Fabrication Of Devices Research Articles

A Fenestrated Balloon-Expandable Stent for Aortoiliac Occlusive Disease: Device Fabrication and Feasibility

A Fenestrated Balloon-Expandable Stent for Aortoiliac Occlusive Disease: Device Fabrication and Feasibility

Molecular dynamics simulations of nanoparticle sintering in additive nanomanufacturing: The role of particle size, misorientation angle, material type, and temperature

Additive nanomanufacturing, where nanoparticles (NPs) are generated via laser material ablation and sintered via laser, permits the fabrication of novel electronic devices with adequate flexibility, such as tunable material composition, adjustable sintered state, and a wide selection of substrates—including biodegradable ones—to name a few. The laser energy input often needs to be carefully balanced between achieving adequate sintering and avoiding substrate damage. The sintered state of NPs, a key influencing factor of the resistivity of electronic circuits, depends not only on temperature (the result of laser energy input), but also on NPs size, size ratio, and crystallographic misorientation. While the minuteness of NPs and the transient nature of their sintering (typically within a nanosecond) make direct experimental evaluation of such parameters challenging, the length and time scales are uniquely suitable for molecular dynamic (MD) studies. This study utilizes MD to investigate the sintering characteristics of silver and copper NP doublets at different temperatures and examines the effects of NP size, size ratios, misorientation angle (including both tilt and twist), and material type. A mathematical framework to describe the characteristic sintering time, i.e., time needed for a NP doublet to achieve a given normalized neck size, was proposed based on MD results.

Superb Silk Hydrogels with High Adaptability, Bioactivity, and Versatility Enabled by Photo-Cross-Linking.

The exceptional biocompatibility and adaptability of hydrogels have garnered significant interest in the biomedical field for the fabrication of biomedical devices. However, conventional synthetic hydrogels still exhibit relatively weak and fragile properties. Drawing inspiration from the photosynthesis process, we developed a facile approach to achieve a harmonious combination of superior mechanical properties and efficient preparation of silk fibroin hydrogel through photo-cross-linking technology, accomplished within 60 s. The utilization of riboflavin and H2O2 enabled a sustainable cyclic photo-cross-linking reaction, facilitating the transformation from tyrosine to dityrosine and ultimately contributing to the formation of highly cross-linked hydrogels. These photo-cross-linking hydrogels exhibited excellent elasticity and restorability even after undergoing 1000 cycles of compression. Importantly, our findings presented that hydrogel-encapsulated adipose stem cells possess the ability to stimulate cell proliferation along with stem cell stemness. This was evidenced by the continuous high expression levels of OCT4 and SOX2 over 21 days. Additionally, the utilization of photo-cross-linking hydrogels can be extended to various material molding platforms, including microneedles, microcarriers, and bone screws. Consequently, this study offered a significant approach to fabricating biomedical hydrogels capable of facilitating real-time cell delivery, thereby introducing an innovative avenue for designing silk devices with exceptional machinability and adaptability in biomedical applications.

On the quality of commercial chemical vapour deposited hexagonal boron nitride

The semiconductors industry has put its eyes on two-dimensional (2D) materials produced by chemical vapour deposition (CVD) because they can be grown at the wafer level with small thickness fluctuations, which is necessary to build electronic devices and circuits. However, CVD-grown 2D materials can contain significant amounts of lattice distortions, which degrades the performance at the device level and increases device-to-device variability. Here we statistically analyse the quality of commercially available CVD-grown hexagonal boron nitride (h-BN) from the most popular suppliers. h-BN is of strategic importance because it is one of the few insulating 2D materials, and can be used as anti-scattering substrate and gate dielectric. We find that the leakage current and electrical homogeneity of all commercially available CVD h-BN samples are significantly worse than those of mechanically exfoliated h-BN of similar thickness. Moreover, in most cases the properties of the CVD h-BN samples analysed don’t match the technical specifications given by the suppliers, and the sample-to-sample variability is unsuitable for the reproducible fabrication of capacitors, transistors or memristors in different batches. In the short term, suppliers should try to provide accurate sample specifications matching the properties of the commercialized materials, and researchers should keep such inaccuracies in mind; and in the middle term suppliers should try to reduce the density of defects to enable the fabrication of high-performance devices with high reliability and reproducibility.

Tunable and enhanced thermoelectric properties in transition metal–terpyridine complex based molecular devices

Using the density function theory in combination with the non-equilibrium Green’s function method, the thermoelectric properties of molecular devices based on transition metal–terpyridine complexes are investigated. The results show that their thermoelectric properties can be significantly improved by changing the transition metal and the twist angle of the complex molecule, which is caused by shifting the molecular energy levels, resulting in increased coupling strength between the electrodes and the central molecule. The ZT value of the Ru-containing molecular device can reach up to 0.9 at room temperature, which is three orders of magnitude greater than that of the graphene nanoribbons of the same width. In addition, its thermoelectric performance can be further promoted by suppressing phonon thermal conductance through enhanced isotope scattering. The ZT value of doped devices can reach up to 1.0 in the range of 300–700 K. This work may help in the design and fabrication of transition metal-containing twistable molecular devices and provide effective methods to regulate their thermoelectric properties.

Improving the Stability of Ink-Jet Printed Red QLEDs By Optimizing The Device Fabrication Process

Improving the Stability of Ink-Jet Printed Red QLEDs By Optimizing The Device Fabrication Process

Thinning the Bulk into the Soft: Flexible and Stretchable Germanium Photodetectors

AbstractInorganic semiconductor‐based nano/micro‐membranes are of great interest and can be used as active materials for high‐performance and flexible electronics, due to their unique and stable physical or chemical properties. However, the creation of high‐quality and single‐crystalline semiconducting membranes, particularly germanium (Ge) membranes, remains a significant challenge. In this study, a wet etching approach is developed to thin bulk Ge into soft Ge membranes, which are further used to fabricate flexible and stretchable photodetectors. The thickness of the obtained Ge membranes can be precisely controlled, with a minimum thickness of ≈1.6 µm. Investigations on the surface morphology, surface chemical composition, and Raman shifts indicate that the prepared Ge membranes are single‐crystalline and suitable for the following device fabrication. As an example, flexible and stretchable Ge photodetectors, of which the stretchability is realized by a meshed‐structure design, are demonstrated. Bending (with a minimum radius of 4 mm and a bending cycle of 10 000 times) and stretching (with a stretching strain of up to 10%) tests result in negligible variations in the device performance, revealing good flexibility, and stretchability, as well as the significant potentials of the prepared Ge membranes as candidates for flexible electronics.

Waveguide-Coupled Light Photodetector Based on Two-Dimensional Molybdenum Disulfide.

The integration of transition metal dichalcogenides with photonic structures such as sol-gel SiOx:TiOy optical waveguides (WGs) makes possible the fabrication of photonic devices with the desired characteristics in the visible spectral range. In this study, we propose and experimentally demonstrate a MoS2-based photodetector integrated with a sol-gel SiOx:TiOy WG. Based on the spectroscopic measurements performed for our device, we concluded that the light entering the WG is almost completely channeled out from the WG and absorbed by the MoS2 flake, which is deposited on the WG. Therefore, this device works as a photodetector. The light coupling into the MoS2 region in this device construction is due to the high contrast of refractive index between the van der Waals crystal and the sol-gel WG, which is ∼4 and ∼1.8, respectively. The obtained MoS2-based photodetectors exhibit a photoresponsivity of 0.3 A W-1 (n-type MoS2) and 7.53 mA W-1 (p-type MoS2) at a bias voltage of 2 V. These results reveal great potential in the integration of sol-gel WGs with van der Waals crystals in optoelectronic applications.

Upgrading Polyolefin Plastic Waste into Multifunctional Porous Graphene using Silicone-Assisted Direct Laser Writing.

The widespread use of plastics, especially polyolefin including polyethylene and polypropylene, has led to severe environmental crises. Chemical recycling, a promising solution for extracting value from plastic waste, however, is underutilized due to its complexity. Here, a simple approach, silicone-assisted direct laser writing (SA-DLW) is developed, to upgrade polyolefin plastic waste into multifunctional porous graphene, called laser-induced graphene (LIG). This method involves infiltrating polyolefins with silicone, which retards ablation during the DLW process and supplies additional carbon atoms, as confirmed by experimental and molecular dynamic results. A remarkable conversion yield of 38.3% is achieved. The upgraded LIG exhibited a porous structure and high conductivity, which is utilized for the fabrication of diverse energy and electronic devices with commendable performance. Furthermore, the SA-DLW technique is versatile for upgrading plastic waste in various types and forms. Upgrading plastic waste in the form of fabric has significantly simplified pre-treatment. Finally, a wearable flex sensor is fabricated on the non-woven fabric of a discarded medical mask, which is applied for gesture monitoring. This work offers a simple but effective solution to upgrade plastic waste into valuable products, contributing to the mitigation of environmental challenges posed by plastic pollution.

Geometrical properties of three-dimensional crossed nanowire networks

Three-dimensional interconnected nanowire networks have recently attracted notable attention for the fabrication of new devices for energy harvesting/storage, sensing, catalysis, magnetic and spintronic applications, and for the design of new hardware neuromorphic computing architectures. However, the complex branching of these nanowire networks makes it challenging to investigate these 3D nanostructured systems theoretically. Here, we present a theoretical description and simulations of the geometric properties of these 3D interconnected nanowire networks with selected characteristics. Our analysis reveals that the nanowire segment length between two crossing zones follows an exponential distribution. This suggests that shorter nanowire segments have a more pronounced influence on the nanowire network properties compared to their longer counterparts. Moreover, our observations reveal a homogeneous distribution in the smallest distance between the cores of two crossing nanowires. The results are highly reproducible and unaffected by changes in the nanowire network characteristics. The density of crossing zones and interconnected nanowire segments is found to vary as the square of the nanowire density multiplied by their diameter, further multiplied by a factor dependent on the packing factor. Finally, densities of interconnected segments up to 1013cm−2 can be achieved for 22-µm-thick nanowire networks with high packing factors. This has important implications for neuromorphic computing applications, suggesting that the realization of 1014 interconnections, which corresponds to the approximate number of synaptic connections in the human brain, is achievable with a nanowire network of about 10cm2. Published by the American Physical Society 2024

Advancing Frontiers: A High-Impact Study on the Synthesis, Characterization, and Superior Device Performance of AlCr2O4/MXene Nanocomposites

Abstract Here we present the fabrication of a multilayer resistive memory device (ReRAM) utilizing AlCr2O4/MXene nanocomposite. Comprehensive investigations into the structural and morphological properties of the nanostructures were conducted using various characterization techniques. The fabricated device was tested by measuring I-V characteristics at different current applications which encompasses all previous results. The band gap value for the nanocomposite was reduced to 2.42 eV while that for AlCr2O4 was measured at 3.25 eV via photoluminescence spectrum. Average particle size of the AlCr2O4/MXene nanocomposite was determined to be 25 nm through powder X-ray diffraction analysis. Crystallographic analysis revealed that all crystal peaks conform to the R-3c (167) space group, indicative of a standard hexagonal crystal structure. Energy-dispersive X-ray readings provided further confirmation that all required elements are present in the sample, affirming successful synthesis of the nanocomposite. Notably, the nanocomposite demonstrated exceptional performance as an electrode material in ReRAM, as evidenced by its current-voltage characteristics, making the AlCr2O4/MXene nanocomposite suitable for a wide range of next-generation device applications.

A Systematical Study on Bands and Defects of CsBX3 (B = Pb, Sn, Ge, X = Cl, Br, I) Perovskite Based on First Principles

Metal halide perovskites have attracted considerable attention as novel optoelectronic materials for their excellent optical and electrical properties. Inorganic perovskites (CsPbX3, X = Cl, Br, I) are now viable alternative candidates for third-generation photovoltaic technology because of their high photoelectric conversion efficiency, high carrier mobility, good defect tolerance, simple preparation method and many other advantages. However, the toxicity of lead is problematic for practical implementation. Thus, the fabrication of lead-free perovskite materials and devices has been actively conducted. In this work, the energy band and photoelectric properties of inorganic perovskites CsBX3 (B = Pb, Sn, Ge, X = Cl, Br, I) have been investigated with the first principles calculation, and the possible defect energy levels and their formation energies in different components, in particular, have been systematically studied. The advantages and disadvantages of Sn and Ge as replacement elements for Pb have been demonstrated from the perspective of defects. This study provides an important basis for the study of the properties and applications of lead-free perovskites.

Single-step batch fabrication of microfluidic paper-based analytical devices with a 3D printer and their applications in nanoenzyme-enhanced visual detection of dopamine.

Wax printing is the most widely used method for fabricating microfluidic paper-based analytical devices (μPADs), but it still suffers from disadvantages like discontinuation of wax printers and need for additional equipment for heating treatment. To address these issues, this work initially describes a new class of wax printing approach for high-precision, batch fabrication of μPADs using a household 3D printer. It only involves a one patterning step of printing polyethylene wax into rice paper body. Under optimized parameters, a fabrication resolution, namely the minimum hydrophilic channel width, down to ~189 ± 30 μm could be achieved. In addition, the analytical applicability of such polyethylene wax-patterned μPADs was demonstrated well with enhanced colorimetric detection of dopamine as a model analyte by combining metal-organic framework (MOF) based nanoenzymes (ZIF-67) with a smartphone (for portable quantitative readout). The developed nanosensor could linearly detect dopamine over a concentration range from 10 to 1000 μM, with a detection limit of ca. 2.75 μM (3σ). The recovery results for analyzing several real samples (i.e., pig feed, chicken feed, pork and human serum) were between 91.82 and 102.79%, further validating its good detection accuracy for potential practical applications in food safety and medical diagnosis.

Evaluating Free Thermal Expansion and Glass Transition of Ultrathin Polymer Films on Heated Liquid.

Thermomechanical properties of ultrathin films are crucial for fabrication and use of reliable thin electronic devices. Due to the lack of precise measurement techniques, the thermal deformation behavior of ultrathin films has not yet been clarified. Here, we propose a film on heated liquid (FOHL) method to simultaneously measure the coefficient of thermal expansion (CTE) and glass transition temperature (Tg) of multiple ultrathin polymer films. Free thermal expansion of thin films without substrate interaction can be guaranteed when the thin films are afloat on a liquid surface. To investigate the thermal behavior in a wide temperature range, glycerol is adopted as a thermally stable heating platform owing to its high boiling point of 290 °C. The thin films are transferred onto the glycerol surface from the water surface using the hygroscopic properties of glycerol. Highly accurate and high-throughput thermal strain measurement is achieved using three-dimensional digital image correlation (3D-DIC). The thermomechanical properties of ultrathin polystyrene thin films of various thicknesses (25-400 nm) are precisely characterized utilizing the FOHL and 3D-DIC method.

Validation of Fluid Flow Speed Behavior in Capillary Microchannels Using Additive Manufacturing (SLA Technology)

This research explores fluid flow speed behavior in capillary channels using additive manufacturing, focusing on stereolithography (SLA). It aims to validate microchannels fabricated through SLA for desired fluid flow characteristics, particularly capillary-driven flow. The methodology involves designing, fabricating, and characterizing microchannels via SLA, with improvements such as an air-cleaning step facilitating the production of microchannels ranging from 300 to 1000 µm. Experimental validation assesses fluid flow speed behavior across channels of varying dimensions, evaluating the impact of channel geometry, surface roughness, and manufacturing parameters. The findings affirm the feasibility and efficacy of SLA in producing microchannels with consistent and predictable fluid flow behavior between 300 to 800 µm. This study contributes insights into microfluidic device fabrication techniques and enhances the understanding of fluid dynamics in capillary-driven systems. Overall, it underscores the potential of additive manufacturing, specifically SLA, in offering cost-effective and scalable solutions for microfluidic applications. The validated fluid flow speed behavior in capillary channels suggests new avenues for developing innovative microfluidic devices with improved performance and functionality, marking a significant advancement in the field.

Structurally Tunable Donor-Bridge-Fluorophore Architecture Enables Highly Efficient and Concentration-Independent Narrowband Electroluminescence.

Luminescent materials with narrowband emission have extraordinary significance for developing ultrahigh-definition display. B-N-containing multiple resonance thermally activated delayed fluorescence (MR-TADF) materials are strong contenders. However, their device performances pervasively encounter detrimental aggregation-caused quenching effect that is highly vulnerable to doping concentration, complicating device fabrication. Therefore, constructing highly efficient and concentration-independent MR-TADF emitters is of pragmatic importance for improving device controllability and reproducibility, simplifying manufacturing procedures, and conserving production costs. Here, by systematic arrangement of donor triphenylamine and fluorophore BNCz on distinct bridges, we have developed a spatial confinement strategy with a donor-bridge-fluorophore (D-B-F) architecture. Structurally fine modulation and progressive evolution to construct molecular entities with congested steric hindrance effect that can suppress intermolecular interactions without substantially affecting the luminescence tone of fluorophore BNCz, resulting in highly efficient and concentration-independent narrowband emitters; through isomer engineering, two isomers BN-PCz-TPA and TPA-PCz-BN with different crystal stacking patterns are synthesized by altering the connection mode between triphenylamine and BNCz. As a result, BN-PCz-TPA-based device showcases maximum external quantum efficiency (EQE) of 36.3% with narrow full-width at half-maximum (FWHM) of 27nm at 10 wt% doping concentration. Even at 20 wt% doping concentration, the maximum EQE remains at 32.5% and the emission spectrum is almost unchanged. This article is protected by copyright. All rights reserved.

Designing semiconductor materials and devices in the post-Moore era by tackling computational challenges with data-driven strategies.

In the post-Moore's law era, the progress of electronics relies on discovering superior semiconductor materials and optimizing device fabrication. Computational methods, augmented by emerging data-driven strategies, offer a promising alternative to the traditional trial-and-error approach. In this Perspective, we highlight data-driven computational frameworks for enhancing semiconductor discovery and device development by elaborating on their advances in exploring the materials design space, predicting semiconductor properties and optimizing device fabrication, with a concluding discussion on the challenges and opportunities in these areas.

Flexible Low‐Voltage MXene Floating‐Gate Synaptic Transistor for Neuromorphic Computing and Cognitive Learning

AbstractNeuromorphic computing, inspired by the functionality of biological neural networks, has emerged as a promising paradigm for artificial intelligence applications, especially in the field of flexible electronics. Among the various artificial synaptic devices, floating‐gate synaptic transistors exhibit long‐term synaptic plasticity, but they face the challenge of achieving flexible compatibility. In this work, the first demonstration of a flexible MXene floating‐gate synaptic transistor is reported, which uses multiple layers of MXene as floating gates and MXene nanosheets as charge state modulators. The device shows excellent mechanical flexibility and can operate at low voltages, which improves its suitability for wearable electronic devices. It can also emulate Pavlovian conditioned reflexes under external stress, suggesting its potential for cognitive learning. Moreover, the device is utilized for handwritten digit recognition by simulating a fully connected neural network, achieving a high recognition accuracy of 92.0%. This demonstrates its practical applicability in neuromorphic computing. Besides, this research achieves the patterning of MXene and its application in flexible floating‐gate transistors. It provides a new solution for the integrated fabrication of flexible artificial synaptic devices.

An InGaAs-based Fin-EHBTFET with heterogate and barrier layer for high performance

Abstract This paper proposes a fin electron-hole bilayer tunneling field-effect transistor with a heterogate and an InAlAs barrier layer (HBF-EHBTFET). The heterogate can suppress off-state leakage caused by point tunneling, while the InAlAs barrier layer prevents source-drain direct tunneling, significantly reducing off-state current (Ioff). P-type Gaussian doping can not only solve the problem of inability to generate a hole layer during device fabrication, but also reduce the turn-on voltage of line-tunneling, ultimately increasing on-state current and reducing average subthreshold swing (SSavg). By optimizing parameters of the heterogate and InAlAs barrier layer, HBF-EHBTFET can obtain Ioff of 2.37×10-16 A/μm, SSavg of 17.97 mV/dec, cutoff frequency (fT) of 13.2 GHz, and gain bandwidth product (GBW) of 1.58 GHz. Compared with traditional EHBTFET, HBF-EHBTFET exhibits a reduction in Ioff by four orders of magnitude, a decrease in SSavg by 65.27%, and an increase in fT and GBW by 78.59 % and 93.62 %, respectively.

A Systematic Study of Methyl Carbodithioate Esters as Effective Gold Contact Groups for Single‐Molecule Electronics

There are several binding groups used within molecular electronics for anchoring molecules to metal electrodes (e.g., R–SMe, R–NH2, R–CS2−, R–S−). However, some anchoring groups that bind strongly to electrodes have poor/unknown stability, some have weak electrode coupling, while for some their binding motifs are not well defined. Further binding groups are required to aid molecular design and to achieve a suitable balance in performance across a range of properties. We present an in‐depth investigation into the use of carbodithioate esters as contact groups for single‐molecule conductance measurements, using scanning tunnelling microscopy break junction measurements (STM‐BJ) and detailed surface spectroscopic analysis. We demonstrate that the methyl carbodithioate ester acts as an effective contact for gold electrodes in STM‐BJ measurements. Surface enhanced Raman measurements demonstrate that the C=S functionality remains intact when adsorbed on to gold nanoparticles. A gold(I) complex was also synthesised showing a stable C=Sׄ→AuI interaction from the ester. Comparison with a benzyl thiomethyl ether demonstrates that the C=S moiety significantly contributes to charge transport in single‐molecule junctions. The overall performance of the CS2Me group demonstrates it should be used more extensively and has strong potential for the fabrication of larger area devices with long‐term stability.