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Conventional papers are not suitable for printed electronics because they have a rougher surface than the plastic film commonly used for electronics printing. The paper surfaces were modified by coating and calendering processes to reduce surface roughness and electrical resistance of inkjet-printed UHF RFID antennas. The composition of coatings, t...
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Context 1
... RFID antennas were inkjet-printed on base papers A and B, coated papers and PET film. The designs of antennas are presented in Fig. 2. The electrical resistance of inkjet-printed antennas was measured after drying and sintering as the antennas must be conductive. Figs. 3 and 4 compare the electrical resistances of UHF RFID inkjet-printed antennas on base and coated papers with antennas printed on commercial PET film, which is a suitable substrate for printing UHF ...
Citations
... 101 One application of inkjetprinted antennas is RFID tagging. [102][103][104][105][106][107][108] In biomedical applications, RFID tagging is used for smart blood storage/blood bag tagging and patient monitoring. 109 The tags are combined with a sensor, such as a strain sensor, to monitor patient parameters and transmit them to providers. ...
In recent years, inkjet printing has become a popular form for creating sensors and antennas. These devices are fabricated using different materials with inkjet printing using various (conductive, oxide, biological) inks on predominantly flexible substrate. This form of fabrication has attracted much attention for a variety of reasons such as relatively cheap cost of manufacturing and materials, as well as the ease of use and high customization. These devices also provide a lighter frame and added flexibility allowing them to be incorporated as devices on non-planar surfaces. It is also possible for inkjet printing to be used as a sustainable manufacturing method, providing a method of reducing electronic waste. In this article, several topics related to inkjet printing are covered. These topics include a general overview of the fabrication process of inkjet devices through an inkjet printer, recent applications of inkjet-printed sensors, applications of inkjet-printed antennae, challenges in inkjet printing, and an outlook on the inkjet printing. In the fabrication section, the different materials and printing process are explored. Topics covered in the application section include gas sensors, biomedical sensors, pressure sensors, temperature sensors, glucose sensors, and more. In the inkjet antennas portion of the article, RFID tagging and 5G applications are highlighted. The main challenges covered are specific to fabrication that are being currently addressed.
... Ordinary papers are porous and have a rougher surface than the plastic film used to print electronics. To modify the surface of the paper, it is possible to use the processes of coating and smoothing in a calender [20][21] or a hot stamping machine. Smoothing in a hot stamping machine achieved a higher bending stiffness of coated paperboards compared to calendering. ...
... Depending on the composition of coatings, properties such as surface roughness, porosity, permeability and wettability can be varied. 20,[23][24] The surface properties of papers can be adjusted at the same time to achieve the desired functional properties, such as water, oil and grease resistance, low vapour and gas permeability, [25][26][27][28][29] and flame retardation. 30 Lowtemperature plasma processing of surfaces and interfaces is an interesting option for applications in flexible and printed electronics where surface cleaning, activation or functionalization are required. ...
... Electrical conductivity of inkjetprinted UHF RFID antennas increased after calendering the coated papers, however, as the basis weight of the coating on the paper increased, the electrical conductivity of the antennas decreased. 20 While in thermal transfer printing, the addition of cationic polymers to coating compositions did not play any role, their addition as well as their type was decisive in inkjet printing. UHF RFID antennas printed on smooth functional coated paper with a functional hydrophilic coating based on inorganic pigments did not reach the electrical conductivity achieved on PET film for inkjet printing. ...
In the present work, various surface treatments of base paper were investigated in order to make it suitable for application in printed electronics. A functional coating based on silica pigment was preceded by PVOH-containing precoating, and differently surface treated papers were characterized in terms of surface roughness, relative area of surface pores, wettability, printability and by FTIR spectroscopy. The precoating had a significant effect on the constriction of through-pores, the reduction of their number, and on the permeability of the functional coating, and it increased the dynamic contact angle of the liquids. Analysis of FTIR spectra of precoated and functionally coated paper confirmed a higher content of polyvinyl alcohol binder and cationic polymer in the functional coating, compared to that of functionally coated paper, without precoating. SEM analysis showed that the silver layer of the RFID antenna printed by inkjet on the precoated and functionally coated paper was continuous. Better printability of the precoated and functionally coated paper, compared to the functionally coated paper, without precoating, was also confirmed by higher electrical conductivity of the dipole of the RFID antenna, which reached the level of the antenna printed on a commercial inkjet PET film.
... The resulting inconsistent and disperse coverage of functional inks leads to poor performance, such as low conductivity for conducting inks. The wicking of functional inks also limits the printing resolution [31][32][33]. Formulating functional inks to control the wettability, surface tension, and viscosity is one approach to minimize these issues; however, this optimization process must be done individually for each functional ink [34,35]. A more general approach focuses on the paper substrate itself. ...
Printed electronic devices that sense and communicate data will become ubiquitous as the Internet of Things continues to grow. Devices that are low cost and disposable will revolutionize areas such as smart packaging, but a major challenge in this field is the reliance on plastic substrates such as polyethylene terephthalate. Plastics discarded in landfills degrade to form micro- and nanoplastics that are hazardous to humans, animals, and aquatic systems. Replacing plastics with paper substrates is a greener approach due to the biodegradability, recyclability, low cost, and compatibility with roll-to-roll printing. However, the porous microstructure of paper promotes the wicking of functional inks, which adversely affects printability and electrical performance. Furthermore, truly sustainable printed electronics must support the separation of electronic materials, particularly metallic inks, from the paper substrate at the end of life. This important step is necessary to avoid contamination of recycled paper and/or waste streams and enable the recovery of electronic materials. Here, we describe the use of shellac – a green and sustainable material – as a multifunctional component of green, paper-based printed electronics. Shellac is a cost-effective biopolymer widely used as a protective coating due to its beneficial properties (hardness, UV resistance, and high moisture- and gas-barrier properties); nonetheless, shellac has not been significantly explored in printed electronics. We show that shellac has great potential in green printed electronics by using it to coat paper substrates to create planarized, printable surfaces. At the end of life, shellac acts as a sacrificial layer. Immersing the printed device in methanol dissolves the shellac layer, enabling the separation of printed electronic materials from the paper substrate.
... This also decreases ink transfer, resulting in thinner ink layers and thus poorer conductivity and ink adhesion [8,10,11]. Despite the possibilities to easily affect and improve paper properties, higher electrical resistance is typically expected on papers than plastic foils [12]. Other flexible bio-based materials, such as biopolymer polylactic acid (PLA), silk fibroin, nanocellulose (NCF), and nanochitin, have also been developed for printed electronics applications where transparency and high smoothness of the flexible substrate are required [8,[13][14][15][16]. ...
... Paper-based electronics is a widely studied area. Paper has been evaluated as a substrate for thermochromic and electrochromic displays, resistive memory devices, transistors, capacitors, disposable radio frequency identification (RFID) tags, batteries, photovoltaic cells, and sensors and actuators [4][5][6]12,[17][18][19]. In recent years, the use of paper-based substrates in diagnostics, pharmaceutical, energy harvesting, and wearable applications has grown due to paper's high breathability consequently from porosity, flexibility, and sustainability [6,20]. ...
Flexible plastic substrates are widely used in printed electronics; however, they cause major climate impacts and pose sustainability challenges. In recent years, paper-based electronics has been studied to increase the recyclability and sustainability of printed electronics. The aim of this paper is to analyze the printability and performance of metal conductor layers on different paper-based substrates using both flexography and screen printing and to compare the achieved performance with that of plastic foils. In addition, the re-pulpability potential of the used paper-based substrates is evaluated. As compared to the common polyethylene terephthalate (PET) substrate, the layer conductivity on paper-based substrates was found to be improved with both the printing methods without having a large influence on the detail rendering. This means that a certain surface roughness and porosity is needed for the improved ink transfer and optimum ink behavior on the surface of the substrate. In the case of uncoated paper-based substrates, the conductivity and print quality decreased by preventing the formation of the proper and intimate ink-substrate contact during the ink transfer. Finally, the re-pulpability trials together with layer quality analysis detected very good, coated substrate candidates for paper-based printed electronics competing with or even outperforming the print quality on the reference PET foil.
Abstrakt
Hodnotil sa vplyv drsnosti povrchu a počiatočného kontaktného uhla vody komerčnej skladačkovej lepenky pred a po úprave povrchu kalandrovaním, natieraním a kalandrovaním a plazmovou na elektrickú vodivosť UHF RFID antén vytlačených hliníkovou termotransferovou páskou. Po natieraní alebo úprave plazmou vznikol hydrofilný povrch, ktorý zlepšil zmáčavosť povrchu skladačkovej lepenky, rozstieranie termoplastickej spojovacej vrstvy a priľnavosť vodivej hliníkovej vrstvy. Natieraním vznikol nový produkt s trvalou zmáčavosťou povrchu bez nutnosti úpravy plazmou pred tlačou. Zníženie povrchovej drsnosti zlepšilo potlačiteľnosť skladačkových lepeniek a elektrickú vodivosť vytlačených UHF RFID antén. Po inštalácii pamäťového čipu k anténam vytlačených na kalandrovanej a plazmou upravenej skladačkovej lepenke sa hodnotila kvalita pasívnych UHF RFID tagov po ich umiestnení na natieranej lepenke, polystyréne a drevotrieskovej doske. Komunikačná kvalita UHF RFID tagov umiestnených na natieranej lepenke a polystyréne bola lepšia ako tagov umiestnených na drevotrieskovej doske, ktorej elektrická permitivita je vyššia ako natieranej lepenky a polystyrénu. Na komunikačnú kvalitu UHF RFID tagov mal vplyv aj dizajn antény.
Abstract
The effect of surface roughness and initial water contact angle of commercial paperboard before and after surface treatment by calendering, coating and calendering and plasma on the electrical conductivity of UHF RFID antennas printed with aluminum thermal transfer ribbon was evaluated. After coating or plasma treatment, a hydrophilic surface was formed, which improved the wettability of the paperboard surface, the spreading of the thermoplastic tie layer and the adhesion of the conductive aluminum layer. By coating, a new product was created with permanent surface wettability, without the need for plasma treatment before printing. The reduction of surface roughness improved the printability of paperboards and the electrical conductivity of printed UHF RFID antennas. After installing a memory chip to antennas printed on calendered and plasma-treated paperboard, the quality of passive UHF RFID tags was evaluated after they were placed on coated paperboard, polystyrene and particle board. The communication quality of UHF RFID tags placed on coated paperboard and polystyrene was better than that of tags placed on particle board, whose electrical permittivity is higher than that of coated paperboard and polystyrene. The antenna design also had an impact on the communication quality of UHF RFID tags.
The effect of surface roughness and water contact angle of commercial paperboard before and after surface modification by calendering, coating and calendering and plasma treatment on the functionality of UHF RFID antennas printed with thermal transfer aluminum ribbon was evaluated. A hydrophilic surface was created by coating or plasma treatment, which improved the wettability of the paperboard surface, the spreading of the thermoplastic tie layer and the adhesion of the conductive aluminum layer. A new paper product was created with permanent surface wettability by coating, without the need for plasma treatment before printing. The plasma treatment provided time-limited wettability, needed only during printing, and made it possible to restore the original hydrophobic surface of the paperboard. In addition to the meaning of these surface modifications, the importance and need to reduce the surface roughness was confirmed, as the higher surface roughness of the paperboard limited the effect of the plasma treatment in terms of its printability and the functionality of the printed aluminum antenna. The printability of the paperboard and the functionality of the printed antennas were evaluated using electrical conductivity. The electrical conductivities of the dipole and inductor loop of the UHF RFID antennas printed on modified paperboards varied depending on the antenna design.
The need for disposable, simpler, and accurate paper‐based analytical devices represents an open research field that is focused on simpler fabrication methods. To achieve this, four feasible methodologies are proposed for the direct printing of an electrochemical sensor on a biodegradable paper substrate using commercial gold and silver inks, which are compatible with inkjet printing technology. Four substrate treatment strategies are evaluated: printing the active elements directly on the hydrophilic bare paper, a hydrophobic gas‐phase coating over all the substrate, a hydrophobic silane ink that is selectively printed on the paper, and a hydrophobic coating that is selectively printed and blocks the surface porosity. Thanks to the ability of the inks to conform the cellulose fibers, the resulting working electrodes tune their electrochemical active area, showing higher active electrochemical areas when the roughness is increased. The most planar consideration is achieved blocking the paper porosity with SU‐8 and the direct printing on bare paper maximizes the electrochemical response with the smallest geometric area, with current values 2.7‐times higher than the theoretical one. Although all methods allow a functional electrochemical sensor, the highest reproducible results are accomplished with the blocked paper, consequently allowing a higher controlled and robust manufacturing approach. The feasibility of printing necessary metallic/insulating layers on different treated papers is demonstrated. The roughness and hydrophobicity of the paper surface have been modified (bare paper, a silanized paper in the vapor phase, a paper printed with silane, and a blocked SU8) for the successful fabrication of electrochemical sensor.
UHF RFID printed antennas on conventional and experimentally coated papers by thermal transfer and inkjet technique were not conductive due to high surface roughness. Reducing the surface roughness of paper and hence the electrical resistance of the antennas printed by thermal transfer and inkjet printing was achieved by coating and subsequent calendering process. Papers for thermal transfer and inkjet printed of aluminum and silver antennas were prepared by coating with top functional coating, whose main component was pigment-precipitated calcium carbonate with addition of polyvinyl alcohol, cationic polymer PDADMAC and glyoxal. The desired quality of inkjet-printed silver antennas was achieved by using coated paper with a polyvinyl alcohol barrier layer and a top functional hydrophilic layer. Silver nanoparticles of inkjet ink require a sintering process to obtain a conductive printed trace. The microstructure and thickness of antennas printed by thermal transfer and inkjet technique were compared. Thermal transfer printing created a more homogeneous antenna with greater sharpness of drawing compared to inkjet printing.
