Showing papers on "Fabrication published in 2018"

Zeolitic imidazolate framework membranes made by ligand-induced permselectivation

Abstract: Zeolitic imidazolate framework (ZIF) membranes are emerging as a promising energy-efficient separation technology However, their reliable and scalable manufacturing remains a challenge We demonstrate the fabrication of ZIF nanocomposite membranes by means of an all-vapor-phase processing method based on atomic layer deposition (ALD) of ZnO in a porous support followed by ligand-vapor treatment After ALD, the obtained nanocomposite exhibits low flux and is not selective, whereas after ligand-vapor (2-methylimidazole) treatment, it is partially transformed to ZIF and shows stable performance with high mixture separation factor for propylene over propane (an energy-intensive high-volume separation) and high propylene flux Membrane synthesis through ligand-induced permselectivation of a nonselective and impermeable deposit is shown to be simple and highly reproducible and holds promise for scalability

Facile fabrication of high-performance QCM humidity sensor based on layer-by-layer self-assembled polyaniline/graphene oxide nanocomposite film

Abstract: This paper demonstrates a layer-by-layer self-assembled polyaniline (PANI)/graphene oxide (GO) film on quartz crystal microbalance (QCM) for humidity sensing. The morphological and compositional properties of PANI/GO composite films were examined by means of SEM, XRD and FT-IR. The humidity sensing properties of the PANI/GO nanocomposite-based QCM sensor were investigated by exposing to a broad range of 0–97%RH. The experimental results showed that the presented PANI/GO nanocomposite sensor has a high sensitivity, a good repeatability and fast response/recovery characteristics, which surpasses the previous reported counterparts. Moreover, the underlying humidity sensing mechanism of the PANI/GO-based QCM sensor was discussed by using Langmuir adsorption model. This work highlights the unique advantage of layer-by-layer self-assembled route for QCM sensor fabrication.

EGaIn-Assisted Room-Temperature Sintering of Silver Nanoparticles for Stretchable, Inkjet-Printed, Thin-Film Electronics

Abstract: Coating inkjet-printed traces of silver nanoparticle (AgNP) ink with a thin layer of eutectic gallium indium (EGaIn) increases the electrical conductivity by six-orders of magnitude and significantly improves tolerance to tensile strain. This enhancement is achieved through a room-temperature "sintering" process in which the liquid-phase EGaIn alloy binds the AgNP particles (≈100 nm diameter) to form a continuous conductive trace. Ultrathin and hydrographically transferrable electronics are produced by printing traces with a composition of AgNP-Ga-In on a 5 µm-thick temporary tattoo paper. The printed circuit is flexible enough to remain functional when deformed and can support strains above 80% with modest electromechanical coupling (gauge factor ≈1). These mechanically robust thin-film circuits are well suited for transfer to highly curved and nondevelopable 3D surfaces as well as skin and other soft deformable substrates. In contrast to other stretchable tattoo-like electronics, the low-cost processing steps introduced here eliminate the need for cleanroom fabrication and instead requires only a commercial desktop printer. Most significantly, it enables functionalities like "electronic tattoos" and 3D hydrographic transfer that have not been previously reported with EGaIn or EGaIn-based biphasic electronics.

Incorporation of Conductive Materials into Hydrogels for Tissue Engineering Applications

Abstract: In the field of tissue engineering, conductive hydrogels have been the most effective biomaterials to mimic the biological and electrical properties of tissues in the human body. The main advantages of conductive hydrogels include not only their physical properties but also their adequate electrical properties, which provide electrical signals to cells efficiently. However, when introducing a conductive material into a non-conductive hydrogel, a conflicting relationship between the electrical and mechanical properties may develop. This review examines the strengths and weaknesses of the generation of conductive hydrogels using various conductive materials such as metal nanoparticles, carbons, and conductive polymers. The fabrication method of blending, coating, and in situ polymerization is also added. Furthermore, the applications of conductive hydrogel in cardiac tissue engineering, nerve tissue engineering, and bone tissue engineering and skin regeneration are discussed in detail.

Fabrication and characterization of 3D printed BaTiO3/PVDF nanocomposites:

Abstract: This paper presents a fabrication process to enhance homogeneous dispersion of BaTiO3 nanoparticles in polyvinylidene fluoride matrix nanocomposites using fused deposition modeling (FDM) 3D printin...

A Review of Recent Progress in Solid State Fabrication of Composites and Functionally Graded Systems Via Friction Stir Processing

Abstract: Friction stir processing (FSP) is a rapidly emerging newer solid-state technique for composite fabrication. It involves surface modification which in turn enables successful adaptation of surface p...

Coaxial Triboelectric Nanogenerator and Supercapacitor Fiber-Based Self-Charging Power Fabric.

Abstract: Although there has been rapid advancement in wearable electronics, challenges still remain in developing wearable and sustainable power sources with simple fabrication and low cost. In this work, we demonstrate a flexible coaxial fiber by fabricating a one-dimensional triboelectric nanogenerator (TENG) outside and a supercapacitor (SC) inside, which can not only harvest mechanical energy but also store energy in the all-in-one fiber. In such a coaxial fiber, carbon fiber bundles are utilized as the electrode material for the TENG as well as the active and electrode material for the SC. Meanwhile, silicone rubber serves as the separator between the SC and TENG, as the triboelectric material for the TENG, and as the encapsulation material for the whole fiber as well. Moreover, both SC and TENG exhibit good performance and stability, which ensures their long-term use in daily life. Because of the flexibility and durability of the carbon fiber and silicone rubber, the proposed coaxial fibers show great flexibility, which could be further knitted as cloth for sustainably powering wearable electronic devices. This work presents a promising platform for wearable electronics as well as smart textiles.

Metal oxide modified ZnO nanomaterials for biosensor applications

Abstract: Advancing as a biosensing nanotechnology, nanohybrids present a new class of functional materials with high selectivity and sensitivity, enabling integration of nanoscale chemical/biological interactions with biomedical devices. The unique properties of ZnO combined with metal oxide nanostructures were recently demonstrated to be an efficient approach for sensor device fabrication with accurate, real-time and high-throughput biosensing, creating new avenues for diagnosis, disease management and therapeutics. This review article collates recent advances in the modified ZnO nanostructured metal oxide nanohybrids for efficient enzymatic and non-enzymatic biosensor applications. Furthermore, we also discussed future prospects for nanohybrid materials to yield high-performance biosensor devices.

A Metallographic Review of 3D Printing/Additive Manufacturing of Metal and Alloy Products and Components

Abstract: Applications and examples of light and electron micrographs illustrating microstructures, which describe metallurgical phenomena in 3D printing/additive manufacturing of metal and alloy products and components, are presented along with extensive process and processing parameter descriptions and review. Examples include microstructures that have defined turbine blade fabrication and optimization over the past half century, including contemporary electron beam melting fabrication of turbine blade alloys and other novel microstructures and architectures, which result from layer by layer, non-equilibrium melt solidification and epitaxial growth involving powder bed laser and electron beam fabrication. Phase transformations and second-phase formation by rapid cooling in metal and alloy components fabricated by laser and electron beam melting technologies are illustrated for a range of high-temperature materials. Using a range of examples, the advantages of fabricating complex (especially porous) biomedical and related commercial products are described. Prospects for future developments of direct 3D metal and alloy droplet printing, as a key component of the digital factory of the future, are described. This technology is compared with more conventional solidification and powder bed layer building thermo-kinetics, especially in the context of large structure and component fabrication.

Mussel‐Inspired Polymer‐Based Universal Spray Coating for Surface Modification: Fast Fabrication of Antibacterial and Superhydrophobic Surface Coatings

Abstract: DOI: 10.1002/admi.201701254 of dopamine results in the formation of PDA and the deposition of thin polymeric films on nearly any kind of substrate.[9–12] While in nature, the adhesion and solidification of a mussel byssus only requires 3–10 min, a PDA coating requires several hours to form a nanometer-scale coating. To overcome PDA’s inherent drawbacks, various strategies have been developed to accelerate the polymerization by coformulation with additives or through microwave or UV irradiation.[13–16] However, such methods result in a more complicated process and/or contamination of the resulting polymer. The direct attachment of catechol derivatives to multivalent polymer architectures has been reported as an alternative approach to accelerate the coating time and offers novel strategies for fabricating functional polymer coatings.[17–21] Despite the widespread academic interest in musselinspired adhesives, industrial application is rather limited, because most of the functionalization methods involve dipcoating processes. Regarding practical applications, the disadvantage of dip coating is obvious. Dip coating is only suitable for small surface areas, because it is highly dependent on the coating vessel. As a result, many surfaces, such as walls, windscreens, or ships, cannot be coated via dip coating. For larger surface areas, spray coating is clearly superior because it allows the coating of any substrates, combined with high throughput, and low material waste for large surface area deposition. Recently, Lee and co-workers addressed these problems and reported an NaIO4-accelerated, PDA-based spray coating as an alternative to classical dip coating approaches.[22] However, in this case, the slow coating speed was again compensated by the addition of oxidizing agents. Although mussel-inspired coatings can already be obtained by spraying processes, the postmodification without dip coating to achieve a specific function, such as superhydrophobicity or anti-bacterial properties, is still a great challenge. Spray coatings that utilize the rapid coating time of mussel-inspired polymers, and can be postmodified via spray coating process, are still highly limited. Herein, we report a novel mussel-inspired dendritic polyglycerol-based spraycoating strategy (sMI-dPG) for substrate-independent surface modification using a simple spray coater. Various coated substrates were tested regarding their coating mechanism, surface roughness, stability of the coatings, and postmodification Although mussel-inspired surface chemistry is one of the most utilized strategies for surface functionalization, its practical and/or industrial applications are rather limited, because dip coating can only treat small surface areas and is dependent on the coating vessel. Herein a musselinspired, polymer-based, multifunctional, and substrate-independent spray coating strategy for surface modification under extremely mild conditions using mussel-inspired polyglycerol is described. The postfunctionalization of the obtained surface via spray coating with silver nanoparticles results in a nanoparticle embedded coating with excellent, long-term antibacterial properties. Furthermore, a simple method for preparing a superhydrophobic, highly water-repellent coating by coformulation of the mussel-inspired spray coating with hydrophobic nanoparticles is presented.

Roles of Phase Junction in Photocatalysis and Photoelectrocatalysis

Abstract: Photogenerated charge separation is one of the key factors determining the solar energy conversion efficiency in photocatalysis and photoelectrocatalysis Fabrication of phase junction has been dem

15% efficient carbon based planar-heterojunction perovskite solar cells using a TiO2/SnO2 bilayer as the electron transport layer

Abstract: Perovskite solar cells (PSCs) are one of the most promising lab-scale technologies to deliver inexpensive solar electricity. Low-temperature printable carbon counter electrode based planar-heterojunction PSCs are particularly suitable for future large-scale manufacturing, but suffer from an inferior efficiency. Here, we demonstrate a TiO2/SnO2 bilayer as the electron transport layer (ETL) for carbon counter electrode based planar-heterojunction PSCs together with micromolecule Cu-phthalocyanine (CuPc) as the hole transport layer (HTL), yielding a high power conversion efficiency of 15.39% and an excellent stability over 1200 h. The improved performances are attributed to a better energy level transition, a suppressed electron–hole recombination, and a wider depletion region of the TiO2/SnO2 bilayer. Our work represents a great advancement in the fabrication and popularization of carbon counter electrode based PSCs. More importantly, the whole devices are processed at a temperature below 200 °C, providing potential application of PSCs in monolithic tandem devices and paving the way for the development of carbon based flexible PSCs.

High-Performance Vertical Organic Electrochemical Transistors.

Abstract: Organic electrochemical transistors (OECTs) are promising transducers for biointerfacing due to their high transconductance, biocompatibility, and availability in a variety of form factors. Most OECTs reported to date, however, utilize rather large channels, limiting the transistor performance and resulting in a low transistor density. This is typically a consequence of limitations associated with traditional fabrication methods and with 2D substrates. Here, the fabrication and characterization of OECTs with vertically stacked contacts, which overcome these limitations, is reported. The resulting vertical transistors exhibit a reduced footprint, increased intrinsic transconductance of up to 57 mS, and a geometry-normalized transconductance of 814 S m−1. The fabrication process is straightforward and compatible with sensitive organic materials, and allows exceptional control over the transistor channel length. This novel 3D fabrication method is particularly suited for applications where high density is needed, such as in implantable devices.

Ultrahigh Metal-Organic Framework Loading and Flexible Nanofibrous Membranes for Efficient CO2 Capture with Long-Term, Ultrastable Recyclability.

Abstract: In the global transition to a sustainable low-carbon economy, CO2 capture and storage technology plays a key role in reducing emissions Metal–organic frameworks (MOFs) are crystalline materials with ultrahigh porosity, tunable pore size, and rich functionalities, holding the promise for CO2 capture However, the intrinsic fragility and depressed processability of MOF crystals make the fabrication of the flexible MOF nanofibrous membrane (NFM) rather challenging Herein, we demonstrate an effective strategy for the versatile preparation of self-supported and flexible HKUST-1 NFM with ultrahigh HKUST-1 loading (up to 82 wt %) and stable and uniform HKUST-1 growth through the combination of electrospinning, multistep seeded growth, and activation process The loading rate of MOF is the highest level among the reported analogues Significantly, the HKUST-1 NFM exhibits a prominent CO2 adsorption capacity of 39 mmol g–1, good CO2/N2 selectivity, and remarkable recyclability The CO2 capacity retains ∼95% (3

Sewing machine stitching of polyvinylidene fluoride fibers: programmable textile patterns for wearable triboelectric sensors

Abstract: Textile-based sensors can perceive and respond to environmental stimuli in daily life, and hence are critical components of wearable devices. Herein, self-powered triboelectric wearable sensors are fabricated using polyvinylidene fluoride (PVDF) fibers stitched by using a sewing machine. The excellent mechanical properties of dry-jet wet spun PVDF fibers allow the use of a sewing machine to stitch them into diverse programmable textile patterns on various fabric substrates. Such stitches can provide remarkable triboelectric signals when in contact with the opposing surfaces of commercial fabrics, since PVDF has higher electron affinity than other polymers. In addition, PVDF stitch-based triboelectric sensors are flexible, lightweight, wearable, washable, and comfortable. Furthermore, they can detect a broad pressure range (326 Pa to 326 kPa), which is unachievable with conventional textile force sensors, enabling diverse pressure-sensor applications. To demonstrate their use in wearable devices, a smart glove and joint pads are fabricated based on PVDF stitch-based triboelectric sensors. These wearable sensors enable the detection of and distinguishing diverse hand gestures and body motions by generating intrinsic signal patterns for the specific gesture and motions. These sensors also enable real-time self-powered pulse signal monitoring. This work demonstrates a feasible fabrication approach to realize stitched textile sensors using a sewing machine, with many possible e-textile applications.

Directed self-assembly of block copolymers for 7 nanometre FinFET technology and beyond

Abstract: The drive to deliver increasingly powerful and feature-rich integrated circuits has made technology node scaling—the process of reducing transistor dimensions and increasing their density in microchips—a key challenge in the microelectronics industry. Historically, advances in optical lithography patterning have played a central role in allowing this trend to continue. Directed self-assembly of block copolymers is a promising alternative patterning technique that offers sub-lithographic resolution and reduced process complexity. However, the feasibility of applying this approach to the fabrication of critical device layers in future technology nodes has never been verified. Here we compare the use of directed self-assembly and conventional patterning methods in the fabrication of 7 nanometre node FinFETs, using an industrially relevant and high-volume manufacturing-compliant test vehicle. Electrical validation shows comparable device performance, suggesting that directed self-assembly could offer a simplified patterning technique for future semiconductor technology. A comparison between the use of directed self-assembly and conventional patterning methods in the fabrication of 7 nm node FinFETs shows similar device performance, suggesting directed self-assembly could offer a simplified patterning technique for future semiconductor technology nodes.

Superior electromagnetic interference shielding effectiveness and electro-mechanical properties of EMA-IRGO nanocomposites through the in-situ reduction of GO from melt blended EMA-GO composites

Abstract: Fabrication of high-performance electromagnetic interference shielding efficient polymer-graphene nanocomposite is very challenging approach against electromagnetic pollution. Present work emphasizes on the preparation of in-situ reduced graphene oxide (IRGO) through in-situ melt blending of ethylene methyl acrylate (EMA) and graphene oxide (GO) to achieve enhanced shielding efficiency (SE) with controlled electro-mechanical properties of the composites. It involves the reduction mechanism of graphene oxide (GO) within polymer matrices, where efficacy highly influenced by methodologies, polymer chemistry as well as the processing parameters. 5 wt% IRGO loaded nanocomposite showed most improved shielding effectiveness (∼30 dB) over the frequency range of 8.2–12.4 GHz whereas beyond this loading (7 wt%) the re-aggregation of the IRGO platelets cannot be ruled out due to high surface energy of the GO. High abundance of GO in polymer matrix can form better conducting pathways but due to lack of dispersion, the stress transfer during mechanical workout become inferior than other GO loaded composites. This hybrid nanocomposite fashioned 3D conductive network through segregated architecture in the matrix to commit lower conductive percolation with remarkable mechanical strength for its structural integrity. We believe this promising strategy of developing single step EMA-in-situ RGO (EIRGO) nanocomposites with enhanced shielding efficiency and amendable electro-mechanical properties can endorse large-scale production for techno-commercial applications.

Large-Area Preparation of Robust and Transparent Superomniphobic Polymer Films.

Abstract: Transparent superamphiphobic surfaces that repel various liquids have many important applications, but there are critical challenges in their fabrication, such as expensive or complicated fabrication methods, contradictions between the rough surface for superamphiphobicity and smooth surface for transparency, large-area fabrication, etc. Herein, we report a simple and effective strategy for large-scale fabrication of robust, transparent, and superomniphobic polymer films by combined unidirectional rubbing and heating-assisted assembly technology. The obtained polymer films display two kinds of special structures of monolayer ordered re-entrant geometries with either hexagonally triangular protrusions or with hexagonally rectangular micropillars, depending upon the sphere diameters of silica templates, and demonstrate excellent repellence to water and low-surface-tension liquids, as well as high transparency.