By the combination of the inkjet printing of PEDOT:PSS transfer template and selective transfer of silver nanowires (AgNW), AgNWs of customizable transparency can be patterned with high degree of freedom, without need of high equipment cost and complicated process. The AgNW‐transferred PEDOT:PSS transparent electrodes exhibit both great figure of merit and easily tunable optoelectronic properties. With maintaining the advantages and overcoming the issues of the AgNWs, the method developed by Yongtaek Hong and co‐workers in article number 2000042 can be applied to various flexible electronics.
Inkjet and transfer printing processes are combined to easily form patterned poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films as top anodes of all solution-processed inverted polymer light emitting diodes (PLEDs) on rigid glass and flexible plastic substrates. An adhesive PEDOT:PSS ink is formulated and fully customizable patterns are obtained using the inkjet printing process. In order to transfer the patterned PEDOT:PSS films, adhesion properties at interfaces during multistep transfer printing processes are carefully adjusted. The transferred PEDOT:PSS film on the plastic substrates shows not only a sheet resistance of 260.6 Ω/□ and a transmittance of 92.1% at 550 nm wavelength but also excellent mechanical flexibility. The PLEDs with spin-coated functional layers sandwiched between the transferred PEDOT:PSS top anodes and inkjet-printed Ag bottom cathodes are fabricated. The fabricated PLEDs on the plastic substrates show a high current efficiency of 10.4 cd A −1 and high mechanical stability. It is noted that because both Ag and PEDOT:PSS electrodes can be patterned with a high degree of freedom via the inkjet printing process, highly customizable PLEDs with various pattern sizes and shapes are demonstrated on the glass and plastic substrates. Finally, with all solution process, a 5 × 7 passive matrix PLED array is demonstrated.
A stretchable display would be the ultimate form factor for the next generation of displays beyond the curved and foldable configurations that have enabled the commercialization of deformable electronic applications. However, because conventional active devices are very brittle and vulnerable to mechanical deformation, appropriate strategies must be developed from the material and structural points of view to achieve the desired mechanical stretchability without compromising electrical properties. In this regard, remarkable findings and achievements in stretchable active materials, geometrical designs, and integration enabling technologies for various types of stretchable electronic elements have been actively reported. This review covers the recent developments in advanced materials and feasible strategies for the realization of stretchable electronic devices for stretchable displays. In particular, representative strain‐engineering technologies for stretchable substrates, electrodes, and active devices are introduced. Various state‐of‐the‐art stretchable active devices such as thin‐film transistors and electroluminescent devices that consist of stretchable matrix displays are also presented. Finally, the future perspectives and challenges for stretchable active displays are discussed.
Electronic skin (E-skin) based on tactile sensors has great significance in next-generation electronics such as biomedical application and artificial intelligence that requires interaction with humans. To mimic the properties of human skin, high flexibility, excellent sensing capability, and sufficient spatial resolution through high-level sensor integration are required. Here, we report a highly sensitive pressure sensor matrix based on a piezoresistive cellulose/ single-walled carbon nanotube-entangled fiber network, which forms its own porous structure enabling a superior pressure sensor with a high sensitivity (9.097 kPa −1 ), a fast response speed (<2 ms), and orders of magnitude detection range with a detection limit of 1 Pa. Furthermore, the remarkable device expandability based on the ease of patterning and scalability allows easy implementation of a largearea pressure sensor matrix which has 2304 (48 × 48) pixels. Combined with a real-time pressure distribution monitoring system, a flexible 3D touch sensor that simultaneously displays plane coordinates and pressure information and a scanning device that detects the morphology of the soft body 3D surface are successfully demonstrated.
The common, broad-spectrum herbicide diuron poses some risks to the environment due to its long persistence and high toxicity. Therefore, the effective monitoring of diuron residues will inform efforts to assess its impacts on ecosystems. In this study, we evaluated the toxicity targets of diuron in the model aquatic macrophyte Lemna minor at the physiological (growth and photosynthetic efficiency), biochemical (pigment biosynthesis and reactive oxygen species (ROS) levels), and molecular (rbcL transcript) levels. The toxicity of diuron was detectable after 48 h of exposure and the order of sensitivity of toxicity endpoints was gene transcription > maximum electron transport rate (ETRmax) > non-photochemical quenching (NPQ) > maximum quantum yield (Fv/Fm) > ROS > fresh weight > chlorophyll b > chlorophyll a > total frond area > carotenoids. Under diuron stress, pigment, ROS, and gene transcript levels increased while frond area, fresh weight, and photosynthesis (Fv/Fm and ETRmax) gradually decreased with the increasing duration of exposure. Notably, ROS levels, Fv/Fm, frond area, and fresh weight were highly correlated with diuron concentration. The growth endpoints (frond area and fresh weight) showed a strong negative correlation with ROS levels and a positive correlation with Fv/Fm and ETRmax. These findings shed light on the relative sensitivity of different endpoints for the assessment of diuron toxicity.
Investigation of the prebiotic activities of LM742 dextran produced by Leuconostoc mesenteroides SPCL742 in the aspect of the human gut microbial ecosystem focusing on microbiome and metabolome changes in in vitro colonic fermentation.
Fructooligosaccharides (FOS), Ad-fructooligosaccharides (Ad-FOS), resistant maltodextrin (RMD), and maltooligosaccharides (MOS) are commercially available prebiotic oligosaccharides. In this study, the effects of prebiotics on the human gut microbial ecosystem were evaluated using an in vitro gut model. FOS and Ad-FOS showed tolerance to digestion, whereas RMD and MOS showed moderate digestion by digestive enzymes. In in vitro fecal fermentation, Bifidobacterium spp. increased in the following order: FOS, Ad-FOS, MOS, and RMD, whereas Bacteroides spp. increased in RMD medium. Bacteroides xylanisolvens exhibited cross-feeding by enabling the growth of other beneficial bacteria during co-culture in RMD medium. In metabolome analysis, total short-chain fatty acids (SCFAs) were highly produced in the following order: RMD, FOS, MOS, and Ad-FOS; acetate in the order of FOS, MOS/RMD, and Ad-FOS; butyrate in the order of RMD, MOS, FOS, and Ad-FOS; and propionate only in RMD. In addition, the conversion of betaine to trimethylamine was rarely affected in the following order: MOS, RMD, FOS, and Ad-FOS. Lastly, the four oligosaccharides inhibited the adhesion of pathogenic Escherichia coli to human epithelial cells to a similar extent. The comparative analysis results obtained in this study will provide comprehensive information of these substances to manufacturers and customers.
The common duckweed (Lemna minor), a freshwater monocot that floats on the surfaces of slow-moving streams and ponds, is commonly used in toxicity testing. The novel Lemna root- regrowth test is a toxicity test performed in replicate test vessels (24-well plates), each containing 3 mL test solution and a 2–3 frond colony. Prior to exposure, roots are excised from the plant, and newly developed roots are measured after 3 days of regrowth. Compared to the three internationally standardized methods, this bioassay is faster (72 h), simpler, more convenient (requiring only a 3-mL) and cheaper. The sensitivity of root regrowth to 3,5-dichlorophenol was statistically the same as using the conventional ISO test method. The results of interlaboratory comparison tests conducted by 10 international institutes showed 21.3% repeatability and 27.2% reproducibility for CuSO4 and 21.28% repeatability and 18.6% reproducibility for wastewater. These validity criteria are well within the generally accepted levels of <30% to 40%, confirming that this test method is acceptable as a standardized biological test and can be used as a regulatory tool. The Lemna root regrowth test complements the lengthier conventional protocols and is suitable for rapid screening of wastewater and priority substances spikes in natural waters.
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