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Three new cationic cyclometalated iridium(III) complexes equipped with differently substituted benzo[

Background: Fine dust particles in the air travel into our body via the airway tract and cause severe respiratory diseases. Thus, the analysis of the effects of dust particles on the respiratory system has been receiving significant research interest. However, most studies on the toxicity of dust particles involve two-dimensional (2D) cell cultures, animal models, and epidemiology. Here, we inkjet-printed an three-dimensional (3D) alveolar barrier model to study how dust particles cause respiratory diseases. The three-layered in vitro model was exposed to A2 fine test dust with varying concentrations and exposure durations. Results: The results highlighted the destruction of the tissue architecture along with apoptosis in the bioprinted alveolar barrier. The damage at the cellular level induced an increase in the amount of pro-inflammatory cytokines secreted, followed by triggering of the signal transduction pathway and activation of transcription factors. As a consequence of the release of cytokines, the extracellular matrix was degraded, which led to the collapse of the cell structure, loss of cell polarity, and a decrease in the barrier tightness. Further, the pulmonary surfactant protein-related genes in the dust-treated alveolar tissue were investigated to evaluate the possible role of dust particles in pulmonary surfactant dysfunction. Conclusions: This study demonstrated the use of 3D-printed tissue model to evaluate the physiological impact of fine dust particles on cytotoxicity, alveolar barrier rigidity, and surfactant secretion of an alveolar barrier.

Digital inkjet printing (IJP) can greatly reduce the manufacturing cost and waste of flexible large-area electronics by adding micro-fine patterns onto plastic foils. Advanced system design using IJP has been limited by the lack of an electronic design automation (EDA) approach. An EDA approach based on a vector-based layout drawing requires parameterized IJP design rules. This study proposes a layout-to-bitmap (L2B) conversion procedure and line-based design rules that leverage the existing circuit layout EDA tools for advanced IJP designs. The L2B conversion is accomplished by optimizing the parameters of the horizontal and vertical lines by varying the drop spacings and platen temperatures. Next, the line-based layouts are converted to bitmap files which are used as IJP input data for printing multiple metal layers. This study systematically investigated the development of an IJP process employing Ag nanoparticles. The physical characteristics of the proposed process were evaluated based on theories concerning inkjet-printed bead formation. The design rules for fabricating printed thin-film transistor (TFT) circuits were documented. Documentation is the first step in creating an IJP process design kit for advanced electronics design. Using the optimized L2B conversion procedure and the design rules, a 10 × 10 array of printed organic TFTs was fabricated to demonstrate the reliability of the developed process. Additionally, the fabricated printed organic TFTs indicated that the proposed process could be extended to large-scale system designs.

Current organoid models are limited by their inability to mimic mature organ architecture and associated tissue microenvironments1,2. Here we create multilayer bladder ‘assembloids’ by reconstituting tissue stem cells with stromal components to represent an organized architecture with an epithelium surrounding stroma and an outer muscle layer. These assembloids exhibit characteristics of mature adult bladders in cell composition and gene expression at the single-cell transcriptome level, and recapitulate in vivo tissue dynamics of regenerative responses to injury. We also develop malignant counterpart tumour assembloids to recapitulate the in vivo pathophysiological features of urothelial carcinoma. Using the genetically manipulated tumour-assembloid platform, we identify tumoural FOXA1, induced by stromal bone morphogenetic protein (BMP), as a master pioneer factor that drives enhancer reprogramming for the determination of tumour phenotype, suggesting the importance of the FOXA1–BMP–hedgehog signalling feedback axis between tumour and stroma in the control of tumour plasticity. Multilayer 3D reconstitution of bladder stem cells with stromal cells enables recapitulation of the architecture and molecular functions of bladder tissue.

Seaweed beds are productive marine ecosystems; they provide habitat and serve as spawning, breeding, and feeding sites for fish and shellfish. Seaweed beds are declining with environmental change and pollution. In affected areas, including “urchin barrens” and those affected by “whitening events,” coralline algae appear, preventing the attachment of seaweed spores to the substrate. Many methods have been used to restore seaweed beds, such as those employing artificial reefs, seaweed ropes, spore bags, and transplanted cultures. However, such efforts are insufficient to overcome the disappearance of seaweed beds from coastal areas. This study examined the use of a new technique that involves encapsulating seaweed zygotes with polysaccharide-like alginates to improve their attachment using the brown alga Sargassum fulvellum, which plays an important role in seaweed forests. We tested the efficacy of encapsulated zygotes using polyvinyl chloride (PVC) panels and concrete bricks in the sea. In the laboratory, the germination percentage of encapsulated Sargassum zygotes was 70% ± 1.6%, similar to the rate of unencapsulated zygotes. In the field experiment, PVC panels and concrete bricks were coated with encapsulated and unencapsulated zygotes; the germination density and growth rates of encapsulated zygotes were 4 (p

The macroalgal forest is being transformed to barren ground in coastal areas due to climate change. Current recovery technologies are ineffective, and an understanding of the fouling mechanism of m...

In this review, recent advances in compact modeling of organic field-effect transistors (OFETs) are presented. Despite the inherent strength for printed flexible electronics and the extremely aggressive research conducted over more than three decades, the OFET technology still seems to remain at a relatively low technological readiness level. Among various possible reasons for that, the lack of a standard compact model, which effectively bridges the device- and system-level development, is clearly one of the most critical issues. This article broadly discusses the essential requirements, up-to-date progresses, and imminent challenges for the OFET compact device modeling toward a universal, physically valid, and applicable description of this fast-developing technology.

Organic thin-film transistors (TFTs) with an electrochemically functionalized sensing gate are promising platforms for wearable health-monitoring technologies because they are light, flexible, and cheap. Achieving both high sensitivity and low power is highly demanding for portable or wearable devices. In this work, we present flexible printed dual-gate (DG) organic TFTs operating in the subthreshold regime with ultralow power and high sensitivity. The subthreshold operation of the gate-modulated TFT-based sensors not only increases the sensitivity but also reduces the power consumption. The DG configuration has deeper depletion and stronger accumulation, thereby further making the subthreshold slope sharper. We integrate an enzymatic lactate-sensing extended-gate electrode into the printed DG TFT and achieve exceptionally high sensitivity (0.77) and ultralow static power consumption (10 nW). Our sensors are successfully demonstrated in physiological lactate monitoring with human saliva. The accuracy of the DG TFT sensing system is as good as that of a high-cost conventional assay. The developed platform can be readily extended to various materials and technologies for high performance wearable sensing applications.

Wearable pressure sensors have demonstrated great potential in detecting pulse pressure waves on the skin for the noninvasive and continuous diagnosis of cardiac conditions. However, difficulties lie in positioning conventional single-point sensors on an invisible arterial line, thereby preventing the detection of adequate signal amplitude for accurate pulse wave analysis. Herein, we introduce the spatiotemporal measurements of arterial pulse waves using wearable active-matrix pressure sensors to obtain optimal pulse waveforms. We fabricate thin-film transistor (TFT) arrays with high yield and uniformity using inkjet printing where array sizes can be customizable and integrate them with highly sensitive piezoresistive sheets. We maximize the pressure sensitivity (16.8 kPasup-1/sup) and achieve low power consumption (10sup1/supnW) simultaneously by strategically modulating the TFT operation voltage. The sensor array creates a spatiotemporal pulse wave map on the wrist. The map presents the positional dependence of pulse amplitudes, which allows the positioning of the arterial line to accurately extract the augmentation index, a parameter for assessing arterial stiffness. The device overcomes the positional inaccuracy of conventional single-point sensors, and therefore, it can be used for medical applications such as arterial catheter injection or the diagnosis of cardiovascular disease in daily life.

Pulmonary fibrosis (PF) is known as a chronic and irreversible disease characterized by excessive extracellular matrix accumulation and lung architecture changes. Large efforts have been made to develop prospective treatments and study the etiology of pulmonary fibrotic diseases utilizing animal models and spherical organoids. As part of these efforts, we created an all-inkjet-printed three-dimensional (3D) alveolar barrier model that can be used for anti-fibrotic drug discovery. Then, we developed a PF model by treating the 3D alveolar barrier with pro-fibrotic cytokine and confirmed that it is suitable for the fibrosis model by observing changes in structural deposition, pulmonary function, epithelial–mesenchymal transition, and fibrosis markers. The model was tested with two approved anti-fibrotic drugs, and we could observe that the symptoms in the disease model were alleviated. Consequently, structural abnormalities and changes in mRNA expression were found in the induced fibrosis model, which were shown to be recovered in all drug treatment groups. The all-inkjet-printed alveolar barrier model was reproducible for disease onset and therapeutic effects in the human body. This finding emphasized that the in vitro artificial tissue with faithfully implemented 3D microstructures using bioprinting technology may be employed as a novel testing platform and disease model to evaluate potential drug efficacy.

Aromatic soluble polyimides (PIs) have been widely used in organic field-effect transistors (OFETs) as gate dielectric layers due to their promising features such as outstanding chemical resistance, thermal stability, low-temperature processability, and mechanical flexibility. However, the molecular structures of soluble PIs on the electrical characteristics of OFETs are not yet fully understood. In this work, the material, dielectric, and electrical properties are evaluated to systematically investigate the chemical structure effect of aromatic dianhydride and diamine monomers on the device performance. Four soluble PIs based on 4,4'-(Hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 5-(2,5-Dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, in which the monomeric precursors contain different backbones, side groups, and linkages, were employed to compare the chemical structure impact. The dielectric properties, which significantly affect the charge transport and crystallinity of OSC thin films, clearly depended on the soluble PI types as well as the surface energy and the thermal stability. Furthermore, the electrical characteristic measurement and parameter extraction of OFETs based on TIPS-pentacene revealed that the 6FDA-based soluble PIs, which lead to high field-effect mobility, near-zero threshold electric field, and outstanding electrical stability under bias stress, are the most promising gate dielectric candidates. Finally, low-temperature solution-processed OFETs are successfully integrated with ultrathin flexible substrates, and they exhibit no significant electrical performance loss after mechanical flexibility tests. This work presents a step forward in the development of soluble PI gate dielectrics for flexible electronic devices with high device performance.

Organic thin-film transistor (TFT)-based pressure sensors have received huge attention for wearable electronic applications such as health monitoring and smart robotics. However, there still remains a challenge to achieve low power consumption and high sensitivity at the same time for the realization of truly wearable sensor systems where minimizing power consumption is significant because of limited battery run time. Here, we introduce a flexible pressure-sensitive contact transistor (PCT), a new type of pressure-sensing device based on organic TFTs for next-generation wearable electronic skin devices. The PCT consists of deformable S/D electrodes integrated on a staggered TFT. The deformable S/D electrodes were fabricated by embedding conducting single-walled carbon nanotubes on the surface of microstructured polydimethylsiloxane. Under pressure loads, the deformation of the electrodes on an organic semiconductor layer leads modulation of drain current from variation in both the channel geometry and contact resistance. By strategic subthreshold operation to minimize power consumption and increase the dominance of contact resistance because of gated Schottky contact, the PCT achieves both ultralow power consumption (order of 10

A dual-gate configuration has been introduced to organic thin-film transistors (TFTs) for full-depletion behavior to enhance the transconductance, subthreshold slope, and drain current on–off ratio. In this letter, we show how those dual-gate effects influence the static and dynamic responses of three-dimensional (3-D) complementary organic logic gates in comparison to their single-gate counterpart. For the comparative study, 3-D inverters and ring oscillators were fabricated by printing directly on plastic foil in both single- and dual-gate configurations. In the static inverter operation, the fully depleted characteristics of the dual-gate TFTs lead to an increase in voltage gain and a dramatic decrease in standby power consumption. In the dynamic ring oscillator operation, the two configurations have comparable gate delays because the use of an additional gate increases not only the drain current but also the load input gate capacitance. Our findings demonstrate the performance of an inverter that can represent the overall operation of complementary logic gates consisting of pull-up and pull-down networks, thereby providing significant insight into the printed organic TFT circuit design using dual gating effects.

This transaction proposes a symmetric bistaggered dual-gate organic thin-film transistor (TFT) to minimize the difference between the top and bottom channel current characteristics and demonstrates it through experiment and 2-D simulation. In dual-gate organic TFTs, asymmetric top and bottom channel currents are mainly a result of their asymmetric contact geometry. To address this geometric limitation, the contact electrodes were sandwiched between the two organic semiconductor layers to be placed in a staggered position to both top and bottom gates. Two-way current crowding at the bistaggered contact electrodes leads to high-charge injection efficiency in both channels.

Polyimide (PI) has been widely used as a gate dielectric due to its remarkable thermal stability, chemical resistance, and mechanical flexibility. However, the high processing temperature and high surface energy of PI gate dielectrics hinder the realization of flexible and reliable electronic applications with low-cost manufacturing. Here, a low-temperature solution-processed organic field-effect transistor (OFET) is successfully demonstrated using a fully imidized soluble PI gate dielectric. The low temperature processability of soluble PI gate dielectrics is confirmed by investigating the effect of annealing temperature on the dielectric properties and electrical characteristics. By blending 6,13-Bis(triisopropylsilylethynyl)pentacene with polystyrene, the reliability of OFET is considerably enhanced while maintaining high device performance. As a result, OFETs exhibit excellent flexibility and can be integrated with ultrathin parylene substrates without degrading device performance. This work presents the steps to develop flexible and reliable electronic applications with low-cost manufacturing.

For color-pure phosphorescence organic light emitting diodes (PHOLEDs), we synthesized the trifluoromethyl sulfonyl substituted ligand and two new blue Iridium complexes with perfluoro-sulfonyl group (SOCF3pic and SOCF3mpic). The both iridium complexes showed similar photophysical and thermal properties while the HOMO energy leves of two Iridium complexes slightly differnet to be −5.84 eV for SOCF3pic and −5.74 eV for SOCF3mpic, respectively. The device with the SOCF3mpic dopant exhibited higher device efficiencies of 7.17 cd/A and 3.7% compared to that with the SOCF3pic dopant (4.03 cd/A and 2.78%). Two-dimensional GIXD images of scattered X-ray intensity from surface to full depth for SOCF3pic-doped and SOCF3mpic-doped TCTA:4PTPS films were characterized for preferential orientation along the out-of-plane direction.

Direct printing of thin-film transistors has enormous potential for ubiquitous and lightweight wearable electronic applications. However, advances in printed integrated circuits remain very rare. Here we present a three-dimensional (3D) integration approach to achieve technology scaling in printed transistor density, analogous to Moore’s law driven by lithography, as well as enhancing device performance. To provide a proof of principle for the approach, we demonstrate the scalable 3D integration of dual-gate organic transistors on plastic foil by printing with high yield, uniformity, and year-long stability. In addition, the 3D stacking of three complementary transistors enables us to propose a programmable 3D logic array as a new route to design printed flexible digital circuitry essential for the emerging applications. The 3D monolithic integration strategy demonstrated here is applicable to other emerging printable materials, such as carbon nanotubes, oxide semiconductors and 2D semiconducting materials., The scalability of printable integrated circuits is lagging far behind that of conventional silicon-based technologies. Here, Kwon et al. show a three-dimensional integration approach by stacking printeddual-gate organic transistors on plastic foils with a density of 60 transistors per centimeter square.

A double-layer gate dielectric has been used to overcome the drawbacks of organic field-effect transistors with a single-layer gate dielectric. However, the double-layered dielectrics require additional fabrication processes, resulting in increased manufacturing cost and complexity. Here, we present parylene copolymer gate dielectrics fabricated by in situ codeposition of two different families, parylene C and parylene F while maintaining double-layer structures. The effect of the copolymer dielectric on device performance is systematically investigated by evaluating dielectric properties and electrical characteristics. The results show that an organic transistor with a codeposited parylene dielectric exhibits high performance and stable operation without increasing the manufacturing complexity.

Correct parameterization of the Gaussian disorder model (GDM) on spatially random sites is necessary for a complete description of charge transport in disordered materials and concomitant device characteristics. Because the GDM on spatially random sites considers both energetic and spatial disorder, it is superior to the GDM on a cubic lattice. However, analytical arguments and experimental evidence are still lacking for correct parameterization of the model over a wide range of model parameters, energetic and spatial disorder, and electric fields. We show that the model requires a set of parameters to correctly account for high mobility and its charge density dependence, and we develop such a model. The model is implemented in a numerical simulation tool for comparison with the measured device characteristics. Accurate agreement with experimental data, particularly with the high mobility values in organic field-effect transistors, is achieved throughout a wide range of temperature by adjusting both the localization length and the attempt-to-escape frequency.

Direct printing of thin-film transistors has enormous potential for ubiquitous and lightweight wearable electronic applications. However, advances in printed integrated circuits remain very rare. Here we introduce a three-dimensional (3D) integration approach to achieve technology scaling in printed transistor density, analogous to Moore’s law driven by lithography. Recent progress on design and fabrication of 3D-integrated organic printed transistors and circuits is reviewed in the first part of the chapter. We then discuss 3D-printed integrated circuits (ICs) development process with a focus on modeling and simulation of the 3D devices and circuits, which is essential to transfer printed electronics technology from lab to fab manufacturing. This chapter provides insights into the realization of functional organic 3D ICs and unconventional electronics applications.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Intense seaweed grazing by sea urchins has destroyed kelp forests and accelerated the transformation of these forests into barren areas known as urchin barrens. Once the sea urchins occupy the barren ground, it becomes more challenging to restore the kelp forests. Although phlorotannin, a primary herbivore defense chemical secreted by kelp, has been reported to discourage feeding activities of marine herbivores but the direct application of naturally extracted phlorotannin does not effectively repel sea urchins. In this study, we applied a simple and green Tannin-Fe

Quantification of intratumoral heterogeneity is essential for designing effective therapeutic strategies in the age of personalized medicine. In this study, we used a piezoelectric inkjet printer to enable analysis of intratumoral heterogeneity in a bladder cancer for the first time. Patient-derived tumor organoids were dissociated into single cell suspension and used as a bioink. The individual cells were precisely allocated into a microwell plate by drop-on-demand inkjet printing without any additive or treatment, followed by culturing into organoids for further analysis. The sizes and morphologies of the organoids were observed, so as the expression of proliferation and apoptotic markers. The tumor organoids also showed heterogeneous responses against chemotherapeutic agent. Further, we quantified mRNA expression levels of representative luminal and basal genes in both type of tumor organoids. These results verify the heterogeneous expression of various genes among individual organoids. This study demonstrates that the fully automated inkjet printing technique can be used as an effective tool to sort cells for evaluating intratumoral heterogeneity.

We synthesized the heptaflurosulfonyl-substituted iridium complexes with SOCF7pic, SOCF7mpic, and SOCF7taz as a dopants for blue phosphorescent organic light emitting diodes (PHOLEDs). The ...

Anodization of gate metals can form thin and robust oxide dielectrics of low-voltage-driven organic thin-film transistors (TFTs) for low-cost, flexible electronics. However, anodic oxide dielectrics have rarely been applied to circuit fabrication with complex layouts because separate gate electrode islands cannot be anodized at the same time. To overcome this limitation, we devise a method to simultaneously anodize multiple aluminum gate islands using removable interconnects. The anodic oxide properties, including dielectric constant, film thickness, and leakage current, were thoroughly investigated by varying anodization voltages from 5 to 50 V and a self-assembled monolayer treatment. By printing p-type polymer ink on top of the pattern-grown anodic oxide dielectrics, p-type organic TFTs were fabricated on a 2-μm-thick Parylene substrate. The printed TFTs exhibited subthreshold swing of 200 mV·dec−1, carrier mobility of 0.3 cm2 V−1 s−1, and threshold voltage of 0.17 V on average. Even when the substrate film was crumpled, the TFT characteristics did not substantially changed. Finally, a 3 V differential amplifier with multiple gate islands was successfully demonstrated. These findings suggest that high-quality anodic metal oxide films, when fully incorporated into a low-cost, large-area manufacturing process, can be applied to the fabrication of complex, low-voltage-driven TFT circuits on flexible substrates.

We demonstrate high-performance and stable organic field-effect transistors (OFETs) using parylene-based double-layer gate dielectrics (DLGDs). DLGDs, consisting of parylene C as the upper layer and F as the lower layer, are designed to simultaneously provide good interface and bulk gate dielectric properties by exploiting the advantages of each gate dielectric. The structural effects of DLGDs are systematically investigated by evaluating the electrical characteristics and dielectric properties while varying the thickness ratio of each gate dielectric. The OFET with the optimized DLGD exhibits high performance and operational stability. This systematic approach will be useful for realizing practical electronic applications.

Vacuum-processed diphenylbis(3-(pyridine-2-yl)phenyl)silane (2PTPS), diphenylbis(3-(pyridine-3-yl)phenyl)silane (3PTPS), and diphenylbis(3-(pyridine-4-yl)phenyl)silane (4PTPS) have been used as electron-transporting host materials combined with tris(4-carbazoyl-9-ylphenyl)amine (TCTA) as the hole-transporting host, which induce balanced charge carrier transport for high-efficiency phosphorescent organic light-emitting diodes. The 4PTPS-based organic light-emitting diodes with tris[2-phenylpyridinato-C2,N]iridium(III) [Ir(ppy)3] dopant showed highest current efficiency and external quantum efficiency of 53.54 cd/A and 15.61%, compared to 2PTPS (40.75 cd/A, 11.84%) and 3PTPS (29.35 cd/A, 8.54%). These results were attributed to the well-aligned structure with preferential horizontal orientation of the emitting material layer by the diffraction intensity distribution as a function of azimuthal angle in two-dimensional grazing incidence X-ray diffraction analysis. The molecular orientation of TCTA:4PTPS material with a narrow azimuthal intensity distribution had better priority to the horizontal direction than the other TCTA:2PTPS and TCTA:3PTPS materials, which is related to the charge transport as well as the device efficiency. We found that the preferential horizontal orientation of the co-host material with a balanced charge carrier was not affected by Ir(ppy)3 dopant with a homoleptic structure and bis-[2-(4,6-difluorophenyl)pyridinato-N,C2](picolinato)iridium [Firpic] dopant with a heteroleptic structure in the co-host/dopant system.

Poly(4-vinylphenol) (PVP) is a promising gate dielectric material for organic field-effect transistors (OFETs) and circuits fabricated on plastic substrates. Thermal cross-linking of PVP with a cross-linker, such as poly(melamine- co-formaldehyde) methylated (PMF), at a high temperature (above 170 °C) is widely considered an effective method to remove residual hydroxyl groups that induce polarization effects in the dielectric bulk. However, the threshold voltage shift in transfer characteristics is still observed for an OFET with a PVP-PMF dielectric when it is operated at a slow gate voltage sweep rate. The present study examines the cause of the undesired hysteresis phenomenon and suggests a route to enable a reliable operation. We systematically investigate the effect of the PVP-PMF weight ratio and their annealing temperature on the transfer characteristics of OFETs. We discover that the size of the hysteresis is closely related to the concentration of nonhydrogen-bonded hydroxyl groups in the dielectric bulk and this is controlled by the weight ratio. At a ratio of 0.5:1, a complete elimination of hysteresis was observed irrespective of the annealing temperature. We finally demonstrate a highly reliable operation of small-molecule-based OFETs fabricated on a plastic substrate at a low temperature.

Research on near-infrared- (NIR-) emitting materials and devices has been propelled by fundamental and practical application demands surrounding information-secured devices and night-vision displays to phototherapy and civilian medical diagnostics. However, the development of stable, highly efficient, low-cost NIR-emitting luminophores is still a formidable challenge owing to the vulnerability of the small emissive bandgap toward several nonradiative decay pathways, including the overlapping of ground- and excited-state vibrational energies and high-frequency oscillators. Suitable structural designs are mandatory for producing an intense NIR emission. Herein, we developed a series of deep-red to NIR emissive iridium(III) complexes (Ir1–Ir4) to explore the effects of electron-donating and electron-withdrawing substituents anchored on the quinoline moiety of (benzo[b]thiophen-2-yl)quinoline cyclometalating ligands. These substituents help engineer the emission bandgap systematically from the deep-red to the NIR region while altering the emission efficiencies drastically. Single-crystal X-ray structures authenticated the exact coordination geometry and intermolecular interactions in these new compounds. We also performed an in-depth and comparative photophysical study in the solution, neat powder, doped polymer film, and freeze matrix at 77 K states to investigate the effects of substitution on the excited-state properties. These studies were conducted in conjunction with density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. Most importantly, the –CH3 substituted Ir1, unsubstituted Ir2, and –CF3 substituted complex (Ir4) were promising novel compounds with bright phosphorescence quantum efficiency in doped polymer films. Using these novel molecules, deep-red to NIR emissive organic light-emitting diodes (OLEDs) were fabricated using a solution-processable method. The unoptimized device exhibited maximum external quantum efficiency (EQE) values of 2.05% and 2.11% for Ir1 and Ir2, respectively.

We study the influence of spatial heterogeneity on the antiviral activity of mouse embryonic fibroblasts (MEF) infected with influenza A. MEF of type Ube1L−/− are composed of two distinct sub-populations, the strong type that sustains a strong viral infection and the weak type, sustaining a weak viral load. We present new data on the virus load infection of Ube1L−/−, which have been micro-printed in a checker board pattern of different sizes of the inner squares. Surprisingly, the total viral load at one day after inoculation significantly depends on the sizes of the inner squares. We explain this observation by using a reaction diffusion model and we show that mathematical homogenization can explain the observed inhomogeneities. If the individual patches are large, then the growth rate and the carrying capacity will be the arithmetic means of the patches. For finer and finer patches the average growth rate is still the arithmetic mean, however, the carrying capacity uses the harmonic mean. While fitting the PDE to the experimental data, we also predict that a discrepancy in virus load would be unobservable after only half a day. Furthermore, we predict the viral load in different inner squares that had not been measured in our experiment and the travelling distance the virions can reach after one day.

Fabrication of human skin equivalents is one of the challenging issues in many areas, including biology, medicine, cosmetics, and ethics. However, conventional skin models have problems with their quality, reproducibility, and production methods. One effective solution for this issue is bioprinting, which solves the limitations of conventional manufacturing. In this study, we tried to fabricate a skin equivalent with a layered structure by coupling two printing techniques. We performed pneumatic microextrusion technique to generate a stable dermal layer composed of collagen and primary human dermal fibroblasts. This was followed by piezoelectric inkjet printing of primary human epidermal keratinocytes to apply an epidermal layer with high viability and uniformity. Shear viscosity of collagen ink containing dermal fibroblasts was measured to optimize printability. The epidermal bioink, composed of only media and epidermal keratinocytes, was also examined under various conditions to improve the inkjet printing process. The culture conditions, including the bioink and culture media, were also validated in terms of cell viability. After approximately 2 weeks of submerged dermal culture and more than 2 weeks of air–liquid interface culture, we performed histological staining and immunostaining to assess our printed skin models. This hybrid process could be used to implement a simple and reproducible printing method for generating multilayered skin models and also make it possible to regulate epidermal layer by adjusting inkjet printing parameters. We expect that this method would provide additional varieties of skin models with further investigation.