzopyrylium (flavylium) backbone for further development of thermochromic smart labels. The influence of electron-donating and electron-withdrawing groups on the five synthesized dyes was studied in terms of color modification, acid-base behavior and thermochromic properties. By using UV–Vis absorption and emission spectroscopies, molar absorptivity, oscillator strength, Stokes shift, and fluorescence quantum yield were determined for each dye to evaluate the impact on color and excited state properties of the designed structures. The acid-base behavior and the ability to evolve towards leuco species was assessed by titrations with triethylamine and N,N-diisopropylethylamine in non-polar and polar aprotic solvents such as acetonitrile and octan-1-ol. In addition, the reversibility of the color was also evaluated by titrations with polar protic solvents (water and ethanol) and Lewis acids (gallic acid and iron(III) chloride). The number of equivalents of base/acid required to reach the leuco product and then to reverse the color were determined by representing the absorption maximum as a function of added base/acid in acetonitrile (water content less than 0.01-v/v). Finally, the thermochromic properties were evaluated in the presence of long-chain organic amines and water-insoluble solvents with melting points close to room temperature. The synthesized compounds can switch between two species if the appropriate conditions are used. Moreover, the tests carried out to assess their thermochromic behavior concluded that all dyes display thermochromism to some extent. The dyes that have electron-withdrawing groups attached, such as cyano, display stronger chromogenic effects useful for future applications.

The Impact of Citizens’ Participation Level on Smart Sustainable Cities Outcomes: Evidence from Saudi Arabia

It is imperative to expand the concept of smart cities beyond merely focusing on technology to include human, social, and environmental capital investing to develop smart sustainable cities (SSC). In recognition of smart cities’ advantages, several cities have adopted smart city labels. Although citizens’ engagement in public urban development and decision-making has been acknowledged globally in many countries, evaluating the outcomes that allow citizens to contribute does not measure and compare with other factors. This study examines the impact between the citizens’ participation level (CPL) and the smart sustainable cities outcome (SSCO). Four factors were extracted from the literature review and interviews were conducted with 12 decision and policymakers to establish the importance of these factors and to suggest any other additional factors. In addition, a questionnaire survey was utilised to assess and validate the result by experts in the field of the built environment. The mean score (MS) ranking was used to confirm the importance of these predicted correlations with SSCO. Endogeneity tests and multivariate regression analysis were adopted to validate the causality between CLP and SSCO. The results suggest that a positive significant correlation exists between the CPL and SSCO. A higher CPL leads to a higher level of SSCO, but this does not apply the other way around. The four significant factors of CPL to engage and empower citizens are accountability and responsibility, transparency, participation, and inclusion. This paper contributes to knowledge by identifying the measures of CPL and SSCO that can support the implementation of SSC by understanding what can be expected from the government and decision-makers and what can be expected from the citizens.

Green Production of Anthocyanin-Fixed Poplar Veneers toward a Smart Label with Higher and Long-Term Accuracy for Supervising the Freshness of Pork

Green Production of Anthocyanin-Fixed Poplar Veneers toward a Smart Label with Higher and Long-Term Accuracy for Supervising the Freshness of Pork