Transparent Micromesh Patterned OLED Fabricated Using the In-Situ Deposition Process of an Ultrathin Mg:Ag Interconnection Layer

TOLEDs (transparent organic light-emitting diodes) have emerged as one of the most promising ways to implement next-generation display form factors. Transparent OLEDs can provide new added value to HMDs (head mounted displays), automobiles, smart windows, mobile devices, TVs, etc. through their transparency, which allows objects to be seen from the other side. However, previous approaches using metal thin films have faced limitations in attempting to achieve high transmittance. In this study, TOLEDs were designed using a new cathode structure consisting of an interlayer and an emission pattern layer, and these layers connect the light-emitting part and the nonemitting part by themselves without requiring the use of another interconnection layer. This structure, which was intended to improve transmittance, was implemented by applying an in situ evaporation process that adds only one shadow mask without the need to use any difficult methods. Through this process, the optimal condition was found when the light-emitting part was deposited in a mesh pattern with a length of 120 μm and a width of 80 μm, in which case the transmittance of the TOLED improved by up to 83% while maintaining electro-optical performance. It was also confirmed that this new structure can be applied to flexible devices.

Highly Transparent Red Organic Light-Emitting Diodes with AZO/Ag/AZO Multilayer Electrode

Free-form factor optoelectronics is becoming more important for various applications. Specifically, flexible and transparent optoelectronics offers the potential to be adopted in wearable devices in displays, solar cells, or biomedical applications. However, current transparent electrodes are limited in conductivity and flexibility. This study aims to address these challenges and explore potential solutions. For the next-generation transparent conductive electrode, Al-doped zinc oxide (AZO) and silver (AZO/Ag/AZO) deposited by in-line magnetron sputtering without thermal treatment was investigated, and this transparent electrode was used as a transparent organic light-emitting diode (OLED) anode to maximize the transparency characteristics. The experiment and simulation involved adjusting the thickness of Ag and AZO and OLED structure to enhance the transmittance and device performance. The AZO/Ag/AZO with Ag of 12 nm and AZO of 32 nm thickness achieved the results of the highest figure of merit (FOM) (Φ550 = 4.65 mΩ-1) and lowest roughness. The full structure of transparent OLED (TrOLED) with AZO/Ag/AZO anode and Mg:Ag cathode reached 64.84% transmittance at 550 nm, and 300 cd/m2 at about 4 V. The results demonstrate the feasibility of adopting flexible substrates, such as PET, without the need for thermal treatment. This research provides valuable insights into the development of transparent and flexible electronic devices.

355 nm Nanosecond Ultraviolet Pulsed Laser Annealing Effects on Amorphous In-Ga-ZnO Thin Film Transistors

Bottom-gate thin-film transistors (TFTs) with n-type amorphous indium-gallium-zinc oxide (a-IGZO) active channels and indium-tin oxide (ITO) source/drain electrodes were fabricated. Then, an ultraviolet (UV) nanosecond pulsed laser with a wavelength of 355 nm was scanned to locally anneal the active channel at various laser powers. After laser annealing, negative shifts in the threshold voltages and enhanced on-currents were observed at laser powers ranging from 54 to 120 mW. The energy band gap and work function of a-IGZO extracted from the transmittance and ultraviolet photoelectron spectroscopy (UPS) measurement data confirm that different energy band structures for the ITO electrode/a-IGZO channel were established depending on the laser annealing conditions. Based on these observations, the electron injection mechanism from ITO electrodes to a-IGZO channels was analyzed. The results show that the selective laser annealing process can improve the electrical performance of the a-IGZO TFTs without any thermal damage to the substrate.

Wearable and Wavelength-Tunable Near-Infrared Organic Light-Emitting Diodes for Biomedical Applications

Near-infrared organic light-emitting diodes (NIR OLEDs) have significant potential for wearable phototherapeutic applications because of the unique properties of the OLEDs, including their free-form electronics and the excellent biomedical effects of NIR emission. In spite of their tremendous promise, given that the majority of NIR OLEDs in previous research have relied on the utilization of an intrinsically brittle indium tin oxide (ITO) electrode, their practicality in the field of wearable electronics is inherently constrained. Here, we report wearable and wavelength-tunable NIR OLEDs that employ a high-performance NIR emitter and an innovative architecture by replacing the ITO with a silver (Ag) electrode. The NIR OLEDs permit wavelength tuning of emissions from 700 to 800 nm and afford stable operation even under repeated bending conditions. The NIR OLEDs provide a lowered device temperature of 37.5 °C even during continuous operation under several emission intensities. In vitro experiments were performed with freshly fabricated NIR OLEDs. The outcomes were evaluated against experimental results performed using the same procedure utilizing blue, green, and red OLEDs. When exposed to NIR light irradiation, the promoting effect of cell proliferation surpassed the proliferative responses observed under the influence of visible light irradiation. The proliferation effect of human hair follicle dermal papilla cells is clearly related to the irradiation wavelength and time, thus underscoring the potential of wavelength-tunable NIR OLEDs for efficacious phototherapy. This work will open novel avenues for wearable NIR OLEDs in the field of biomedical application.

Analyses of All Small Molecule-Based Pentacene/C60 Organic Photodiodes Using Vacuum Evaporation Method

The vacuum process using small molecule-based organic materials to make organic photodiodes (OPDIs) will provide many promising features, such as well-defined molecular structure, large scalability, process repeatability, and good compatibility for CMOS integration, compared to the widely used Solution process. We present the performance of planar heterojunction OPDIs based on pentacene as the electron donor and C60 as the electron acceptor. In these devices, MoO3 and BCP interfacial layers were interlaced between the electrodes and the active layer as the electron- and hole-blocking layer, respectively. Typically, BCP played a good role in suppressing the dark current by two orders higher than that without that layer. These devices showed a significant dependence of the performance on the thickness of the pentacene. In particular, with the pentacene thickness of 25 nm, an external quantum efficiency at the 360 nm wavelength according to the peak absorption of C60 was enhanced by 1.5 times due to a cavity effect, compared to that of the non-cavity device. This work shows the importance of a vacuum processing approach based on small molecules for OPDIs, and the possibility of improving the performance via the optimization of the device architecture.

Study of mechanical degradation of freestanding ALD Al2O3 by a hygrothermal environment and a facile protective method for environmentally stable Al2O3: toward highly reliable wearable OLEDs

Al2O3 deposited via atomic layer deposition (ALD) has been used as an insulating and barrier film for thin-film transistors, organic electronics, and microelectromechanical systems. However, ALD Al2O3 films are easily degraded by hydrolysis under harsh hygrothermal conditions, owing to their poor environmental stability. In this study, the mechanical properties and water-vapor transmission rate (WVTR) of environmentally degraded Al2O3 films were investigated by varying the temperature and relative humidity (RH). The hygrothermal environment led to surface and pinhole-concentrated degradation based on aluminum hydroxide, which caused an increased WVTR and reduced elongation of the films in harsher environments. In particular, the elongation of the degraded Al2O3 films was reduced to 0.3%, which is one-third of that of as-deposited Al2O3, and their WVTR increased on the order of 10-1 g m-2 day-1, which is more than 1000 times that of as-deposited Al2O3. Therefore, we introduced a functional silane-based inorganic-organic hybrid layer (silamer) onto the Al2O3 films to improve their environmental stability. The silamer helped preserve the characteristics of Al2O3 films by forming a strong and continuous aluminate phase of Al-O-Si at their interface in hygrothermal environments. Furthermore, the silamer-capped Al2O3 was shown to be an environmentally stable encapsulation for application in wearable organic devices.

Highly Air-Stable, Flexible, and Water-Resistive 2D Titanium Carbide MXene-Based RGB Organic Light-Emitting Diode Displays for Transparent Free-Form Electronics

Flexible see-through displays are considered to be the next generation smart display, providing improved information flow, safety, situational awareness, and overall user experience in smart windows, automotive displays, glass-form biomedical displays, and augmented reality systems. 2D titanium carbides (MXenes) are promising material as electrodes of the transparent and flexible displays due to their high transparency, metallic conductivity, and flexibility. However, current MXene-based devices have insufficient air stability and lack engineering schemes to develop matrix-addressable display forms with sufficient pixels to display information. Here, we develop an ultraflexible and environmentally stable MXene-based organic light-emitting diode (OLED) display by combining high performance MXene electrodes, flexible OLEDs, and ultrathin and functional encapsulation systems. The MXene material was synthesized and used to fabricate a highly reliable MXene-based OLED that can stably operate in air condition for over 2000 h, endure repetitive bending deformation of 1.5 mm radius, and maintain environmental stability for 6 h when exposed to wet surroundings. The RGB MXene-based OLEDs were fabricated, (1691 cd m^-2 at 40.4 mA cm^-2 for red, 1377 cd m^-2 at 4.26 mA cm^-2 for green, and 1475 cd m^-2 at 18.6 mA cm^-2 for blue) and a matrix-addressable transparent OLED display was demonstrated that could display letters and shapes.

Fiber-based quantum-dot pulse oximetry for wearable health monitoring with high wavelength selectivity and photoplethysmogram sensitivity

Increasing demand for real-time healthcare monitoring is leading to advances in thin and flexible optoelectronic device-based wearable pulse oximetry. Most previous studies have used OLEDs for this purpose, but did not consider the side effects of broad full-width half-maximum (FWHM) characteristics and single substrates. In this study, we performed SpO₂ measurement using a fiber-based quantum-dot pulse oximetry (FQPO) system capable of mass production with a transferable encapsulation technique, and a narrow FWHM of about 30 nm. Based on analyses we determined that uniform angular narrow FWHM-based light sources are important for accurate SpO₂ measurements through multi-layer structures and human skin tissues. The FQPO was shown to have improved photoplethysmogram (PPG) signal sensitivity with no waveguide-mode noise signal, as is typically generated when using a single substrate (30-50%). We successfully demonstrate improved SpO₂ measurement accuracy as well as all-in-one clothing-type pulse oximetry with FQPO.

Rapid photonic curing effects of xenon flash lamp on ITO-Ag-ITO multilayer electrodes for high throughput transparent electronics

High-throughput transparent and flexible electronics are essential technologies for next-generation displays, semiconductors, and wearable bio-medical applications. However, to manufacture a high-quality transparent and flexible electrode, conventional annealing processes generally require 5 min or more at a high temperature condition of 300 °C or higher. This high thermal budget condition is not only difficult to apply to general polymer-based flexible substrates, but also results in low-throughput. Here, we report a high-quality transparent electrode produced with an extremely low thermal budget using Xe-flash lamp rapid photonic curing. Photonic curing is an extremely short time (~ μs) process, making it possible to induce an annealing effect of over 800 °C. The photonic curing effect was optimized by selecting the appropriate power density, the irradiation energy of the Xe-flash lamp, and Ag layer thickness. Rapid photonic curing produced an ITO-Ag-ITO electrode with a low sheet resistance of 6.5 ohm/sq, with a high luminous transmittance of 92.34%. The low thermal budget characteristics of the rapid photonic curing technology make it suitable for high-quality transparent electronics and high-throughput processes such as roll-to-roll.

Wearable Photomedicine for Neonatal Jaundice Treatment Using Blue Organic Light-Emitting Diodes (OLEDs): Toward Textile-Based Wearable Phototherapeutics

Neonatal jaundice is a very common disease in newborns and can lead to brain damage or death in severe cases. Phototherapy with light-emitting diode (LED) arrays is widely used as the easiest and fastest way to relieve jaundice in newborns, but it has distinct disadvantages such as loss of water in the patient, damage to the retina, and separation from parents. In this paper, a novel light source-based phototherapy for neonatal jaundice is proposed using a textile-based wearable organic light-emitting diode (OLED) platform that can move flexibly and conform to the curvature of the human body. The soft and flexible textile-based blue OLED platform is designed to have a peak wavelength of 470 nm, suitable for jaundice treatment, and shows performance (>20 µW cm^-2 nm^{- 1} ) suitable for intensive jaundice treatment even at low voltage (<4.0 V). The textile-based OLEDs fabricated in this study exhibit an operating reliability of over 100 h and low-temperature operation (<35 °C). The results of an in vitro jaundice treatment test using a large-area blue OLED confirm that the bilirubin level decreases to 12 mg dL^-1 with 3 h of OLED irradiation.

A Review of Various Attempts on Multi-Functional Encapsulation Technologies for the Reliability of OLEDs

As the demand for flexible organic light-emitting diodes (OLEDs) grows beyond that for rigid OLEDs, various elements of OLEDs, such as thin-film transistors, electrodes, thin-film encapsulations (TFEs), and touch screen panels, have been developed to overcome OLEDs' physical and chemical limitations through material and structural design. In particular, TFEs, which protect OLEDs from the external environment, including reactive gases, heat, sunlight, dust, and particles, have technical difficulties to be solved. This review covers various encapsulation technologies that have been developed with the advent of atomic layer deposition (ALD) technology for highly reliable OLEDs, in which solutions to existing technical difficulties in flexible encapsulations are proposed. However, as the conventional encapsulation technologies did not show technological differentiation because researchers have focused only on improving their barrier performance by increasing their thickness and the number of pairs, OLEDs are inevitably vulnerable to environmental degradation induced by ultraviolet (UV) light, heat, and barrier film corrosion. Therefore, research on multi-functional encapsulation technology customized for display applications has been conducted. Many research groups have created functional TFEs by applying nanolaminates, optical Bragg mirrors, and interfacial engineering between layers. As transparent, wearable, and stretchable OLEDs will be actively commercialized beyond flexible OLEDs in the future, customized encapsulation considering the characteristics of the display will be a key technology that guarantees the reliability of the display and accelerates the realization of advanced displays.

Cell proliferation effect of deep-penetrating microcavity tandem NIR OLEDs with therapeutic trend analysis

Long wavelengths that can deeply penetrate into human skin are required to maximize therapeutic effects. Hence, various studies on near-infrared organic light-emitting diodes (NIR OLEDs) have been conducted, and they have been applied in numerous fields. This paper presents a microcavity tandem NIR OLED with narrow full-width half-maximum (FWHM) (34 nm), high radiant emittance (> 5 mW/cm²) and external quantum efficiency (EQE) (19.17%). Only a few papers have reported on biomedical applications using the entire wavelength range of the visible and NIR regions. In particular, no biomedical application studies have been reported in the full wavelength region using OLEDs. Therefore, it is worth researching the therapeutic effects of using OLED, a next-generation light source, and analyzing trends for cell proliferation effects. Cell proliferation effects were observed in certain wavelength regions when B, G, R, and NIR OLEDs were used to irradiate human fibroblasts. The results of an in-vitro experiment indicated that the overall tendency of wavelengths is similar to that of the cytochrome c oxidase absorption spectrum of human fibroblasts. This is the first paper to report trends in the cell proliferation effects in all wavelength regions using OLEDs.

Effect of synthetic cholesterol (Synthechol) supplementation in an egg yolk-free extender on dog sperm cryopreservation

BACKGROUND

SyntheChol is a new synthetic, non-animal-derived cholesterol that is easily dissolved in ethanol, ready to use, and behaves in a similar way as natural cholesterol. Therefore, it could be used as a substitute of natural cholesterol in dog sperm freezing extender.

OBJECTIVE

To evaluate the effect of supplementing an egg yolk-free (EY-free) extender with synthetic cholesterol (SyntheChol) on cryopreserved dog sperm.

MATERIALS AND METHODS

Spermatozoa (1 × 10⁸ sperm/mL) were suspended in EY-free extender supplemented with 0 % (control), 0.25, 0.5, 1, 2, 4, or 6 % SyntheChol (Extender 1), cooled at 4 degree C for 1 h, and diluted (1:1, v/v) with Extender 1 containing 1 M glycerol. The spermatozoa were then cooled to 4 degree C for 30 min. Sperm-containing straws were frozen using LN2 vapor. Sperm motility (computer-assisted sperm analysis, CASA), sperm membrane integrity (SYBR-14 and PI staining), and acrosome integrity (FITC-PSA) were evaluated after thawing. Thereafter, optimal concentrations were determined (0.25, 0.5, 1, or 2 %) and used to evaluate reactive oxygen species (ROS) generation, apoptosis, and the gene expression of motility-related sperm mitochondria-associated cysteine-rich protein, apoptosis-related B-cell lymphoma 2 (BCL2), and BCL2-associated X protein (BAX) in cryopreserved sperm.

RESULTS

Sperm progressive motility, membrane integrity, and acrosome integrity were markedly greater in the SyntheChol-supplemented groups (0.25, 0.5, 1, or 2 %) than in the control group. Only BAX expression was significantly reduced in the SyntheChol groups (0.25, 1, or 2 %) compared with the control group. However, there were no significant effects on the ROS generation or apoptosis index.

CONCLUSION

SyntheChol (0.25, 1, or 2 %) proved to be effective in reducing the BAX gene expression level and improving sperm progressive motility, and membrane and acrosome integrity. doi.org/10.54680/fr22210110212.

Cryopreservation of Dog Spermatozoa Using Essential and Non-Essential Amino Acids Solutions in An Egg Yolk-Free Polyvinyl Alcohol Extender

BACKGROUND

Amino acids (AAs) have been indicated to have cryoprotective and antioxidative effects on sperm freezing using egg yolk (EY)-based extender. However, EY-based extender is difficult to be standardized for the effect of amino acids because the EY composition varies with the animal's diet.

OBJECTIVE

To test the effect of AAs in EY-free polyvinyl alcohol (EY-free PVA) extender and develop a chemically defined extender for dog sperm cryopreservation.

MATERIALS AND METHODS

In the first experiment (E1), dog spermatozoa (1ｘ10⁸ sperms/mL) were frozen with EY-free PVA extender without AAs or supplemented with essential (EAAs, 50 x: 1, 2, 4 %) or non-essential amino acids (NEAAs, 100 x: 1, 2, 4 %). In the second experiment (E2), spermatozoa were frozen with EY-free PVA extender supplemented with 0, 0.5, 1 or 2 % of an EAA-NEAA mixture. Motility, viability and acrosome integrity were evaluated after thawing in E1 and E2. In the third experiment (E3), spermatozoa were frozen using an extender supplemented with 2 % EAAs, 2 % NEAAs or a 0.5 % EAA-NEAA mixture. Reactive oxygen species (ROS) and phosphatidylserine (PS) translocation were assessed. Expression of genes for motility-related sperm mitochondrial-associated cysteine-rich protein (SMCP), apoptosis-related B-cell lymphoma 2 (BCL2) and BCL2 associated X protein (BAX) was measured.

RESULTS

Addition of EAAs, NEAAs or an EAA-NEAA mixture to EY-free PVA extender significantly increased sperm motility without affecting viability. Only 1 % NEAAs significantly increased the acrosome membrane. EAA-NEAA mixture (0.5 %) significantly increased SMCP, BCL2 and BAX expression compared to the control group without significant effect on PS translocation or ROS.

CONCLUSION

EAAs and NEAAs addition in EY-free PVA extender improved sperm motility, with limited effect on acrosome integrity and gene expression of SMCP, BCL2 and BAX during dog sperm cryopreservation.

Parallel-Stacked Flexible Organic Light-Emitting Diodes for Wearable Photodynamic Therapeutics and Color-Tunable Optoelectronics

Deformable organic light-emitting diode (OLED) based optoelectronic devices hold promise for various wearable applications including biomedical systems and displays, but current OLED technologies require high voltage and lack the power needed for wearable photodynamic therapy (PDT) applications and wearable displays. This paper presents a parallel-stacked OLED (PAOLED) with high power, more than 100 mW/cm², at low voltage (<8 V). The current dispersion ratio can be tuned by optimizing the structure of the individual OLEDs stacked to create the PAOLED, allowing control of the PAOLED's wavelength shapes, current efficiency, and power. In this study, a fabricated PAOLED operated reliably for 100 h at a high power of 35 mW/cm². Confirming its potential application to PDT, the measured singlet oxygen generation ratio of the PAOLED was found to be 3.8 times higher than the reference OLED. The high-power PAOLED achieved a 24% reduction in melanoma cancer cell viability after a short (0.5 h) irradiation. In addition, a white light PAOLED with color tuning was realized through OLED color combination, and a high brightness of over 30 000 cd/m² was realized, below 8.5 V. In conclusion, the PAOLED was demonstrated to be suitable for a variety of low-voltage, high-power wearable optoelectronic applications.

Two-Dimensionally Stretchable Organic Light-Emitting Diode with Elastic Pillar Arrays for Stress Relief

Recent advanced studies on flexible and stretchable electronic devices and optoelectronics have made possible a variety of soft and more functional electronic devices. With consumer demand for highly functional or free-form displays, high flexibility and stretchability in light-emitting devices are needed. Herein, we developed a unique structure of stretchable substrates with pillar arrays to reduce the stress on the active area of devices when strain is applied. We confirmed the advantages of the produced structures using mechanical simulation tools and determined that the structures effectively lessen the applied stress of interconnection as well as the active area in a stretched state. With this stress-relief stretchable substrate, we realized stretchable OLEDs that are compliant and maintain their performance under high strain deformation. Also, devices can be stretched in the biaxis, which is superior to only one-directional stretchable electronics; as such, devices can be used in practical applications like wearable electronics and health monitoring systems. We propose, for the first time, stretchable OLEDs patterned by the thermal evaporation fabrication process onto stress-relief substrates. These OLEDs can mitigate certain problems in previous studies of stretchable OLEDs without need to find new materials or to use a prestrained fabrication process.

Recent Progress of Fiber Shaped Lighting Devices for Smart Display Applications-A Fibertronic Perspective

Advances in material science and nanotechnology have fostered the miniaturization of devices. Over the past two decades, the form-factor of these devices has evolved from 3D rigid, volumetric devices through 2D film-based flexible electronics, finally to 1D fiber electronics (fibertronics). In this regard, fibertronic strategies toward wearable applications (e.g., electronic textiles (e-textiles)) have attracted considerable attention thanks to their capability to impart various functions into textiles with retaining textiles' intrinsic properties as well as imperceptible irritation by foreign matters. In recent years, extensive research has been carried out to develop various functional devices in the fiber form. Among various features, lighting and display features are the highly desirable functions in wearable electronics. This article discusses the recent progress of materials, architectural designs, and new fabrication technologies of fiber-shaped lighting devices and the current challenges corresponding to each device's operating mechanism. Moreover, opportunities and applications that the revolutionary convergence between the state-of-the-art fibertronic technology and age-long textile industry will bring in the future are also discussed.

Sandwich-structure transferable free-form OLEDs for wearable and disposable skin wound photomedicine

Free-form optoelectronic devices can provide hyper-connectivity over space and time. However, most conformable optoelectronic devices can only be fabricated on flat polymeric materials using low-temperature processes, limiting their application and forms. This paper presents free-form optoelectronic devices that are not dependent on the shape or material. For medical applications, the transferable OLED (10 μm) is formed in a sandwich structure with an ultra-thin transferable barrier (4.8 μm). The results showed that the fabricated sandwich-structure transferable OLED (STOLED) exhibit the same high-efficiency performance on cylindrical-shaped materials and on materials such as textile and paper. Because the neutral axis is freely adjustable using the sandwich structure, the textile-based OLED achieved both folding reliability and washing reliability, as well as a long operating life (>150 h). When keratinocytes were irradiated with red STOLED light, cell proliferation and cell migration increased by 26 and 32%, respectively. In the skin equivalent model, the epidermis thickness was increased by 39%; additionally, in organ culture, not only was the skin area increased by 14%, but also, re-epithelialization was highly induced. Based on the results, the STOLED is expected to be applicable in various wearable and disposable photomedical devices.

Low-Temperature and Corrosion-Resistant Gas Diffusion Multibarrier with UV and Heat Rejection Capability-A Strategy to Ensure Reliability of Organic Electronics

When placed in an outdoor environment, organic electronic devices (OEDs) can degrade on exposure to moisture, UV light, and heat, owing to the chemical sensitivity and decomposition of the organic materials. Therefore, to protect OEDs from outdoor environments, thin-film passivation, which can block harmful elements from reaching organic materials, is required. To meet the demands and trends in encapsulation technologies, in this study, we developed a low-temperature, simple, and effective gas diffusion multibarrier (GDM), which is UV and heat reflective as well as corrosion resistant. The designed UV- and heat-reflective GDM (UHGDM) has a multistacked structure in the form of a UV filter/Ag/gas diffusion barrier (GDB)/polymer based on a dielectric/metal/dielectric (DMD) configuration. First, the DMD structure was used as a heat mirror for infrared reflectance. Second, the bottom dielectric layer of the DMD structure was used as the UV filter, and it consisted of a ZnS/LiF multistacked structure with large differences in refractive indexes. Third, a nanolaminate-based GDB barrier with multi-interfacial and defect-decoupling systems, which achieved a water vapor transmission rate of 1.58 × 10^-5 g/m²/day at a thickness of 60 nm, was used as the top dielectric layer of the DMD structure. Finally, an inorganic/organic hybrid polymer layer was coated on the DMD structure to provide corrosion-resistance and waterproofing properties. The fabricated UHGDM showed high transparency in the visible region and excellent reflectance in the UV and IR regions, resulting in excellent UV and heat rejection capability in practical UV and heat reflection tests. In addition to optical functionalities, the UHGDM maintained its functionality against harsh environmental conditions because of the GDB/polymer structure. Finally, the feasibility of the UHGDM was demonstrated using organic solar cells through water immersion and shelf lifetime tests.

Protective effect of a brown algae, Sargassum horneri on particulate matter-induced oxidative stress and inflammation in MLE-12 cells

The constant exposure to fine particulate matter (PM) induces oxidative stress and proinflammatory cytokine production. The ROS formed by oxidative stress is related to activate NF-κB signal pathway for inflammation. Sargassum horneri, a brown algae found in East Asia, is known to be an excellent source for bioactive components. In this study, the antioxidant and anti-inflammation effects of Sargassum horneri ethanol extract (SHE) on the PM-induced oxidative stress in MLE-12, a type II alveolar epithelial cell line were investigated. As the exposure concentration of PM increased to 1,000 μg/mL, the cell viability was reduced; however, it was increased when treated with SHE. The ROS generation and lipid peroxidation of MLE-12 cells were increased from the PM concentration of 125 μg/mL and they were reduced after treatment of SHE at 62.5 and 125 μg/mL. The expressions of antioxidant enzymes, catalase (CAT) and superoxide dismutase (SOD2), in MLE-12 cells exposed to PM were lower than those exposed to PM with SHE. The PM was proved to increase the expression of 8-OHdG, one of DNA oxidative damage markers, and OGG1, the repair enzyme of 8-OHdG, while SHE protected the DNA damage of cell. The expression of NF-κB signaling was reduced by SHE. These results suggest that SHE can adjust the expression of antioxidant enzymes, help to suppress the oxidative stress induced by PM, and attenuate its oxidative damage and NF-κB pathway to lung epithelial cells by eliminating over-produced ROS.

This research is part of a project titled ‘Development of functional food products with natural materials derived from marine resources’ funded by the Ministry of Oceans and Fisheries, Republic of Korea in 2017 (Project NO. 20172085).

Design of Highly Water Resistant, Impermeable, and Flexible Thin-Film Encapsulation Based on Inorganic/Organic Hybrid Layers

The lack of a transparent, flexible, and reliable encapsulation layer for organic-based devices makes it difficult to commercialize wearable, transparent, flexible displays. The reliability of organic-based devices sensitive to water vapor and oxygen must be guaranteed through an additional encapsulation layer for the luminance efficiency and lifetime. Especially, one of the major difficulties in current and future OLED applications has been the absence of thin-film encapsulation with superior barrier performance, mechanical flexibility, and water-resistant properties. In this work, we fabricated highly water-resistant, impermeable, and flexible inorganic/organic multilayers with optimized Al₂O₃ and functional organic layers. The key properties of the fabricated multilayers were compared according to the thickness and functionality of the inorganic and organic layers. Improvement of the barrier performance is mainly attributed to the optimized thickness of the Al₂O₃ films, and is additionally due to the increased lag time and effective surface planarization effects caused by the use of micrometer-thick organic layers. As a result, the 3-dyad multilayer structure composed of 60 nm-thick Al₂O₃ layers deposited at 70 °C and 2-μm-thick silane-based inorganic/organic hybrid polymer (silamer) layers with layered silica exhibited the lowest WVTR value of 1.11 × 10^-6 g/m²/day in storage conditions of 30 °C/90% relative humidity. In addition, the multibarrier exhibited good mechanical stability through the use of alternating stacks of brittle inorganic and soft organic layers, without showing a large increase in the WVTR after bending tests. In addition, silamer layers improved the environmental stability of the Al₂O₃ ALD film. The silamer layer coated on the Al₂O₃ film effectively worked as a protective layer against harsh environments. The effective contact at the interface of Al₂O₃/silamer makes the barrier structure more impermeable and corrosion-resistant. In this study, we not only demonstrated an optimized multilayer based on functional organic layers but also provided a methodology for designing a wearable encapsulation applicable to wearable organic electronics.

A New Technique to Determine the Size of Double-lumen Endobronchial Tubes by the Two Perpendicularly Measured Bronchial Diameters

The cross-section of the mainstem bronchi is not completely round. For preoperative selection of a double-lumen endobronchial tube size, it may be necessary to measure the mediolateral and the anteroposterior bronchial diameters, which can be measured respectively on chest radiograph and computed tomography. With Internal Review Board approval and patients’ informed consent, 105 elective thoracic surgical patients who needed left-sided double-lumen tubes were enrolled. Double-lumen tube size was selected depending on the arithmetic mean of the mediolateral and anteroposterior bronchial diameters. Moreover, the outer diameters of the bronchial tube should be smaller than both mediolateral and anteroposterior diameters. The recommended bronchial diameter for each double-lumen tube size was chosen so that the mean of the two bronchial diameters was 0 to 2.0 mm larger than the upper limit of 95% confidence interval of the averaged outer diameter of the bronchial tube of the selected double-lumen tube. In no case was the predicted double-lumen tube size inappropriate. Generally, anteroposterior bronchial diameters appeared to be different from mediolateral diameters (P=0.001). The double-lumen tube size to be selected based on only one bronchial diameter was different from the one selected based on two perpendicularly measured bronchial diameters in 54.3% of patients (57/105). Preoperative selection of the double-lumen tube size based on the anteroposterior, mediolateral and mean bronchial diameters seems to be useful in that this may obviate the need to change an inappropriately sized double-lumen tube and may be helpful in reducing the related complications.

Intraoperative Management of a Patient With Impaired Cardiac Function Undergoing Simultaneous ABO-Compatible Liver and ABO-Incompatible Kidney Transplant From 2 Living Donors: A Case Report

BACKGROUND

Combined liver and kidney transplant is a very complex surgery. To date, there has been no report on the intraoperative management of patients with impaired cardiac function undergoing simultaneous ABO-compatible liver and ABO-incompatible kidney transplant from 2 living donors.

CASE REPORT

A 60-year-old man underwent simultaneous ABO-compatible liver and ABO-incompatible kidney transplant from 2 living donors because of IgA nephropathy and alcoholic liver cirrhosis. The preoperative cardiac findings revealed continuous aggravation, shown by large left atrial enlargement, severe left ventricular hypertrophy, a very prolonged QT interval, and a calcified left anterior descending coronary artery. Severe hypotension with very weak pulsation and severe bradycardia developed, with an irregular junctional rhythm noted immediately after the liver graft was reperfused. Although epinephrine was administered as a rescue drug, hemodynamics did not improve, and central venous pressure and mean pulmonary arterial pressure increased to potentially fatal levels. Emergency phlebotomy via the central line was performed. Thereafter, hypotension and bradycardia recovered gradually as the central venous pressure and mean pulmonary arterial pressure decreased. The irregular junctional rhythm returned to a sinus rhythm, but the QTc interval was slightly more prolonged. Because of poor cardiac capacity, the volume and rate of fluid infusion were increased aggressively to maintain appropriate kidney graft perfusion after confirming vigorous urine production of the graft.

CONCLUSIONS

A heart with impaired function due to both end-stage liver and kidney diseases may be less able to withstand surgical stress. Further study on cardiac dysfunction will be helpful for the management of patients undergoing complex transplant surgery.

Robust Transparent and Conductive Gas Diffusion Multibarrier Based on Mg- and Al-Doped ZnO as Indium Tin Oxide-Free Electrodes for Organic Electronics

Thin-film encapsulation is strictly required to protect transparent, flexible organic light-emitting diodes (OLEDs) based on plastic substrates with poor moisture barrier performances against water vapor and oxygen. However, additional encapsulation process makes OLED fabrication complex and expensive, resulting in lower yield and higher costs for the manufacture of OLEDs. Therefore, to develop simple, transparent conductive gas diffusion barrier (TCGDB) technologies by providing barrier performances to electrodes can be alternatives. Furthermore, TCGDB based on dielectric/metal/dielectric structures exhibit not only excellent barrier performances to protect metallic and organic layers against the ambient environment but also mechanical flexibility overcoming the brittleness of oxides. In this work, to improve the moisture-resistant, electrical, and optical properties of ZnO film, periodical dopant layers were inserted during the deposition of atomic layer deposition ZnO film. These dopant layers make the intrinsic ZnO film more optically and electrically functional. The dopant of MgO with a wide band gap enables blue-shifted optical transmittance, and the dopant of Al atoms makes doped ZnO more electrically conductive. In addition, these dopant layers in the ZnO film interrupt the film crystallization, making the film less crystalline with fewer channels and grain boundaries. This effect results in significant improvement of its GDB properties. With a functional and material design that takes full advantage of the synergetic combination of highly flexible conductive Ag and a moisture-resistant MAZO layer, the MAZO/Ag/MAZO (MAM) multilayer with a thickness of approximately 110 nm achieves a sheet resistance of 5.60 Ω/sq, an average transmittance of 89.72% in the visible range, and a water vapor transmission rate on the order of 10^-5 g/m²/day. In addition, OLEDs with the MAM electrode demonstrated a great potential of indium tin oxide- and encapsulation-free organic electronics.

Low-Temperature Fabrication of Robust, Transparent, and Flexible Thin-Film Transistors with a Nanolaminated Insulator

The lack of reliable, transparent, and flexible electrodes and insulators for applications in thin-film transistors (TFTs) makes it difficult to commercialize transparent, flexible TFTs (TF-TFTs). More specifically, conventional high process temperatures and the brittleness of these elements have been hurdles in developing flexible substrates vulnerable to heat. Here, we propose electrode and insulator fabrication techniques considering process temperature, transmittance, flexibility, and environmental stability. A transparent and flexible indium tin oxide (ITO)/Ag/ITO (IAI) electrode and an Al₂O₃/MgO (AM)-laminated insulator were optimized at the low temperature of 70 °C for the fabrication of TF-TFTs on a polyethylene terephthalate (PET) substrate. The optimized IAI electrode with a sheet resistance of 7 Ω/sq exhibited the luminous transmittance of 85.17% and maintained its electrical conductivity after exposure to damp heat conditions because of an environmentally stable ITO capping layer. In addition, the electrical conductivity of IAI was maintained after 10 000 bending cycles with a tensile strain of 3% because of the ductile Ag film. In the metal/insulator/metal structure, the insulating and mechanical properties of the optimized AM-laminated film deposited at 70 °C were significantly improved because of the highly dense nanolaminate system, compared to those of the Al₂O₃ film deposited at 70 °C. In addition, the amorphous indium-gallium-zinc oxide (a-IGZO) was used as the active channel for TF-TFTs because of its excellent chemical stability. In the environmental stability test, the ITO, a-IGZO, and AM-laminated films showed the excellent environmental stability. Therefore, our IGZO-based TFT with IAI electrodes and the 70 °C AM-laminated insulator was fabricated to evaluate robustness, transparency, flexibility, and process temperature, resulting in transfer characteristics comparable to those of an IGZO-based TFT with a 150 °C Al₂O₃ insulator.

Functional Design of Highly Robust and Flexible Thin-Film Encapsulation Composed of Quasi-Perfect Sublayers for Transparent, Flexible Displays

In this study, a structurally and materially designed thin-film encapsulation is proposed to guarantee the reliability of transparent, flexible displays by significantly improving their barrier properties, mechanical stability, and environmental reliability, all of which are essential for organic light-emitting diode (OLED) encapsulation. We fabricated a bioinspired, nacre-like ZnO/Al₂O₃/MgO laminate structure (ZAM) using atomic layer deposition for the microcrack toughening effect. The ZAM film was formed with intentional voids and defects through the formation of a quasi-perfect sublayer, rather than the simple fabrication of nanolaminate structures. The 240 nm thick ZAM-based multibarrier (ZAM-TFE) with a compressively strained organic layer demonstrated an optical transmittance of 91.35% in the visible range, an extremely low water vapor transmission rate of 2.06 × 10^-6 g/m²/day, a mechanical stability enduring a strain close to 1%, and a residual stress close to 0, showing significant improvement of key TFE properties in comparison to an Al₂O₃-based multibarrier. In addition, ZAM-TFE demonstrated superior environmental resistance without degradation of barrier properties in a severe environment of 85 °C and 90% relative humidity (RH). Thus, our structurally and materially designed ZAM film has been well optimized in terms of its applicability as a gas diffusion barrier as well as in terms of its mechanical and environmental reliability. Finally, we confirmed the feasibility of the ZAM-TFE through application in OLEDs. The low-temperature ZAM-TFE technology showed great potential to provide a highly robust and flexible TFE of TFOLEDs.

Performance of the Minto model for the target-controlled infusion of remifentanil during cardiopulmonary bypass

We studied the predictive performance of the Minto pharmacokinetic model during cardiopulmonary bypass in patients undergoing cardiac surgery. Patients received remifentanil target-controlled infusion using the Minto model during total intravenous anaesthesia with propofol. From 56 patients, 275 arterial blood samples were drawn before, during and after bypass to determine the plasma concentration of remifentanil, and the predicted concentrations were recorded at each time. For pooled data, the median prediction error and median absolute prediction error were 21.3% and 21.8%, respectively, and 22.1% and 22.3% during bypass. Both were 148.4% during hypothermic circulatory arrest and measured concentrations were more than three times greater than predicted (26.9 (17.0) vs. 7.1 (1.6) ng.ml^-1 ). The Minto model showed considerable bias but overall acceptable precision during bypass. The target concentration of remifentanil should be reduced when using the Minto model during hypothermic circulatory arrest.

Functional Design of Dielectric-Metal-Dielectric-Based Thin-Film Encapsulation with Heat Transfer and Flexibility for Flexible Displays

In this study, a new and efficient dielectric-metal-dielectric-based thin-film encapsulation (DMD-TFE) with an inserted Ag thin film is proposed to guarantee the reliability of flexible displays by improving the barrier properties, mechanical flexibility, and heat dissipation, which are considered to be essential requirements for organic light-emitting diode (OLED) encapsulation. The DMD-TFE, which is composed of Al₂O₃, Ag, and a silica nanoparticle-embedded sol-gel hybrid nanocomposite, shows a water vapor transmission rate of 8.70 × 10^-6 g/m²/day and good mechanical reliability at a bending radius of 30 mm, corresponding to 0.41% strain for 1000 bending cycles. The electrical performance of a thin-film encapsulated phosphorescent organic light-emitting diode (PHOLED) was identical to that of a glass-lid encapsulated PHOLED. The operational lifetimes of the thin-film encapsulated and glass-lid encapsulated PHOLEDs are 832 and 754 h, respectively. After 80 days, the thin-film encapsulated PHOLED did not show performance degradation or dark spots on the cell image in a shelf-lifetime test. Finally, the difference in lifetime of the OLED devices in relation to the presence and thickness of a Ag film was analyzed by applying various TFE structures to fluorescent organic light-emitting diodes (FOLEDs) that could generate high amounts of heat. To demonstrate the difference in heat dissipation effect among the TFE structures, the saturated temperatures of the encapsulated FOLEDs were measured from the back side surface of the glass substrate, and were found to be 67.78, 65.12, 60.44, and 39.67 °C after all encapsulated FOLEDs were operated at an initial luminance of 10 000 cd/m² for sufficient heat generation. Furthermore, the operational lifetime tests of the encapsulated FOLED devices showed results that were consistent with the measurements of real-time temperature profiles taken with an infrared camera. A multifunctional hybrid thin-film encapsulation based on a dielectric-metal-dielectric structure was thus effectively designed considering the transmittance, gas-permeation barrier properties, flexibility, and heat dissipation effect by exploiting the advantages of each separate layer.