Smart and Safe packaging

In line with the latest innovations in the packaging field, this joint project aims at implementing new and innovative micro- and nanoparticles for the development of active and intelligent packaging solutions dedicated to food and medical packaging applications. More specifically, the project combines two major developments which both falls within the scope of active and intelligent packaging. In this work, a specific focus was given to the development of an antibacterial packaging solution and to the development of smart gas sensors. The antibacterial strategy developed was based on the combination of two active materials - silver nanowires and cellulose nanofibrils - to prepare antibacterial surfaces. The formulation as an ink and the deposition processing has been deeply studied for different surface deposition processes that include coatings or screen-printing. Results showed surfaces that display strong antibacterial activity both against Gram-positive and Gram-negative bacteria, but also interesting properties for active packaging applications such as a highly retained transparency or enhanced barrier properties. Regarding the second strategy, gas sensors have been prepared using a combination of Copper benzene-1,3,5-tricarboxylate Metal Organic Framework and carbon-graphene materials, deposited on flexible screen-printed electrodes. The easy-to-produce and optimized sensors exhibit good performances toward ammonia and toward humidity sensing, proving the versatility and the great potential of such solution to be adapted for different target applications. The results of this project lead to innovative solutions that can meet the challenges raised by the packaging industry

Cellulose nanofibrils and silver nanowires active coatings for the development of antibacterial packaging surfaces

An active ink composed of cellulose nanofibrils and silver nanowires was deposited on flexible and transparent polymer films using the bar coating process, achieving controlled thicknesses ranging from 200 nm up to 2 µm. For 350 nm thick coating on polyethylene terephthalate films, high transparency (75.6% transmittance) and strong reduction of bacterial growth equal to 89.3% and 100% was noted respectively against Gram-negative Escherichia Coli and Gram-positive Staphylococcus Aureus bacteria using AATCC contact active standard test. Retained antibacterial activity was found with films produced by reverse gravure roll-to-roll process, showing the promising capability of this antibacterial solution to be deployed industrially. Finally, the same ink was also deposited on polylactic acid substrate to investigate barrier properties: for 350 nm thick coating, a reduction of 49% of oxygen transmission rate (dry conditions) and 47% reduction of water vapor transmission rate was noted, proving the enhanced barrier properties of the coatings

Développement d'emballages antimicrobiens et intelligents

In line with the latest innovations in the packaging field, this joint project aims at implementing new and innovative micro- and nanoparticles for the development of active and intelligent packaging solutions dedicated to food and medical packaging applications. More specifically, the project combines two major developments which both falls within the scope of active and intelligent packaging. In this work, a specific focus was given to the development of an antibacterial packaging solution and to the development of smart gas sensors. The antibacterial strategy developed was based on the combination of two active materials - silver nanowires and cellulose nanofibrils - to prepare antibacterial surfaces. The formulation as an ink and the deposition processing has been deeply studied for different surface deposition processes that include coatings or screen-printing. Results showed surfaces that display strong antibacterial activity both against Gram-positive and Gram-negative bacteria, but also interesting properties for active packaging applications such as a highly retained transparency or enhanced barrier properties. Regarding the second strategy, gas sensors have been prepared using a combination of Copper benzene-1,3,5-tricarboxylate Metal Organic Framework and carbon-graphene materials, deposited on flexible screen-printed electrodes. The easy-to-produce and optimized sensors exhibit good performances toward ammonia and toward humidity sensing, proving the versatility and the great potential of such solution to be adapted for different target applications. The results of this project lead to innovative solutions that can meet the challenges raised by the packaging industry.En lien avec les dernières innovations dans le domaine des emballages, ce projet collaboratif a pour but d’implémenter de nouveaux micro- et nanomatériaux innovants pour le développement d’emballages actifs et intelligents dans le domaine alimentaire et médical. Il se focalise en particulier sur deux stratégies : le développement d’emballages antibactériens d’un côté et de capteurs de gaz de l’autre. La première stratégie est donc dédiée à l’utilisation combinée de nanofils d’argent et de nanofibrilles de cellulose pour la production de surfaces antibactériennes. La formulation d’encres ainsi que les paramètres de dépôt ont été optimisés pour différent procédés tels que l’enduction ou l’impression sérigraphique. Une forte activité antibactérienne contre des souches bactériennes Gram-positive mais aussi Gram-négative a été prouvée pour toutes les surfaces préparées. Des propriétés intéressantes relatives au domaine des emballage actifs ont aussi été démontrées telles que la conservation d’une haute transparence et l’amélioration des propriétés barrières. Dans la seconde stratégie, des capteurs de gaz ont été préparés en utilisant un mélange actif composé de Cuivre benzène-1,3,5-tricarboxylate Metal Organic Framework et de carbone-graphène, déposé sur des électrodes flexibles produites par sérigraphie. Les capteurs sont faciles à produire et ont été optimisés pour présenter de bonnes performances à la fois pour détecter et quantifier l’ammoniac gazeux mais aussi servir de capteurs d’humidité, ce qui prouve leur versatilité et leur important potentiel industriel. Ce projet a donc conduit à différentes solutions innovantes qui peuvent relever les défis de l’industrie des emballages

Cellulose nanofibrils/silver nanowires suspensions for the development of barrier properties and antibacterial surfaces

International audienc

Cellulose nanofibrils/silver nanowires suspensions for the development of barrier properties and antibacterial surfaces

International audienc

Rheology of cellulose nanofibrils and silver nanowires for the development of screen-printed antibacterial surfaces

TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl)-oxidized cellulose nanofibrils (T-CNF) and silver nanowires (Ag NWs) were formulated as active inks. Their rheological properties were investigated to design optimal conditions for processing by the screen-printing process, with the aim of preparing antibacterial patterns. Rheological experiments mimicking the screen-printing process were applied to different ink formulations to investigate their thixotropic and viscosity properties. The experiments conducted at 1wt% total mass content and different ratios of T-CNF/Ag NWs showed that the recovery (%), the recovery time and the viscosity are formulation dependent. A ratio 2:1 (T-CNF/Ag NWs) and total mass content of 2.5wt% were then selected to prepare an ink suitable for screen printing. Printing defects were corrected by addition of water-soluble polymer hydroxypropyl methylcellulose (HPMC). The selected formulation printed on flexible polyethylene terephthalate (PET) substrate displayed a 67.4% antibacterial activity against E. coli in a standard contact active test, with a transparency superior to 70%, proving the promising features of the developed solution for active packaging applications

Aeroacoustic wave equation based on Pierce's operator applied to the sound generated by a mixing layer

International audienceFor the first time, this paper presents the sound prediction capabilities of an aeroacoustic wave equation based on Pierce's operator (AWE-PO). The wave equation is applied to a twodimensional mixing layer, providing a solution which is compared with the far-field acoustics of a direct numerical simulation. In contrast to a direct numerical simulation, the computed Lighthill's wave equation and the AWE-PO rely on a hybrid workflow to predict the generated sound. Special attention is put on the visualization and interpretation of the right-hand side of both equations. Finally, the results of the acoustic far-field pressure are compared. It is shown that the radiated sound field's directivity, propagation, and convection effects are captured well for both wave equations. The error of the acoustic intensity compared with the direct numerical simulation is less than 2 dB for Lighthill's equation and AWE-PO. This error is comparable with the errors reported for Lighthill's equation in previous studies. To conclude, the presented wave equation reasonably predicts mixing layer sound, and the acoustic far-field pressure results are in good agreement with the DNS

Metal organic framework sensors on flexible substrate for ammonia sensing application at room temperature

International audienceThe application of sensitive gas sensors manufactured in high volume at low cost is of great interest due to an extensive array of potential applications. Such areas include industrial processing, biotechnology and intelligent food packaging. This work reports a straightforward and versatile technique using screen-printing and drop-casting processes, to produce gas sensors on a flexible plastic substrate, based on a combination of metal organic framework and graphene-carbon materials. We demonstrate a sensitive and stable ammonia sensor (4.6% maximal response) over a range from 20 to 100 ppm. The sensitivity of the optimized formulation is 36 times higher than a carbon–graphene only sensor and makes the developed devices suitable for intelligent packaging. The sensor production process is fast, reliable and low-cost and so there is a strong potential for the process principles to be adapted industrially for a different gas target or application