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The alumina slurry with high solid content was prepared, and a rapid lamination route for fabricate the Nextel™ 610 fiber reinforced alumina composite was proposed in this work. The microstructure and mechanical properties of the as-received all-oxide composite were investigated by a series of techniques. The shrinkage cracks in matrix were reduced, while porous structure in composite was maintained. The N610/alumina composite has weak matrix and weak interface, as the Young’s modulus of the alumina matrix and the interfacial shear strength of the composite are 140.8±2.5GPa and 129.1±14.6MPa. The mechanical properties of the composite are much higher than lots of oxide/oxide composites, given its flexural strength, interlaminar shear strength and the fracture toughness are 398.4±5.7MPa、27.0±0.5MPa and 14.1±0.9MPa·m1/2, respectively. The flexural strength of the virgin composite keep stable at 25–1050 °C, while dramatically decrease at 1100–1200 °C.

Purpose The use of a gas metal arc welding-based weld-deposition, referred to as wire-direct energy deposition or wire-arc additive manufacturing, is one of the notable additive manufacturing methods for producing metallic components at high deposition rates. In this method, the near-net shape is manufactured through layer-by-layer weld-deposition on a substrate. However, as a result of this sequential weld-deposition, different layers are subjected to different types of thermal cycles and partial re-melting. The resulting microstructural evolution of the material may not be uniform. Hence, the purpose of this study is to assess microstructure variation along with the lamination direction (or build direction). Design/methodology/approach The study was carried out for two different boundary conditions, namely, isolated condition and cooled condition. The microstructural evolution across the layers is hypothesized based on experimental assessment; this included microhardness, scanning electron microscopy imaging and electron backscatter diffraction analysis. These conditions subsequently collaborated with the help of thermal modeling of the process. Findings During a new layer deposition, the previous layer also is subject to re-melt. While the newly added layer undergoes rapid cooling through a combination of convection, conduction and radiation losses, the penultimate layer, sees a slower cooling curve due to its smaller exposure area. This behavior of rapid-solidification and subsequent re-melting and re-solidification is a progressing phenomenon across the layers and the bulk of the layers have uniform grains due to this remelt-re-solidification phenomenon. Research limitations/implications This paper studies the microstructure variation along with the build direction for thin-walled components fabricated through weld-deposition. This study would be helpful in addressing the issue of anisotropy resulting from the distinctive thermal history of each layer in the overall theme of metal additive manufacturing. Originality/value The unique aspect of this paper is the postulation of a generic hypothesis, based on experimental findings and supported by thermal modeling of the process, for remelt-re-solidification phenomenon followed by temperature raising/lowering repetitively in every layer deposition across the layers. This is implemented for different types of base plate conditions, revealing the role of boundary conditions on the microstructure evolution.

The objective of this study is to clarify the effect of resin lamination on the tensile strength characteristics of SUS304 stainless steel thin films. We conducted tensile and stepwise tensile tests using several types of specimens prepared with 20-μm- and 40-μm-thick SUS304 films, 25-μm-thick polypropylene (PP) film, and 6-μm-thick polyethylene terephthalate (PET) film. Their macroscopic and microscopic tensile deformation behaviors were observed using an optical microscope and a reflection-configured digital holographic microscope, respectively. As a result, laminating the PP or PET films onto the SUS film did not significantly change the macroscopic and microscopic strain changes against the tensile load or microscopic surface changes in the low-strain region. Laminating the PET film onto the SUS film did not reduce the fracture strain, whereas laminating the PP film onto the SUS film did reduce it. One of the reasons may be that burrs formed on the side surface of the PP/SUS laminate. Polishing the side surface of the PP/SUS laminate may suppress the reduction in its fracture strain. The reduction of the fracture strain due to the PP lamination in the 20 μm thick SUS film was larger than that of the 40-μm-thick SUS film. In thin SUS films, small stress concentrators that have almost no effect on macroscopic and microscopic deformation might significantly reduce the fracture strain.

In this research, cellulose acetate/blends of polyvinyl alcohol and polyacrylic acid (CA/PA) bilayer porous membrane was prepared by electrospinning and esterification. Then the developed membrane was laminated onto polyester fabrics to examine their practical applications in the textile area. Investigations for surface morphology, the water content distribution and the moisture absorption were done in detail to examine the unidirectional moisture transport performance of the CA/PA bilayer porous membrane and the laminated fabrics. The results illustrated that when the electrospinning arrangement time was PA-CA=6h-4h, the lamination pressure 2 MPa and the lamination time 35 seconds, the laminated fabric had the best performance. At this time, the composite laminated fabric exhibited a value for one-way moisture transport capability (R) of 960.76 % with overall moisture management capacity (OMMC) performance of 0.84 %. Additionally, the moisture absorption and perspiration of the laminated fabric can reach level 5.

The laser micro-spot welding process was studied to implement a sheet lamination process-based methodology for the fabrication of austenitic stainless steel scaffolds. AISI 302 sheets with a thickness of 254 μm were laser cut and laser welded. Experimental tests were carried out with different values of average laser power (i.e., 180, 200, and 220 W) and different exposure times (25, 50, 75, 100, 125 ms). The micro-spot welds were visually inspected according to the ISO 13919-1 Class B requirements. Spot welds were qualitatively characterized, and weld dimensions were measured (i.e., penetration depth, top, middle, and bottom width and the heat-affected zone (HAZ)) to identify the cross-sectional shape. Furthermore, process efficiencies (i.e., coupling, melting, and process) were studied. A seam welding model was adapted to calculate the required exposure time and was used to obtain a micro-spot weld to accomplish the quality requirements of the scaffold. A scaffold prototype was designed and manufactured using the selected parameters by experimental trials and using the mathematical model (i.e., a laser power of 220 W and an exposure time of 45 ms).

The stochastic investigation of fracture response of centrally cracked symmetric angle ply laminated composite plates subjected to different types of biaxially applied stresses by implementing stochastic extended finite element method (SXFEM) is carried out. The second-order perturbation technique is used in the framework of well-established extended finite element method to obtain the mean and coefficient of variance of mixed-mode stress intensity factors by random change in input parameters. The various system properties such as material elastic properties, lamination angle, loading, crack parameters like crack length and crack angle are modelled as independent, and they combine uncorrelated and correlated input random Gaussian variables. Typical numerical results are presented to examine the effect of various levels of uncertainties in biaxial load factors, fibre angle, crack eccentricity in X and/or Y direction, crack angles and crack lengths. The results obtained using SXFEM approach are compared with the results available in the published literature, and by performing Monte Carlo simulations, an excellent agreement is seen.

Flexible copper clad laminate has been used to fabricate flexible electronics such as bio-inspired tactile sensor, microfluidics-based sensor, and flexible printed circuits board. Herein, the effects of thermal property difference between the component layers on the residual interfacial deformation in a flexible copper clad laminate occurring during roll-to-roll composite film manufacturing were analyzed. The thermal behaviors of polyimide film and copper meshes in the laminate were examined, and it was found that differences of the coefficient of thermal expansion and elastic modulus between the two components could cause the residual deformation in the laminate. The three factors affecting the residual strain due to the thermal characteristic difference, i.e., temperature and pressure of the lamination roll and web tension, were selected in the controllable operating conditions in a roll-to-roll lamination process. Mathematical models to estimate the elastic and thermal residual strains according to the factors were developed and experimentally verified. Finally, the effects of the three factors on the residual strain in the laminate were determined using the developed model. In this study, we demonstrate that, in the lamination process, the thermal strain of the laminate component materials after thermal cycling generates a significant residual deformation, which causes defects in the flexible copper clad laminate. The developed model can be used to accurately estimate the residual elastic and thermal residual strains occurring during the roll-to-roll manufacturing according to the process conditions.

A new process of activating sizing film free (removed sizing) carbon fiber (SFF-CF) mats directly with electron beam irradiation (EBI) under oxygen-rich nitrogen gas prior to lamination assembly and hot-press was found to increase bending strength of CFRTP (CF reinforced thermoplastic polypropylene (PP)) interlayered composite composed of 3 SFF-CF mats between 4 PP sheets, [PP]4[SFF-CF]3. The hot-press fabrication was performed under 4.0 MPa at 473 K for 1 min. Experimental results showed optimal condition of 0.22 MGy-EBI under 2,000 ppm-O2-rich, protective N2 atmosphere improved bending strength, σb at all accumulative probabilities, Pf over that of untreated. This could be explained by maximum number of the strong covalent bonds of CF:C:C:PP and oxygen assisted CF:C:O:C:PP bonds adhering bare SFF-CF surface to PP, instead of the weak intermolecular bonding of CF(H2O, N2, O2)PP of untreated. The optimal concentration of O2 molecules together with the EBI probably purified the SFF-CF surface simultaneously generating dangling bonds, which already naturally exist in SFF-CF as evidenced by the highest intensity ESR peak whose inflection point was at B = 323 mT. This, along with attaching O groups to the SFF-CF surface can explain the increased SFF-CF to PP adhesion sites and bending strength increase. Fracture analysis showed the optimum condition prevented ply delamination and reduced damage area along sample length appearing to increase cohesion between the difficult to adhere thermoplastic PP and SFF-CF plies to take on higher loads. Although bending strength was increased, carefulness is always highly recommended when investigating unsized CF composites.

In this study, the coating process is employed on metal wire to help improve the friction resistant property of carbon fibers, thereby provides more application feasibility. The yarn coating technique for reinforcement and woven fabric process are used to produce carbon/stainless steel/polyester/polypropylene/acrylic (CSPPA) woven fabrics that are characterized with softness and a light weight. The constituent coated yarns exhibit good conductivity after being coated with a PP layer, and likewise strengthen the woven fabrics in terms of mechanical behavior of tensile strength, elongation, bending torsion, creep resistance, and wear-resistant properties. The test results indicate that in the woven process, samples retain good morphology. Due to PP sheath, the tensile strength of woven fabrics increases from 23 MPa to 42 MPa. Although the lamination layer numbers does not improve the EMI SE of woven fabrics, the EMI SE still reaches over 40 dB. The manufacturing design proposed in this study provides an innovative finishing for carbon fibers without affecting the intrinsic properties, and provides a greater range of application for carbon fibers.

Metal additive manufacturing technologies, such as powder bed fusion process, directed energy deposition (DED) process, sheet lamination process, etc., are one of promising flexible manufacturing technologies due to direct fabrication characteristics of a metallic freeform with a three-dimensional shape from computer aided design data. DED processes can create an arbitrary shape on even and uneven substrates through line-by-line deposition of a metallic material. Theses DED processes can easily fabricate a heterogeneous material with desired properties and characteristics via successive and simultaneous depositions of different materials. In addition, a hybrid process combining DED with different manufacturing processes can be conveniently developed. Hence, researches on the DED processes have been steadily increased in recent years. This paper reviewed recent research trends of DED processes and their applications. Principles, key technologies and the state-of-the art related to the development of process and system, the optimization of deposition conditions and the application of DED process were discussed. Finally, future research issues and opportunities of the DED process were identified.

The strength and brittleness of rocks are among the most important mechanical parameters in the design of geotechnical projects. Anisotropy is one of the prominent factors affecting the rock properties including strength and brittleness. This paper investigates the effect of anisotropy on the strength and brittleness of laminated sandstone samples collected from the northwest of Khorramabad (west of Iran). For this purpose, the laminated sandstone samples were drilled at different lamination angles (β) of 0°, 30°, 45°, 60°, and 90°. Here, β is the angle between lamination planes and loading direction. After preparation of specimens, petrographical and physical properties were investigated. Then, uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) tests were carried out on the specimens at different β angles, and their strengths were determined. Using data analysis, brittleness was indirectly obtained as a function of UCS and BTS. The results showed that the anisotropy of the sample has a significant influence on UCS, BTS, and brittleness. Moreover, UCS and brittleness of the sample showed a shoulder-shaped anisotropy with the maximum value at β = 0° or β = 90° and minimum value at β = 30°. Meanwhile, the BTS of the sample increased with an increase in β from 0° to 90°. According to the classifications of UCS and brittleness of rocks in the literature, in terms of the β angle, the sample falls into the different categories of rock classes.

The originality of this work consists in the study of the stamping behaviour of tufted and un-tufted carbon preforms. Several preforms by varying the tufting thread orientations (0°, 90° and 0°/90°) and with different stratifications ([0°/90°,-45°/+45°] and [0°/90°,-45°/+45°]2) were manufactured in order to study their out-of-plane deformability. The stamping test was carried out using a hemispherical punch and conducted at two blank-holder pressures (0.05 and 0.2 MPa). The experimental data highlight the influence of tufting threads on the forming force, maximum material draw-in, shear angle mapping and wrinkling phenomenon during the forming process. Furthermore, the orientations of tufting thread, the number of layers and the pressure of the blank-holder significantly affected the forming behaviour: all tufted preforms present a higher forming force, lower maximum material draw-in and shear angles and notable structural defects than the un-tufted preform. The increase in the pressure of the blank-holder from 0.05 to 0.2 MPa increases all these characteristics and emphasizes the structural defects on the fibrous reinforcements. Similarly, the transition from two layers to four layers in lamination at the same blank-holder pressure is followed by an increase of the forming force required for stamping operation, reducing the material draw-in and the shear angles especially those measured at the transient zone, and causes more structural defects on all stamped tufted and un-tufted preforms. For all these reasons, two localized tufting configurations, Right Localized Tufted (RLT) and Inclined Localized Tufted (ILT), at the stamping transition area are proposed. The stamping results show that these two original configurations present a minimum punch force and a maximum material draw-in similar to those measured on the un-tufted structure. The shear angles are higher than those recorded on the conventionally tufted preforms (over the entire surface).

The photovoltaic (PV) cell fracture reduces the efficiency of solar PV modules and the residual stresses generated in the silicon cells by various stages of manufacturing process are attributed as one of the primary reasons among others. In this study, a unified approach to investigate the residual stresses present across the PV module owing to differing material properties and thermal cycles during manufacturing process is attempted. In particular, an in-plane residual stress map for different layers of solar PV module and the stress jump across the layered structure arisen during the manufacturing process are quantified through finite element method by considering ethylene vinyl acetate encapsulant as a linear viscoelastic material. The maximum residual stress presence in the cell is observed during the encapsulant curing cycle of lamination process. The predictions on the stress pattern and magnitudes from the simulations collaborate well with the experimental observations reported in literature.

PMC (Polymer Matrix Composites), in addition to static loads, can also be exposed to dynamic loads as a result of impacts. Aircraft or cars are particularly vulnerable to this type of loading, where small objects, e.g. pebbles, sand grains, and metal debris may hit. Such loads can cause cracking or lead to complete damage. Therefore, the paper presents research results for the most commonly used polymer composite reinforced with glass fibers (GFRP). For GFRP samples, hand lay-up lamination was used. The tests were carried out using SHPB (Split Hopkinson Pressure Bar) the device equipped with steel bars with a diameter of 20.5 mm. Three load levels were used: 1 bar (≈1000 1/s), 1.5bars (≈1500 1/s) and 2bars (≈2000 1/s). The dimensions of the samples were 12 × 12mm, and the thickness was depending on the tested material. The analysis of the results was carried out in the WASP (Waves Analysis and Study Program) program, obtaining the true stress – true strain diagrams.

HfC nanowires modified carbon fiber cloth laminated carbon/carbon (HfCnw-C/C) composites were fabricated by in situ growth of HfC nanowires on carbon cloths via catalytic CVD, followed with lamination of the cloths and densification by pyrolytic carbon (PyC). Morphologies, thermal conductivity, coefficient of thermal expansion (CTE), and ablation resistance of the composites were investigated. Due to the loading of HfC nanowires, the matrix PyC with low texture was obtained; the thermal conductivity of the composites in the Z direction was enhanced from 100℃ to 2500℃; CTE along the X–Y direction also decreased in the range of 2060 ℃ – 2500 ℃, which reaches the maximum of 24 % at 2500℃. Moreover, the 20s-ablation-resistance of HfCnw-C/C composites exhibits mass and linear ablation rates of 5.3 mg/s and 21.0 μm/s, which are 40 % and 37 % lower than those of pure C/C composites, respectively. Our work shows laminated HfCnw-C/C composites are a promising candidate for high-temperature applications.

In this work, an experimental and numerical study of the High Velocity Impact (HVI) behaviour for hybrid structures was presented. HVI at different velocities were carried out on the structures, evaluating failure phenomena and impact damage using high-speed camera and ultrasound techniques (C-scan). In order to predict the complex impact response and damage extension in the structure, a 3D explicit Finite Element Model (FEM) was developed for each structure using a commercial LS-DYNA software. Experimental and numerical results were then presented showing a good correlation with an error between the 6% and 17% in terms of absorbed energy and damage extension. Afterwards, an optimisation analysis was carried out on the numerical model in order to identify the best design parameters when a TPU layer is introduced in the lamination sequence of the material for damage mitigation purposes. Results were presented reporting a reduction of at least 54% in absorbed energy, damage extension and maximum indentation respectively when 1 mm thick Thermoplastic Polyurethane (TPU) layer is applied on the Carbon Fibre Reinforced Polymer (CFRP) impact surface.

Designing modern composite structures requires sound understanding about the deformation and failure behavior of the combined materials. Hybridization of glass–epoxy layers into boron-epoxy has the potential to reduce the cost of the structure, nevertheless the failure behavior has not been established especially under biaxial loading condition. Therefore, this paper aims to perform simulation and analyze the failure behavior of boron/glass hybrid composite laminates under biaxial tension. The first stage of the work focused on replicating established experimental work on composite laminates made of boron-epoxy under biaxial tension. Prior to that, mesh convergence analysis and numerical validation has been performed. Finally, finite element simulation was performed to investigate the effect of hybridization of glass–epoxy layers into boron-epoxy under biaxial tension. Three lamination schemes, [0/90]s, [0/±45/90]s and [0/±45]s, where glass–epoxy was added either at the skin or core of the hybrid laminates were modelled and loads constituting the failure of each lamination scheme, were determined. The built-in function for failure analysis and Maximum Stress Theory, available in ANSYS software were employed. Based on the results, it could be observed that there is significant difference between boron laminates and its hybrid laminates failure behavior. Moreover, it is also simulated that the hybrid laminate could withstand more load compared to the original boron-epoxy laminates. Based on these findings, it can be concluded that the current study is useful and has provided significant knowledge about understanding the behavior of boron/glass hybrid composite laminates under biaxial tension.

Kajian ini merupakan tahap awal dari kajian yang bertujuan menentukan ketebalan minimal lapisan laminasi FRP (Fiber Reinforced Plastic) pada kapal kayu ukuran 5-7 GT (Gross Tonnage). Konstruksi laminasi FRP bertujuan mengurangi kontak langsung bagian kapal dengan air disekitarnya serta mampu menahan benturan kapal ketika sandar pada dermaga khususnya bagian kasko kapal. Saat ini laminasi FRP dilakukan berdasarkan keahlian dan pengalaman yang dimiliki oleh pengrajin. Tujuan dari kajian ini untuk mengetahui kekuatan benturan pada kapal yang akan dijadikan acuan untuk menentukan ketebalan laminasi FRP. Metode yang digunakan adalah dengan identifikasi dimensi utama kapal, kecepatan kapal dan kekuatan benturan yang kemudian dianalisis secara deskriptif numerik. Data diperoleh dari 13 kapal sampel selama bulan Oktober-Desember 2019. Hasil dari penelitian ini menunjukkan bahwa kapal yang digunakan termasuk towed or dragged gear. Dimensi utama kapal dengan rata-rata Loa 9,5 m; Bmax 3,2 m; D 1,2 m dengan ton displacement 13,6 ton/m3. Kecepatan kapal ketika terjadi benturan pertama mengalami penurunan berkisar 0,4-1,0 m/s atau sekitar 20-75%. Kekuatan benturan yang terjadi pada kapal ketika benturan pertama berkisar 7,13-87,48 kN.m. Oleh karena itu, kekuatan bentur yang akan dijadikan acuan dalam menentukan ketebalan lapisan laminasi FRP pada kapal kayu adalah sebesar 87,48 kN.m.

A typical photovoltaic (PV) module is composed of different layers bonded together, each with a different material and thus, a different coefficient of thermal expansion (CTE). While under operation, it is subjected to thermal loads due to continuous temperature variations. The CTE mismatch induces thermo-mechanical stresses, whose cyclic nature causes fatigue failure. Due to their relative small size, the copper interconnects are one of the most vulnerable constituents. In this work, the finite element (FE) analysis has been used to calculate these thermal stress/strain variations. To make the simulations more reliable, well-known material models have been adopted from the literature and used for each constituent of the PV module. Furthermore, to reduce computational time and complexity, a simplified modeling approach has been proposed in this work. In this approach, a 2-D FE global model was first used to identify the region that undergoes maximum strain. Then a 3-D FE local model was used for that particular region only. This approach helps calculate the maximum stress/strain variations. Thus, using the proposed modeling approach coupled with a fatigue criterion, one can calculate the fatigue life of the PV module, while significantly reducing the computational time. The initial conditions, in terms of residual stresses, due to the lamination process for the fabrications of the PV module are also accounted for in our approach. We applied our approach to silicon-based PV module under desert weather conditions of Doha (Qatar) and the results show a reduced life compared to the one provided by the manufacturer.

Lamination of thin bladed composite marine propellers necessitates dropping layers following thickness variation to produce lighter propeller with good elastic damping. Composite blade is subjected to multiaxial loads resulted from nonuniformly distributed hydrodynamic pressure that cause the blade to undergo combined structural response of bent and twist therefore, strength evaluation of such tapered laminate is a highly nontrivial process that include significant fluid–structure interaction (FSI). This research aims to investigate the strength of composite propeller using unconstrained stacking-sequence optimization based on fully coupled CFD-FEA analysis. Different hub idealization techniques were studied to determine the most accurate treatment in predicting stress and deformation of the blade. Composite model configured for propeller VP1304 after modification on blade thickness and, initial analysis on balanced-stacking of [0, 90, 45,−45] were set as a benchmark for optimization process targeting to minimize failure index; calculated according to Puck failure theory considering fiber and matrix failure as well as delamination. Delamination is evidenced to be utmost critical mode of failure whereas, the optimization resulted in an optimum laminate with unbalanced nonsystematic stacking that succeeded to; reduce interlaminar stresses, avoid failure and, reduce maximum value of IRF (Inverse Reserve Factor) by 50% compared to the predefined balanced-stacking benchmark.

The soft nature of metal halide perovskites makes them potentially applicable as flexible X-ray detectors. Here we report a structure of perovskite-filled membranes (PFMs) for highly sensitive, flexible and large-area X-ray detectors. PFMs with areas up to 400 cm2 are formed by infiltrating saturated perovskite solution through porous polymer membranes followed by hot lamination. The good connectivity and crystallization of perovskite crystals in the membranes enable a large mobility–lifetime product. The sensitivity of the X-ray detectors under a field of 0.05 V µm−1 reaches 8,696 ± 228 µC Gyair−1 cm−2 and shows no degradation after storage for over six months and exposure to a dose of 376.8 Gyair, equivalent to 1.88 million chest X-ray scans. The flexible PFMs can be bent at radii down to 2 mm without losing performance. The stand-alone detector array is curved and put inside metal pipes for the detection of material defects with imaging quality superior to flat-panel detectors. Perovskite-filled-membranes enable flexible, sensitive and large-area X-ray detectors. The structures are made by infiltrating perovskite solution into porous polymer membranes.

A novel process was developed for the fabrication of 5–50 µm lead zirconate titanate (PZT) thick films on metal substrates. Tape cast PZT with a methyl cellulose binder was burned out at 275 °C, humidified, and then partially densified at 300 °C by cold sintering with a wet lead nitrate liquid phase. Lamination of the green tape on dense metal foils led to incomplete densification due to constrained sintering. However, when metal foils were replaced with tape cast Cu, fully sintered PZT/Cu/PZT composites were acquired after a secondary heat treatment at 800 °C. The PZT films has a relative permittivity over 500 and a loss tangent ~12% at 100 Hz because of a Cu2O interface between the PZT and Cu presumably formed during the cold sintering process. The polarization-electric field hysteresis loop shows a remanent polarization over 20 µC/cm2, and the e31,f of the samples is -4.7 C/m2.

This study explores the influences of needle punching and a shear-thickening fluid (STF) on the stab resistance sandwich-structured composites made of nylon nonwoven and aramid fabrics. Needle punching and different treatments of aramid fabric are conducted to obtain the composites. The effects of needle punching and different treatments of aramid fabrics on the sandwich-structured composites were examined using quasi-static puncture resistance, quasi-static stab resistance, dynamic puncture resistance, and bursting property tests. Results show that needle punching and incorporation of STF positively influence the stab resistance of the composites. This study provides an innovative method to reduce the number of lamination layers and decrease the weight.

The highly permeable SiC fiber porous media (FPM) were prepared with impressive combustion performance by optimizing the density. The fiber paper was firstly prepared by suction filtration of chopped SiC fibers. Different layers of fiber paper were laminated to the same thickness and then BN interfaces and SiC shells were deposited to weld the fibers, resulting in the FPM with different densities. The permeability, thermal physical properties and combustion performance of the FPM with different densities were studied. Results show that two types of pore structures exist in the FPM. One is the smaller pores near the fiber joints while the other is larger pores far from that. The increase in lamination layer will result in decreased porosity and pore size. Meantime, as the lamination layer increases, thermal diffusivity decreases while the infrared radiation coefficient, thermal capacity and thermal conductivity increase. In the combustion tests, the FPM with 5 layers of fiber paper shows excellent combustion effect, high gas conversion efficiency and low NOx emission. The combustion temperature is about 800 °C. The NOx and CO content in the flue gas is 3 ppm and 6 ppm, respectively, at a low emission level.

Soft strain sensors that are mechanically flexible or stretchable are of significant interest in the fields of structural health monitoring, human physiology, and human-machine interfaces. However, existing deformable strain sensors still suffer from complex fabrication processes, poor reusability, limited adhesion strength, or structural rigidity. In this work, we introduce a versatile, high-throughput fabrication method of nanostructured, soft material-enabled, miniaturized strain sensors for both structural health monitoring and human physiology detection. Aerosol jet printing of polyimide and silver nanowires enables multifunctional strain sensors with tunable resistance and gauge factor. Experimental study of soft material compositions and multilayered structures of the strain sensor demonstrates the capabilities of strong adhesion and conformal lamination on different surfaces without the use of conventional fixtures and/or tapes. A two-axis, printed strain gauge enables the detection of force-induced strain changes on a curved stem valve for structural health management while offering reusability over 10 times without losing the sensing performance. Direct comparison with a commercial film sensor captures the advantages of the printed soft sensor in enhanced gauge factor and sensitivity. Another type of a stretchable strain sensor in skin-wearable applications demonstrates a highly sensitive monitoring of a subject's motion, pulse, and breathing, validated by comparing it with a clinical-grade system. Overall, the presented comprehensive study of materials, mechanics, printing-based fabrication, and interfacial adhesion shows a great potential of the printed soft strain sensor for applications in continuous structural health monitoring, human health detection, machine-interfacing systems, and environmental condition monitoring.

Additive manufacturing (AM) is an emerging process that has been extremely improved in terms of technology and application in recent years. In this technology review, new industrial improvements in laser powder bed fusion (LPBF) of metals are discussed. LPBF has the lowest build rate among all AM processes that produce metals such as electron beam powder bed fusion, direct energy deposition, binder jetting and sheet lamination. The findings of the current research show that the most innovations and future directions of LPBF printers are toward increasing the speed of the process by using interchangeable feedstock chamber, closed-loop control powder handling, automated powder sieving, multi-layer concurrent printing, 2-axis coating and multi powder hoppers. To increase the speed of the process, the new improvements for transferring time and using fast lasers are presented. Another innovation in the building of LPBF printers is enhancing part quality by improving lasers with the shorter beam diameter, multi-lasers, uniform inert gas flow, accurate positioning systems, using high vacuum systems and using sensors and automation.

Laminated composite structures have attracted the interest of the modern industry due to their high performances and reduced weight when compared to traditional structural materials. However, they are very sensitive towards out-of-plane dynamic loading that can generate Barely Visible Impact Damage (BVID) within the structure and cause a drastic detriment of mechanical properties. One solution is proposed to overcome this problem by the hybridisation of the laminate stacking sequence using Shear Thickening Fluids (STFs) for absorption of large fractions of impact energy with a minimal damage generation. This work numerically investigated the impact response of Carbon Fibre Reinforced Polymers (CFRP) when a silica-based STF is embedded within the lamination sequence utilising an innovative Ls-Dyna-based Finite-Element Model (FEM). This was developed using an Arbitrary Lagrangian Element (ALE) approach in a fluid-structure interaction (FSI) analysis and calibrated with an experimental impact campaign to determine the best impact resistance as a function of the STF position along the thickness of the laminate. The results showed an improvement in impact resistance for all the hybrid configurations identifying the optimal STF location in the upper portion of the laminate with a reduction in absorbed energy of ~ 42%, damaged area of ~ 35% alongside an increase in contact force (~ 36%) with respect to conventional laminate with same stacking sequence and number of plies. The results showed that STF/CFRP structures can be successfully employed for applications in several advanced sectors including aerospace, automotive and energy (wind blades) representing an important step-up in the development of high-impact resistant hybrid composite structures.

This paper presents the current state-of-the art of additive manufacturing (AM) applications in the biomedical field, especially in tissue engineering. Multiple advantages of additive manufacturing allow to precise three-dimensional objects fabrication with complex structure using various materials. Depending on the purpose of the manufactured part, different AM technologies are implemented, in which a specific material can be utilized. In the biomedical field, there are used several techniques such as: Binder Jetting, Material Extrusion, Material Jetting, Powder Bed Fusion, Sheet Lamination, Vat Polymerization. This article focuses on the utilization of polymer materials (natural and synthetic) taking into account hydrogels in scaffolds fabrication. Assessment of polymer scaffolds mechanical properties enables personalized patient care, as well as prevents damage after implantation in human body. By controlling process parameters it is possible to obtain optimised mechanical properties of manufactured parts.

This paper presents a new intelligent data-driven adaptive method (IDAM) of performing automatic online searches in real time. An online implementation of the proposed IDAM achieved rapid real-time optimization of system integration scaling factors for an automatic touch panel lamination machine. The proposed IDAM combines three-level orthogonal arrays (OAs), signal-to-noise ratios (SNRs), the best combined strategy, and a stepwise ratio. Three-level OA experiments with factor values are used to perform positional experiments, and SNRs are calculated for each experimental value. After the best combination of factor values (in terms of factor effect) is determined, new three-level factor values are derived by applying a stepwise ratio and used in further three-level OA experiments. These steps are repeated until the stopping criterion is met. Compared to conventional methods, the use of the IDAM in practical industrial applications, i.e., online real-time precision positioning for automatic touch panel lamination machines, reduces the number of experiments needed to obtain the system integration scaling factors that minimize the iteration count. For example, the IDAM required less than 40 online real-time experiments with a specific stepwise ratio for system integration scaling factors that met the minimum requirement of two iterations. In 50 independent experimental runs using the robust scaling factors obtained by the method, an average of 2.15 iterations was needed to achieve a positional accuracy within 5 ${\mu }\text{m}$ . The main advantage of the proposed IDAM over conventional methods is its effectiveness for automatically finding robust parameters for online alignment systems in real time and with fewer experiments.

In order to make conductive woven fabrics with electromagnetic shielding effectiveness (EMSE) and flame retardance, polysufonamide (PSA)/stainless steel (SS) core yarn are used as the weft yarns and PSA yarns are used as the warp yarns. The conductive woven fabrics are denoted as SS-60, SS-80, SS-100, SS-120, and SS-140 according to the twist counts of the core yarn, and evaluated in terms of mechanical properties, flame retardance, surface resistivity. The test results show that the best twist of the core yarn is 120 turns/10 cm. SS-60 has the maximum burnt length, while SS-140 has the minimum burnt length. Moreover, the surface resistivity of the PSA/SS woven fabrics is proportional to the twist counts, and the surface resistivity along the warp direction is higher than that along the weft direction. Changing the fabric lamination angle can form a complete shielding network, and the EMSE is significantly increased. For SS-80, SS-100, and SS-120, when they are composed of 4–6 layers with lamination angles of 0°/45°/90°/-45°/0°/45° and 0°/90°/0°/90°/0°/90°, the EMSE is above 40 dB and the shielding effect is above 99.99 % against the incident waves at 2000–3000 MHz. Specifically, SS-120 has the maximum EMSE of 64 dB against incident waves at 2844 MHz.

Purpose This study aims to characterize a novel glass/epoxy architecture sandwich structure for electronic boards. Understanding the thermo-mechanical behavior of these composites is important because it is possible to pre-determine whether defined “internal” thick laminates will be suitable for embedding components in the direction of the axis “z,” i.e. this method of manufacturing multilayer laminates can be used for incoming miniaturization in electronics. Design/methodology/approach Laminates with a low glass transition temperature (Tg) and high Tg with E-glass type were treated, tested and compared. Testing samples were manufactured by nonstandard two steps unidirectional lamination as a multilayer structure based on prepreg layers and as “a sandwich structure” to explore its effect on thermo-mechanical properties. The proposed tested method determines the time and temperature-dependent viscoelastic properties of the board by using dynamic mechanical analysis, thermo-mechanical analysis and three-point bend tests. Findings This testing method was chosen because the main property that promotes sandwich structure is their high stiffness. Glass/epoxy stiff and thermal stabile sandwich structure prepared by nonstandard two-stage lamination is proper for embedding components and the next miniaturization in electronics. Originality/value Compared with by-default applied glass-reinforced homogenous laminates, novel architecture sandwich structure is attractive because of a combination of strength, stiffness and all while maintaining the miniaturization requirement and multifunctional application in electronics.

The favorable mechanical properties and performance of TEMPO-oxidized cellulose nanofibril (TOCNF) films has been limited by their brittleness and the incapability of obtaining thick enough materials for self-supported applications. In this study, lamination with room temperature curable epoxy was used to combat brittleness, increase thickness, and produce a more damage tolerant material. The effect of the volume fraction and layer thickness of both phases (e.g., TOCNF, epoxy), the number of layers, and the overall total thickness of the laminate, on the tensile and flexural properties are investigated. Lamination was successful at increasing the toughness and thickness of TOCNF composites, resulting in an increased work of fracture that was associated with fracture retardation by crack digression in three-point bending specimens. The ultimate tensile strength and Young’s modulus were higher for laminates with low volume fractions of epoxy although not statistically different than the neat TOCNF films, but decreased with increasing volume fraction of epoxy, and with increasing number of TOCNF layers.

An outstanding enhancement of corrosion resistance and mechanical properties of Al-Zn-Mg-Cu alloy was achieved by ultrasonic surface rolling treatment (USRT). The results showed that the precipitates were dissolved into Al matrix, the deformation texture was weakened, and the nanometer/micron/nanometer lamination structure was formed after USRT, which enhanced the corrosion resistance and provided the alloy with an excellent ultimate tensile strength of 578.1 MPa, tensile yield strength of 517.6 MPa and elongation to fracture of 8.5 pct.

We examined a working hypothesis of sticky thermoelectric (TE) materials, which is inversely designed to mass-produce flexible TE sheets with lamination or roll-to-roll processes without electric conductive adhesives. Herein, we prepared p-type and n-type sticky TE materials via mixing antimony and bismuth powders with low-volatilizable organic solvents to achieve a low thermal conductivity. Since the sticky TE materials are additionally injected into punched polymer sheets to contact with the upper and bottom electrodes in the fabrication process, the sticky TE modules of ca. 2.4 mm in thickness maintained temperature differences of ca. 10°C and 40°C on a hot plate of 40 °C and 120°C under a natural-air cooling condition with a fin. In the single-cell resistance analysis, we found that 75~150-μm bismuth powder shows lower resistance than the smaller-sized one due to the fewer number of particle-particle interfaces in the electric pass between the upper and bottom electrodes. After adjusting the printed wiring pattern for the upper and bottom electrodes, we achieved 42 mV on a hot plate (120°C) with the 6 × 6 module having 212 Ω in the total resistance. In addition to the possibility of mass production at a reasonable cost, the sticky TE materials provide a low thermal conductivity for flexible TE modules to capture low-temperature waste heat under natural-air cooling conditions with fins for the purpose of energy harvesting.

We present an evaluation of the silicon solar cell as well as the photovoltaic (PV) module size and its effect on thermomechanical stress. The evaluation is based on finite-element method (FEM) simulations. Within these simulations, we perform parameter variations of the number of solar cells within a PV module from 60-140 cells, of the cell size from 156.0-161.75 mm, and the cell format from full cells down to quarter cells. The FEM simulations cover the lamination process, mechanical load, and thermal cycling for glass-foil as well as glass-glass modules. The presented results reveal correlations between the solar cell and module size with the stress in the solar cells. We also find that the interaction of the laminate with the module frame plays a significant role in thermal cycling. Of the varitations under investigation, the increase in cell size has the largest effect on the stress. However, at a mechanical load of 2400 Pa, glass-foil modules with less than 96 solar cells have a negligible failure probability. The advantage of placing the solar cells in the neutral axis of the laminate is proven by the negligible tensile stress values for all variations of the glass-glass modules.

The domain of Biomaterials has provided a vast scope for research and development and this work is one such effort to develop a Bio Hybrid Composite that is bio degradable and hence eco-friendly with enhanced mechanical properties as well. The present investigation is on fabrication and evaluation of mechanical properties of Bio Hybrid Composite with different natural fibres–flax fibre woven mat, Aloe Vera fibre woven mat, and sisal fibre that are used as reinforcing lamination materials bonded with epoxy resin. This hybrid composite is prepared by the hand lay-up process and the experimental tests for tension, flexural, impact, and hardness are carried out in accordance with ASTM standards. The prepared composite material is also analysed by Finite Element Analysis Method (ANSYS 16.2) and the obtained analytical results are compared with real time experimental values.

World-wide blanking is the most popular technique for producing the non-oriented electrical steel lamination. However, blanking has a great effect on magnetic property and mechanical property, such as the introduction of uneven residual stress, the deterioration of magnetic properties and the increase of micro-hardness. In this research, non-oriented electrical steel sheets are investigated via blanking test by 3 kinds of punches. The blanking edges are examined by the optical microscopy and micro-hardness test to visualize the distribution of micro-hardness. The magnetic properties are also measured. The results show that the blanking clearance has a great influence on magnetic properties and mechanical properties of the blanked material.

Soft Magnetic Composite (SMC) materials possess isotropic magnetic and thermal properties, very low eddy current loss and relatively low total core loss at medium and higher frequencies. This paper presents the application potential of iron powder SMC in switched reluctance machine (SRM) and its performance enhancement. The results of extensive finite element simulation and experimental validation of the proposed fabricated prototype are delineated. The study concludes that the use of SMC as magnetic core of a switched reluctance motor enhances its thermal and vibration characteristics in comparison with the conventional lamination counterpart.

Polymer-dispersed liquid crystals (PDLCs) exhibiting transmittance switching are utilized for preserving energy and protecting privacy. Here we prepared a typical PDLC mixture from a commercially available polymer and liquid crystal with nano-beads. A wire-bar coater was used to coat the PDLC mixture on indium-tin-oxide-coated glass, and a PDLC cell was assembled by coupling another glass in a vacuum, instead of a polymer film. Uniform glass-based PDLCs were fabricated successfully with an area of 15 × 15 cm2, while an injection process with capillary action was not available for this large-scale device fabrication. The switching behavior of the cells was characterized by ramping the AC voltage, and a transmittance change of ∼70% was measured. In a typical roll-to-roll process, only flexible polymer films have been used in lamination, in which deterioration in transparency occurs over the course of time, reducing the efficiency. In this study, to improve the optical properties, PDLC switchable glazing is fabricated directly onto glass substrates instead of onto plastic polymers. This PDLC switchable glazing, exhibiting low haziness and wide-angle vision, can be fabricated at a large scale by a vacuum-coupling process, with potential use as glass windows for energy-efficient buildings.

The nonlinear eigenvalue responses of conical composite shell structure with cluster of multiple delaminations are investigated numerically using the displacement-type finite element technique including the influence of the moisture and elevated thermal environment. The governing equation for the free vibrated structure case of the layered conical panel is obtained through a generalization of the principle of virtual displacement. The numerical solutions are obtained through a customized computer code developed via the higher order displacement field model imposing the zero stresses at the top and bottom surfaces of the laminate. The panel model has been discretized using an eight-nodded isoparametric element to maintain the desired C0 continuity and to avoid the mathematical complexity involved in C1-type continuity. A delamination model is developed by accounting single and cluster of delaminations. The delamination is located at centre of the laminates, either in cluster form or segregated over the lamina. The model is developed by considering the laminate is exposed to elevated moisture and temperature environment. The contribution of moisture and temperature effects on delaminated lamina is examined. The solution methodology is validated with published results. Influence of various parameters such as lamination schemes, aspect ratios, support conditions, thickness ratios, curvature ratios and material properties of the linear and nonlinear free vibration frequencies are analysed in detail and presented. The inferences from the study signify the reduction trend of fundamental frequency due to the presence of single/multi-delamination and moisture content.

High-performance organic field-effect transistors (OFETs) based on conjugated polymers have received extensive attention in recent years. However, the relationships between the multiscale structures of conjugated polymers and electrical properties are not well established. Here, laminated, ultrathin poly(3-hexylthiophene) (P3HT) films have been prepared using a sequential, repeated transfer-etching process from the precursor conjugated/insulating polymer blend films and used to study the structure-property relationship at the transition of the film structure from 2D to 3D. The molecular packing of the films is improved by lamination as certified by grazing incidence X-ray diffraction, UV-visible spectroscopy, and Raman spectroscopy. The laminated ultrathin P3HT films exhibit excellent electrical properties with a maximum mobility of 0.23 cm2 V-1 s-1 at three layers, which is close to the highest value reported for undoped P3HT OFETs. Temperature-dependent FET characteristics reveal that the laminated films have low activation energy and a 2D charge transport profile regardless of the number of layers. These charge transport properties are attributed to the well-ordered molecular packing and low trap density in the films, which are enabled by the phase separation of the precursor blend films and the lamination process. In addition, OFETs based on these films have good photostability under different wavelengths of light, indicating that this approach has promising practical application prospects.

The thermal conductivity of polymer composites can be enhanced by the vertical alignment of anisotropic aluminum nitride (AlN) platelet fillers in polymer matrices. The AlN platelets in polymer matrix were aligned in the direction of in-plane and out-of-plane by using the doctor blading and the lamination process. The alignment of AlN plates in the out-of-plane or the in-plane direction has been confirmed by XRD and FE-SEM investigations. The polymer composite with the out-of-plane aligned AlN platelets showed almost 1.5 times or 2 times higher thermal conductivity than those with the AlN spheres or the in-plane aligned AlN platelets at the same filler content, respectively. This result could be attributed to the improvement of thermal pathway generated along the plane of platelets and the decrease of interfaces between the filler and the polymer. Keywords: Thermal conductivity, Aluminum nitride plate, Polymer composite, Alignment, Out-of-direction, In-plane direction

Large-area electronics is becoming an embedded part of structural elements such as automotive and architectural glasses. In this paper, the effect of glass-lamination-based fabrication process on the electrical performance and production throughput yield (TPY) of printed conductive wires and surface-mounted (SMD) connectors on polyethylene terephthalate (PET) carrier film was investigated by measuring their electrical conductivity after lamination. Based on the experiments, lamination decreases the production yield of conductive wires and connectors due to broken wires or dislocated connectors, especially if they are located close to the corners of the laminate. On the other hand, lamination was observed to improve the electrical conductivity of wires. In addition, some potential failure mechanisms are discussed.

Recently, various types of displays have been developed for use in smartphones. In particular, the shape of the glass used as the cover window of a smartphone has developed from a flat shape to a vandal shape with multiple curvatures. The lamination process for bonding an OLED backplane to such a bended cover window requires a relatively high level of skill. To develop such a technique, we designed a silicone pad with sufficient adhesive strength to suit the various curvatures. In this paper, we have confirmed the results.

Wood-based materials in current additive manufacturing (AM) feedstocks are primarily restricted to the micron scale. Utilizing large-scale wood in existing AM techniques remains a challenge. This paper proposes an AM method&mdash, laser-cut veneer lamination (LcVL)&mdash, for wood-based product fabrication. Inspired by laminated object manufacturing (LOM) and plywood technology, LcVL bonds wood veneers in a layer-upon-layer manner. As demonstrated by printed samples, LcVL was able to retain the advantageous qualities of AM, specifically, the ability to manufacture products with complex geometries which would otherwise be impossible using subtractive manufacturing techniques. Furthermore, LcVL-product structures designed through adjusting internal voids and wood-texture directionality could serve as material templates or matrices for functional wood-based materials. Numerical analyses established relations between the processing resolution of LcVL and proportional veneer thickness (layer height). LcVL could serve as a basis for the further development of large-scale wood usage in AM.

Lamination is a common industrial problem during the production of pharmaceutical tablets. It corresponds to a failure of the tablet in one or several planes parallel to the surface and passing through the tablet band. But different kinds of lamination exist, and a classification of the different cases is proposed in this work. Type 1 corresponds to a multiple fracture caused by air entrapment. Type 2 occurs because of the shear stresses developing when the tablet goes out of the die. Type 3, which is limited to convex tablets, is due to a tensile stress developing at the center of the tablet at the end of the unloading that further propagates toward the band. One case of each type was studied experimentally in order to test three solutions classically used at the industrial level: slowing down the press, using a precompression and using a tapered die. Results shows that, in coherence with the proposed mechanisms, lamination type 1 can be mitigated by slowing down the press or using a precompression. For type 2, only the tapered die solution stopped lamination. None of the solutions completely solved lamination type 3. Nevertheless, the use of a tapered die decreased the severity of the problem avoiding the propagation of the crack until the surface.

A multi-level cell (MLC) operation as a 1–3 bit/cell of the FeFET emerging memory is reported by utilizing optimized Si doped hafnium oxide (HSO) and hafnium zirconium oxide (HZO) based on ferroelectric laminates. An alumina interlayer was used to achieve the thickness independent of the HSO and HZO-based stack with optimal ferroelectric properties. Various split thicknesses of the HSO and HZO were explored with lamination to increase the FeFET maximum memory window (MW) for a practical MLC operation. A higher MW occurred as the ferroelectric stack thickness increased with lamination. The maximum MW (3.5 V) was obtained for the HZO-based laminate, the FeFETs demonstrated a switching speed (300 ns), 10 years MLC retention, and 104 MLC endurance. The transition from instant switching to increased MLC levels was realized by ferroelectric lamination. This indicated an increased film granularity and a reduced variability through the interruption of ferroelectric columnar grains. The 2–3 bit/cell MLC levels and maximum MW were studied in terms of the size-dependent variability to indicate the impact of the ferroelectric area scaling. The impact of an alumina interlayer on the ferroelectric phase is outlined for HSO in comparison to the HZO material. For the same ferroelectric stack thickness with lamination, a lower maximum MW, and a pronounced wakeup effect was observed in HSO laminate compared to the HZO laminate. Both wakeup effect and charge trapping were studied in the context of an MLC operation. The merits of ferroelectric stack lamination are considered for an optimal FeFET-based synaptic device operation. The impact of the pulsing scheme was studied to modulate the FeFET current to mimic the synaptic weight update in long-term synaptic potentiation/depression.

Fabrication of 3D microfluidic devices is normally quite expensive and tedious. A strategy was established to rapidly and effectively produce multilayer 3D microfluidic chips which are made of two layers of poly(methyl methacrylate) (PMMA) sheets and three layers of double-sided pressure sensitive adhesive (PSA) tapes. The channel structures were cut in each layer by cutting plotter before assembly. The structured channels were covered by a PMMA sheet on top and a PMMA carrier which contained threads to connect with tubing. A large variety of PMMA slides and PSA tapes can easily be designed and cut with the help of a cutting plotter. The microfluidic chip was manually assembled by a simple lamination process.The complete fabrication process from device design concept to working device can be completed in minutes without the need of expensive equipment such as laser, thermal lamination, and cleanroom. This rapid frabrication method was applied for design of a 3D hydrodynamic focusing device for synthesis of gold nanoparticles (AuNPs) as proof-of-concept. The fouling of AuNPs was prevented by means of a sheath flow. Different parameters such as flow rate and concentration of reagents were controlled to achieve AuNPs of various sizes. The sheet-based fabrication method offers a possibility to create complex microfluidic devices in a rapid, cheap and easy way.

Composite stacked material is widely used in many fields, such as aircraft, rocket, missile, and soon. In the process of drilling carbon fiber-reinforced polymer and titanium alloy lamination materials (CFRP/TC4, which is a typical structure in aircraft), tool wear is quick and serious, because the machining condition of the respective layers in stack is different. To ensure the drilling quality, drilling tool needs to be changed frequently. Therefore, if there is a detecting system in automatic drilling device to monitor and predict the tool wear effectively, it will help to improve the production efficiency and reduce the tool cost. Based on the experiments of drilling CFRP/TC4 stacks, the acoustic emission (AE) signals were carefully analyzed using the method of statistical analysis, spectrum analysis, and wavelet packet. The results show that the root-mean-square value of the AE signals and the energy of the wavelet packet are correlated with the tool wear. Meanwhile, experiments indicate that chips and tool fracture will cause instantaneous signal mutation, which may be appeared as disturbances. This has increased the difficulty of identifying the tool wear. With repeated experiments and comparison, it was found that the percentage of wavelet packet energy of some certain frequency sections increased with the tool wear, while some decreased. These variations will be possible to be used as features for further prediction in monitoring system.

Takaaki Kasuga, Hitomi Yagyu, Kojiro Uetani, Hirotaka Koga, and Masaya Nogi. “Return to the Soil” Nanopaper Sensor Device for Hyperdense Sensor Networks. ACS Applied Materials & Interfaces 2019 11 (46), 43488-43493. https://doi.org/10.1021/acsami.9b13886., A nanopaper sensor device that combines humidity sensing, wireless information transmission, and degradability has been fabricated using wood-derived nanopaper as the substrate and dielectric layers. The nanopaper shows excellent suitability for capacitor dielectric layers because of its high dielectric constant, insulating properties suitable for thin-film formation, and lamination properties. A wireless transmission circuit containing the nanopaper capacitor can transmit radio signals in the megahertz band, and the relative humidity change can be output as a change in the radio signal owing to the humidity sensitivity of the nanopaper capacitor. More than 95% of the total volume of the nanopaper sensor device decomposes in soil after 40 days. Because the nanopaper sensor device does not need to be recovered, it is expected to greatly contribute to a sustainable society through realization of hyperdense observation networks by mass installation of sensor devices.