Stretchable electronics are mechanically compatible with a variety of objects, especially with the soft curvilinear contours of the human body, enabling human‐friendly electronics applications that ...could not be achieved with conventional rigid electronics. Therefore, extensive research effort has been devoted to the development of stretchable electronics, from research on materials and unit device, to fully integrated systems. In particular, material‐processing technologies that encompass the synthesis, assembly, and patterning of intrinsically stretchable electronic materials have been actively investigated and have provided many notable breakthroughs for the advancement of stretchable electronics. Here, the latest studies of such material‐based approaches are reviewed, mainly focusing on intrinsically stretchable electronic nanocomposites that generally consist of conducting/semiconducting filler materials inside or on elastomer backbone matrices. Various approaches for fabricating these intrinsically stretchable electronic materials are presented, including the blending of electronic fillers into elastomer matrices, the formation of bi‐layered heterogeneous electronic‐layer and elastomer support‐layer structures, and modifications to polymeric molecular structures in order to impart stretchability. Detailed descriptions of the various conducting/semiconducting composites prepared by each method are provided, along with their electrical/mechanical properties and examples of device applications. To conclude, a brief future outlook is presented.
The latest research developments and progress regarding material‐based approaches for the fabrication of stretchable electronics are comprehensively reviewed. Detailed descriptions of various stretchable conducting/semiconducting composites are given, along with their electrical/mechanical properties, material processing strategies, and examples of device applications. In addition, the outlook for future research in this field is discussed.
Recent technological advances in nanomaterials have driven the development of high‐performance light‐emitting devices with flexible and stretchable form factors. Deformability in such devices is ...mainly achieved by replacing the rigid materials in the device components with flexible nanomaterials and their assemblies (e.g., carbon nanotubes, silver nanowires, graphene, and quantum dots) or with intrinsically soft materials and their composites (e.g., polymers and elastomers). Downscaling the dimensions of the functional materials to the nanometer range dramatically decreases their flexural rigidity, and production of polymer/elastomer composites with functional nanomaterials provides light‐emitting devices with flexibility and stretchability. Furthermore, monolithic integration of these light‐emitting devices with deformable sensors furnishes the resulting display with various smart functions such as force/capacitive touch‐based data input, personalized health monitoring, and interactive human–machine interfacing. These ultrathin, lightweight, and deformable smart optoelectronic devices have attracted widespread interest from materials scientists and device engineers. Here, a comprehensive review of recent progress concerning these flexible and stretchable smart displays is presented with a focus on materials development, fabrication techniques, and device designs. Brief overviews of an integrated system of advanced smart displays and cutting‐edge wearable sensors are also presented, and, to conclude, a discussion of the future research outlook is given.
The recent research developments and progress regarding flexible and stretchable smart displays are reviewed comprehensively. Important advancements concerning materials development, fabrication techniques, and device designs are summarized, compared, and discussed, with a detailed description of smart display applications. In addition, the outlook for future research in this field is discussed.
This study demonstrates the effectiveness of using thin‐film electrolytes to enhance protonic ceramic fuel cells (PCFCs). The material tested in this study is yttrium‐doped barium cerate‐zirconate ...(BCZY), which is a representative electrolyte material of PCFCs. The thickness of the electrolyte membrane is as small as 1 µm and designed to minimize ohmic loss in proton transport pathways. Integration of this thin BCZY electrolyte is attempted on a multilayered anode comprised of two‐step supports with bulk nickel‐yttria stabilized zirconia cermet as a base and thin nickel‐BCZY as an anode functional layer atop the base. The compatibility of this support with the deposited thin electrolyte is able to be confirmed from the results of iterated tests. The power of the fabricated cell is greater than 1.1 W cm−2 at 600 °C, which is a record high for PCFCs and is reproducible. In this paper, the origin of this high power is discussed and improvements that could be made to cell performance are further suggested.
Record‐high performance is achieved from a protonic ceramic fuel cell fabricated here after careful optimization. Columnar‐structured thin electrolyte gives rise to minimized resistance in proton conducting pathways, while nanostructured electrodes give rise to sufficiently low polarization resistance, contributing to the outstanding power output enhancement. The repeated and saturated results confirm reliability of the high‐performance data.
In reducing the high operating temperatures (≥800 °C) of solid-oxide fuel cells, use of protonic ceramics as an alternative electrolyte material is attractive due to their high conductivity and low ...activation energy in a low-temperature regime (≤600 °C). Among many protonic ceramics, yttrium-doped barium zirconate has attracted attention due to its excellent chemical stability, which is the main issue in protonic-ceramic fuel cells. However, poor sinterability of yttrium-doped barium zirconate discourages its fabrication as a thin-film electrolyte and integration on porous anode supports, both of which are essential to achieve high performance. Here we fabricate a protonic-ceramic fuel cell using a thin-film-deposited yttrium-doped barium zirconate electrolyte with no impeding grain boundaries owing to the columnar structure tightly integrated with nanogranular cathode and nanoporous anode supports, which to the best of our knowledge exhibits a record high-power output of up to an order of magnitude higher than those of other reported barium zirconate-based fuel cells.
Sensory receptors in human skin transmit a wealth of tactile and thermal signals from external environments to the brain. Despite advances in our understanding of mechano- and thermosensation, ...replication of these unique sensory characteristics in artificial skin and prosthetics remains challenging. Recent efforts to develop smart prosthetics, which exploit rigid and/or semi-flexible pressure, strain and temperature sensors, provide promising routes for sensor-laden bionic systems, but with limited stretchability, detection range and spatio-temporal resolution. Here we demonstrate smart prosthetic skin instrumented with ultrathin, single crystalline silicon nanoribbon strain, pressure and temperature sensor arrays as well as associated humidity sensors, electroresistive heaters and stretchable multi-electrode arrays for nerve stimulation. This collection of stretchable sensors and actuators facilitate highly localized mechanical and thermal skin-like perception in response to external stimuli, thus providing unique opportunities for emerging classes of prostheses and peripheral nervous system interface technologies.
Abstract Coronary computed tomography angiography (CCTA)-derived computational FFR (CT-FFR) may provide better diagnostic performance over CCTA alone, but the complexity of its method limits the use ...in clinical environment. The aim of this study is to validate a newly developed vessel-length based computational fluid dynamics (CFD) scheme for the computation of fractional flow reserve (FFR) based on CCTA data, compare them with invasively measured FFR, and evaluate its diagnostic performance with that of CCTA. One hundred seventeen patients from 4 medical institutions who had clinically indicated invasive coronary angiography for suspected coronary artery disease (CAD) were enrolled. Invasive FFR measurement was performed in 218 vessels and these measurements were regarded as the reference standard. The accuracy, sensitivity, specificity, positive predictive value and negative predictive value of CT-FFR on a per-vessel basis were 85.8%, 86.2%, 85.5%, 79.8%, 90.3%, respectively, for CT-FFR ≤ 0.80, and were 66.1%, 75.9%, 59.5%, 55.5%, 78.8%, respectively, for CCTA ≥ 50%. A higher area under the receiver operating characteristic curve for CT-FFR was observed as compared with CCTA (0.93 vs. 0.74, p < 0.0001). The CT-FFR and FFR were correlated well (r = 0.76, p < 0.001) with slight underestimation by CT-FFR (0.014 ± 0.077, p = 0.007). With a novel method of vessel-length based CFD scheme, CT-FFR can be performed at a personal computer enhancing its applicability in clinical situation. The diagnostic accuracy of CT-FFR for the detection of functionally significant CAD was good and was superior to that of CCTA within a population of suspected CAD.
Herein we propose silver surface-coated with nano-scale yttria-stabilized zirconia (YSZ) as a high-performance cathode for use in low-temperature solid oxide fuel cells (LT-SOFCs). YSZ was coated on ...the Ag cathode surface by sputtering of Y/Zr alloy films followed by thermal annealing for oxidation of YSZ. An electrolyte-support type SOFC was fabricated on 350-μm-thick gadolinium-doped ceria (GDC) pellets. The yttrium concentration and sputtering time for obtaining the YSZ coating layer was varied to optimize the cathode composition. It was determined that the GDC SOFCs with optimized Ag-YSZ cathodes significantly outperform cells with bare silver or platinum cathodes, which are considered to be the best-performing catalysts at low temperatures. The peak power density obtained using cells with Ag-YSZ cathodes was as high as ∼100 mW/cm2 at 450 °C, 3–4 times greater than the performance of cells with Ag or Pt cathodes. Electrochemical impedance spectroscopy was performed during fuel cell testing to compare polarization and charge transport performances of the Ag-YSZ cathodes. The long-term stability of the Ag-YSZ cathode was evaluated by monitoring the change in cathode morphology compared to the bare Ag and Pt cathodes.
•Ag cathode surface-coated with nano-YSZ is prepared by sputtering.•Ag-YSZ cathode outperforms Ag and Pt in terms of fuel cell performance.•GDC pellet cells with Ag-YSZ achieves over 100 mW/cm2 at 450 °C.•YSZ surface-coating helps enhancement of electrochemical surface kinetics.
Atomic layer deposition (ALD) is a powerful tool for nanoscale film deposition. It can uniformly deposit films at a monolayer level even in complex 3D structures, while the deposition temperature is ...relatively low with its potential scalability. In this work, surface tuning of solid oxide fuel cell (SOFC) cathodes is successfully demonstrated by modifying the surface of La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) with nanoscale lanthanum strontium cobaltite (LSC) using ALD. The ALD‐LSC surface‐tuning layer can enhance the charge transfer kinetics at the cathode surface, while the backbone LSCF cathode provides a means for ionic and electronic transport. Microstructural analysis shows that the ALD‐LSC on LSCF has excellent step coverage, which is enabled by the conformal characteristic of the ALD process. It is found that the electrochemical performance of SOFCs can be enhanced enormously by surface tuning of the cathodes with nanoscale LSC film corresponding to 1–12 nm. Using density functional theory calculations, the enhanced catalytic activity of the surface‐tuned SOFC cathode using ALD‐LSC could be confirmed. This result demonstrates the possibility of nanoscale surface tuning of SOFC cathodes by using the ALD process to improve the surface activity.
Surface tuning of a solid oxide fuel cell (SOFC) cathode using lanthanum strontium cobaltite fabricated by atomic layer deposition (ALD‐LSC) has been successfully demonstrated to improve surface catalytic activity. For samples with an ALD‐LSC thickness of 8 nm, the peak power density was recorded at 394 mW cm–2 (@600 °C), 1.8 times higher than the performance of the bare one.
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