Roll-to-roll Research Articles

Site-Selective Nanowire Synthesis and Fabrication of Printed Memristor Arrays with Ultralow Switching Voltages on Flexible Substrate.

Large area electronics (LAE) with the capability to sense and retain information are crucial for advances in applications such as wearables, digital healthcare, and robotics. The big data generated by these sensor-laden systems need to be scaled down or processed locally. In this regard, brain-inspired computing and in-memory computing have attracted considerable interest. However, suitable architectures have mainly been developed using costly and resource-intensive conventional lithography-based methods. There is a need for the development of innovative, resource-efficient fabrication routes that enable such devices and concepts. Herein, we present ZnO nanowire (NW)-based memristors on a polyimide substrate fabricated by a LAE-compatible and resource-efficient route comprising solution processing and printing technologies. High-resolution "drop-on-demand" and "direct ink write" printers are employed to deposit metallic layers (silver and gold) and a ZnO seed layer, needed for the site-selective growth of ZnO NWs via a low-cost hydrothermal method. The printed memristors show high bipolar resistance switching (ON/OFF ratio >103) between two nonvolatile states and consistent switching at ultralow voltages (all devices showed switching at amplitudes <200 mV), with the best performing device showing consistent cycled resistance switching over 4 orders of magnitude with SET and RESET voltages of about 71 and -57 mV, respectively. Thus, the presented devices offer reliable high resistance switching at the lowest reported voltage for printed memristors and prove to be competitive with many conventional nanofabrication-based devices. The presented results show the potential printed memristors technology holds for large-area, low-voltage sensing applications such as electronic skin.

An innovative strategy for Gefitinib quantification in pharmaceutical and plasma samples using a graphene quantum dots-combined gold nanoparticles composite electrochemical sensor.

Aninnovative methodology is proposedfor quantifying Gefitinib(GFT) using an electrochemical sensor constructed from a composite of graphene quantum dots (GQDs) and gold nanoparticles (AuNPs). GQDs were synthesized from graphite, preserving graphene's large surface area and excellent electron transfer capabilities while enhancing dispersibility. The combination of GQDs with AuNPs resulted in an AuNPs@GQDs composite, which was used to construct the sensor. The synthesized nanomaterials were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the electrochemical performance of the sensor was evaluated via cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimized conditions, the sensor displayed a linear calibration curve for GFT detection within the range 0.01 to 10.0 µM, with a limit of detection (LOD) of 0.005 µM (S/N = 3). The sensor demonstrated excellent anti-interference properties and stability in tests using pharmaceutical formulations and plasma samples. Compared to chromatographic methods, the sensor exhibited similaraccuracy and recovery. Its easy fabrication and high sensitivity make it a promising tool for pharmaceutical analysis and clinical therapeutic drug monitoring.

Solidification and crystallographic texture modeling of laser powder bed fusion Ti-6Al-4V using finite difference-monte carlo method

Laser powder bed fusion (LPBF) additive manufacturing makes near-net-shaped parts with reduced material cost and time, rising as a promising technology to fabricate Ti-6Al-4 V, a widely used titanium alloy in aerospace and medical industries. However, LPBF Ti-6Al-4 V parts produced with 67° rotation between layers, a scan strategy commonly used to reduce microstructure and property inhomogeneity, have varying grain morphologies and weak crystallographic textures that change depending on processing parameters. This study predicts LPBF Ti-6Al-4 V solidification at three energy levels using a finite difference-Monte Carlo method and validates the simulations with large-area electron backscatter diffraction (EBSD) scans. The developed model accurately shows that a 〈001〉 texture forms at low energy and a 〈111〉 texture occurs at higher energies parallel to the build direction but with a lower strength than the textures observed from EBSD. A validated and well-established method of combining spatial correlation and general spherical harmonics representation of texture is developed to calculate a difference score between simulations and experiments. The quantitative comparison enables effective fine-tuning of nucleation density (N0) input, which shows a nonlinear relationship with increasing energy level. Future improvements in texture prediction code and a more comprehensive study of N0 with different energy levels will further advance the optimization of LPBF Ti-6Al-4 V components. These developments contribute a novel understanding of crystallographic texture formation in LPBF Ti-6Al-4 V, the development of robust model validation and calibration pipeline methodologies, and provide a platform for mechanical property prediction and process parameter optimization.

Thermally induced Modulation of optoelectronic characteristics In (ZrO2)0.8 doped (CuO) 0.2 screen printed thick films: An Innovative approach to enhanced materials

The Zirconium Dioxide (ZrO2) dopedCopper Oxide (CuO) thick films were fabricated on a glass substrate using the screen printing method, employing sintering temperatures of 500 °C, 550 °C, and 600 °C. The structural characteristics of the doped films were analyzed through Scanning Electron Microscopy (SEM), X-Ray Powder Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). Additionally, the optical properties were assessed via UV–Vis spectroscopy and Photoluminescence (PL) spectroscopy. SEM investigations revealed an increase in nanoparticle grain size and agglomeration as the sintering temperature was raised. XRD results exhibited the polycrystalline nature of the films and an augmented intensity of the monoclinic phase of ZrO2, with a noticeable preferred orientation along the (111) plane, which increased with higher sintering temperatures. FTIR analysis demonstrated slight peak shifts and increased sharpness as the sintering temperature was elevated. UV–Vis spectroscopy indicated a redshift in the reflectance edge, with the band gap transitioning from 3.81 eV (at 500 °C) to 3.65 eV (at 600 °C). These findings were corroborated by PL spectroscopy, which exhibited a redshift in the band emission as the sintering temperature increased. Electrical conductivity displayed semiconducting behavior of the sample. These investigations collectively indicate that elevating the sintering temperature leads to enhanced crystallinity in the films and a reduction in lattice deformations within the composite materials which is crucial for applications in large-area and flexible electronics.

Design and fabrication of reduced graphene oxide (RGO) incorporated NiCo2S4 hybrid composites as electrode materials for high performance supercapacitors

One of the most promising bimetallic sulphides for use in energy-storage systems is NiCo2S4, but further research is required to give it a high reversibility and electrochemical reaction capacity. In this study, we show the rational materials design of an ideal NiCo2S4 nanoparticle as a NiCo2S4/RGO nanocomposite, embedded in a reduced graphene oxide (RGO) matrix. NiCo2S4 nanoparticles, which ranged in size from 20 to 25 nm and were firmly fixed on the surface of RGO sheets, made up the produced composite. As predicted, the produced nanocomposite displayed a high specific surface area, a mesoporous structure, and high conductivity, resulting in a large electroactive area and rapid electron and ion motion. Additionally, we present the advancements in material science, showcasing the NiCo2S4/RGO nanocomposite electrode, which has a long cycle life of 5000 cycles, a high capacitance retention of 85.6 %, and an exceptional specific capacitance of 1505 Fg-1 at 1 Ag-1. A high active-material loading asymmetric supercapacitor serves as an example of the real-world use. The NiCo2S4/RGO nanocomposite exhibits an exceptional 48 Whkg-1 energy density at a power density of 985 Whkg-1, while maintaining a high power density of 7227 Wkg-1 density of 25 Whkg-1. The exceptional stability and electrochemical efficiency of the NiCo2S4/RGO nanocomposite validate that our methodical materials science and technology optimisation in the areas of active substance synthesis, electrode expansion, and device design/fabrication will help advance the development of high-performance supercapacitors in future years.

Development characteristics and controlling mechanism of different microfracture combinations in shale reservoir: A case study of silurian longmaxi formation in Weiyuan area

Fractures in organic-rich shale are important reservoir spaces and seepage channels of shale gas, and they are closely related to the gas-bearing properties of shale. The development characteristics and laws of fractures are of great significance in the exploration and development of shale oil and gas. This study examines organic-rich shales of the Wufeng–Longmaxi Formation in the Weiyuan area of the Sichuan Basin. On the basis of two-dimensional large-area multi-scale combination electron microscopy characterization and digital core platform technology, the development degree and distribution of different fractures are quantitatively characterized. The results show the following. (1) The shale of the Wufeng and Longmaxi formations developed a variety of fractures with different occurrences, sizes, and origins. According to the number and combination relationship between fractures of different occurrences, the shale can be divided into four fracture combination types: horizontal bedding fractures; vein fractures; reticular fractures; and ring fractures. Of these, the horizontal bedding fracture group has the largest number of samples and a higher average fracture surface porosity. (2) The degree of fracture development in the shale is affected by many factors, such as the laminar type, mineral composition, mineral particle size, mineral distribution, and total organic carbon, and the controlling mechanisms of different fracture combination types differ. Factors such as horizontal stratification, high clay mineral content, and uneven mineral particle size are conducive to the development of horizontal bedding joints. (3) Differences in the sedimentary environment affect the variation laws of the vertical fracture combination types and density. The total organic carbon and organic quartz content of the Long111 layer with deeper sedimentary water is higher, and the vein fracture formation is more developed than in other small layers, while the clay mineral content of the Long112 and Long114 layers with shallower sedimentary water is higher and the horizontal layer is more developed; the fracture combination type is dominated by the horizontal bedding fracture combination. At the same time, the fractures at the junction of each layer of the Long11 sub-member are the most developed because sea level rise and fall make the mineral particle size heterogeneity most prominent at the junction of the small layer.

Improving both performance and stability of n-type organic semiconductors by vitamin C.

Organic semiconductors (OSCs) are one of the most promising candidates for flexible, wearable and large-area electronics. However, the development of n-type OSCs has been severely held back due to the poor stability of their most candidates, that is, the intrinsically high reactivity of negatively charged polarons to oxygen and water. Here we demonstrate a general strategy based on vitamin C to stabilize n-type OSCs, remarkably improving the performance and stability of their device, for example, organic field-effect transistors. Vitamin C scavenges reactive oxygen species and inhibits their generation by sacrificial oxidation and non-sacrificial triplet quenching in a cascade process, which not only lastingly prevents molecular structure from oxidation damage but also passivates the latent electron traps to stabilize electron transport. This study presents a way to overcome the long-standing stability problem of n-type OSCs and devices.

Transferable GeSn ribbon photodetectors for high-speed short-wave infrared photonic applications

We experimentally demonstrate a low-cost transfer process of GeSn ribbons to insulating substrates for short-wave infrared (SWIR) sensing/imaging applications. By releasing the original compressive GeSn layer to nearly fully relaxed state GeSn ribbons, the room-temperature spectral response of the photodetector is further extended to 3.2 μm, which can cover the entire SWIR range. Compared with the as-grown GeSn reference photodetectors, the fabricated GeSn ribbon photodetectors have a fivefold improvement in the light-to-dark current ratio, which can improve the detectivity for high-performance photodetection. The transient performance of a GeSn ribbon photodetector is investigated with a rise time of about 40 μs, which exceeds the response time of most GeSn (Ge)-related devices. In addition, this transfer process can be applied on various substrates, making it a versatile technology that can be used for various applications ranging from optoelectronics to large-area electronics. These results provide insightful guidance for the development of low-cost and high-speed SWIR photodetectors based on Sn-containing group IV low-dimensional structures.

Localized Stress Effects on the Single Event Effects Sensitivity of Microelectronics

Understanding the single event effects (SEE) sensitivity of microelectronic devices and circuits is essential for long-term mission success in ionizing radiation environments. SEEs occur when a single ionizing particle strikes a device with enough energy to cause anomalous malfunction or even a catastrophic failure event. It is conventionally viewed as an electrical phenomenon, whereas this study investigates the possible role of multi-physics. Specifically, we show that localized mechanical stress in electronic devices significantly impacts the degree of SEE sensitivity. We present a technique that indirectly maps both electrical and mechanical field localization to spatially map SEE sensitivity without any need for radiation test sources. It is demonstrated on the operational amplifier LM124 under both pristine and stressed conditions. To validate our hypothesis, our experimental results are compared with those obtained from the well-established pulsed laser SEE technique. Excellent agreement between these results supports our hypothesis that SEE susceptibility may have fundamental roots in both electrical and mechanical fields. Therefore, the ability to map the localizations in these fields may indirectly map the SEE sensitivity of large area electronics, which is very expensive in time and resources.

Special Issue on Large-Area and Flexible Electronics, IEEE Electron Devices Magazine [From The Guest Editors

Special Issue on Large-Area and Flexible Electronics, IEEE Electron Devices Magazine [From The Guest Editors

Probing the physics of star formation (ProPStar)

Context. Electron fraction and cosmic-ray ionization rates in star-forming regions are important quantities in astrochemical modeling and are critical to the degree of coupling between neutrals, ions, and electrons, which regulates the dynamics of the magnetic field. However, these are difficult quantities to estimate. Aims. We aim to derive the electron fraction and cosmic-ray ionization rate maps of an active star-forming region. Methods. We combined observations of the nearby NGC 1333 star-forming region carried out with the NOEMA interferometer and IRAM 30 m single dish to generate high spatial dynamic range maps of different molecular transitions. We used the DCO+ and H13CO+ ratio (in addition to complementary data) to estimate the electron fraction and produce cosmic-ray ionization rate maps. Results. We derived the first large-area electron fraction and cosmic-ray ionization rate resolved maps in a star-forming region, with typical values of 10−65 and 10−16.5 s−1, respectively. The maps present clear evidence of enhanced values around embedded young stellar objects (YSOs). This provides strong evidence for locally accelerated cosmic rays. We also found a strong enhancement toward the northwest region in the map that might be related either to an interaction with a bubble or to locally generated cosmic rays by YSOs. We used the typical electron fraction and derived a magnetohydrodynamic (MHD) turbulence dissipation scale of 0.054 pc, which could be tested with future observations. Conclusions. We found a higher cosmic-ray ionization rate compared to the canonical value for N(H2) = 1021−1023 cm−2 of 10−17 s−1 in the region, and it is likely generated by the accreting YSOs. The high value of the electron fraction suggests that new disks will form from gas in the ideal-MHD limit. This indicates that local enhancements of ζ(H2), due to YSOs, should be taken into account in the analysis of clustered star formation.

Design and Characterization of High Quality-Factor Inductors for Wireless Systems Compatible With Flexible Large-Area Electronics

Design and Characterization of High Quality-Factor Inductors for Wireless Systems Compatible With Flexible Large-Area Electronics

A Monolithically Integrable Reconfigurable Antenna Based on Large-Area Electronics

A Monolithically Integrable Reconfigurable Antenna Based on Large-Area Electronics

Bias-stress-stable sub-1.5V oxide thin-film transistors via synergistic composition of sol-gel quaternary high-k oxide dielectrics

A rising demand in reliable, energy-efficient, and large-area electronics, particularly in the realm of sol-gel oxide thin-film transistors (TFTs), has steered research focus away from semiconductor towards dielectrics. However, achieving both bias stability and low-voltage operation remains a significant hurdle. While typical oxide TFTs employ high-dielectric-constant (high-k) dielectrics with lowered film thickness to acquire low-voltage operation, they inevitably suffer from undesired defects at both bulk and interfacial trap sites in dielectric layer. In this study, bias-stress-stable all solution-processed oxide TFTs were demonstrated with operation voltage under 1.5 V via sol-gel quaternary high-k oxide dielectric (Al-Hf-Zr-O, AHZO). In-depth understanding of their individual contributions to dielectric performance leads to the acquisition of optimized composition ratios of AHZO with amorphous feature and outstanding dielectric performance, marked by dielectric constant (k) over 11, leakage current density (Jleak) below 10−5.5 A cm−2, and sturdy breakdown strength (EB) exceeding 5 MV cm−1. By integrating the AHZO with In-Ga-Zn-O (IGZO) layer, we achieved sub 1.5 V TFTs while maintaining excellent bias stability with threshold voltage (VTH) shift lower than 0.20 V for 3600 s. Our findings offer a detailed insight into the realm of multi-component oxide dielectrics, paving the way for miniaturization and reliability in functional devices and sensors.

Multi-project wafers for flexible thin-film electronics by independent foundries

Flexible and large-area electronics rely on thin-film transistors (TFTs) to make displays1–3, large-area image sensors4–6, microprocessors7–11, wearable healthcare patches12–15, digital microfluidics16,17 and more. Although silicon-based complementary metal–oxide–semiconductor (CMOS) chips are manufactured using several dies on a single wafer and the multi-project wafer concept enables the aggregation of various CMOS chip designs within the same die, TFT fabrication is currently lacking a fully verified, universal design approach. This increases the cost and complexity of manufacturing TFT-based flexible electronics, slowing down their integration into more mature applications and limiting the design complexity achievable by foundries. Here we show a stable and high-yield TFT platform for the fabless manufacturing of two mainstream TFT technologies, wafer-based amorphous indium–gallium–zinc oxide and panel-based low-temperature polycrystalline silicon, two key TFT technologies applicable to flexible substrates. We have designed the iconic 6502 microprocessor in both technologies as a use case to demonstrate and expand the multi-project wafer approach. Enabling the foundry model for TFTs, as an analogy of silicon CMOS technologies, can accelerate the growth and development of applications and technologies based on these devices.

Experimental study of flake graphite large-area explosion electron emission cathode performance based on particle size discrepancy

Graphite is the most commonly used large-area cathode material in the high-power vacuum electron device for its long life and good repetitive-frequency performance, but its particle size selection scheme has not been elucidated. Therefore, in the present work, the explosive electron emission properties of flake graphite large area explosive electron emission cathodes with varied particle sizes are studied. The 320 mesh flake graphite has a current delay reduction of 0.2–0.9 ns compared to other samples at the same peak voltage. According to the Murphy–Good equation, the emission performance of each sample during the priming stage was calculated, and the threshold characteristics of 320 mesh flake graphite were significantly better than the other samples. After the space charge limited current is formed, the plasma expansion rate of all samples is 1.2±0.2cm/μs with a difference not exceeding 4% between samples. Our research provides a strong basis for the selection of raw materials for graphite based large area explosive electron emission cathodes and contributes to the development of cross-field high-power vacuum devices.

Selenium-alloyed tellurium oxide for amorphous p-channel transistors.

Compared to polycrystalline semiconductors, amorphous semiconductors offer inherent cost-effective, simple and uniform manufacturing. Traditional amorphous hydrogenated Si falls short in electrical properties, necessitating the exploration of new materials. The creation of high-mobility amorphous n-type metal oxides, such as a-InGaZnO (ref. 1), and their integration into thin-film transistors (TFTs) have propelled advancements in modern large-area electronics and new-generation displays2-8. However, finding comparable p-type counterparts poses notable challenges, impeding the progress of complementary metal-oxide-semiconductor technology and integrated circuits9-11. Here we introduce a pioneering design strategy for amorphous p-type semiconductors, incorporating high-mobility tellurium within an amorphous tellurium suboxide matrix, and demonstrate its use in high-performance, stable p-channel TFTs and complementary circuits. Theoretical analysis unveils a delocalized valence band from tellurium 5p bands with shallow acceptor states, enabling excess hole doping and transport. Selenium alloying suppresses hole concentrations and facilitates the p-orbital connectivity, realizing high-performance p-channel TFTs with an average field-effect hole mobility of around 15 cm2 V-1 s-1 and on/off current ratios of 106-107, along with wafer-scale uniformity and long-term stabilities under bias stress and ambient ageing. This study represents a crucial stride towards establishing commercially viable amorphous p-channel TFT technology and complementary electronics in a low-cost and industry-compatible manner.

Study on the grain evolution of austenitic steel for nuclear power during hot working based on large area EBSD mapping

To address the issue of non-standard grain sizes and difficult control of uniformity in the manufacturing of large, complex-shaped nuclear power pipelines. In this paper, double wedge-shaped samples of X2 CrNiMo 18.12 (CN) austenitic stainless steel were hot deformed at 1000 °C, 1100 °C, and 1180 °C to obtain deformation samples with a gradient strain, and the deformation sample at 1180 °C was subjected to solid solution treatment at 1060 °C × 4 h (water quenching; the measured cooling rate of water cooling was approximately 4400 °C/min). Large-area electron backscattered diffraction mapping technology was used to characterize the 80 mm × 5 mm full-area range of samples. The initiation sequence of various dynamic recrystallization mechanisms and the grain evolution under continuous effective strain conditions at a hot deformation temperature of 1000–1180 °C were investigated. The influence of the hot deformation process parameters on the grains after solid solution treatment was examined, the process interval for the generation of severe mixed grains was determined. The results show that the recrystallization behavior of X2 CrNiMo 18.12 (CN) austenitic stainless steel is mainly determined by a combination of recrystallization mechanisms dominated by discontinuous dynamic recrystallization, supplemented by continuous dynamic recrystallization, twinning-induced dynamic recrystallization, and geometrical dynamic recrystallization during the hot deformation process at 1000–1180 °C. The effective strain intervals of the solid solution sample that produces severely mixed grains are in the range of 0.11–0.22 mm/mm, with the probability of producing severely mixed grains with an effective strain in the range of 0.13–0.14 mm/mm reaching 74%.

A silver nanowires@Prussian blue composite aerogel-based wearable sensor for noninvasive and dynamic monitoring of sweat uric acid

Wearable sweat sensors have shown promise for noninvasive and dynamic monitoring of uric acid (UA), a key indicator in gout management. However, limited UA sensors are reported due to the low concentration in sweat and the inefficient sweat collection. Here, we presented a core–shell aerogel comprised by strongly conductive Ag nanowires (AgNWs) and highly active Prussian blue (PB) to continuously and accurately track sweat UA with the assistance of the microfluidic channel. The AgNWs@PB aerogel possessed a high intrinsic activity, a large active area and ample electron transfer pathways. In addition, the porous structure of the aerogel also provided abundant accessible channels, facilitating the diffusion of electrolyte and UA molecules. Therefore, the AgNWs@PB composite aerogel as a sensing unit demonstrated a high sensitivity of 50.6 µA mM−1 cm−2 towards UA detection, as well as a wide linear range. By integrating the microfluidic channel as a sweat collection unit, we tested the performance of the AgNWs@PB aerogel-based sensor in subjects before and after a purine-rich diet, the results of which were consistent with those detected by a commercial colorimetric assay kit. Furthermore, the as-prepared wearable sensor possessed a satisfactory accuracy in dynamic on-body monitoring of sweat UA within 12 h, which presented a good correlation with blood UA measured with a commercial UA meter. The personalized wearable sweat sensor has a great potential to provide the effective evidence for noninvasive UA control in future.

Highly sensitive hybrid silicon carbonitride piezoresistive sensors enabled by coupling piezoelectric effect

Piezoresistive sensors with high working temperature and excellent sensitivity are highly desired for in-situ measuring pressure in various high temperature applications. Polymer-derived silicon carbonitrides (SiCNs) are a novel class of materials with excellent stability and piezoresistive performance at high temperature, yet challenging to build to meet the rapid growth of large-area electronics. This work demonstrates a thin and highly sensitive hybrid SiCN piezoresistive films enabled by coupling piezoelectric effect of Al-doped ZnO (AZO). The hybrid thin films with the optimal nano-domain phase of SiCN features ultrahigh gauge factors of 6518 to 31,195 upon various compressive stresses, which are significantly larger than those of single-layer SiCN and other existing piezoresistive materials. First-principles calculations reveal that the charges from AZO layer accumulate and move toward the carbon clusters in SiCN under compressive stress, resulting in greater tunneling currents between carbon clusters and more significant piezoresistive effect. Moreover, superior piezoresistive performance of the optimal hybrid system can be characterized by atomic-scale binding energy and band gap change, as formation of the hybrid structure facilitates interfacial charge separation and increases density of electron at conduction band. This work opens an avenue for improving sensitivity of piezoresistive sensors by effective coupling of piezoelectric materials.