Fabrication Of Substrates Research Articles

The Impact of Structural Variations and Coating Techniques on the Microwave Properties of Woven Fabrics Coated with PEDOT:PSS Composition

Minimizing the impact of electromagnetic radiation (EMR) holds paramount importance in safeguarding individuals who frequently utilize electrical and electronic devices. Electrically conductive textiles, which possess specialized EMR shielding features, present a promising solution to mitigate the risks related to EMR. Furthermore, these textile-based shielding materials could find application as radar-absorbing materials in stealth technology, emphasizing the need for substantial absorption capabilities in shielding mechanisms. In this study, various textile-based materials with an electrically conductive coating that contain the conjugated polymer system poly(3,4-ethylene-dioxythiophene)-polystyrene sulfonate (PEDOT:PSS) were prepared and investigated. The influence of the textile substrate structural parameters, coating deposit, and coating method on their microwave properties—transmission, reflection, and absorption—was investigated. Reflection and transmission measurements were conducted within a frequency range of 2 to 18 GHz. These measurements revealed that, for the tested samples, the shielding properties are determined by the combined effect of reflection and absorption. However, the role of these two parameters varies across the tested frequency range. It was defined that for fabrics coated on one side, better reflection reduction is obtained when the shielding effectiveness (SE) is below |20| dB. It was found that by controlling the coating deposition on the fabric, it is possible to fine-tune the electrical properties to a certain extent, thereby influencing the microwave properties of the coated fabrics. The studies of prepared samples have shown that reflection and transmission parameters depend not only on the type and quantity of conductive paste applied to the fabric but also on the fabric’s construction parameters and the coating technique used. It was found that the denser the substrate used for coating, the more conductive paste solidifies on the surface, forming a thicker coat on the top. For conductive fabrics with the same substrate to achieve a particular SE value using the knife-over-roll coating technology, the required coating deposit amount is considerably lower as compared with the deposit necessary in the case of screen printing: for the knife-over-roll-coated sample to reach SE 15 dB, the required deposit is approximately 14 g/m2; meanwhile, for a sample coated via screen printing, this amount rises to 23 g/m2.

Vector Substrates: Idea, Design, and Realization

AbstractSubstrates are essential in thin‐film deposition, yet they do not always meet the requirements of a given application. For example, they might be prohibitively expensive or not even available with the necessary crystal lattice structures. This paper introduces the innovative concept of “vector substrates,” where the template layer for thin‐film growth, referred to as vector, is chemically and crystallographically independent of the bulk of the substrate. This approach reduces material costs and offers unparalleled flexibility. The fabrication of vector substrates leverages thin‐film membrane technology. The process begins by growing a template layer on a parent substrate. The template layer is then transferred onto a carrier substrate, thereby generating the vector substrate. Vector substrate technology enables researchers and manufacturers with thin‐film deposition facilities to fabricate optimized substrates that would otherwise be difficult to obtain using bulk single‐crystal growth technology. An in‐depth discussion of the benefits and limitations of vector substrates compared with traditional substrates is provided. Furthermore, the practical viability of the concept is demonstrated by fabricating sets of vector substrates. Although this concept is still in its infancy, it has a significant potential to complement conventional substrates for future advancements in substrate technology and thin‐film deposition.

Textile‐Based Stretchable Supercapacitors with Liquid Metal Current Collectors

AbstractStretchable supercapacitors (SCs) have attracted attention as energy storage devices for wearable electronics due to their excellent power performance, low heat generation, and ease of integration into clothing. This paper presents a stretchable SC composed of liquid metal current collectors on textile substrates. For the liquid metal and textile‐based supercapacitors (LM/Tex SCs), the wetting characteristics and electrical resistance of the liquid metal on different types of textile substrates are investigated. The wettability of the carbon nanotube suspension for an electrochemically active material is also affected by the chemical and structural properties of the textile substrates. The intrinsically stretchable LM/Tex SCs are fabricated by sandwiching a soft gel electrolyte layer between the two liquid metal and textile‐based electrodes. The optimized SCs based on the polyester/neoprene textile exhibit a high areal capacitance of 527.8 mF cm−2 and maintain more than 90% of their initial capacitance after 1000 repetitive stretching cycles. Finally, it is demonstrated that the LM/Tex SC is readily integrated into a shirt and reliably supplies electrical energy to light up a light‐emitting diode even under human motion.

Fabrication of flat stainless steel substrates with improved oxidation behavior for metal-supported solid oxide cells using aqueous tape casting

An aqueous tape casting procedure was developed and optimized to fabricate thick, flat tapes for use as porous stainless-steel substrates for metal-supported solid oxide cells (MS-SOCs). Curling tape is one of the main challenges when using aqueous based slurry formation. This work demonstrated that the sedimentation problem can be solved by increasing solid loading rather than adding excessive binder to raise viscosity. The effect of various casting surfaces on tape curling was also investigated. Materials that allow easy tape release resulted in flatter tapes once the water was evaporated. In addition, substrate oxidation resistance at high temperature was evaluated with respect to starting powder size, sintering extent, and pore former types. High sintering extent that removes or encloses the porosity between steel particles while retaining porosity left by pore formers can effectively prevent breakaway oxidation due to local chromium depletion. Carbon residue in the steel substrates from the slurry organic content can be decreased when formulating the slurry to prevent Cr-rich phase formation in the steel, which severely compromises the substrate oxidation resistance and ductility. By dwelling the substrate in high purity hydrogen, the sensitization can be reversed, but more detailed investigation of the reaction dynamics is needed. By combining the strategies described, this work produced crack-free, flat, 400–500 μm thick stainless steel substrates with 28.7 vol% porosity and improved oxidation resistance compared to previous substrates fabricated by dry pressing of fine powders.

Multifunctional energy harvesting and storage textile technology based on thermionic effect

The development of effective dual-function energy harvesting/storage technologies is a milestone demand for the emerging generation of low-consumption autonomous electronics. This work reports the development of a multifunctional thermionic power textile device merging thermal energy harvesting and electrochemical energy storage for application in self-powered systems. An everyday cost-effective non-conductive natural fabric was transformed into an all-solid-state textile-based thermally-chargeable supercapacitor (T-TCSC) via dyeing with multiwalled carbon nanotubes and subsequent assembly with H3PO4-doped poly(vinyl alcohol) (PVA) solid-gel polyelectrolyte.When subjected to an out-of-plane temperature gradient, the T-TCSC was able to convert the thermal energy into electrical output and store the harvested energy. A Soret coefficient of 1.85 mV K−1 was obtained, which is the highest value achieved so far for TCSCs developed on non-conductive textile substrates reported in literature and ∼10× higher than those of conventional thermoelectric devices. Additionally, a maximum output potential of ∼30 mV was achieved for ΔT = 24.7 K. Concerning the energy storage performance, an energy density of 9.39 μW h cm−2 was obtained at 1.62 mW cm−2 power density.The smart T-TCSC outputs demonstrated its potentialities as a two-in-one self-chargeable textile device that can harvest the thermal energy generated by a temperature gradient, convert it into electrical energy and simultaneously store it.

Design of UWB MIMO antenna using lean wearable textile substrate for reduced SAR

PurposeThis paper aims to propose a two-element dual fed ultra-wideband (UWB) multiple input multiple output (MIMO) antenna system with no additional decoupling structures. The antenna operates from 3.1 to 10.6 GHz. The antenna finds its usage in on-body wearable device applications.Design/methodology/approachThe antenna system measures 63.80 × 29.80 × 0.7 mm. The antenna radiating element is designed by using a modified dumbbell-shaped structure. Jean cloth material is used as substrate. The isolation improvement is achieved through spacing between two elements.FindingsThe proposed antenna has a very low mutual coupling of S21 < −20 dB and impedance matching of S11 < −10 dB. The radiation characteristics are stable in the antenna operating region. It provides as ECC < 0.01, diversity gain >9.9 dB. The antenna offers low average specific absorption rate (SAR) of 0.169 W/kg. The simulated and measured results are found to be in reasonable match.Originality/valueThe MIMO antenna is proposed for on-body communication, hence, a very thin jean cloth material is used as substrate. This negates the necessity of additional material usage in antenna design and the result range indicates good diversity performance and with a low SAR of 0.169 W/kg for on-body performance. This makes it a suitable candidate for textile antenna application.

Paper-based 3D SERS immunoassay array based on self-assembly of AuNBPs@Ag nanorods for ultrasensitive and highly stable detection of α-fetoprotein

Establishing a simple, sensitive, and accurate α-fetoprotein (AFP) detection methods is of great significance for the early diagnosis of hepatocellular carcinoma (HCC). Surface-enhanced Raman spectroscopy (SERS) has been identified as one of the most promising techniques for clinical monitoring. However, accurate detection of AFP is still challenging due to the poor stability of SERS substrate and the low abundance of AFP in the early stages of HCC. Herein, we developed an ultrasensitive and highly stable paper-based 3D SERS immunoassay array for AFP detection, combining the superior advantages of self-assembled AuNBPs@Ag nanorods, filter paper, and sandwich immunoassay. In the immunoassay array, 4-mercaptobenzoic acid (4-MBA) linked to the secondary antibody was employed as the Raman reporter, while the array modified with antibodies was used to capture AFP. The SERS immunoassay array sensor exhibited a wide linear range (3 pg mL−1 to 10 µg mL−1), low detection limit (0.086 pg mL−1), good specificity, and high signal reproducibility (RSD < 5 %). Meanwhile, the sensor is further used for accurate detection of trace AFP in serum, which paves an avenue for the fabrication of SERS substrates with high stability and provides a new outlook for their application in the early diagnosis of cancer.

SkinAid: A Wirelessly Powered Smart Dressing Solution for Continuous Wound-Tracking Using Textile-Based Frequency Modulation.

In this article, SkinAid, a battery-free, low-cost, robust, and user-friendly smart bandage for electrochemical monitoring and sensing of chronic wounds is proposed. The working principle of the bandage is based on direct frequency modulation of a tri-electrode electrochemical sensing of wound data. The electronics and biotelemetry links were realized using low-cost manufacturing process of textile embroidery onto fabric substrate. The transmitter was represented by a bedsheet with novel corrugated crossed-dipole made of Elektrisola-7 embroidered onto gauze fabric. An input RF signal of 1 W was transmitted at 462 MHz from the bedsheet to the all-textile bandage featuring a rectifying circuit, a voltage-controlled oscillator (VCO), an electrochemical sensor, and a 915-MHz dipole for re-transmission of the modulated wound data. We demonstrate that for wound fluid emulated by various uric acid concentrations from 0.2 mM to 1.2 mM, corresponding modulated frequency varies from 1090 MHz to 1145 MHz for signals captured at 25 cm away from the bandage. For pH modulation ranging from 2 to 10, the corresponding modulated frequency was between 800 MHz and 830 MHz for signals received at more than 6 feet away from the bandage. For quick and reliable assessment, two empirical models were developed for the direct frequency modulation as a function of uric acid and pH. To the best of our knowledge, this is the first time an all-textile (fabric-integrated), battery-free and wirelessly powered smart bandage have been proposed for wound monitoring. This result can be used as a first step in developing RFID-type, battery-free, and low-cost 5G/6G smart bandages using millimeterwave and terahertz frequencies where the bedsheet can be host to a MIMO-aided beamforming.

A Real-Time Supervisory Control Strategy for Roll-to-Roll Dry Transfer of 2D Materials and Printed Electronics

With the advancement of manufacturing technology in transfer printing and two-dimensional materials fabrication, roll-to-roll (R2R) dry transfer by mechanical peeling is becoming a promising process for efficient transfer of thin film materials from a donor substrate to a target substrate for device fabrication. As a key process variable, the peeling angle determines the loading condition of the R2R dry transfer process and thus the quality of the transferred material. Controlling the peeling angle is challenging in a R2R process because of the adhesion energy and peeling front velocity in addition to the flexible substrates involved in the peeling process. In this article, a real-time supervisory control strategy is developed for the R2R mechanical peeling process. A strain energy-based peeling process model is employed to estimate the peeling front velocity and the adhesion energy. The real-time estimation is then used to generate reference signals for web tension controllers to track the desired peeling angles. The proposed control strategy is demonstrated with both simulation and experimental results.

Nanodot zirconium trisulfide modified conducting thread: A smart substrate for fabrication of next generation biosensor

In present work, we report an eco-friendly, flexible and highly conducting cotton thread (CT) as a smart substrate for the development of biosensing platform towards ultrasensitive detection of swine flu serum amyloid A (SAA) biomarker. The biosensor was fabricated by optimized coating of CT with poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) conductive ink followed by incorporation of nanodot zirconium trisulfide (nZrS3) which helped in enhancing the electrochemical properties and improving stability of PEDOT:PSS polymeric film. The fabricated nZrS3/PEDOT:PSS/CT electrode was then used for sequential immobilization of monoclonal antibodies of SAA (anti-SAA) and bovine serum albumin (BSA). The synthesized nanomaterials and fabricated electrodes were characterized through X-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy and contact angle analyser techniques. The electrochemical response of the fabricated smart thread based biosensor (BSA/anti-SAA/ZrS3/PEDOT:PSS/CT) was recorded against SAA using chronoamperometry technique which revealed superior sensitivity {30.2 μA [log (μg mL−1)]−1 cm−2}, excellent lower detection limit (0.72 ng mL−1) and prolonged shelf life up to 48 days. The response of the biosensor was also validated by analysing the electrochemical response of SAA spiked serum samples and the obtained results showed good correlation with that of standard samples.

Superhydrophobic Surface Modification of Polymer Microneedles Enables Fabrication of Multimodal Surface-Enhanced Raman Spectroscopy and Mass Spectrometry Substrates for Synthetic Drug Detection in Blood Plasma.

Microneedles are widely used substrates for various chemical and biological sensing applications utilizing surface-enhanced Raman spectroscopy (SERS), which is indeed a highly sensitive and specific analytical approach. This article reports the fabrication of a nanoparticle (NP)-decorated microneedle substrate that is both a SERS substrate and a substrate-supported electrospray ionization (ssESI) mass spectrometry (MS) sample ionization platform. Polymeric ligand-functionalized gold nanorods (Au NRs) are adsorbed onto superhydrophobic surface-modified polydimethylsiloxane (PDMS) microneedles through the control of various interfacial interactions. We show that the chain length of the polymer ligands dictates the NR adsorption process. Importantly, assembling Au NRs onto the micrometer-diameter needle tips allows the formation of highly concentrated electromagnetic hot spots, which provide the SERS enhancement factor as high as 1.0 × 106. The micrometer-sized area of the microneedle top and high electromagnetic field enhancement of our system can be loosely compared with tip-enhanced Raman spectroscopy, where the apex of a plasmonic NP-functionalized sharp probe produces high-intensity plasmonic hot spots. Utilizing our NR-decorated microneedle substrates, the synthetic drugs fentanyl and alprazolam are analyzed with a subpicomolar limit of detection. Further analysis of drug-molecule interactions on the NR surface utilizing the Langmuir adsorption model suggests that the higher polarizability of fentanyl allows for a stronger interaction with hydrophilic polymer layers on the NR surface. We further demonstrate the translational aspect of the microneedle substrate for both SERS- and ssESI-MS-based detection of these two potent drugs in 10 drug-of-abuse (DOA) patient plasma samples with minimal preanalysis sample preparation steps. Chemometric analysis for the SERS-based detection shows a very good classification between fentanyl, alprazolam, or a mixture thereof in our selected 10 samples. Most importantly, ssESI-MS analysis also successfully identifies fentanyl or alprazolam in these same 10 DOA plasma samples. We believe that our multimodal detection approach presented herein is a highly versatile detection technology that can be applicable to the detection of any analyte type without performing any complicated sample preparation.

Correlation between filament deposition path, microstructural and mechanical properties of dense alumina parts printed by robocasting

Robocasting is an extrusion-based additive manufacturing (AM) process widely used to produce porous structures. It enables to build three-dimensional (3D) ceramic parts, thanks to computer numerical control of the filament deposition path onto a fabrication substrate. Despite its high potential, robocasting is much less explored than other AM techniques for producing dense parts. This work focused on the robocasting of dense alumina parts by varying the filament deposition path of an environmentally friendly paste. Taguchi method was used to establish a correlation between the printing parameters and the microstructural and mechanical properties of the sintered parts. Closed pores located between adjacent filaments were found to dictate crack propagation mechanisms, depending on the infill pattern. The optimal printing strategy led to 93% dense alumina samples having a flexural strength of 140 MPa, a Young’s modulus of 355 GPa and a Poisson’s ratio of 0.23.

The Durable Chitosan Functionalization of Cellulosic Fabrics.

In this work, the durability of chitosan functionalization of cellulosic textile substrates, cotton and cotton/polyester blended fabrics, was studied. Chitosan is a naturally occurring biopolymer that can be produced inexpensively. It should be dissolved in an acidic solution to activate its antimicrobial and other properties, i.e., good biocompatibility, bioabsorbability, wound healing, hemostatic, anti-infective, antibacterial, non-toxic, and adsorptive properties. The application of chitosan to textile products has been researched to achieve antimicrobial properties, but the durability, after several maintenance cycles, has not. Chitosan functionalization was carried out using maleic acid (MA) and 1,2,3,4-butanetetracarboxylic acid (BTCA) as crosslinking and chitosan-activating agents and sodium hypophosphite monohydrate as a catalyst. To determine durability, the fabrics were subjected to 10 maintenance cycles according to ISO 6330:2012 using Reference detergent 3 and drying according to Procedure F. The properties were monitored after the 3rd and 10th cycles. The crosslinking ability of chitosan with cellulosic fabrics was monitored by Fourier infrared spectrometry using the ATR technique (FTIR-ATR). Changes in mechanical properties, whiteness and yellowing, and antimicrobial properties were determined using standard methods. Compared to maleic acid, BTCA proved to be a better crosslinking agent for chitosan.

The influence of electrode geometry on the electrochemical performance of fabric-based screen-printed coplanar supercapacitors

Coplanar supercapacitors are promising flexible energy storage systems due to the excellent flexibility and tailored shapes and sizes of electrodes. However, the influence mechanism of electrode’ geometry parameter on the electrochemical performance of the flexible coplanar supercapacitors needs to be elucidated to realize the performance enhancement. Herein, the flexible coplanar supercapacitors with different thicknesses, widths and lengths of screen-printed electrodes were constructed on the cotton fabric substrates utilizing multi-walled carbon nanotubes ink and polymer gel electrolytes. The relationship between electrodes' geometry and overall electrochemical performance of flexible coplanar supercapacitors was detailed analyzed and demonstrated by employing equivalent series circuit model and electrode kinetic theory. Furthermore, due to the favorable aspect ratio and relatively low electrode and electrolyte resistance, the fabric-based coplanar supercapacitor with electrode size of 4 × 10 mm shows optimal electrochemical performance with areal capacitance of 3.08 mF cm−2 at 20 mV s−1, fast electrode response and effective kinetic process. Most importantly, the fabric-based supercapacitor exhibits excellent flexibility and cycling performance with capacitance retention rate over 79.6 % after 4000 charge and discharge cycles, indicating application potential in wearable electronic devices. The analysis and assessments of electrodes' geometry provides theoretical reference for the electrode design and optimization of flexible coplanar supercapacitors.

Atomic layer deposition assisted fabrication of insertable silver dendrites-based SERS substrates with high adhesion

Considerable efforts have been dedicated to the development of low-cost and highly sensitive surface-enhanced Raman spectroscopy (SERS) substrates, which have found applications in numerous fields. However, the critical factors of adhesion and stability have been insufficiently addressed. Such as Ag dendrites (Ag D) have been recognized for their cost-effectiveness and superior efficiency as SERS substrates, nonetheless, the issue of weak adhesion to the substrate has remained a challenge. Herein, a novel strategy to fabricate a Planar Ag dendrites-based SERS substrate with high adhesion is reported, that employs a combination of atomic layer deposition, roll milling, and chemical etching. The resulting Planar Ag dendrites show excellent adhesion, with a surface stripping force 18 times greater than that of pristine Ag dendrites, allowing for prolonged ultrasonic cleaning. Moreover, the substrate can be used as an insertable SERS sensor to obtain spectral information inside apples due to its excellent adhesion. The proposed design achieves high SERS sensitivity, with a limit of detection of 10-9 M and an analytical enhancement factor of 1.5 × 108 for R6G. Overall, this work provides a valuable reference for improving the adhesion of noble metal nanostructures on supporting substrates, offering a reliable SERS substrate for practical applications.

Harnessing Bio-Immobilized ZnO/CNT/Chitosan Ternary Composite Fabric for Enhanced Photodegradation of a Commercial Reactive Dye.

Growing demand for sustainable wastewater treatment drives interest in advanced photocatalytic materials. Immobilized photocatalysts hold potential for addressing industrial wastewater organic pollutants, offering substantial surface area, agglomeration prevention, and easy removal. In this study, we successfully immobilized ZnO and carbon nanotubes onto a textile substrate through bilateral esterification and explored their effectiveness as a potent photocatalyst for degrading of commercial textile colorant reactive blue 4 (RB-4) colorant. Findings demonstrated significant improvements in photocatalytic performance upon integrating ZnO and CNTs into the fabric, coupled with chitosan immobilization. The immobilization process of ZnO and CNTs onto the substrate was elucidated through a proposed reaction mechanism, while the appearance of carbonyl peaks at 1719.2 cm-1 in the composite fabric further confirmed bilateral esterification. The as-developed immobilized nano-catalyst exhibited remarkable photocatalytic efficiency with an impressive 93.54% color degradation of RB-4. This innovative approach underscores the immense potential of the ternary immobilized (ZnO/fCNT/chitosan) composite fabric for efficient photocatalytic degradation in textile coloration processes. Exploring the early-stage development of immobilized photocatalysts contributes to safer and more eco-friendly practices, addressing pressing environmental challenges effectively.

Synergizing tin dioxide/perovskite interface with fluorine-doped zinc oxide for stabilized and efficient carbon-based perovskite solar cells

The new generation of solar cell technology, perovskite solar cells (PSCs), are the most promising candidates to meet global energy demands. In the current study, we improved the efficiency of their cost-effective type, i.e., carbon-based PSCs, by employing an interface engineering on the tin dioxide (SnO2) electron transport layer (ETL). A fluorine doped-zinc oxide material was used to treat the SnO2 layer and prepare a better substrate for perovskite fabrication. The fabricated perovskite layer on the treated SnO2 reveals better charge transfer, lower charge recombination, and lower leakage current. In addition, the fabricated perovskite layer on the modified ETL showed improved crystalline properties with passivated grain boundaries. As a result, a champion efficiency of 15.22% was recorded for the target carbon-based PSCs, referring to improved photovoltaic performance. Notably, the target devices showed a higher stability behavior against ambient air and kept 95% of their initial efficiency after 1658 h ageing time.

PEDOT:PSS/Natural Rubber Latex Inks for Screen‐Printing Multifunctional Wearable Strain–Humidity Sensors

Wearable strain–humidity sensors are increasingly recognized for their role in healthcare and detecting human motion signals. However, many strain–humidity sensors require complex manufacturing processes and have limited applicability. In this study, based on the good miscibility between natural rubber latex (NRL) and poly (3,4‐ethylenedioxythiophene):poly (4‐styrenesulfonate) (PEDOT:PSS), PEDOT:PSS/NRL composite conductors are transferred onto fabric substrate through screen printing and prepared high‐performance strain–humidity sensor. The PEDOT:PSS/NRL blends strain–humidity sensor exhibited good stability and durability (500 cycles) at 10% strain, achieves a gauge factor (GF) of 123.8 with excellent linearity, making it operational in detecting various human motions, such as finger bending, elbow bending, wrist bending, and so on. In addition, the PEDOT:PSS and water molecules interaction results in a humidity response time as low as 0.72 s and recovery time as low as 0.85 s for the PEDOT:PSS/NRL composite strain–humidity sensor, and a wide relative humidity detection range (6–83%), allowing it to be utilized for precise detection of human breathing. Furthermore, it can monitor the use's joint movement, facial muscle movement, and respiratory rate, which show its potential application prospect in health monitoring.

Fabric‐Based Smart Metasurface

AbstractFabric presents several advantages including excellent flexibility, lightweight, bend resilience, breathable properties, and significant price advantage compared to commercial low‐loss boards, providing a natural advantage for the preparation of flexible electromagnetic (EM) devices and wearable systems. A key challenge when using fabric as the substrate for active devices lies in the contradiction between the poor high‐temperature resistance of fabric materials and the welding requirements for semiconductor components, leading to a significant gap between flexible and traditional RF technology. Benefiting from the unique fiber structure of fabric materials, a conjecture is creatively proposed for integrating lumped components onto fabric substrates through the sewing method and successfully verifying its validity and stability. As an application, a fabric‐based smart metasurface (FSM) is designed and realized for potential portable EM protection applications. The proposed FSM has the advantage of good flexibility, low cost, and a high strength‐to‐weight ratio. By carefully designing the structure of the metasurface and also the sensing module, large‐angle stable EM performance is achieved, and the FSM can function well even under highly distorted conditions. The proposed method and product inspire promising application aspects in wearable electronics, portable EM protection, and related flexible RF technologies.

Towards fully green printed device with environmental perspectives

Printed electronics (PE) is growing rapidly through innovation in several pathways: ink formulation, substrate improvement, printing and drying process optimization. All these developments are combining to enable the production of a new generation of PE devices that reduce e-waste. However, the main question of the recyclability of these devices is critical. This article is focused on (1) the industrial fabrication of recyclable substrates prepared by roll-to-roll printing using flexographic printing units to cover paper with shellac solution and (2) the environmental impact assessment of new development of PE. To investigate the performance of the produced substrate, a battery-less near-field communication antenna was printed with a flatbed screen printing using silver ink. The print quality, electrical resistance and the basic functional characterization of these paper-based antennas were investigated and reported. To validate the functionality of printed devices, a mm2 electronic chip was integrated onto the printed device. In order to predict the future perspectives and development of the PE, environmental challenges of the ink and substrates, during the production and end-of-life phases, are explored and discussed.