Solution processing, including printing technology, is a promising technique for oxide thin‐film transistor (TFTs) fabrication because it tends to be a cost‐effective process with high composition ...controllability and high throughput. However, solution‐processed oxide TFTs are limited by low‐performance and stability issues, which require high‐temperature annealing. This high thermal budget in the fabrication process inhibits oxide TFTs from being applied to flexible electronics. There have been numerous attempts to promote the desired electrical characteristics of solution‐processed oxide TFTs at lower fabrication temperatures. Recent techniques for achieving low‐temperature (<350 °C) solution‐processed and printed oxide TFTs, in terms of the materials, processes, and structural engineering methods currently in use are reviewed. Moreover, the core techniques for both n‐type and p‐type oxide‐based channel layers, gate dielectric layers, and electrode layers in oxide TFTs are addressed. Finally, various multifunctional and emerging applications based on low‐temperature solution‐processed oxide TFTs are introduced and future outlooks for this highly promising research are suggested.
Solution‐processed oxide thin‐film transistors (TFTs) conventionally require high‐temperature annealing, which may hinder their potential application in flexible devices. To solve this problem, this review provides the latest approaches for achieving low‐temperature (<350 °C) solution‐processed and printed oxide TFTs in terms of the materials, processes, and structural engineering methods, and perspectives for emerging flexible applications.
It is challenging to develop alloying anodes with ultrafast charging and large energy storage using bulk anode materials because of the difficulty of carrier‐ion diffusion and fragmentation of the ...active electrode material. Herein, a rational strategy is reported to design bulk Bi anodes for Na‐ion batteries that feature ultrafast charging, long cyclability, and large energy storage without using expensive nanomaterials and surface modifications. It is found that bulk Bi particles gradually transform into a porous nanostructure during cycling in a glyme‐based electrolyte, whereas the resultant structure stores Na ions by forming phases with high Na diffusivity. These features allow the anodes to exhibit unprecedented electrochemical properties; the developed Na–Bi half‐cell delivers 379 mA h g−1 (97% of that measured at 1C) at 7.7 A g−1 (20C) during 3500 cycles. It also retained 94% and 93% of the capacity measured at 1C even at extremely fast‐charging rates of 80C and 100C, respectively. The structural origins of the measured properties are verified by experiments and first‐principles calculations. The findings of this study not only broaden understanding of the underlying mechanisms of fast‐charging anodes, but also provide basic guidelines for searching battery anodes that simultaneously exhibit high capacities, fast kinetics, and long cycling stabilities.
With the difficulty in simultaneously achieving a large capacity, ultrafast charging capability, and long cycling stability in a battery anode, a bulk Bi anode is presented for Na‐ion batteries that provides a simple yet practical route to address this issue without using expensive nanoscale materials and additional complex modifications.
Mechanical metamaterials possess unusual mechanical properties that cannot be found in nature. Auxetic metamaterials have negative Poisson's ratios and tend to expand in a direction perpendicular to ...the axial extension direction. When the Poisson's ratio of a display circuit board is forced to be −1 by adopting an auxetic metamaterial, a display can be stretchable without image distortion, and this display is called a meta‐display in this study. The critical obstacles to implementing a stretchable display are large stretchability, high deformation uniformity, and low image distortion. The meta‐display overcomes these obstacles by incorporating micro‐LEDs and a kirigami‐based auxetic circuit board. An auxetic meta‐display with a stretchability of 24.5%, Poisson's ratio of −1, and no image distortion under uniaxial stretching is demonstrated. Finally, the roll transfer process enabled the scaling‐up of a 3‐inch meta‐display attachable to surfaces with non‐zero Gaussian curvatures. This conformity to the non‐zero Gaussian curvature helps realize biomedical applications such as wearable display, phototherapy, and skincare.
An auxetic meta‐display overcomes the obstacles of conventional stretchable displays by realizing large stretchability, high deformation uniformity, and low image distortion. It is fabricated by transferring micro‐LEDs on the circuit board based on auxetic metamaterials, and exhibits conformal wrapping on non‐Gaussian surfaces, enabling a skin‐attachable biomedical device.
The uniform growth of single-crystal graphene over wafer-scale areas remains a challenge in the commercial-level manufacturability of various electronic, photonic, mechanical, and other devices based ...on graphene. Here, we describe wafer-scale growth of wrinkle-free single-crystal monolayer graphene on silicon wafer using a hydrogen-terminated germanium buffer layer. The anisotropic twofold symmetry of the germanium (110) surface allowed unidirectional alignment of multiple seeds, which were merged to uniform single-crystal graphene with predefined orientation. Furthermore, the weak interaction between graphene and underlying hydrogen-terminated germanium surface enabled the facile etch-free dry transfer of graphene and the recycling of the germanium substrate for continual graphene growth.
The development of input device technology in a conformal and stretchable format is important for the advancement of various wearable electronics. Herein, we report a capacitive touch sensor with ...good sensing capabilities in both contact and noncontact modes, enabled by the use of graphene and a thin device geometry. This device can be integrated with highly deformable areas of the human body, such as the forearms and palms. This touch sensor detects multiple touch signals in acute recordings and recognizes the distance and shape of the approaching objects before direct contact is made. This technology offers a convenient and immersive human–machine interface and additional potential utility as a multifunctional sensor for emerging wearable electronics and robotics.
An active matrix‐type stretchable display is realized by overlay‐aligned transfer of inorganic light‐emitting diode (LED) and single‐crystal Si thin film transistor (TFT) with roll processes. The ...roll‐based transfer enables integration of heterogeneous thin film devices on a rubber substrate while preserving excellent electrical and optical properties of these devices, comparable to their bulk properties. The electron mobility of the integrated Si‐TFT is over 700 cm2 V−1 s−1, and this is attributed to the good interface between the Si channel and the thermally grown SiO2 insulator. The light emission properties of the LED are of wafer quality. The resulting display stably operates under tensile strains up to 40%, over 200 cycles, demonstrating the potential of stretchable displays based on inorganic materials.
All‐inorganic‐based stretchable active matrix display is demonstrated by integration of inorganic light‐emitting diode and single‐crystal Si thin film transistor. Overlay‐aligned roll transfer technique provides good integration of two devices on rubber substrate with outstanding electrical and optical properties. Furthermore, a serpentine‐shaped interconnector allows the effective strain division for stable operation of display over 40% applied strain.
•Stronger association in exercise duration than exercise time in each session is showed.•Regular physical exercise has a low chance of exhibiting symptoms of depression.•Exercise regularly to be ...relieved from depressive symptoms should be encouraged.
This study is to estimate the relation between regular physical exercise and the risk of depressive disorder and depressive symptoms. Data from the Korean Longitudinal Study of Aging (KLoSA) from 2008 to 2018 were used, and 3,070 research samples were included at baseline at 2008. To analyze the relation between physical exercise and risk of depression, a generalized estimating equation (GEE) model and chi-square test were used. The estimate of Center for Epidemiologic Studies Depression (CESD) in those with “< 3 h” of exercise per week was 0.033 higher (95% Confidence Interval CI: 0.001 – 0.065 p-value: 0.046) compared to those with “5 h or more” of exercise per week. In terms of exercise duration, the estimates for CESD was 0.153 higher (95% CI: 0.111 – 0.195 p-value: <0.0001) in “< 1 year” and 0.143 higher (95% CI: 0.109–0.178 p-value: <0.0001) in “1–2 year”, compared to “5 years or more” of exercise duration. This study showed a negative relationship between regular exercise and depressive symptoms in community-dwelling adults aged 45 years and above. To develop the habit of regular physical exercise and to reinforce self-esteem, simple and practical strategies of effective exercise may become important but effective exercise interventions.
Additional surgeries for implantable biomedical devices are inevitable to replace discharged batteries, but repeated surgeries can be a risk to patients, causing bleeding, inflammation, and ...infection. Therefore, developing self‐powered implantable devices is essential to reduce the patient's physical/psychological pain and financial burden. Although wireless communication plays a critical role in implantable biomedical devices that contain the function of data transmitting, it has never been integrated with in vivo piezoelectric self‐powered system due to its high‐level power consumption (microwatt‐scale). Here, wireless communication, which is essential for a ubiquitous healthcare system, is successfully driven with in vivo energy harvesting enabled by high‐performance single‐crystalline (1 − x)Pb(Mg1/3Nb2/3)O3−(x)Pb(Zr,Ti)O3 (PMN‐PZT). The PMN‐PZT energy harvester generates an open‐circuit voltage of 17.8 V and a short‐circuit current of 1.74 µA from porcine heartbeats, which are greater by a factor of 4.45 and 17.5 than those of previously reported in vivo piezoelectric energy harvesting. The energy harvester exhibits excellent biocompatibility, which implies the possibility for applying the device to biomedical applications.
In vivo self‐powered wireless transmission using a flexible single‐crystalline piezoelectric energy harvester is demonstrated. The high‐performance energy harvester generates an output voltage of 17.8 V and a current of 1.75 µA from the contraction and relaxation motion of porcine heart. The energy from in vivo physiological motion enables self‐powered wireless transmission, thus realizing practical application in the ubiquitous healthcare system.
The purpose of this study was to investigate the association between grip strength and hypertension in the Korean population aged 65 years or older. Furthermore, individual differences in BMI were ...taken into account to examine whether grip strength or a relative grip strength predicted hypertension better.
Data from the Korean Longitudinal Study of Ageing from 2006 to 2016 were assessed, and a total of 3,383 participants were analyzed in our study (Male: 1,527, Female: 1,856). Using the generalized estimating equation model, the association between grip strength and hypertension, assessed by the response to the question 'have you ever been diagnosed with hypertension from your doctor?', over the follow-up period was analyzed. The relative grip strength, calculated by dividing the mean grip strength by BMI, was also analyzed in association of hypertension.
Both grip strength and relative grip strength were significantly associated with hypertension in our sample. However, the results were more significant in the total sample when relative grip strength was used. In terms of grip strength, as the High group as reference: Low (Odds Ratio (OR): 1.238, 95% Confidence Interval (CI): 1.096, 1.397), Middle Low (OR: 1.104, 95% CI: 0.990, 1.231), and Middle high (OR: 1.024, 95% CI: 0.934, 1.122). In the analysis using relative grip strength, as High group as reference: Low (OR: 1.393, 95% CI: 1.234, 1.573), Middle low (OR: 1.232, 95% CI: 1.104, 1.374), and Middle high (OR:1.104, 95% CI: 1.009, 1.209). Furthermore, the lower QIC measure in the model with relative grip strength (QIC: 25,251) compared with the one using grip strength (QIC: 25,266) indicated a better model fit in the former.
The results of the current study strengthen the previous findings in regards to hand grip strength and health. Furthermore, the results of our study shines light on the necessity of considering individual differences in BMI, when using a physical measure as a study variable.
The poor cycling stability and low volumetric energy density of lithium–sulfur batteries compared with lithium‐ion batteries are hindering their practical applications. Here, it is demonstrated that ...a dense sulfur electrode containing heavy TiS2/TiO2@MXene heterostructures can tackle these issues. It is observed that the TiO2 part functionally anchors the lithium polysulfides through the strong chemical affinity, and the TiS2 part serves as an efficient electrocatalyst to enhance the kinetics of sulfur evolution reactions. Benefitting from these synergistic effects, the TiS2/TiO2@MXene heterostructures effectively suppress the shuttle effects, leading to superior cyclability of the sulfur cathode with a low capacity decay of 0.038% per cycle for 500 cycles at a current rate of 1 C. More encouragingly, a highly dense S/TiS2/TiO2@MXene cathode exhibits a high volumetric energy density of 2476 Wh L−1 (based on the volume of the composite) at a high sulfur mass loading of 7.5 mg cm−2 and lean electrolyte of 5 µL mg−1. The electrochemical performance is comparable to or even superior to the lithium‐ion and lithium–sulfur batteries reported in the literature. This study provides an effective strategy to design stable and high‐volumetric‐energy‐density lithium–sulfur batteries for practical energy storage applications.
Heavy TiS2/TiO2@MXene heterostructures simultaneously possessing superior adsorption capability and catalytic properties toward lithium polysulfides can be used as a cathode host of Li–S batteries with excellent cyclability and high volumetric energy density.
PDF
