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The obtaining of BiFeO3 in the form of a thin film represents a critical issue for its application in electronic devices since this is the required geometry for the integration of this material in microelectronic circuits. There are several techniques for this purpose, from those that use a gas or plasma phase to transport the precursors to the substrate, which would be included within the PVD or CVD techniques (for its acronym Physical Vapor Deposition and Chemical Vapor Deposition) to those that use a phase liquid for this transport, which would be included under the CSD (Chemical Vapor Deposition) techniques. However, among the large number of published papers, there is much controversy about which of them would be most suitable. It has been clearly demonstrated that all of them have the sufficient capacity to produce uniform and homogeneous thin films in thickness throughout the entire substrate, and although in many articles pure BiFeO3 films have been obtained with an exploitable functional response, others have reported the typical drawbacks that usually entails the obtaining this material: appearance of secondary phases, high leakages or a poor functional response. Nevertheless, there is a common aspect in the specialized literature that seems to be in agreement: the first group of techniques require very sophisticated equipment that involves high energy consumption in terms of temperature and pressure (vaccum), while the techniques that are based on solutions are characterized by their higher simplicity. In this context, the purpose of the present review is to summarize the main aspects of each technique in the obtaining of BiFeO3 thin films, from those that are more sophisticated to the simplest and environmentally benevolent ones, in order to provide an easier understanding of them.

A flexible wireless electrocardiogram (ECG) device, integrated with fabric was fabricated for monitoring physiological signals in wearable biomedical applications. The ECG device consists of dry electrodes and a readout module. The dry electrode was fabricated by depositing multi-walled carbon nanotube (MWCNTs)/polydimethylsiloxane (PDMS) composite on a thermoplastic polyurethane (TPU) substrate with screen printed silver (Ag) layer. The readout module with wireless data transmission capability was designed and fabricated on a flexible polyimide substrate. The ECG device was attached to fabric, and its performance was investigated by measuring the ECG signals and comparing them with the results of conventional wet Ag/AgCl electrode. It was observed that the device demonstrated similar performance in terms of signal intensity and correlation when compared to the conventional wet ECG electrodes. Signal-to-noise-ratio (SNR) analysis clearly showed that the dry electrodes with an average SNR of 23.1 dB, perform better than the commercially available Ag/AgCl electrodes (SNR of 21.2 dB). In addition, the capability of the fabric based dry electrodes to measure ECG signals during the physiological activities under exercise motions was studied. This enabled understanding the effect of motion artifacts on the dry electrode response and allowed comparing the obtained ECG signals with the responses of conventional wet ECG electrodes (subjected to similar conditions). It was observed that, even though dry electrodes didn’t use any kind of adhesive gel for measuring the ECG signals, they performed very similar to conventional wet electrodes. The results obtained clearly demonstrated the feasibility of employing fabric based flexible dry ECG electrodes for continuous monitoring of ECG signals in health care applications and can potentially replace the wet electrodes.

Silicon sensors date back to before 1960 with early Hall and piezoresistive devices. These used simple processing that was part of the early integrated circuit (IC) industry. As the IC industry developed, silicon sensors could benefit from the technological advances. As silicon sensors advanced, there came the need for new technologies specifically for microsystems. This led to a range of 3-D structures using micromachining and enabled the development of both sensors and actuators. The integration of sensors with electronics on a single chip also presented new challenges to ensure that both sensor and electronics would function correctly at the end of the processing. In recent years many new technologies and new materials were introduced to enhance the functionality of microsystems. Some sensors are still based on silicon, but others introduce new materials such as carbon nanotubes and graphene. Technologies that have been used in other applications for many years are now integral part of the microsystem technology portfolio. These include screen printing and inkjet printing. Moving more into the third dimension, 3-D printing presents many new opportunities to fabricate novel structures on a silicon substrate. This tutorial focuses on the additional technologies which have been developed to supplement standard IC processes to create MEMS structures.

The increasing throughput of experiments in biomaterials research makes automatic techniques more and more necessary. Among all the characterization methods, microscopy makes fundamental contributions to biomaterials science where precisely focused images are the basis of related research. Although automatic focusing has been widely applied in all kinds of microscopes, defocused images can still be acquired now and then due to factors including background noises of materials and mechanical errors. Herein, we present a deep-learning-based method for the automatic sorting and reconstruction of defocused cell images. First, the defocusing problem is illustrated on a high-throughput cell microarray. Then, a comprehensive dataset of phase-contrast images captured from varied conditions containing multiple cell types, magnifications, and substrate materials is prepared to establish and test our method. We obtain high accuracy of over 0.993 on the dataset using a simple network architecture that requires less than half of the training time compared with the classical ResNetV2 architecture. Moreover, the subcellular-level reconstruction of heavily defocused cell images is achieved with another architecture. The applicability of the established workflow in practice is finally demonstrated on the high-throughput cell microarray. The intelligent workflow does not require a priori knowledge of focusing algorithms, possessing widespread application value in cell experiments concerning high-throughput or time-lapse imaging., Graphical abstract Image 1, Highlights • An automatic workflow for the sorting and reconstruction of defocused images. • Representative data containing varied cells, substrate materials, and magnifications. • Effectiveness of the workflow in high-throughput experiments. • Publicly accessible image datasets and codes.

Biosurfactants are active compounds capable of reducing surface tensions produced by microorganisms, having low toxicity and high biodegradability with possible production from renewable sources. This work aims at presenting a patents search on the biosurfactants production through fermentation, using waste as substrate. The methodology consisted of searching keywords and their blending, using the database of Derwent innovation. The search returned 15 patent registrations filed in the last 8 years. Of the 15, 10 orders are active. After analysis, 3 of the 10 selected patents showed strong adherence to the subject, describing the use of waste as substrates to produce more economical biosurfactants.

A novel method is described for remotely interrogating bulk molecular composition of rocky materials. Laser energy heats a local area on the substrate; flux is optimized to melt and evaporate targe...

Roll-to-roll (R2R) slot-die coating of polymer electrolyte membrane fuel cell (PEMFC) catalyst layers represents a scalable deposition method for producing 10-20 m2·min-1 of catalyst-coated gas diffusion layers (GDLs). This high-throughput production technique will help lower the cost of PEMFC catalyst layers. The uniformity of the wet layer applied by slot die deposition is affected by process parameters such as substrate speed, vacuum pressure applied at the upstream meniscus, gap between the slot die lips and substrate, ink rheology, and other ink and substrate properties. The set of conditions for producing a defect-free coating with a dilute ink typically requires little to no upstream vacuum pressure, so suitable operating conditions can be found easily through trial and error and operator intuition. However, the higher viscosity of more concentrated inks dramatically shifts the range of settings that result in a homogeneous coating to higher vacuum levels, which are harder to find through hit or miss. A predictive model showing the range of operable conditions decreases material wastage inherent in experimentally searching for suitable parameters. In this study, the defect-free coating parameter window is explored experimentally and theoretically for two concentrations of PEFC cathode inks. Both a full capillary hydrodynamic model and a computationally cheaper viscocapillary model successfully predict the experimentally determined coating window within the experimental and model uncertainty limits for inks with 5.3 wt.% and 12.0 wt.% solids ink while maintaining the 0.1 mgPt·cm-2 Pt areal loading target. This paper demonstrates a viable pathway for meeting the $30/kWnet ultimate cost target of the United States Department of Energy (U.S. DOE) Hydrogen Fuel Cells Technologies Office (HFTO). The concentrated ink lowers the thermal energy and capital expenditure (CapEx) budget of the coating process by decreasing the amount of time, energy, and floorspace required for drying the coating.

Polycarbonate (PC) is a durable and transparent optical plastic material commonly used as shatter-resistant alternative to traditional optical glass. Broadband antireflective (AR) coatings with excellent mechanical strength and environmental stability are essential for PC to achieve high light transmission and visual quality. In this work, chloroform vapor treatment was employed to partially embed the silica coating into the PC substrate for adhesion enhancement, which also divided the silica coating layer into bottom and middle layers with different refractive indices. The contact between the silica nanoparticles and the substrate was transformed from “point-contact” to “area-contact”, which enhanced the adhesion between coating and PC substrate. After the deposition of a top layer coating consisted of silica nanoparticles with smaller diameter, a triple-layer refractive index graded AR structure was constructed. Hexamethyldisilazane vapor surface modification was performed to decrease the surface free energy of top coating layer. The triple-layer coating coated PC exhibits superior antireflection property with an average reflectance of only 0.43% over a wide wavelength range of 400–1000 nm. After 100 times of friction or 5 months of exposure to a contaminated environment, the reflectance of coated PC shows barely noticeable difference, indicating its excellent mechanical strength and environmental stability.

The identification of natural organic pigments is important for the conservation, preservation, and historical interpretation of artwork. Due to the fugitive nature of the natural dye components in pigments, their analysis can be complicated by issues such as low concentration and sample complexity. In addition, these pigments are exceedingly diverse, and often represent complex mixtures which are difficult to analyse without a separation step. A particularly challenging class of dyes are the natural yellow polyphenols (i.e. quercetin, rhamnetin, emodin, etc.) Several techniques have been used successfully for the identification of phenolic compounds in a complex mixture, but the majority of these methods require advanced instrumentation and one or more separation steps. In addition, these methods may lack the sensitivity needed to detect minute amounts of pigment remaining in a faded artwork. As a result, there is a need for innovative methods of analysis which can be applied to the interpretation of artworks containing natural dyes. In this work, cost-effective screen printed electrodes (SPEs) modified with silver nanoparticles (AgNP) were used to amplify the SERS response of phenolic compounds. In particular, application of a voltage to the SERS substrate allows for a fine-tuning of the SERS signal, and in addition was successfully used to separately characterize dye components in two natural yellow lake pigments, Reseda Lake and Stil de Grain. To our knowledge, this work represents the first electrochemical surface-enhanced Raman spectroscopy (EC-SERS) study of polyphenolic dye mixtures, and is the first application of EC-SERS for natural pigment analysis. This work establishes EC-SERS as a useful technique for the identification of complex natural dyes which may find potential use in the cultural heritage realm.

In this study, a novel coupling structure based on half‐mode substrate‐integrated waveguide (HMSIW) is proposed with a small size and broad bandwidth. The HMSIW coupler is realised by connecting their equivalent magnetic walls with metal strips, which avoids exposing the semi‐enclosed magnetic walls outside. Hence, it has greater anti‐interference capability than the existing HMSIW couplers. The directional coupling principle is introduced by analysing the proposed single connecting strip coupler. In order to lower return loss and higher isolation, a 3 dB directional coupler working from 10.8 to 16.8 GHz is designed with two connecting strips. Finally, a six‐port circuit is achieved by utilising this compact 3 dB directional coupler. Furthermore, a broadband HMSIW power divider is optimised to satisfy the performance of this six‐port circuit. The proposed coupler with metal strips helps to increase bandwidth and reduce size, which makes it more applicable to demanding systems with complex requirements such as detecting and transceiver systems. The 3 dB coupler and six‐port circuit are fabricated and measured. The measured results are in accordance with the simulated data.

Dyes are the substances that are used to impart color to textiles, fabrics, leather, or other materials. These are such colored substances that bond chemically to any substrate to which they are being applied. Any fabric’s attraction is its color. Regardless of how great its development is, if not colored as expected to be, it will fall flat as a business material. Therefore, the turn of events and utilization of manufactured colors for texture coloring has formed into a multibillion-dollar industry. In actual, humanity has known about the specialty of adding color to texture since 3500 BCE. They look attractive after coloring but their waste is toxic to the environment. Scientists, then again, are worried about their toxic nature. Engineered colors adversely affect all parts of life. Dyes have harmful effects upon water bodies as much waste from industries goes to rivers, lakes, etc. which ultimately causes water pollution. So, quick prevention measures need to be taken for saving the environment from dye waste. This paper likewise tells the classification and toxicity of some synthetic dyes and provides a brief idea about present methods for the removal of dyes from the environment which includes adsorption, chemical precipitation, inorganic materials usage, membrane filtration, and ion exchange. It also provides aspects affecting adsorption of color like arrangement pH, adsorbent portion, and temperature.

Blown powder directed energy deposition of SS316L powder is carried out on various substrate surface conditions of SS304 such as cleaned, sand blasted, milled, oily, cold galvanised and painted to study their influence on the process. High-speed imaging is used for process observation and the deposited tracks are analysed qualitatively and quantitatively using surface images, cross sectional macrographs and x-ray images. Frames from high-speed imaging reveal the removal of additional material from the substrate surface such as paint and oil. The stages involved in their removal: peeling and evaporation are presented. EDS analysis showed that no additional elements other than powder and substrate material are found in the track volume. The quantitative results for all specimens show that the surface conditions had minor influences on track width, track height, wetting angle, dilution and deposited cross sectional area. Defects such as porosity, inclusions and cracking were not observed related to the surface conditions. These findings could significantly reduce processing time by skipping the cleaning step before directed energy deposition such as laser cladding or repair in industrial applications.

Here, an extremely cost-effective and simple method is proposed in order to morphologically self-transform stainless steel from a completely inactive material to a fully operational, nanowire-structured, 3D anode material for lithium ion batteries. The reagentless process of a single heating step of the plain stainless steel in a partially reducing atmosphere, converts the stainless steel into an active anode via metal-selective oxidation, creating vast spinel-structured nanowires directly from the electrochemically inactive surface. The simple process allows the complete utilization of the 3D mesh structure as the electrochemically-active spinel nanowires greatly enhance the active surface area. The novel material and architecture exhibits high capacities (~1000 mAh/g after ~400 cycles), long cycle life (>1100 cycles) and fast rate performance (>2C). Simple modulation of the substrate can result in very high areal and volumetric capacities. Thus, areal capacities greater than 10 mAh/cm2 and volumetric capacities greater than 1400 mAh/cm3 can be achieved. Using the proposed method, the potential reduction in cost from the use of battery-grade graphite is at least an order of magnitude, with considerable better results achieved in terms of capacity and intrinsic structural benefits of the substrate, which include direct contact of the active material with the current collector, lack of delamination and binder-free performance. This work provides a new paradigm and a key step in the long route to replace the commercial graphite anode as the next-generation anode material.

The microstrip antenna mainly consists of four modules. They are ground plane, dielectric substrate, feed line and radiating patch. Most of time, the patch, feed line and ground plane use copper material whereas the substrate will take different dielectric materials. Hence, the antenna substrate material plays a major role on antenna performance characteristics. This paper presents different types of antenna substrate materials available and also describes the effect of FR4 substrate material on a compact Luna shaped high gain UWB antenna in the frequencies starting from 3.1 GHz to 10.6 GHz. So, this design is produced on the FR4 substrate of size 20 × 18 × 1.6 mm3. It results in S11 ≤ -10 dB from 3.09 GHz to 11.02 GHz. It observes highest radiation efficiency as 98% at 8.6 GHz and maximum peak gain as 5.68dBi at 9.7 GHz. The study of fractional grounds with different types of slots is also shown. The simulation software used is ANSYS HFSS. The simulated and measured return loss is compared.

This paper investigates the Digital Glass Forming (DGF) process for printing transparent fully-dense borosilicate structures. In this process, glass is deposited by laser heating the intersection of a continuously fed filament with the workpiece. The laser provides control of the surface temperature but thermal diffusion through a low-thermal conductivity filament limits deposition rates. Introducing the laser from the side is shown to deliver energy directly to the glass that will form the interface with the workpiece. This permits the filament to deform the molten zone and significantly improves deposition rates.

Wearable sensors have been widely studied because of their small size, light weight, and potential for the noninvasive tracking and monitoring of human physiological information. Wearable flexible sensors generally consist of two parts: a flexible substrate in contact with the skin and a signal processing module. At present, wearable electronics cover many fields, such as machinery, physics, chemistry, materials science, and biomedicine. The design concept and selection of materials are very important to the function of a sensor. In this review, we summarize the latest developments in flexible materials for wearable sensors, including developments in flexible materials, electrode materials, and new flexible biodegradable materials, and describe the important role of innovation in material and sensor design in the development of wearable flexible sensors. Strategies and challenges related to the improvement of the performances of wearable flexible sensors, as well as the development prospects of wearable devices based on flexible materials, are also discussed.

The surface coating is a cost-effective way of fabrication of different materials that need the preferred surface properties such as corrosion, wear, erosion, and thermal resistance. Research is still going on over years to reduce erosion, wear, and corrosion resistance or by improving these properties in the current material by surface coating. This study sum up the current hi-tech progress of coatings on different materials and an attempt has been made to review the work of some researchers who led experimental studies of different surface coatings on different substrate materials by different coating methods. Results obtained by the surface coating and effects of coating on the properties of the substrates have been discussed.

Public safety and environmental monitoring are of great significance to maintain human health. Therefore, a simple and effective strategy for preparing the substrate layer of a film-based fluorescent sensor is developed by a nanomesh scaffold technology. The limit of detection of the nanomesh scaffold-modified sensor ranges from 4.8 ppb to 3750 ppm. This can provide an effective method for detecting potential biological warfare agent, 2,6-dicarboxyridine.

Two-dimensional (2D) materials have received extensive attention in the fields of electronics, optoelectronics, and magnetic devices attributed to their unique electronic structures and physical properties. The application of strain is a simple and effective strategy to change the lattice structure of 2D materials thus modulating their physical properties, which further facilitate their applications in carrier mobility transistor, magnetic sensor, single-photon emitter etc. In this short review, we focus on the strain applied via substrate engineering. Firstly, the relationship between the strain and physical properties has been summarized. Secondly, the methods for achieving substrate engineering-induced strain have been demonstrated. Finally, the latest applications of strained 2D materials have been introduced. In addition, the future challenges and development prospects of strain-modulated 2D materials have also been proposed.

Supercapacitor electrode slurry is prepared for mass production by mixing activated carbon powder, conductive agent, and binder, which is then deposited on a substrate using the doctor-blade method. Polyvinylidene fluoride (PVDF) and 1-methyl-2-pyrrolidone (NMP) are used as binder and solvent, respectively, to form the electrode slurry on a metal substrate. In this study, ethyl cellulose (EC) is evaluated as a binder to prepare an electrode on an indium-tin-oxide (ITO) substrate obtaining transparent supercapacitors. Terpineol and isopropyl alcohol (IPA) are compared as suitable solvents for the EC binder. When terpineol is employed as a solvent, the conductive agent is uniformly deposited around the activated carbon powder. An electrode prepared using EC and terpineol exhibits slightly lower specific capacitance and rate performance than that using conventional PVDF and NMP. However, the electrode prepared using EC and terpineol securely adheres to the electrode components, resulting in a robust electrode. In contrast, an electrode prepared using EC and IPA exhibits high charge transfer resistance at the interface of the electrode/electrolyte, leading to a low specific capacitance and rate performance. Thus, ecofriendly EC and terpineol can substitute the conventional PVDF and NMP for depositing activated carbon powder on an ITO substrate, while improving the specific capacitance of manufactured electrodes.

This fundamental research aims to analyse the effect of heat transfer coefficients, plasticity model of evolved material properties and simplified meshing strategy on substrate deformation induced by wire arc additive manufacturing (WAAM) process with dissimilar materials based on experiment and numerical simulation. Throughout the experiment, stainless steel wire SS316L was used as feedstock to build a five-layer and three-string component on an 8-mm-thick low carbon steel S235 as substrate plate by means of a robotic GMAW system with pure argon as shielding gas and diagonal clamping. In order to define heat transfer coefficients by adjusting simulation to experimental results, the transient thermal distribution was to be measured at specific points located in the component layer using Type K thermocouple inserted during the process and on the substrate implanted beforehand. For modelling and simulation, a non-linear thermo-mechanical method was applied in which the component was modelled using rectangular element shape with optimized hexagonal mesh size obtained through sensitivity analysis in accordance to actual specimen geometry and clamping condition. Non-linear isotropic hardening rule with von Mises yield criterion and temperature-dependent material properties was implemented into the simulation which were generated by means of advanced material modelling software based on elemental composition of evolved component characterized using SEM/EDX. For numerical and experimental validation purpose, substrate deformation was measured using coordinate measurement machine before and after the process. It can be concluded that the result of the computed substrate deformation showed an acceptable agreement compared to experiment within the range of error between 0.5 and 27.5% at each specific measurement points and 10.1% as average single error. This basic investigation can be enhanced in the case where cost-effective WAAM application with dissimilar materials towards single-piece substrate component is concerned.

A comprehensive study of developing a novel printing system using a low-cost open-source printer for fully 3D printing frequency selective surface is presented in this paper. The novel printing setup employs a low-cost printer to print a plastic based filament and a conductive silver ink paste simultaneously. As there were no printers available in the market for this application, the open-source Fused Filament Fabrication (FFF) printer was modified to accommodate two extruders mounted on the same extruder carriage. Techcon TS250 air pressure dispenser was employed for the extrusion of silver ink. Extension pieces for the extruder carriage were also 3D printed using a Fused Deposition Modelling (FDM) printer to reduce the production costs. A bandstop FSS comprising of square loop elements was designed to demonstrate the full fabrication. The FSS operated at a central frequency of 2.55 GHz and provided a good angle of response with wide bandwidths. Surface profiles of the printed FSS and substrate demonstrate the reliable fabrication of the FSS design. This full 3D printing method provides an economical, eco-friendly, swift, reliable, and viable substitute for the fabrication of FSS designs that could be highly customised in terms of fabricating three-dimensional FSS designs with reliable performances. The designs can be printed and deployed to reduce the drop in signal within an enclosed environment.

With the rapid development of the electronics industry, electronic products based on silicon and glass substrates electronic products will gradually be unable to meet the rising demand. Flexibility, environmental protection, and low costs are important for the development of electronic products. In this study, an efficient and low-cost method for preparing silver electrode structures by direct writing on paper has been demonstrated. Based on this method, a flexible paper-based sensor was prepared. The liquid printing ink used mainly comprises a precursor liquid without pre-prepared nanomaterials. The precursor liquid is transparent with good fluidity. Simple direct writing technology was used to write on the paper substrate using the precursor ink. When the direct-writing paper substrate was subsequently heated, silver nanostructures precipitated from the precursor liquid ink onto the paper substrate. The effect of different temperatures on the formation of the silver nanostructures and the influence of different direct writing processes on the structures were studied. Finally, a paper-based flexible sensor was prepared for finger-bending signal detection. The method is simple to operate and low in cost and can be used for the preparation of environment-friendly paper-based devices.

This paper presents a novel die-level, rePlaceable INtegrated CHiplet (PINCH) assembly using a socketed platform. To enable the replaceability of this tightly-integrated system, the appropriate set of enabling technologies is required. To this end, the PINCH assembly incorporates a non-permanent, off-chip interconnection system via Compressible MicroInterconnects (CMIs) and a non-permanent self-alignment technology using Positive-Self-Alignment Structures (PSAS) in a PSAS-to-PSAS configuration. As the PSAS-to-PSAS self-alignment technology is substrate agnostic, the PINCH assembly can also incorporate heterogeneous integrated systems. This paper discusses this PINCH assembly and it provides a design analysis for building this socketed system. The fabrication of all the components of the PINCH assembly (e.g., chiplet, interposer) is then performed, followed by a manual assembly process using the PSAS-to-PSAS self-alignment technology. Four-point resistance of the 150 μm pitch and 200 μm pitch CMIs are then measured after the socket is secured into the socket base of the PINCH assembly.

A switched‐line substrate integrated waveguide 1‐bit phase shifter is designed and measured at 28 GHz. Reconfigurability is achieved through a set of floating metallized vias whose connection to the waveguide top and bottom layers can be controlled using PIN diodes. The reconfigurable vias are used to dynamically create alternative paths having different phase delays. A three‐metal layer printed circuit board stack‐up is employed to fully integrate the diode biasing network and to ease the routing of the bias signal. The high integration of the proposed configuration makes it well suited for the implementation of reconfigurable Butler matrices. The phase shift offset between the two states of this digital 1‐bit phase shifter equals 262° at 28 GHz, leading to a measured figure of merit of 161°/dB, and input 1‐dB compression point over 20 dBm. The total area is 13.72 × 10.9 mm without feeding lines and bias.

The objective of this article is to devise a cost-effective, conformal, polarization-insensitive, and broadband metamaterial absorber for X-band applications. A periodic subwavelength conducting grid pattern is printed over flexible papers in a multi-layered fashion to achieve the broadband behavior. A silver nanoparticle incorporated inkjet printing technique is employed that does not require any post-processing such as sintering. The absorber is eco-friendly and suitable for rapid mass production at a low-cost. Moreover, the printed patterns do not crack when bent or applied over curved surfaces. The characteristics, working principle, and equivalent circuit of the absorber are described. The absorber is designed on a 1.06 mm (0.03 $\mathbf {{\lambda} _{\it l}}$ at the lowest working frequency) ultrathin substrate. It exhibits more than 90% absorptivity from 8.43 to 10.38 GHz for all angles of polarization with wide angular stability up to 45 $\text{\boldmath $^\circ $}$ . The flexibility and broadband feature is also confirmed by the experimental measurement of the fabricated prototype.

Noble metal nanoparticles have special properties in optical, electronic, and physical chemistry due to their high surface area and volume. With the development of electronic printing technology, inkjet printing has gradually replaced traditional spin coating and blade coating, since it leads to more material savings and a faster batch production, and the pattern can be easily designed by a computer. In this study, Ag nanoparticles were prepared by a chemical reduction method. Non-toxic, environment-friendly agents were selected to fabricate a single-shape, uniform-size, crystal-form, and monodisperse product. The effects of the reducing agent ratio and the stabilizer ratio on the size, shape, and stability of the nanoparticles are discussed. The silver nanoparticles were characterized by an ultraviolet-visible spectrophotometer (UV-vis) and a transmission electron microscope (TEM). In addition, in order to prepare conductive ink that can stably disperse for a long time and that can be applied to inkjet printing on a PET flexible substrate at a lower sintering temperature, a sintering agent and a commercial surfactant were added. The experimental results show that the best addition ratio of the precursor to the reducing agent and the stabilizer is 1:6:1. The conductive silver ink was printed and treated by a70 mM NaCl solution, and the electric resistivity was 5.17×10−4 Ω· cm.

Digital light processing (DLP)-based ceramic stereolithography has attracted significant attentions due to the high printing speed and high dimensional accuracy of DLP printers. However, undesired dropping of unfinished ceramic parts during printing, owing to inadequate adhesion between the first cured layer and the substrate of the building platform, still remains a challenge. In this study, the relationship between the adhesion properties of ultraviolet (UV)-curable alumina (α-Al2O3) suspensions and the functionalities and structures of UV-curable acrylate monomers was investigated. With an increase in the proportions of monofunctional monomers, the adhesion abilities of UV-curable alumina suspensions enhanced because of reduced volume shrinkage, however, inferior curing performances were observed due to a decrease in the double bond densities. Furthermore, the large-volume branched chain structures in monofunctional monomers and ethyoxyl groups in polyfunctional monomers effectively decreased the volume contraction, improving the adhesion performances of UV-curable alumina suspensions and facilitating the conversion of double bonds to provide excellent curing properties, further guaranteeing strong adhesion of these suspensions to the substrate.

This paper presents a novel substrate-agnostic self-alignment technology with submicron alignment accuracy targeted for heterogeneous integrated systems. This self-alignment technology, referred to as PSAS-to-PSAS self-alignment, incorporates positive self-alignment structures (PSAS) or reflowed patterned photoresist structures that couple with other PSAS to achieve submicron alignment accuracy without the need for an advanced placement tool. The PSAS-to-PSAS self-alignment technology is non-substrate invasive and hence does not consume any substrate real estate. These PSAS structures can also be fabricated atop any material substrate; hence, this technology is suitable for heterogeneous integrated systems where a variety of different material substrates may be incorporated. This paper discusses this PSAS-to-PSAS self-alignment technology and it provides a design analysis relating the inter-substrate gap between aligning substrates and the dimensions of the PSAS structures. The fabrication of the PSAS on two separate substrates is then performed, followed by a manual assembly process to couple the PSAS on one substrate to the PSAS on the other aligning substrate. Vernier scales are incorporated on these substrates to measure the misalignment between said substrates; submicron alignment is recorded. As these structures may also enable a non-permanent system configuration, alignment repeatability measurements were also performed.

This paper proposes three balanced multiple‐layer dual‐mode substrate integrated waveguide (SIW) bandpass filters. The first balanced filter has two substrate layers, and two pairs of balanced feeding ports are located on the upper substrate layer. The lower and upper dual‐mode SIW cavities are coupled by two crossed slots in the middle metal layer. The second balanced filter has two substrate layers, and two pairs of balanced feeding ports locate parallelly on the upper and lower substrate layers, respectively. The third balanced filter has three substrate layers, and two pairs of balanced feeding ports locate vertically on the upper and lower substrate layers, respectively. The proposed three balanced filters can produce three, two and one finite‐transmission zeros (FTZs), respectively. Characteristics of the proposed multiple‐layer SIW filters with controllable FTZs' locations are analysed in detail. For the demonstration, some design examples with the centre frequency of 7.5 GHz and bandwidth of 240 MHz are presented, and three design examples are fabricated to verify the performance of the proposed balanced filters. The measured results agree well with simulated ones.

The dependences of the thermal radiation (TR) lines contrast and amplitude of the systems (photonic structure)/substrate on the optical characteristics of both the photonic structure and the substrate have been investigated theoretically and experimentally. As it has been ascertained, these dependences demonstrate non-monotonic behavior, and the characteristics of the system TR can both increase and decrease depending on the ratio of individual optical parameters of the system components. The results of theoretical research were confirmed by experimental studies of TR systems Ge/GaAs, Ge/GaAs/Al, GaAs/Au and GaAs/(opaque substrate). The results of the research can be used in the development of narrow-band emitters for the middle and far IR range, which can be applied in the optical infrared devices for a wide range of applications.

Discontinuous dewetting is an attractive technique that can produce droplet array of specific volume, geometry and at predefined location on a substrate. Droplet array has great potential in bioanalysis such as high-throughput live cell screening, digital PCR, and drug candidates. Here, we propose a self-dispersing droplet array generation method, which has advantages of low cost, simple operation, and easy large-area production ability. Droplet array of specific volumes was generated on a polymethyl methacrylate (PMMA) substrate using a simple reusable polyimide (PI) adhesive mask. Experiment shows that the generated droplet array can be used to successfully capture single particles which obeys Poisson distribution in a high-throughput manner. Furthermore, a droplet-array sandwiching chip was created based on the self-dispersion method for rapid detection of human serum albumin (HSA) at wide range of 183-11,712 μg/mL with low reagent consumption of 2.2 μL, demonstrating its potential applications in convenient high-throughput bioanalysis and bioassays.

Liquid-infused slippery surfaces have replaced structural superhydrophobic surfaces in a plethora of emerging applications, hallmarked by their favorable self-healing and liquid-repelling characteristics. Their ease of fabrication on different types of materials and increasing demand in various industrial applications have triggered research interests targeted toward developing an environmental-friendly, flexible, and frugal substrate as the underlying structural and functional backbone. Although many expensive polymers such as polytetrafluoroethylene have so far been used for their fabrication, these are constrained by their compromised flexibility and non-ecofriendliness due to the use of fluorine. Here, we explore the development and deployment of a biodegradable, recyclable, flexible, and an economically viable material in the form of a paper matrix for fabricating liquid-infused slippery interfaces for prolonged usage. We show by controlled experiments that a simple silanization followed by an oil infusion protocol imparts an inherent slipperiness (low contact angle hysteresis and low tilting angle for sliding) to the droplet motion on the paper substrate and provides favorable anti-icing characteristics, albeit keeping the paper microstructures unaltered. This ensures concomitant hydrophobicity, water adhesion, and capillarity for low surface tension fluids, such as mustard oil, with an implicit role played by the paper pore size distribution toward retaining a stable layer of the infused oil. With demonstrated supreme anti-icing characteristics, these results open up new possibilities of realizing high-throughput paper-based substrates for a wide variety of applications ranging from biomedical unit operations to droplet-based digital microfluidics.

A thin layer of hydroxyapatite (HAp) coating has been developed on Ti6Al4V substrates using a dip-coating process. An intermediate layer of shellac (natural resin) was applied in between the substrate and the coating film to improve the adhesion strength without the need for any secondary annealing process. The adhesion strength was measured as 7.14 MPa. The surface of the developed coating was characterized using a scanning electron microscope. The total coating thickness was found to be 30 microns, and the surface roughness parameters were measured as 0.93 μm (Ra), 1.17 μm (Rq), and 6.67 μm (Rz). The dip-coated samples were also subjected to dissolution behavior study and in vitro study. The measured parameters of the coating suggest the use of this method as an alternative to other expensive and temperature-dependent coating methods for producing HAp coating with better adhesion strength.

All-polymer solar cells (all-PSCs) trigger enormous commercial applications, and great progress has been made in recent years. However, from small-area devices to large-area modules, the poor adoption of the materials for printing methods and the large efficiency loss are still great challenges. Herein, three novel non-conjugated polymer acceptors (PTH-Y, PTClm-Yand PTClo-Y) are developed for all-PSCs. It can be found that non-conjugated polymer acceptors can effectively minimize the technique and efficiency gaps between small-area spin-coating and large-area blade-printing method, which can facilitate the preparation of large-area flexible device. By directly inheriting the spin-coating condition, the blade-coating processed device based on PTClo-Y achieves an impressive power conversion efficiency (PCE) of 12.42%, comparable to the spin-coating processed one (12.74%). Such non-conjugated polymer system also can well tolerate large-scale preparation and flexible substrate. Notable PCE of 11.94% for large-area rigid device and 11.56% for large-area flexible device are obtained, which is the highest value for large-area flexible all-PSCs fabricated by blade-coating. In addition, the non-conjugated PTClo-Y-based devices show excellent thermal stability and mechanical robustness. These results demonstrate that the non-conjugated polymer acceptors are potential candidates for the fabrication of highly-efficient, large-area and robust flexible all-PSCs by printing methods.

Pure niobium substrates were coated using laser cladding method. Pure molybdenum, Yttria Stabilized Zirkonia (YSZ) and corundum (Al2O3) powders were used as coating materials. Coatings were deposited on specimens as seperate paths with 3÷10mm width and 40mm of length. Two different laser power 3kW and 4kW were tested during deposition. In order to assess the quality of the Mo-YSZ and Mo-Al2O3 coatings, the light microscopy, Scanning Electron Microscopy (SEM), chemical analysis (EDS) and Vickers hardness test investigation were performed. The surface roughness and wear volume were also measured. As a result of YSZ-Mo powder cladding on the Nb substrate the composite layers were obtained without cracks and porosity not exceeding 1 μm. In addition, an increase in hardness of about 450 HV0.5 was revealed. As a result of Al2O3-Mo powder cladding on the Nb substrate the composite layers with many voids and cracks were obtained for each of the cladding variants.

Cold spraying metallic coatings on ceramics (Ceramics Metallizing) are widely concerned in electrical industry due to its high density, low oxidation and high electrical conductivity. However, the bonding reliability of cold spraying coating on ceramics is usually considered to be poor since the metal particles don’t experience melting. The present paper is to exam the bonding quality of a cold spraying copper coating on a thermal sprayed alumina layer influenced by ceramics roughness and copper particle hardness. Pure copper coatings were successfully deposited on Al2O3 coated Q235 steel substrate with different roughness by cold spraying at 260 ℃ and 1.6 MPa using different hardness pure copper powders. The bonding quality and characteristics were studied by analyzing the surface, the cross-sectional microstructure of the coating and its interface after pull-off test. The results indicate that the high bonding quality (ranging from 8.26 MPa to 11.35 MPa) between copper coating and Al2O3 layer attributes to both metallurgical and interlock effect, which is mainly influenced by the hardness of the copper powders instead of Al2O3 surface roughness. The soft character of the pure copper powder makes it ready for deformation, subsequently interlocks with Al2O3, fills into the pores more completely, which increases the bonding quality between the copper coating and the Al2O3 layer.

Nanofiber substrates have been used for various biomedical applications, including tissue regeneration, drug delivery, and in-vitro cell culture. However, despite the high volume of studies in this field, current clinical applications remain minimal. Innovations for their applications continuously generate exciting prospects. In this review, we discuss some of these novel innovations and identify critical factors to consider before their adoption for biomedical applications.