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Layer-by-Layer (LbL) assembly of interactive polymers onto surfaces leads to the construction of multilayered ultrathin films, which can be done simply by alternately dipping the substrate into var...

Surface enhanced Raman scattering (SERS) has proven to be increasingly valuable as an analytical tool since this phenomenon was first observed in 1973. However, challenges still exist to ensure their ability to access targeted analytes and adequate levels of sensitivity to them on irregular surfaces. Herein, silver (Ag) nanoparticles are deposited onto cotton fabric through magnetron sputtering to develop a flexible and ultrasensitive SERS-active substrate. To obtain a better enhancement effect, Ag nanoparticles of different sizes are produced by controlling the argon flow rate and the sputtering time. The finite-difference time-domain (FDTD) method and Raman mapping are used to explain the process behind Raman signal enhancement. The cotton fabric sample with Ag nanoparticles deposited at an argon flow rate of 200 sccm (labelled as AC-200) shows a high enhancement factor (EF) of 104 with a Methylene blue (MB) solution of 10−3 M, stability with a related standard deviation (RSD) of 1.03%, excellent reproducibility with an RSD of 1.92% and high sensitivity with 10−9 M of MB solution. Therefore, AC-200 demonstrates exceptional SERS signal reproducibility and stability for different types of chemical analytes and has the potential to be used in future practical applications.

Aim: The main objective of this project is to enhance the Bandwidth of microstrip patch antenna by using an E-shaped slot on the patch and varying substrate thicknesses in comparison with the Rectangular patch antenna. Materials and Methods: The microstrip patch antenna with an E-shaped slot and with varying substrate thicknesses of four groups [1.2mm, 1.6mm, 1.8mm, 2.4mm] is used with a sample size of 40 in comparison with rectangular patch antenna of another group with sample size 10. Results: By using Altair Feko simulation software, the proposed antenna parameters such as Bandwidth and Gain are obtained. The results are Gain=9dB, Bandwidth=225MHz for 1.2mm, Bandwidth=250.1MHz at 1.6mm, Bandwidth=252MHz at 2.4mm substrate thicknesses and bandwidth of conventional Rectangular patch antenna of 1.6mm substrate thickness=243MHz. Attained Significance accuracy ratio p(

Singulation is a process in a semiconductor industry where high dense strips were singulated into single units. Jig saw singulation was the updated technology where strips were seated and vacuumed on a rubber nest jig during singulation. Jig saw singulation is also practical for high volume manufacturing as it demands minimal indirect materials. To cut the strips, jig alignment with the strip was measured by the machine to ensure that the rubber nest jig will not be cut and damaged while the strip is being singulated. However, with the different upstream process that the strip undergone, machine prompt frequent jig alignment errors when the machine detected that the strip saw street has high displacement with the recorded alignment of the saw street of rubber nest jig. Through this study, the authors have driven to understand the jig alignment errors occurrences as well as the assistance that can be made for the strip to be processed. The authors also included the study of the risks that might be imposed on both rubber nest jig and the affected strips, as well as the recommendations when jig alignment errors were encountered.

Aim: In this work a Rectangular Microstrip Patch Antenna is designed by replacing conventional substrate with Air substrate and by adding a U shaped slot in Patch for Gain Enhancement. Materials and Methods: The Microstrip Patch Antenna with Air Substrate is used with 20 samples in comparison with FR-4 substrate of 2mm thickness. Results: Simulation is done by using Ansoft HFSS (High Frequency Structure Simulator) software. The performance of the Antenna is analyzed in terms of Gain, Directivity, Return loss, VSWR and enhancement in Gain is by 1.724 dB in comparison with FR-4 substrate. Attained Significance accuracy ratio (< 0.05). Conclusion: Microstrip Patch Antenna with Air substrate and U Slotted Patch performs better in terms of Gain.

Metal additive manufacturing has extensive application prospects in the aerospace, precision instrument, and biomedical fields, etc. However, the low manufacturing quality of key components is a bottleneck restricting the further development and application of this technology. Because of the extremely complex manufacturing environment, a real-time and online monitoring technology for the manufacturing quality remains lacking. For laser engineered net shaping (LENS), a mainstream technology of metal additive manufacturing, a hybrid method for the online evaluation of stress fields during laser cladding is developed in this paper that combines the real-time measured temperature field, three-dimensional deformation field and finite element method. The proposed method first designed the synchronous measurement optical paths of the temperature field and three-dimensional deformation field of the substrate, and the positions of the temperature and deformation field images were matched. A finite element model was established based on the printing parameters such as the layer thickness and printing speed, and the temperature field and three-dimensional deformation field synchronously measured at each moment were incorporated into the model as boundary conditions to obtain the deformation and stress information inside the model. We compared the stress field obtained at the end of printing with the XRD (X-ray diffraction) measurement results to verify the effectiveness of the proposed method. The proposed method can obtain the three-dimensional stress distribution and evolution of the substrate and printed component. The proposed method can realize the online characterization of the three-dimensional stress field in the LENS printing process and provide important experimental guidance and data for the quality control of 3D printing.

Information on the stress state of protective and decorative coatings during the curing process, in particular on the cohesive state of destruction, is given. The influence of the type of substrate on the change in internal stresses in the coating is considered. It was revealed that the greatest value of shear stresses is observed in coatings on a heavyweight concrete substrate. The subsequent increase in temperature after curing to 50°C leads to an increase in the value of the normal stresses. The probability of cracking of coatings during thermal aging is estimated. It was revealed that during aging there is an exponential decrease in the cohesive strength of coatings and an increase in internal stresses. Aging tends to increase the likelihood of cracking of coatings. The change in stresses in coatings as a result of seasonal fluctuations in air temperature is considered.

In this article, three novel slotted substrate integrated waveguide (SIW) antenna elements are demonstrated with different radiator configurations, namely, two arms Archimedean antenna, single‐arm spiral antenna (monofilar), and four concentric circular loops antenna. Additionally, their near, as well as far‐field characteristics, have been investigated. The two arms Archimedean spiral antenna has a superior radiation characteristic of 18% return loss bandwidth (RLBW), 12% boresight axial ratio bandwidth (ARBW), and five dBi directivity. Furthermore, a 1 × 10 slotted SIW travelling wave antenna array has been designed, fabricated, and measured. The performance of the proposed antenna array versus the last reported antenna was evaluated and the proposed antenna array performance is superior to that of the others. Moreover, the measurements of the proposed array have a good agreement with the simulation results in which, 35%, 13% RLBW, and ARBW, respectively, have been achieved. The directivity of the proposed antenna array is 14 dBi.

The wireless body area networks (WBAN) enable to communicate with the on-body wireless devices and systems. For on-body applications, the key requirement for the antennas is the antennas flexibility to mount the antennas on the body. Wearable antennas are fabricated on a flexible substrate to make these antennas suitable for mounting on the human body. Due to the wearable feature of these antennas, they are used in many on-body applications. The wearable characteristic also makes these antennas suitable for many on-body medical applications. This paper presents the technical review of the WBAN, WBAN frequency bands, wearable antenna fundamentals, flexible substrate characteristics, design and development of wearable antennas for medical applications. The wearable antennas are fabricated using the fabrics. The review of the material properties of various flexible substrates is given in detail. Due to the presence of the air in the gaps of fabrics, the dielectric constants of these materials are very low. Detailed analysis of antenna performance due to flexible substrate material characteristics is also discussed. The developments of wearable antennas for WBAN medical applications are presented. The paper also focuses on the design considerations, fabrication methods, challenges, and proposed solutions for the wearable printed antennas.

Research in van der Waals heterostructures has been rapidly progressing in the past decade, thanks to the art of sequential and deterministic placement of one two-dimensional (2D) material over another. The successful creation of heterostructures however has relied largely on expensive transfer systems that are not easily accessible to researchers. Although a few reports on low-cost systems have recently surfaced, the full functionality, portability features, and overall effectiveness of such systems are still being explored. In this work, we present an "all-in-one" low-cost transfer setup that is compact, lightweight, and portable and which can be quickly installed with a facile and do it yourself (DIY)-style anaerobic glovebox option that performs at par with commercial anaerobic systems. The "installable" glovebox option means the user has the convenience of quickly converting the working environment into an inert one when air-sensitive 2D materials are used. The lowest RH values obtained in our glovebox is

New fields of application are coming along at an outstanding pace for cold spray deposition. More recently cold spray is being introduced as an additive manufacturing method that supersonically accelerates microparticles to induce bonding via severe plastic deformation. However, the thriving of cold spray as a widespread additive manufacturing technology with high production rates is still limited by inadequate geometrical control of the deposit shape. Thus, to establish cold spray in the additive manufacturing sector, substantial development is still required regarding digitalization and automatization of the process. To take a further step towards gaining control on the deposit geometry, present study reports the development of a 3D model able to simulate the cold spray deposit profile. The physical basis of the model is represented by a partial differential equation, which describes the deposit profile evolution as the number of passes grows. The model offers total freedom regarding the choice of the nozzle trajectory and the substrate geometry. The effects of the various process parameters, namely the number of scanning passes, spray angle, scanning speed and stand-off distance are implemented and realistically reflected in the model. More complex conditions like superimposed tracks with different spray angles, curved substrates, shadow effect and non-Gaussian profiles have been effectively simulated. The developed model has been validated with a wide range of experiments, demonstrating high accuracy and notable potential to promote the digitalization of cold spray additive manufacturing.

Coatings on the surface of Mg alloys are inevitably damaged during their practical applications, and corrosion can easily initiate from the damaged areas to accelerate the failure of Mg parts. A dual self-healing coating has already been developed to solve this problem in our previous work. Considering the practical application of this coating, it is necessary to investigate its service behavior in atmospheric environment. Thus, the corrosion behavior of AM60 Mg substrate with and without the self-healing coating was compared in Shenyang industrial atmospheric environment. The results show that the enrichment of sediments and rainwater on the scratch areas can accelerate the corrosion of the exposed Mg substrate. The inhibitors can be released from the damaged coating to inhibit corrosion. The dual self-healing coating shows better inhibition ability to narrow scratches due to the higher inhibitor concentration and less resumption. Also, the coating with wide scratches displays enough inhibition ability as well. The dual self-healing coating is a good alternative for Mg alloy parts in the practical applications.

Carbon fibre-reinforced silicon carbide composites (C/SiC) are a type of high-temperature structural ceramics that can be widely applied in aerospace, hypersonic aircraft, and military fields. However, the practical application of such materials in some complex high-temperature environments is still limited owing to drawbacks such as the bulging problem. In this study, the bulging of a C/SiC coating in a high-temperature wind tunnel is investigated. The surface data of specimens in the high-temperature arc wind tunnel were obtained using optical visualisation equipment, and the entire process of the formation of coating bulges, and their evolution and fusion is illustrated. Then, a fully coupled thermal fluid-solid simulation model is established, and the influence of defects on the internal heat transfer of materials is analysed. Further, the thermal fluid-solid coupling simulation technology is also used to analyse the bulging process of the coating to understand the mechanism of chemical reactions in defects between the coating and substrate. This work can serve as a guide for the screening and improvement of the material coating process.

Because of the importance of large-scale metal-organic framework (MOF) production and processing, the development of practical solutions to obtain commercially relevant MOF-based products is essential. Herein, we demonstrate a feasible pathway to construct functional zeolitic imidazolate framework-8 (ZIF-8)-coated fabric composite from commercially available precursors, through a scalable synthetic protocol to produce a large quantity of nanoscale ZIF-8, followed by a facile mean to drop-cast the powdered nanoparticles onto the fabric substrate. The ZIF-8/fabric composite shows enhanced organic dye adsorption capability and superior antibacterial property. This simple yet effective preparation process might be readily adopted for the large-scale production of useful MOF-based composite materials. Ministry of Education (MOE) Nanyang Technological University National Research Foundation (NRF) This research is supported by the Singapore National Research Foundation Investigatorship (Grant NRF-NRFI2018-03) and the Ministry of Education Singapore under the Academic Research Funds (Grants RT12/19 and MOE-MOET2EP10120-0003). W.L.T. is thankful for a Nanyang President’s Graduate Scholarship supporting his doctoral study.

Results of studying the effect of component surface preparation on coating adhesive strength with a substrate are presented. A new method of surface preparation for plasma spraying is proposed that makes it possible to reduce worn component restoration specific costs and labor intensity, as well as to improve coating quality. A distinctive feature of the method proposed is the effect on treated surface of a thermal-abrasive jet with simultaneous surface heating that provides good coating adhesive strength with a component surface.

Previous research reveals that a flat micropatterned soft pad, which mimics the structure of tree-frog's toes, increases adhesion when gripping an object in a wet environment. However, soft interfaces may change shape to adapt to curved environments, therefore, it is necessary to clarify the mechanics of wet adhesion in such cases. In this letter, we propose a method for evaluation of the adhesive ability of a soft curved interface with a specific micropattern in a concave contact interface. We focused on wet adhesion force in the normal direction on the contact interface in different contact scenarios. The micropattern soft pad used in this analysis has 3600 cells, each has 85 $\mu$ m × 85 $\mu$ m separated by grooves 15 $\mu$ m in width ×44 $\mu$ m in depth. This micropattern soft pad may deform to fit a concave surface. We also compared this micropattern soft pad with a similar soft pad without a micropattern in term of adhesion ability at the interface between the pad and the substrate. Obtained results have good agreement with the estimations, demonstrating that the surface of the micro-patterned pad enhanced contact force at the interface approximately 1-2 times than the non-parttern surface. This approach can be utilized in evaluation of wet adhesion in grasping objects with curved surface using soft pads with patterned surfaces.

Surface-enhanced Raman spectroscopy (SERS) detection in microfluidics is an interesting topic because of its high sensitivity, miniaturization, and ability to perform online detection. However, the difficulties in generating SERS-based microfluidic devices with uniform signal reproducibility and high sensitivity have hindered their widespread application. In addition, the recyclability of the SERS-based microfluidic devices can contribute to their broad commercialization, but the possible contamination in the detection area and cumbersome cleaning procedures remain a challenge. In this study, we describe a repeatable SERS-based microfluidic device comprising a disposable SERS substrate and a reusable microfluidic channel. The microfluidic channel was prepared via mechanical processing, and the SERS substrate was fabricated by nanoimprint lithography and electrodeposition. The SERS substrate and microfluidic channel can be attached easily because they were assembled using screws. The SERS substrate achieved an excellent SERS enhancement factor greater than 108 over a large sample area, signal uniformity, and substrate-to-substrate reproducibility. This guaranteed reliable and sensitive signals in every experiment. Furthermore, the disposable SERS substrate contributed exact detection of target molecules. Finally, their practical application was demonstrated with the repeated use of the microfluidic device by detecting a specific micro-RNA, (miR-34a) at a concentration as low as 5 fM.

Highly reliable signal recording with low electrode-skin impedance makes the microneedle array electrode (MAE) a promising candidate for biosignal sensing. However, when used in long-term health monitoring for some incidental diseases, flexible microneedles with perfectly skin-tight fit substrates lead to sweat accumulation inside, which will not only affect the signal output but also trigger some skin allergic reactions. In this paper, a flexible MAE on a Miura-ori structured substrate is proposed and fabricated with two-directional in-plane bendability. The results from the comparison tests show enhanced performance in terms of (1) the device reliability by resisting peeling off of the metal layer from the substrate during the operation and (2) air ventilation, achieved from the air-circulating channels, to remove sweat. Bio-signal recordings of electrocardiography (ECG), as well as electromyography (EMG) of the biceps brachii, in both static and dynamic states, are successfully demonstrated with superior accuracy and long-term stability, demonstrating the great potential in health monitoring applications.

Two-terminal memristive devices are considering as a potential candidate to mimic human brain functionality to enable artificial intelligence. Particularly, two-terminal nanoscale devices are regarded as a promising solution for implementing bio-synapses due to their small dimensions, extremely compact, and low power to operate neuromorphic functions. Here, we demonstrate that the nanoscale charge transport and resistive switching behavior of VOx thin film can be tuned by modulating the substrate morphology. Particularly, the device prepared with flat-Si shows totally distinguished behavior in comprising of reactive ion-etched-Si substrates. Interestingly, conductive atomic force microscopy current maps revealed the electric field inhomogeneity due to a change in substrate morphology. A reliable bipolar resistive switching behavior of the corresponding etched devices have been demonstrated. Due to an increase in the etching time of substrate, an increase in active area and decrease in work function was observed. Further, nanoscale synaptic functions were generated from the corresponding devices, showing a strong conduction path at preferential bright spots of the particular devices. Moreover, finite element simulations confirm the modulation in generation of localized current conduction in particular etched devices by applying tip voltages. These findings represent a new way to generate nanoscale artificial synaptic functions.

Nowadays, the extensive use of glass-based materials for biomedical, micro-fluidic, and MEMS applications grabbed great attention. The use of glass substrate for the above-said applications require...

Application of artificial neural networks for optimization of plasma spraying parameters was considered. Artificial neural networks were used to select realistic parameters of titanium and hydroxyapatite powder coating of titanium products. For titanium coatings, the optimal arc current was found to be 380-450 A; optimal spraying distance, 100-150 mm; optimal titanium powder dispersity, 40-90 μm. Similar optimal ranges were obtained for hydroxyapatite coatings. The goal of the optimization wais to maximize the coating adhesion to the substrate and to improve its porosity.

In this study, a 2-D mathematical model of a high-directive microwave antenna with a miniaturized volume profile is developed analytically. The antenna is a rectangular patch antenna on a metaferri...

High requirements on the electrical parameters of the filters are made in wireless radio communication systems. A number of tasks require bandpass filters with relative bandwidths of 8-12 %. In this case, the filter must have insertion losses of not more than 10 dB, have a rejection is not worse than 40 dB, unevenness in the bandwidth of not more than 1 dB. In addition, the amplitude frequency responses of the filter must have steep slopes due to the closely spaced frequency bands of neighboring communication systems. Due to its small size and other advantages, ladder resonator filters on surface acoustic waves are widely used in communication systems. To realize the high requirements of this type of filters, it is necessary not only to select all the topology parameters of the individual resonators included in the filter very accurately, but also to have a good computational theory and the necessary material parameters for the selected model at the design stage. Purpose: to show on the example of comparison of calculated and experimental frequency responses of ladder filters the validity of the method of extraction of the necessary parameters obtained for an infinite periodic structure by the finite element method for calculating of finite structures of real inter digital transducer and reflective gratings. Results: the method of extraction of parameters necessary for calculation by the method of connected modes on the basis of P-matrices is offered. The technique is based on the analysis of infinite periodic electrodes by the finite element method. Bandpass filters with a relative bandwidth 8-12 % on a piezosubstrate 49° YX LiNbO3 were designed and manufactured based on the proposed theory. It is shown that for this material, the calculation must take into account the direct radiation of bulk acoustic waves, since the design of ladder type filters, the radiation falls into the projected bandwidth of the filters. These calculations are confirmed by the results of experiments.

This work investigates the possibility of reducing the anisotropic behavior of wire arc additively manufactured (WAAM) parts by a new layer deposition technique. An experiment was carried out in which specimens were printed using AWS E6013 low carbon steel electrodes. In printing the specimens, sets of layers were deposited bottom-up (along Z-axis) at different inclination angles (namely, 0˚, ± 15˚, ± 30˚ and ± 45˚) with respect to X-axis of substrate XZ-plane. Results show that the proposed technique does reduce anisotropic behavior of printed parts when deposition angles of ± 30˚ and ± 45˚ are used. Parts printed with layer sets deposited at ± 45˚ inclinations showed least anisotropy and highest tensile strength, but they also had longer building times as compared with the other specimens.

The presented work focused on the development of temperature sensors based on specially formulated carbon nanotube (CNT) and poly(3,4-ethylene dioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) based inks which are deposited directly onto the adhesive polyamide-based taffeta fabric with low-cost office-type inkjet printer. Stable and uniform dispersions of CNT and PEDOT:PSS with Triton X-100 were formulated to be used as temperature sensitive inkjet inks. Three kinds of temperature sensors were fabricated using sensitive materials including CNT ink, PEDOT:PSS ink, and CNT/PEDOT:PSS composite ink. Developed sensors are connected to the measuring devices via silver yarns and silver adhesive paste. Sensors are covered with translucent polyurethane welding tape for packaging and protection. All the sensors exhibit negative temperature coefficient (NTC) behavior and sensitivity of 0.15 %/degrees C for CNT, 0.41 %/degrees C for PEDOT:PSS, and 0.31 %/degrees C for CNT/PEDOT:PSS for temperatures varying from room temperature to 50 degrees C. CNT/PEDOT:PSS composite ink printed sensor achieved better sensing repeatability and demonstrated higher bending stability with a resistance change of 0.3 % up to 1000 cycles than CNT printed and PEDOT:PSS printed sensors. The softness, lightness, and capability to work on flexible or curved surfaces make the developed CNT/PEDOT:PSS composite ink printed sensor a robust candidate for wearable temperature sensor applications, especially in situations requiring continuous body temperature monitoring while satisfying comfort of the user.

Although high-performance graphene-based micro/nano flexible electronic devices have shown promising applications in numerous fields, there are still many problems in converting graphene into practical applications. Heteroatom-doped graphene materials are of huge importance because heteroatom doping can significantly change the electronic structure and introduce the active site, which benefits the integration with a promising substrate and achieves nondestructive transfer of carbon materials. Herein, we analyze in detail the pyrolysis gas composition of heteroatom-enriched phosphazenes with different structures and prepare a series of high-quality in situ N, P-codoped carbon-based films from phosphazene solid sources on a low-cost glass substrate by a convenient one-step method. The N, P-codoped carbon film shows reflectivity, good conductivity, and transparency. In addition, with the help of in situ "molecular welding", we achieve nondestructive transfer of a conductive carbon-based film from a glass substrate to promising layer-polyimide (PI) and prepare a flexible free-standing carbon/PI hybrid film with an excellent binding interface. The flexible conductive hybrid film shows excellent durability under an extremely low temperature environment and superior bending stability after 800 bending cycles. The results suggest that a phosphazene precursor is an amazing choice for constructing high-quality heteroatom-doped conductive carbon films. Besides, this work provides a promising way for nondestructive transfer of the conductive carbon-based films and large-scale preparation of large-area patterned conductive thin films.

Print mottle is a serious and common uneven printing defect that occurs when printing coated paper by the offset multicolor printing process. It is characterized by a non-uniform appearance in terms of brightness, gloss, or color density that appears mostly in solid printed areas. Back-trap print mottle and water-interference print mottle occur when the quality of the paper substrate, especially the coating layer quality, is not satisfactory. To cope with this quality problem of coated papers, the understanding of the offset printing process, the requirements of coated-paper quality, and the reasons for this problem should be addressed. In this review, the basic process of offset printing and the mechanisms of print mottles were explored, the importance of coating uniformity in both the coating structure and process was reviewed, and the approaches to cope with print mottle were introduced.

Well-tailored nanomaterials with a single-crystal character provide ideal building blocks for on-chip plasmonic devices. Although colloidal methods have demonstrated mastery over the synthesis of such structures, it has proven quite difficult to deploy these same nanomaterials on substrate surfaces in a highly deterministic manner where precise control over position and orientation is ensured. Herein, we demonstrate a room-temperature two-reagent liquid-phase seed-mediated synthesis of gold nanoplates directly on substrate surfaces in arrays over a square-centimeter area. The synthesis is reliant on benchtop lithographic and directed-assembly processes that give rise to single-crystal seeds of gold that express both an epitaxial relationship with the underlying substrate and the internal defect structure required to promote a two-dimensional growth mode. The resulting structures are highly faceted and, because seed-substrate epitaxy is imposed upon the growing nanoplates, are identically aligned on the substrate surface. Nanoplate yields are increased to values as high as 95% using a post-processing sonication procedure that selectively removes a small population of irregularly shaped nanostructures from the substrate surface, and in doing so, gives rise to an uncompromised plasmonic response. The work, therefore, advances the techniques needed to integrate single-crystal nanomaterials with wafer-based technologies and provides leading-edge capabilities in terms of defining large-area arrays of plasmonic structures with the nanoplate geometry.

This paper presents a hybrid additive manufacturing (AM) process combining multilayer friction surfacing (FS) and metal machining operations. While friction surfacing has been known as a part repair or coating process, we here present an attempt to use it to build whole 3D metallic parts. The feasibility of the process is tested using heat-treatable Aluminum alloy AA6061 rod on a mild steel substrate. A series of FS experiments was conducted with the purpose to identify suitable process settings. This included different combinations of rotational and travel speeds of the FS rod. Quality of deposited layers was assessed using different indicators including bond width, layer uniformity, layer thickness, and others. ANOVA was conducted to reveal the effects of process parameter settings on the quality metrics. Two metallic parts were printed successfully, which demonstrates the feasibility of the proposed hybrid process.

Polymeric materials with a low dielectric constant are widely used in the electronic industry due to their properties. In particular, polymer adhesives can be used in many applications such as wafer bonding and three-dimensional integration. Benzocyclobutene (BCB) is a very interesting material thanks to its excellent bonding behavior and dielectric properties. Usually, BCB is applied by spin-coating, although this technology does not allow the fabrication of complex patterns. To obtain complex patterns, it is necessary to use a printing technology, such as inkjet printing. However, inkjet printing of BCB-based inks has not yet been investigated. Here, we show the feasibility of printing complex patterns with a BCB-based ink, reaching a resolution of 130 μm. We demonstrate that with a proper dilution, BCB-based inks enter the printability window and drop ejection is achieved without the formation of satellite drops. In addition, we present the conditions in which there is an appearance of the coffee ring effect. Inks that feature a too high interaction with the substrate are more likely to show the coffee ring effect, deteriorating the printing quality. We also observe that it is possible to achieve a better film uniformity by increasing the number of printed layers, due to redissolution of the BCB-based polymer that helps to level possible inhomogeneities. Our work represents the starting point for an in-depth study of BCB-based polymer fabrication using jet printing technologies, as a comparison of the bonding quality obtained with different materials and different technologies could give more information and broaden the perspective regarding this field.

Die placement reference in die attach process is one of the critical aspects in measuring the actual die placement especially for the device that has a required measurement. This paper focused on the re-design on the layout of the substrate ball grid array (BGA) package with cross fiducials at the singulation lane which are located at the corner portions of the device. The cross fiducial would serve as a reference when measuring the actual placement of the Silicon die in the package. With this improvement, the technicians and operators could now easily identify the reference based on the mount and bonding diagram requirement.

Porous media with directional water-transport capability have great applications in oil-water separation, moisture-harvesting, microfluidics, and moisture-management textiles. However, the previous directional water-transport materials chiefly work in the air. The materials with directional water-transport capability in the oil phase have been less reported. Here, we fabricated a novel Janus fabric with amphibious directional water-transport capability that can work both in the air and oil phases. It was prepared using dip coating and spraying to develop an oleophobic-hydrophobic to oleophobic-hydrophilic gradient across the thickness of the fabric substrate. The fabric allowed water droplets to rapidly transport from the hydrophobic to the hydrophilic side when the fabric was either in the air environment or fully immersed in oil. However, it hindered water transport in the opposite direction. More importantly, the fabric can overcome gravity to capture water from oil. Such an air-oil amphibious water-transport fabric showed excellent water collecting capability. In oil, it does not require any prewetting or extra pressure to perform directional water transport, which is vital for water-oil separation and microfluidics. Such amphibious directional water-transport function may be useful for the development of smart membranes and directional liquid delivery.

Cold spray is a newly developed solid-state metal deposition technology, which allows for preparing various functional coatings and repairing damaged metal components, as well as fabricating freestanding parts. In order to obtain the deposits with the desired shape and accuracy, the coating profile, including its thickness and distribution, is an important indicator to monitor and control. In this work, an artificial neural network (ANN) model has been employed to describe and predict the multi-layer profile of cold-sprayed deposits. Compared to conventional feature-based modeling methods, the ANN model is capable of simulating a complete track profile on defined substrate morphologies. The superiority of the ANN approach is further emphasized by its ability to simulate a multi-layer profile, which differs from previous works that focus on single-layer profiles. It is essential for guiding the coating formation and fabrication of near-net-shape parts. The results imply that the ANN model is well trained and capable of predicting multi-layer profiles with acceptable accuracy. It can be used for profile control during cold spray additive manufacturing.

Peel tests are frequently used to perform measurements of adhesive strength for pressure sensitive adhesive (PSA) tapes. Current lab methodologies for 90° peel tests translate the model substrate orthogonally to the peel direction in order to maintain the peel angle, precluding testing from immovable substrates. It was our objective to develop a peel fixture capable of testing temporary pavement marking (TPM) tapes and other PSA tapes from immovable substrates such as roadways surfaces. We present a modular peel fixture for conducting peel experiments directly on immovable substrates. The fixture was validated through a series of peel tests on consumer tapes to reproduce the linear width dependence and viscoelastic rate dependence found in traditional peeling setups. To test the capabilities of the fixture, a series of peel tests were conducted with various tapes on controlled surfaces, and a commercial tape on various immovable substrates. We demonstrate the ability of our fixture to reproduce results reported for traditional peel tests from literature. In addition, we were able to conduct peel tests directly on immovable substrates such as the benchtop. This fixture shows potential for both traditional peeling tests, and for use in in-situ peel experiments from substrates relevant to the end application of the PSA tape.

Printed piezoresistive strain sensors based on stretchable roll-to-roll screen-printed silver electrodes on polydimethylsiloxane substrates and inkjet-deposited single-wall carbon nanotube micropatterns are demonstrated in this work. With the optimization of surface wetting and inkjet printing parameters, well-defined microscopic line patterns of the nanotubes with a sheet resistance of

A stab-resistant substrate was designed and realized with a triangular pyramidal structure inspired by the biological armor model in the nature. Through numerical simulation and experimental testing of a knife impacting a substrate, the stab-resistant behavior and dynamic response mechanisms were studied. It was found the stab-resistant performance on the triangular pyramidal substrate was better than the flat plate. The surface of the triangular pyramidal substrate effectively avoided the normal force generated from impacting due to a significant dispersion effect on the tilted pyramid structure. The substrate tended to be inclined and the stress of the backing material was inhomogeneous, absorbing more energy. Much of the deformation energy and others, such as heat and light energy, were caused due to intensive collision between the knife and the substrate, all of which leading to a rapid drop of the knife kinetic energy. The substrate with higher tilted angle led to improved energy dispersion, as well as larger area density. The optimal design parameters were achieved with the knife impacting tests, of which the tilted angle was 22.5° and thickness 1.2 mm. The stab-resistant layer made of the titanium alloy through compression molding consisted of the optimal design parameters. A new riveting method was used to perform the total layer, which passed the GA 68-2008 National Standard. The overall areal density of the stab-resistant layer was 5.85 kg/m2, which was 45% lower than a commonly used stab-resistant layer. The method provided may enlighten the future design and manufacturing of stab-resistant clothing. The full version of this abstract will appear in Defence Technology in 2020.

Intersected nonpolar ZnO nanosail arrays were fabricated epitaxially on Au‐coated LiGaO2 (010) substrate by chemical vapor deposition. In spite of five growth directions, the novel two‐dimensional (2D) nanostructure was confirmed to be single‐crystalline by X‐ray diffraction and transmission electron microscopy. The anisotropy of growth and surface energy in three directions as well as the equivalency of crystallography should be responsible for the formation of intersected 2D nanosail arrays. Compared with those of polar nanoprisms and nonpolar film samples, the nanosail arrays exhibit superior photoelectrochemical performances of photocurrent density (620 µA cm–2 at 0.2 V vs. SCE) and photoconversion efficiency. The enhanced photoelectrochemical responses were attributed to the unique nanostructure with large surface area and high surface‐to‐volume ratio as well as nonpolar characteristic. This work demonstrates a simple, low‐cost and pattern‐free pathway to prepare aligned 2D nanosail arrays for technological applications.

In this study, the effects of the lacquer applied to the printing materials which were printed by electrophotographic printing method on printing quality were investigated. In practice, printing materials with the same weight and different optical properties were used and the study was carried out in three stages. The optical and physical properties of the printing materials used in the first part were determined, in the second part, the printing of these materials by electrophotographic printing method and printability tests were performed. In the third chapter, matte and glossy lacquers were applied to these printed materials and printability tests were repeated. As a result of the study, it was observed that the application of gloss and matte lacquer caused a decrease in the printing density values and also the application of matte lacquer caused a decrease in the gloss values.

The object of research is the control of the process of formation of a spraying air flow and the transfer of particles of liquid metal from electrodes during arc spraying. One of the problem areas of the arc spraying process is the oxidation of the sprayed metal particles by the oxygen of the air flow during their transportation to the sprayed surface. This leads to the formation of a sufficiently large amount of oxides of chemical elements, which significantly deteriorate the adhesion strength and burn out alloying elements that are necessary to obtain a wear-resistant and corrosion-resistant coating. The suitability and durability of coatings during use depends on the strength of adhesion to the substrate. In the course of the study, methods were used to determine the adhesion strength of the coating to the base – the Steffens method and methods for studying the microstructure of coatings were taken as the basis. The data was processed and dependencies were plotted. The proposed method makes it possible to improve the quality of the resulting coating in terms of such an indicator as improvements in chemical composition. And also to influence the chemical composition by controlling the process of transfer of molten metal using a pulsating air flow. The obtained results of approbation of the method allow us to consider it effective, as evidenced by the quality of the obtained coatings. This is due to the fact that the correctness of the formulation and solution of the problem provided adequate results. In contrast to the existing methods, the proposed one makes it possible to significantly influence the amount of harmful oxygen involved in the formation of a sprayed coating, which makes it possible to obtain a sprayed layer with the required performance characteristics. And also allows to improve its quality without significant capital costs. In addition, the issues of resource and energy saving are being addressed, since the burnout of chemical elements decreases and the air consumption during arc metallization decreases. To solve this problem, a simple design of the pulsator is proposed, which provides the ability to control the spray flow by adjusting the level of overlapping of the holes.

The restoration of normal functioning of damaged body tissues is one of the major objectives of tissue engineering. Scaffolds are generally used as artificial supports and as substrates for regenerating new tissues and should closely mimic natural extracellular matrix (ECM). The materials used for fabricating scaffolds must be biocompatible, non-cytotoxic and bioabsorbable/biodegradable. For this application, specifically biopolymers such as PLA, PGA, PTMC, PCL etc. satisfying the above criteria are promising materials. Poly(ε-caprolactone) (PCL) is one such potential candidate which can be blended with other materials forming blends, copolymers and composites with the essential physiochemical and mechanical properties as per the requirement. Nanofibrous scaffolds are fabricated by various techniques such as template synthesis, fiber drawing, phase separation, self-assembly, electrospinning etc. Among which electrospinning is the most popular and versatile technique. It is a clean, simple, tunable and viable technique for fabrication of polymer-based nanofibrous scaffolds. The design and fabrication of electrospun nanofibrous scaffolds are of intense research interest over the recent years. These scaffolds offer a unique architecture at nano-scale with desired porosity for selective movement of small molecules and form a suitable three-dimensional matrix similar to ECM. This review focuses on PCL synthesis, modifications, properties and scaffold fabrication techniques aiming at the targeted tissue engineering applications.

This research was carried out in the hydroponics production field at Selcuk University, Cumra School of Applied Sciences between the dates of 01.09.2019 and 28.02.2020. This study was conducted in order to determine the effects of different growing medium (Co: control, Wp: wood powder, Pe: perlite, and Tu: turf (cocopeat)), substrates (Cf: cotton fiber, Pf: polyester fiber, Pm: polyester mesh), and irrigation method (Sp: sprinkler, Ti: tidal, and Fp: fogponic) applications on soilless roll sod, the following characteristics were examined: fresh grass yield (g m² -1), dry matter rate (%), dry grass yield (g m² -1), plant height (mm), emergence speed (day), covering speed (day), root length (cm), overall appearance (1-9), shoot diameter (mm), tiller number (number cm2 -1), leaf blade length (cm), leaf blade width (mm) and the index value (leaf blade length/leaf blade width). It was observed that there was no statistical difference between the applications in terms of overall appearance values. When root length and tiller number values, which are among the important growth parameters in the soilless roll sod production, application conveniences, biodegradability, and production costs are considered together, "Tu" growing medium, "Cf" substrate and "Sp" irrigation method applications came to the fore. To be able to obtain more realistic recommendations on this issue, land applications should be included in future research., Araştırma, 01.09.2019 ile 28.02.2020 tarihleri arasında, Selçuk Üniversitesi Çumra Uygulamalı Bilimler Yüksekokulu hidroponik üretim alanında yürütülmüştür. Çalışma, farklı yetiştirme ortamı (Co; kontrol, Wp; odun tozu, Pe; perlit ve Tu; torf (cocopeat)), altlık (Cf; pamuk elyaf, Pf; polyester elyaf ve Pm; polyester elek) ve sulama yöntemi (Sp; yağmurlama, Ti; gel-git ve Fp; fogponik) uygulamalarının topraksız rulo çim üzerine etkilerini belirlemek amacıyla yürütülmüş ve yeşil ot verimi (g m² -1), kuru madde oranı (%), kuru ot verimi (g m² -1), bitki boyu (mm), çıkış hızı (gün), kaplama hızı (gün), kök uzunluğu (cm), genel görünüm (1-9), sürgün çapı (mm), kardeş sayısı (adet cm2 -1), yaprak ayası uzunluğu (cm), yaprak ayası genişliği (mm) ile indeks değeri (Yaprak ayası uzunluğu/Yaprak ayası genişliği) özellikleri incelenmiştir. Genel görünüm değerleri bakımından uygulamalar arasında istatistiki farklılığın olmadığı görülmüştür. Topraksız rulo çim üretiminde önemli gelişim parametrelerinden kök uzunluğu ve kardeş sayısı değerleri uygulama kolaylıkları, biyo çözünürlük ve üretim maliyetleri birlikte dikkate alınarak değerlendirildiğinde Tu yetiştirme ortamı, Cf altlık ve Sp sulama yöntemi uygulamaları ön plana çıkmaktadır. Bu konuda daha gerçekçi tavsiyeler için ileride yapılacak araştırmalara arazi uygulamaları dahil edilmelidir.

In this letter, a novel eighth‐mode ridged substrate integrated waveguide (EMRSIW) is proposed by bisecting the RSIW resonator along the virtual magnetic walls. The EMRSIW shows a size of nearly one‐eighth of a conventional RSIW resonator and a significant size reduction compared to the conventional eighth‐mode SIW resonator. A prototype of a third‐order bandpass filter with transmission zeros has been designed and tested.