Fibriform Organic Electrochemical Diodes with Rectifying, Complementary Logic and Transient Voltage Suppression Functions for Wearable E-Textile Embedded Circuits.

In this study, a fibriform electrochemical diode capable of performing rectifying, complementary logic and device protection functions for future e-textile circuit systems is fabricated. The diode was fabricated using a simple twisted assembly of metal/polymer semiconductor/ion gel coaxial microfibers and conducting microfiber electrodes. The fibriform diode exhibited a prominent asymmetrical current flow with a rectification ratio of over 102, and its performance was retained after repeated bending deformations and washings. Fundamental studies on the electrochemical interactions of polymer semiconductors with ions reveal that the Faradaic current generated in polymer semiconductors by electrochemical reactions results in an abrupt current increase under a forward bias, in which the threshold voltages of the device are determined by the oxidation or reduction potential of the polymer semiconductor. Textile-embedded full-wave rectifiers and logic gate circuits were implemented by simply integrating the fibriform diodes, exhibiting AC-to-DC signal conversion and logic operation functions, respectively. It was also confirmed that the proposed fibriform diode can suppress transient voltages and thus protect a low-voltage operational wearable e-textile circuit.

Self-powered image array composed of touch-free sensors fabricated with semiconductor nanowires.

We successfully develop a self-powered image array (IA) composed of 16 touch-free sensors (TFSs) fabricated with semiconductor InN nanowires (NWs) as a response medium. Without using a power supply, the InN-NW TFS can detect the position of a human hand 30 cm away from the device surface. It also distinguishes different materials such as polyimide, Al foil, printing paper, latex, and polyvinyl chloride in non-contact mode at a distance of 1 cm. The self-powered TFS-IA clearly distinguishes square-shaped transparent polydimethylsiloxane film attached to the back of a human hand positioned 5 cm from the device, indicating the possibility for detecting changes in the surface texture of human skin, such as skin burns or skin cancer. The performance of the self-powered TFS and TFS-IA is attributed to high electrostatic induction of InN NWs by external triboelectricity resulting from the simple movement of the target object, which differs markedly from conventional sensors designed to detect variations in the temperature or light essentially using a power supply.

Photothermally Crumpled MoS2 Film as an Omnidirectionally Stretchable Platform.

Molybdenum disulfide (MoS2 ) is considered a fascinating material for next-generation semiconducting applications due to its outstanding mechanical stability and direct transition characteristics comparable to silicon. However, its application to stretchable platforms still is a challenging issue in wearable logic devices and sensors with noble form-factors required for future industry. Here, an omnidirectionally stretchable MoS2 platform with laser-induced strained structures is demonstrated. The laser patterning induces the pyrolysis of MoS2 precursors as well as the weak adhesion between Si and SiO2 layers. The photothermal expansion of the Si layer results in the crumpling of SiO2 and MoS2 layers and the field-effect transistors with the crumpled MoS2 are found to be suitable for strain sensor applications. The electrical performance of the crumpled MoS2 depends on the degree of stretching, showing the stable omnidirectional stretchability up to 8% with approximately four times higher saturation current than its initial state. This platform is expected to be applied to future electronic devices, sensors, and so on.

Prognostic role of blood KL-6 in rheumatoid arthritis-associated interstitial lung disease.

Rheumatoid arthritis-associated interstitial lung disease (RA-ILD) has a variable clinical course for which predicting prognosis is difficult. However, the role of blood biomarkers in RA-ILD is ill-defined. The aim of this study was to investigate the prognostic value of Krebs von den Lungen-6 (KL-6) levels in RA-ILD patients. The medical records of 84 patients with RA-ILD were retrospectively reviewed. Plasma KL-6 levels were measured by Nanopia KL-6 assay (SEKISUI MEDICAL, Tokyo), using latex-enhanced immunoturbidimetric assay. The median follow-up period was 61 months. Mean age was 61.4 years, 45.2% were men, 44.0% were ever-smokers, and 35.7% showed a usual interstitial pneumonia (UIP) pattern on high-resolution computed tomography. The median KL-6 level at baseline was 741.2 U/mL (interquartile range, 439.7-1308.9 U/mL). On multivariate logistic regression analysis, a high KL-6 level (≥ 640 U/mL) was an independently associated with a UIP pattern (odds ratio [OR], 5.173; P = 0.005) with old age (OR, 1.104, P = 0.005). On multivariate Cox analysis, a high KL-6 level (≥ 685 U/mL) was an independent prognostic factor for the mortality (hazard ratio [HR], 2.984; P = 0.016) with a older age (HR, 1.061; P = 0.030), male sex (HR, 3.610; P = 0.001), lower forced vital capacity (HR, 0.957; P = 0.002), and a UIP pattern (HR, 4.034; P = 0.002). Our results suggest that high KL-6 levels might be useful as a biomarker for the presence of a UIP pattern and prognosis in patients with RA-ILD.

Layer-Selective Synthesis of MoS2 and WS2 Structures under Ambient Conditions for Customized Electronics.

Transition metal dichalcogenides (TMDs) have attracted significant interest as one of the key materials in future electronics such as logic devices, optoelectrical devices, and wearable electronics. However, a complicated synthesis method and multistep processes for device fabrication pose major hurdles for their practical applications. Here, we introduce a direct and rapid method for layer-selective synthesis of MoS2 and WS2 structures in wafer-scale using a pulsed laser annealing system (λ = 1.06 µm, pulse duration ∼100 ps) in ambient conditions. The precursor layer of each TMD, which has at least 3 orders of magnitude higher absorption coefficient than those of neighboring layers, rigorously absorbed the incoming energy of the laser pulse and rapidly pyrolyzed in a few nanoseconds, enabling the generation of a MoS2 or WS2 layer without damaging the adjacent layers of SiO2 or polymer substrate. Through experimental and theoretical studies, we establish the underlying principles of selective synthesis and optimize the laser annealing conditions, such as laser wavelength, output power, and scribing speed, under ambient condition. As a result, individual homostructures of patterned MoS2 and WS2 layers were directly synthesized on a 4 in. wafer. Moreover, a consecutive synthesis of the second layer on top of the first synthesized layer realized a vertically stacked WS2/MoS2 heterojunction structure, which can be treated as a cornerstone of electronic devices. As a proof of concept, we demonstrated the behavior of a MoS2-based field-effect transistor, a skin-attachable motion sensor, and a MoS2/WS2-based heterojunction diode in this study. The ultrafast and selective synthesis of the TMDs suggests an approach to the large-area/mass production of functional heterostructure-based electronics.