Gravure printing of graphene is demonstrated for the rapid production of conductive patterns on flexible substrates. Development of suitable inks and printing parameters enables the fabrication of ...patterns with a resolution down to 30 μm. A mild annealing step yields conductive lines with high reliability and uniformity, providing an efficient method for the integration of graphene into large‐area printed and flexible electronics.
A resistive flexible humidity sensor based on multi-walled carbon nanotubes (MWCNTs) was designed and fabricated. Screen and gravure printing processes were used for monolithically fabricating the ...humidity sensor containing interdigitated electrodes (IDE), a sensing layer and a meandering conductive heater. An average thickness and surface roughness of <inline-formula> <tex-math notation="LaTeX">0.99~\mu \text{m} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">0.23~\mu \text{m} </tex-math></inline-formula>, respectively, was registered for the printed MWCNTs sensing layer. The capability of the printed sensor, with heater, was investigated by subjecting it to relative humidity (RH) ranging from 10% to 90%. The response demonstrated an overall resistance change of 55% when the sensor was subjected to 90% RH, when compared to 10% RH. A maximum hysteresis of 5.1%, at 70% RH, was calculated for the resistive response of the sensor. The printed sensors can be bend with radius of curvature of 1.5 inch with literally no effect.
Reverse gravure (RG) coating is reported here as an alternate film deposition method for potential large scale roll-to-roll production of organic photovoltaic devices (OPVs). The basic working ...principles of RG coating are shown and compared to the more well-known gravure printing. Gravure printing is similar to RG coating from a process point of view, but the films produced using each method are very different to each other. An optical thickness measurement system was developed and used to monitor film thickness variation of RG coated photo-active layers with various coating parameters in situ in the roll-to-roll process. Partially and fully printed OPV modules were fabricated using, primarily, the roll-to-roll RG coating process and devices showed 2.1% and 1.5% power conversion efficiencies, respectively.
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•R2R printed OPV modules are fabricated by reverse gravure coating for the first time.•Basic working principle of RG coating is demonstrated using photo-active materials•A practical and low cost thickness monitoring system is developed and used in situ.•Fully printed OPV modules with 10×10cm2 dimension are fabricated.
•CNT based thermistor was fabricated using additive print manufacturing processes.•Resistive response of flexible thermistor was investigated from −40 °C to 100 °C.•Accuracy, stability, response and ...recovery time of printed thermistor was measured.•Organic encapsulant was used to minimize the humidity effects on thermistor.
A fully printed carbon nanotube (CNT) based negative temperature coefficient (NTC) thermistor was developed for temperature sensing applications. The multi-layer NTC thermistor was fabricated using additive print manufacturing processes on a flexible polyethylene terephthalate (PET) substrate. Two silver (Ag) electrodes were printed using screen printing process. CNT based active layer was deposited by means of gravure printing. Organic and silver encapsulation layers were deposited using screen printing. The capability of the fabricated thermistor was investigated by measuring its response towards temperatures varying from −40 °C to 100 °C, in steps of 10 °C. As the temperature was increased from −40 °C to 100 °C, the resistive response of the thermistor decreased exponentially with an overall percentage change of 53% with the temperature coefficient of resistance (TCR) of −0.4%/°C. The stability of the printed thermistor towards relative humidity (RH) varying from 20% RH to 70% RH, in steps of 10% RH at two constant temperatures of 30 °C and 50 °C, was also studied. A maximum change of 0.34% and 0.1% was observed at 30 °C and 50 °C, respectively when compared to its base resistance at 20% RH. In addition, a response time of ≈300 ms and a recovery time of 4 s were measured for the printed thermistor with an accuracy of ± 0.5 °C.
Research Printing Defects of Flexible Packaging Ольга Іларіонівна Хмілярчук; Катерина Олександрівна Чепурна; Олександра Павлівна Сфікова ...
Tehnologìâ ì tehnìka drukarstva (Online),
04/2023
1(79)
Journal Article
Recenzirano
Odprti dostop
A study of the modern state of technologies for the production of flexible packages by gravure printing was carried out. The analysis of patent information over the past ten years has revealed the ...constant development of technologies for ensuring the quality of printing, new materials — inks and films. According to the received data, the main number of patents is registered in the USA, Japan and China. Total number of patents devoted to new polymeric materials for printing is more than twice as large as the number of patents for gravure printing inks. From the obtained data, it can be concluded that this area has many unexplored points, and therefore it has a development perspective and space for various researches. The occurrence of defects, as well as the quality of products, is influenced by three main factors: manufacturing, technological, raw material. Another human factor can also influence the occurrence of defects. As a defect caused by the human factor, the most common is the use of the wrong series of ink, abuse of solvents, failure to carry out timely washing and cleaning of form cylinders and squeegees, failure to comply with approved technological regimes (drying temperature, pressure, speed, amount of glue application, etc.). According to the results of the printing of flexible packages, the types of defects caused by the production factor can include: insufficient tension of the canvas, insufficient alignment, insufficient drying of the ink. As a raw’ material shortage, the most common are: sagging of the canvas, non-fixation of ink, non-printing of a shallow raster, low intensity of ink, insufficient activation of the material. The most common printing defects of flexible packages have been determined: no small raster printing, different tone (in one edition), non-combination of design elements, not gluing laminates, layering of laminates, insufficient film activation, stains and splashes, drying of the ink (non-uniform application of the ink layer), ‘Stairs’, Stripes, no printing/poor printing of design elements. According to the results of the analysis of the wastes, no-good of print circulation, the main reasons for its occurrence were analyzed and the primary reason were identified. According to the identified types of defects, possible ways to eliminate each of these types of defects are proposed.
In this work, we describe a novel approach for the fabrication of flexible organic photovoltaic (OPV) modules with an inverted architecture by a versatile and scalable gravure printing process. The ...printing has been carried out using a sheet-to-sheet (S2S) lab scale proofer, while all the printing steps were performed in ambient conditions and were optimized for each of the OPV layers. Commercially available zinc oxide (ZnO) ink was used as the electron transport (ETL) layer, poly(3-hexylthiophene):6,6-phenyl C61 butyric acid methyl ester (P3HT:PCBM) blend comprised the bulk heterojunction (BHJ) photoactive layer, poly-3,4-ethylenedioxy-thiophene:poly(styrenesulfonic-acid) (PEDOT:PSS) was used as the hole transport layer (HTL), and silver (Ag) nanoparticle ink was used as the top contact electrode. The four OPV layers have been successively printed on indium tin oxide (ITO) coated polyethylene terephthalate (PET) flexible substrate using the same printing parameters, allowing the high production throughput in a roll-to-roll (R2R) printing process. The printed OPV modules have size of 45cm2 with an active area of 8cm2 composed of 8 interconnected cells and exhibited a maximum power conversion efficiency (PCE) of 2.22%. The printing parameters were optimized by the contribution from extensive morphological characterization carried out by scanning and transmission electron microscopy (SEM, TEM), as well as from Spectroscopic Ellipsometry (SE) for the determination of the printed layers thickness, optical properties and photoactive layer blend morphology. The above approach revealed the required printing parameters for the further optimization of the layer interface, morphology, thickness and substrate properties in order to implement the above methodology for large-scale manufacturing of flexible OPVs by a R2R process.
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•Flexible organic photovoltaics modules were fully printed by gravure.•One set of printing parameters used for all the OPV layers.•Spectroscopic ellipsometry (SE) revealed the OPV optical and electronic properties.•SEM and TEM showed the geometrical features of the printed OPV cells.•We report a maximum efficiency of 2.22% for 8 serially interconnected cells.
The mechanical flexibility of transparent poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films printed onto a flexible PET substrate using a gravure printing method was ...investigated using a lab-made bending test system. Gravure-printed PEDOT:PSS electrodes with a sheet resistance of 359
Ω/square and a transparency of 88.92% showed outstanding flexibility in several types of flexibility tests, including outer/inner bending, twisting and stretching. Notably, the PEDOT:PSS electrode had a constant resistance change (Δ
R/
R
0) within an outer and inner bending radius of 10
mm. In addition the stretched PEDOT:PSS electrode showed a fairly constant resistance change (Δ
R/
R
0) up to 4%, which is more stable than the resistance change of conventional amorphous ITO electrode. The twisting test revealed that the resistance of the PEDOT:PSS electrode began to increase at an angle of 36° due to delamination of the film from the PET substrate. Despite the high sheet resistance of the PEDOT:PSS electrode the flexible organic solar cells fabricated on the PEDOT:PSS electrode showed a power conversion efficiency of ∼2% (FF: 44.9%, V
o: 0.495
V and J
sc: 9.1
mA/cm
2), indicating the possibility of using gravure printed PEDOT:PSS as a flexible and transparent electrode for printing-based flexible organic solar cells.
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► Mechanical flexibility of gravure printed PEDOT:PSS investigated. ► Printed PEDOT:PSS electrodes showed outstanding flexibility in flexibility tests. ► Flexible OSCs with PEDOT:PSS electrode showed a PCE of ∼2%.
Printing techniques have been extensively used in the fabrication of organic electronic devices, such as light-emitting diodes and display backplanes. These techniques, in particular inkjet printing, ...are being employed for the localized dispensing of solutions containing biological molecules and cells, leading to the fabrication of bio-functional microarrays and biosensors. Here, we report the fabrication of an all-printed and flexible biosensor for antioxidants. Gold (Au) interdigitated electrodes (IDEs) with sub-100 µm features were directly inkjet-printed on plastic substrates using a nanoparticle-based ink. Conductivities as high as 5×10(6) S/m (12% of bulk Au) were attained after sintering was conducted at plastic-compatible 200 °C for 6 h. The enzyme Tyrosinase (Tyr) was used in the active layer of the biosensors, being innovatively deposited by large-area rotogravure printing. A tailor-made ink was studied, and the residual activity of the enzyme was 85% after additives incorporation, and 15.5% after gravure printing. Au IDEs were coated with gravure films of the Tyr-containing ink, and the biosensor was encapsulated with a cellulose acetate dip-coating film to avoid dissolution. The biosensor impedance magnitude increases linearly with the concentration of a model antioxidant, allowing for the construction of a calibration curve. Control experiments demonstrated the molecular recognition characteristic inferred by the enzyme. We found that the biosensor sensitivity and the limit of detection were, respectively, 5.68 Ω/µm and 200 µM. In conclusion, a disposable, light-weight, all-printed and flexible biosensor for antioxidants was successfully fabricated using fast and large-area printing techniques. This opens the door for the fabrication of technological products using roll-to-roll processes.
Gravure printing is a promising electronics printing technology for fabricating flexible-large area devices at high speeds. Ag nanowire (Ag NW)-based transparent conductive electrodes are excellent ...candidates for replacing indium thin oxide in flexible electronics and optical devices, which require the preparation of patterned structures. Here, the gravure printing processing parameters for applying Ag NW ink were investigated to produce large-area patterned transparent and uniform Ag NW lines on polyethylene terephthalate substrates. The ink transfer properties changed with the printing speed and pressure, as discussed, and these parameters modulated the electrical properties of the printed Ag NWs annealed at various temperatures. The importance of the rheological behavior of the ink, the printing speed, and the pressure was confirmed to understand the mechanism underlying Ag NW ink transfer. The printed line resistance for a 450μm of line width dried at 90°C was 32Ωmm−1 with a 95% of transmittance and a 100μm gap between the printed lines. The line width and spacing of the printed patterned Ag NWs may be controlled using the parameters examined here to optimize the application-specific device performance.
•Patterned Ag NW conductive lines were fabricated with the gravure printing method.•The parameters for printing were investigated.•The printed line width was 450μm and 100μm gap between the printed lines.•The resistance was 32Ωmm−1 and transmittance was 95%.•The parameters examined here used to optimize the application-specific device performance.
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