Fabrication Of Patterns Research Articles

Study on the influence of constructional parameters on performance of outer layer of thermal protective clothing

A study was designed to determine the effect of basic construction parameters of woven fabric on the thermal protection and comfort performance of the fabric. Thermal protection performance may be calculated using thermal protective performance (TPP) rating. The thermal resistance and water vapour transmission rate (WVTR) of different fabric woven patterns were used to evaluate their comfort performance. The current research is primarily concerned with determining the influence of fabric weaving pattern (plain, twill 2/2, twill 3/1, satin and honeycomb), picks per inch (40, 50 and 60), ply of yarn (2 ply and 3 ply) and type of material (meta aramid and para aramid). We measured the TPP rating of fabrics against 50:50 combination of radiant heat and flame exposures at high level of heat flux (80 ± 2 kW/m2 or ∼2 cal/cm2/s). It was found that the TPP rating of honeycomb weave was very good for the same picks per inch compare to other weaves. The change in ply of yarn (from 3 ply to 2 ply) reduce the TPP rating and areal density of fabric but % loss in areal density is higher compare to TPP rating. Comparing honeycomb woven fabrics to fabrics with different weaving pattern, thermal resistance of honeycomb woven fabrics were good. As the number of fabric picks per inch increased for each type of woven structure examined, the TPP rating and thermal resistance improved, while WVTR declined. The multiple linear regression equation (model) is significant for TPP rating.

Marginal and Internal Gap of Metal Copings Fabricated Using Three Types of Resin Patterns with Subtractive and Additive Technology: An In Vitro Comparison.

This study analyzes the evidence of the marginal discrepancy and internal adaptation of copings fabricated using three types of resin patterns with subtractive (milling) and additive technology (3D printing), as it is not widely reported. Working casts (n = 15) were scanned and patterns were completed using computer-aided designing (CAD). Resin patterns were fabricated using the designed data and divided into three groups according to the method of fabrication of patterns: subtractive technology–CAD milled polymethyl methacrylate resin (Group-PMMA), additive technology [digital light processing (DLP) technique]–acrylonitrile–butadiene–styrene (ABS) patterns (Group-ABS), and polylactic acid (PLA) patterns (Group-PLA). Resin patterns were casted with Cobalt–Chromium (Co–Cr) alloy (lost wax technique). Internal and marginal gaps of the metal copings were analyzed with the replica technique under optical microscope. The Kruskal–Wallis test was used to compare values among the groups, and post hoc multiple tests confirmed the specific differences within the groups. The median marginal gap was least for CAD milled resin patterns, followed by PLA printed resin patterns and ABS printed resin patterns. There were significant differences between Group-PMMA and Group-PLA and Group-ABS (p = 0.0001). There was no significant difference between Group-PLA and Group-ABS (p = 0.899). The median internal gap was least for metal copings fabricated from Group-PLA, followed by Group-ABS and Group-PMMA. The differences were not statistically significant (p = 0.638) for the internal gap. Full metal Co–Cr copings fabricated from the milled PMMA group had a better marginal fit, followed by the PLA and ABS printed groups. Copings fabricated with the PLA printed group had the best internal fit, though the values were statistically insignificant between the groups.

Femtosecond large-area fabrication of multi-phase titanium oxide LIPSS on thin films

The effect of the laser beam scanning velocity and overlap on the large-area fabrication of Laser-Induced Periodic Surface Structures (LIPSS), on 400 nm thickness titanium films, is investigated. The experiments were performed in ambient air with well below ablation threshold laser fluence by using a femtosecond laser at a wavelength of 1030 nm with a pulse duration of 270 fs, operating at a repetition rate of 20 kHz.For this purpose, single-line experiments were performed to study the LIPSS formation process as a function of fs-laser-beam scanning velocity. Based on these results, the fabrication of large-area LIPSS pattern was investigated by unidirectional scanning of the fs-laser beam across the sample surface using different lateral spacing. The results show the formation of LSFL and TLIPSS, with different orientation with respect to the polarization of the incident radiation. The analysis of the chemical composition, by microRaman spectroscopy, indicates the formation of a mixture of TiO2 (anatase phase) and Ti2O3 (rutile phase) for high scanning velocities and TiO2 (rutile phase) for low scanning velocities. The chemical composition, spatial period, and depth of the LIPSS show a clear dependence with the laser-beam scanning velocity and overlap.

Enhanced Assembly of Ag Nanoparticles for Surface-Independent Fabrication of Conductive Patterns

Polymer stamping is a reliable and cost-effective method for producing charged patterned surfaces. However, charge stability is limited, and they discharge steadily while immersed in polar solvents. Here, we applied polyelectrolytes as the stamping medium to increase this stability. Charged line patterns were fabricated by pressing a polydimethylsiloxane (PDMS) stamp covered with a polyethylenimine (PEI) solution against silicon, glass, or polystyrene. Then, the substrate was immersed in a solution of oppositely charged silver nanoparticles. Finally, silver crystallization on the deposited nanoparticle agglomerates was performed to homogenize the conductive surface. Fabricated structures were characterized by conductive AFM, SEM, and electrical measurements. Simulations of the electric field above the pattern and electrostatic deposition of nanoparticles were performed. The presented method allows for the production of high-resolution microstructures composed of parallel 45 mm paths with a width of 10 μm and a thickness below 100 nm. A conductivity of 104 S/m is high enough to keep a commercial LED on.

Fabrication of a Flexible Strain Sensor with High‐Aspect‐Ratio Liquid‐Metal Galinstan

AbstractFlexible electronic devices containing gallium‐based liquid metal (GbLM) play an important role in human–computer interaction and the sensing elements of motion monitoring owing to the intrinsic fluidity and metallic conductivity of the GbLM. High‐aspect‐ratio liquid‐metal patterns have 3D structures, which can increase the heat radiating area of the circuits and the stability of the sensors. However, fabricating high‐aspect‐ratio patterns in high resolution is challenging owing to easy oxidation at the surface layer and the high surface tension of the liquid metal. This study proposes a simple method for the efficient and reproducible fabrication of GbLM patterns. A flexible strain sensor was obtained with high‐aspect‐ratio Galinstan (height/width > 5), linearity (R‐square = 0.9975), stability (ΔR/R0 < 0.8 after 10 000 cycles), and low hysteresis. In addition, the application of the strain sensor in the flexible display and motion measurement of soft hand exoskeletons is demonstrated. The high‐aspect‐ratio liquid‐metal patterns in this work have the potential to extend the application of the presented flexible electronics to the fields of wearable systems and rehabilitation devices.

An In Vitro Assessment of Marginal Accuracies in Copings Fabricated With Two Dissimilar Alloys: An Original Research Study.

Background: Marginal accuracy is one of the serious factors that play a key role in the overall success of prostheses. It is openly associated with marginal activities of microorganisms, which may develop micro-leakage and other problems. Therefore, this in vitro study was conducted to assess marginal accuracies in copings fabricated with two different alloys used in fixed partial dentures.Materials and Methods: Two popularly used metal alloys, Mealloy (nickel-chromium alloy) (Dentsply India Pvt. Ltd., New Delhi, India) and Supranium (nickel-chromium alloy) (Bombay Precision Alloy Inc., Mumbai, India), were studied. Group 1 has 20 copings of Mealloy; group 2 also has 20 copings of Supranium. Blue inlay wax was used for wax pattern fabrication. All copings were cast and made by similar casting techniques. After adequate seating of copings on metal dies, the marginal difference was assessed under a stereomicroscope at typical intensification. All measurements were noticed and converted to the nearest micron. For each coping sample, four measurements were recorded; however, the means of all four surfaces were taken into account for further analysis.Results: All interrelated data was processed by statistical analysis using the Statistical Package for the Social Sciences (SPSS) software version 22.0 (IBM Corp., Armonk, NY, USA). The overall mean marginal gap of the samples of group 1 was higher than group 2. For group 1 coping samples, a maximum mean marginal gap of 43.379 was noticed at the buccal surface of the copings. P-value computation revealed non-significant values (0.60). For group 2 coping samples, a maximum mean marginal gap of 41.218 was found at the buccal surface of the copings. The measured value was 41.218. One-way ANOVA analysis showed that the degree of freedom was 132.13 for cumulative comparison, while it was 2.930 and 6.837 for calculations between groups and within groups, respectively. Two-sample t-test assessments revealed a p-value of 0.001 (significant) for group 1 and a p-value of 0.810 (non-significant) for group 2.Conclusion: The marginal space at the margin of the metal coping and the die was minimum for Supranium and maximum for Mealloy. Also, highly significant values were also identified for the metal samples of Supranium. Additionally, the selection of the perfect metal alloy should be entirely dependent on operator skills and clinical decision-making.

Damage threshold evaluation of thin metallic films exposed to femtosecond laser pulses: The role of material thickness

The employment of femtosecond pulsed lasers has received significant attention due to its capability to facilitate fabrication of precise patterns at the micro- and nano- lengths scales. A key issue for efficient material processing is the accurate determination of the damage threshold that is associated with the laser peak fluence at which minimal damage occurs on the surface of the irradiated solid. Despite a wealth of previous reports that focused on the evaluation of the laser conditions that lead to the onset of damage, the investigation of both the optical and thermal response of thin films of sizes comparable to the optical penetration depth is still an unexplored area. In this report, a detailed theoretical analysis of the impact of various parameters such as the photon energies and material thickness on the damage threshold for various metals (Au, Ag, Cu, Al, Ni, Ti, Cr, Stainless Steel) is investigated. A multiscale physical model is used that correlates the energy absorption, electron excitation, relaxation processes and minimal surface modification. The satisfactory agreement of the theoretical model with some experimental results indicates that the damage threshold evaluation method could represent a systematic approach towards designing efficient laser-based fabrication systems and optimizing the processing outcome for various applications.

A dynamic weaving simulator for filament-level 3D woven fabric modelling

A dynamic textile weaving simulator is established to connect weaving actions to fabric patterns and microstructures. It utilizes the Digital Element Approach (DEA) under the framework of the software package Digital Fabric and Composite Analyser (DFCA). The key components of a Jacquard loom are explicitly modelled utilising the ‘hole/no hole’ principle. Yarn interlacing motion is guided by weaving matrix specified by steps. Shedding, weft insertion, beat-up, and take-up actions are modelled and explained. The inter-fibre contact force, fibre forces (tensile, shear, and bending), and boundary conditions in the weft direction are considered. The weaving process of five cells in the warp direction of a 10-layer 3D orthogonal woven fabric is simulated at the filament level to derive for its microstructure. The results show that the fabric microstructure continues to change after being woven, and the thickness and length of each individual cell decrease with further weaving steps. The microstructures of newly woven cells converge after the weaving of two further cells in the lengthwise direction. The microstructure of the second cell closely matches that of an actual weaved fabric, as evaluated by microscopy images. Penetration occurs between adjacent weft yarns in the same column, which fundamentally changes their microstructure, composition, and material properties. Parametric studies show that the ratio of binder to warp yarn tension determines the fabric thickness. Increases in the take-up length and binder yarn tension lead to a decrease and increase in the reed tension, respectively. This work provides valuable insights into fabric design and manufacture instruction.

Ultralarge Flakes of Ti3C2Tx MXene via Soft Delamination.

Two-dimensional (2D) titanium carbide MXene (Ti3C2Tx) has attracted significant attention due to its combination of properties and great promise for various applications. The size of the 2D sheets is a critical parameter affecting multiple properties of assembled films, fibers and 3D structures. The increased lateral size of MXene flakes can benefit not only their assemblies by improving the interflake contacts and alignment but also fundamental studies at the individual flake level, allowing for facile patterning and investigation of intrinsic physical properties of MXenes. Increasing the average size of the parent MAX phase is one of the strategies previously used to increase the flake size of the resultant MXene. Here, we show that the protocol used for the next step of the synthesis procedure, delamination of multilayer MXene into individual nanosheets, significantly affects the lateral size of the resultant flakes. We developed a soft delamination approach, which prevents fracture of flakes and preserves their size. Combining this approach with the large-grain Ti3AlC2 MAX phase precursor, we achieved individual flakes of up to 40 μm in lateral size. These flakes can be used for patterning multiple contacts and fabrication of field-effect transistors for multiprobe electrical characterization and other measurements. These findings indicate the importance of controlling the delamination process in order to achieve large MXene flakes and improve properties of MXene-based materials and devices.

Fabrication of high precision grating patterns with a compliant nanomanipulator-based femtosecond laser direct writing system

Femtosecond laser direct writing (LDW) is an enabling technique in the fabrication of micro-/nano-scale devices. In a typical LDW system, the high precision motion system serves as the key component for micro-/nano-fabrication. In this paper, a cost-effective LDW system is proposed with a self-developed compliant nanomanipulator. The accuracy of the LDW system with the proposed nanomanipulator is validated through the fabrication of optical grating patterns with micro-scale feature sizes (<3 μm). The optical grating patterns are fabricated with different spacings, scan speeds and laser powers, and surface characterization and quantitative analysis of the samples are conducted. The characterization results demonstrate that the proposed LDW system is capable of controlling the spacing accuracy within 300 nm in a millimetre-level working range. Compared with the existing commercial laser direct writing system of sub-micrometer level motion accuracy, the proposed compliant nanomanipulator-based femtosecond laser direct writing system achieves comparable performances with much lower costs, and it has broad potential applications to sub-micron level laser direct writing fabrication.

Fabrication of metallic patterns on ordinary polymer substrates by laser direct activation and electroless plating

In recent years, the fabrication of metallic patterns on polymer substrates has been given increasing attention because of its wide and important applications in many fields. This paper reported a selective metallization technology on ordinary polymer substrates basing on laser direct activation of copper hydroxyl phosphate [Cu2(OH)PO4] and electroless deposition of copper. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were utilized to characterize the interaction mechanism between nanosecond-pulsed fiber laser (1064 nm wavelength) and Cu2(OH)PO4. It was found that after laser modification and activation by appropriate parameters, the special surface microstructure (e.g., porous sponge-like) appeared and explained the good adhesion strength (the highest grade of 5B) between the copper layer and substrate. At the same time, Cu+ was generated from the Cu2(OH)PO4, adsorbed on the microstructure, and acted as catalytic active centers to realize the selective copper deposition in the laser-activated zone. In addition, the copper layer possessed good selectivity (< 3% error of line space and width) and electrical conductivity (10−6 Ω·cm volume electrical resistivity). By comparison with laser direct structuring (LDS) technology and with palladium chloride as laser sensitive material, this was a more universal and less-cost technical pathway to fabricate planar and/or three dimensional (3D) metallic patterns on more kinds of ordinary polymer substrates.

Multi-Domains in a Single Lattice Formed by DNA Self-Assembly.

Using sequence programmability and the characteristics of self-assembly, DNA has been utilized in the construction of various nanostructures and the placement of specific patterns on lattices. Even though many complex structures and patterns formed by DNA assembly have been reported, the fabrication of multi-domain patterns in a single lattice has rarely been discussed. Multi-domains possessing specifically designed patterns in a single lattice provide the possibility to generate multiple patterns that enhance the pattern density in a given single lattice. Here, we introduce boundaries to construct double- and quadruple-domains with specific patterns in a single lattice and verify them with atomic force microscopy. ON, OFF, and ST (stripe) patterns on a lattice are made of DNA tiles with hairpins (ON), without hairpins (OFF), and alternating DNA tiles without and with hairpins (formed as a stripe, ST). For double- and quadruple-domain lattices, linear and cross boundaries were designed to fabricate two (e.g., ON and OFF, ON and ST, and OFF and ST) and four (OFF, ST, OFF, and ON) different types of patterns in single lattices, respectively. In double-domain lattices, each linear boundary is placed between two different domains. Similarly, four linear boundaries connected with a seed tile (i.e., a cross boundary) can separate four domains in a single lattice in quadruple-domain lattices. Due to the presence of boundaries, the pattern growth directions are different in each domain. The experimentally obtained multi-domain patterns agree well with our design. Lastly, we propose the possibility of the construction of a hexadomain lattice through the mapping from hexagonal to square grids converted by using an axial coordinate system. By proposing a hexadomain lattice design, we anticipate the possibility to extend to higher numbers of multi-domains in a single lattice, thereby further increasing the information density in a given lattice.

Photon‐Pen Writing for Metal Oxide‐Based Versatile Nanosensors

AbstractLow‐temperature processes and simplification of lithographic techniques are key challenges for the fabrication of solution‐processed metal oxide‐based nanodevices. Recent breakthroughs in location‐specific synthetic methodologies involving inkjet printing and photon‐activation routes have enabled lithography‐free and bottom‐up fabrication of such devices. However, a revolutionary strategy to resolve room‐temperature direct fabrication of metal oxide‐based materials still remains elusive. Here, a pertinent route enabling wafer‐scale, location‐specific direct‐writing, termed “photon‐pen writing (PPW),” of functional metal oxide‐based devices is proposed. Using PPW, fabrication of elaborate patterns of metal oxides is demonstrated through location‐specific dechlorination and subsequent oxidation via thermal energy transfer of a focused infrared laser in ambient environment. By tailoring process parameters, precise manipulation of the chemical and structural features of the PPW‐produced metal‐oxide patterns are demonstrated. The versatility of the PPW process by realizing a highly sensitive, stable, uniform, and wafer‐scale nanosensor array for gas and light detection using PPW‐ZnO channel and PPW‐ITO electrodes is demonstrated, with 4.1% of response at 50 ppb NO2 and 2.93 ± 0.23 µA of photocurrent for 0.76 mW cm−2, 254 nm UV light. A new route toward wafer‐scale production of bespoke nanosensor arrays onto single chip for next‐generation nanoelectronics is introduced.

Fabric Color and Design Identification for Vision Impaired

Abstract - The weave pattern (texture) of woven fabric is considered to be an important element in the design and production of high-quality fabric. Traditionally, the recognition of woven fabric has many challenges due to its visual cues made by hand. In addition, methods based on pre-machine learning algorithms depend directly on manual features, which are timeconsuming and erroneous processes. Therefore, the default system is required to be divided into layers of woven fabric to improve productivity. In this paper, we propose an in-depth study model based on data extraction and a transfer method for the separation and recognition of woven fabrics. The model uses a residual network (ResNet), where the fabric texture features are automatically extracted and segmented in a way that ends. We tested the results of our model using test metrics such as accuracy, approximate accuracy, and F1 score. Keywords – Artificial intelligence, color, design, fabric and image processing

Multimodal Fluorescence Switching Materials: One Dye to Have Them All

AbstractOff/on, on/off, and on1/on2 fluorescence switching systems find application in a variety of areas, for each of which a particular dye or dye‐switch tether must be specifically designed and synthesized. Herein it is demonstrated that such tight requirement can be avoided by using easily prepared mixtures of readily available emitters and phase change materials (PCMs). By proper selection of the PCM and, if needed, additives, thermo‐ and photothermoresponsive materials showing all classes of emission switching modes can be prepared from a single dye and without chemical modifications. This strategy can be generalized to distinct emitters and, thanks to the facile and versatile printability of dye–PCM mixtures, it can be used for the fabrication of fluorescent patterns showing complex (photo)thermal responses with direct applicability in sensing and anti‐counterfeiting.

Designing Rewritable Dual-Mode Patterns using a Stretchable Photoresponsive Polymer via Orthogonal Photopatterning.

The fabrication of dual-mode patterns in the same region of a material is a promising approach for high-density information storage, new anti-counterfeiting technologies, and highly secure encryption. However, dual-mode patterns are difficult to achieve because the two patterns in one material may interfere with each other during fabrication and usage. The development of noninterfering dual-mode patterns requires new materials and patterning techniques. Herein, a novel orthogonal photopatterning technique is reported for the fabrication of noninterfering dual-mode patterns on an azopolymer P1. P1 is a unique material that exhibits both photoinduced reversible solid-to-liquid transitions and good stretchability. In the first step of orthogonal photopatterning, patterned photonic structures are fabricated on a P1 film via masked nanoimprinting controlled by photoinduced reversible solid-to-liquid transitions. In the second step, the P1 film is stretched and irradiated with polarized light through a photomask, which generates a chromatic polarization pattern. In particular, the photonic structures and chromatic polarization in the dual-mode pattern are noninterfering. Another feature of dual-mode patterns is that they are rewritable via photo-, thermal, or solution reprocessing, which are useful for recycling and reprogramming. This study opens an avenue for the development of novel materials and techniques for photopatterning.

Amoxicillin-loaded multilayer pullulan-based nanofibers maintain long-term antibacterial properties with tunable release profile for topical skin delivery applications

Unique physiochemical and biological properties of nanofibers along with the choice of a wide variety of materials for both fabrication and tunable release patterns make nanofibers an ideal option for drug delivery. Loading antibacterial agents into nanofibers has attracted great deal of attention. Whilst there are several studies focusing on applying new generations of antibacterial materials, antibiotics are still the gold standard in clinical applications. Therefore, we aimed at introducing antibiotic-loaded nanofiber substrates with potential for topical skin delivery applications, reduced consumption of antibiotics and increased storage time. We applied Amoxicillin (AMX) as a model drug with low solubility and detected the presence of AMX in our nanofibers using FTIR and Raman spectroscopy. AMX-loaded Pullulan (Pull) nanofibers proved to maintain the antibacterial properties of the AMX drug after electrospinning, and to preserve the antibacterial properties for at least 8 months storage. The release trend can be tuned from burst release in mono-layer AMX:Pull nanofibers to sustained release if sandwiching the Pull layer between two hydrophobic electrospun layers (e.g. PLGA biopolymer). The AMX-loaded Pull construct can be considered as a novel nanofibrous solid dispersion of a poorly water-soluble drug for efficient topical application of antibiotics in wound healing and skin treatments.

Single‐Crystal Capacitive Sensors with Micropatterned Electrodes via Space‐Confined Growth of the Metal–Organic Framework HKUST‐1

AbstractThe polyhedral shape and fragile nature of single crystals of metal–organic frameworks (MOFs) hinder their processing using standard microfabrication techniques. As a result, the fabrication of surface patterns and microelectrodes on MOF single crystals is challenging, which limits both the direct electrical interrogation of crystals in research and their integration into optical and electrical devices. Herein, a new strategy to readily fabricate surface‐embossed micropatterns and surface‐embedded gold electrodes on MOF single crystals using a space‐confined, one‐step solvothermal synthesis is demonstrated. This method is based on the confined growth of the MOF crystal around prefabricated metal patterns with different adhesion strengths to the growth surface, producing features as small as 5 µm. As a proof of concept, micropatterns are created on flat single crystals of the MOF HKUST‐1, exhibiting the function as a diffraction grating. Additionally, a single‐crystal HKUST‐1 capacitive gas sensor with surface‐embedded electrodes that serves as a stable platform for the investigation of ethanol diffusion in the MOF pores is fabricated. The space‐confined fabrication strategy is promising for the integration of fragile MOF single crystals in various optical and electrical devices.

A confined-etching strategy for intrinsic anisotropic surface wetting patterning

Anisotropic functional patterned surfaces have shown significant applications in microfluidics, biomedicine and optoelectronics. However, surface patterning relies heavily on high-end apparatuses and expensive moulds/masks and photoresists. Decomposition behaviors of polymers have been widely studied in material science, but as-created chemical and physical structural changes have been rarely considered as an opportunity for wettability manipulation. Here, a facile mask-free confined-etching strategy is reported for intrinsic wettable surface patterning. With printing technology, the surface wetting state is regulated, enabling the chemical etching of setting locations and efficient fabrication of complex patterns. Notably, the created anisotropic patterns can be used for realizing water-responsive information storage and encryption as well as fabricating flexible electrodes. Featuring advantages of simple operation and economic friendliness, this patterning approach brings a bright prospect in developing functional materials with versatile applications.

Guiding cell migration in 3D with high-resolution photografting

Multi-photon lithography (MPL) has proven to be a suitable tool to precisely control the microenvironment of cells in terms of the biochemical and biophysical properties of the hydrogel matrix. In this work, we present a novel method, based on multi-photon photografting of 4,4′-diazido-2,2′-stilbenedisulfonic acid (DSSA), and its capabilities to induce cell alignment, directional cell migration and endothelial sprouting in a gelatin-based hydrogel matrix. DSSA-photografting allows for the fabrication of complex patterns at a high-resolution and is a biocompatible, universally applicable and straightforward process that is comparably fast. We have demonstrated the preferential orientation of human adipose-derived stem cells (hASCs) in response to a photografted pattern. Co-culture spheroids of hASCs and human umbilical vein endothelial cells (HUVECs) have been utilized to study the directional migration of hASCs into the modified regions. Subsequently, we have highlighted the dependence of endothelial sprouting on the presence of hASCs and demonstrated the potential of photografting to control the direction of the sprouts. MPL-induced DSSA-photografting has been established as a promising method to selectively alter the microenvironment of cells.