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Soft X-ray imaging is a powerful tool to explore the structure of cells, probe material with nanometer resolution, and investigate the energetic phenomena in the universe. Conventional soft X-ray image sensors are by and large Si-based charge coupled devices that suffer from low frame rates, complex fabrication processes, mechanical inflexibility, and required cooling below -60 °C. Here, a soft X-ray photodiode is reported based on low-cost metal halide perovskite with comparable performance to commercial Si-based device. Nanothrough network electrode minimized the optical loss due to the shadowing of insensitive layers, while a multidimensional perovskite heterojunction is generated to reduce the photo-generated carrier loss. This strategy promoted a record quantum efficiency of 8 × 103% without cooling, several orders of magnitude greater than the previously achieved. Flexible and curved soft X-ray imaging arrays are fabricated based on this high-performance device structure, demonstrating stable soft X-ray response and sharp imaging capabilities. This work highlights the low-cost and efficient perovskite photodiode as a strong candidate for the next-generation soft X-ray image sensors.

BiFeO3 (BFO) application in flexible wearable devices is garnering interest because of its unique ferroelectric and magnetic properties. However, the integration of high-quality BFO films onto flexible substrates presents significant technical challenges. Here, we successfully fabricated high-quality BFO films on mica substrates by using pulsed laser deposition, and report the fatigue characteristics of BFO films on flexible substrates for the first time. The results demonstrated that, after 108 bipolar switching cycles, the polarization only degraded by 0.28%, indicating superior fatigue characteristics compared to previously reported BFO films. Additionally, the device ferroelectric properties remained largely unchanged, with a bending radius of 3.5 mm. The fabricated flexible Pt/BFO/La0.65Sr0.35MnO3(LSMO)/SrTiO3(STO)/mica non-volatile memory devices exhibited mechanical flexibility and fatigue resistance. These findings not only highlight the potential of flexible BFO films for wearable electronic devices and flexible memory devices, they also provide valuable insight for the future development of high-performance flexible ferroelectric materials. [ABSTRACT FROM AUTHOR]

A higher quality (Q) factor and a stronger near field are two major advantages for surface plasmon resonance (SPR) applications based on high‐performance nanocavities. However, achieving a plasmonic structure that possesses both an ultra‐high Q‐factor and strong near‐field intensity has received relatively little attention. In this work, plasmonic arrays that offer a tunable Q‐factor, tunable near‐field intensity, and excellent uniformity over a centimeter‐scale area are fabricated on a flexible substrate. The flexibility and uniformity of this plasmonic array have been confirmed by its integration into stable optofluidic sensing systems. An in‐depth investigation into its sensitivity and figure of merit (FOM) highlights the superior performance of plasmonic sensing arrays that feature both an ultra‐high Q‐factor and a strong near‐field. This plasmonic array, together with its fabrication method, provides an optimized platform for a wide range of applications. [ABSTRACT FROM AUTHOR]

Summary Monitoring and localizing molecules on living plants is critical for understanding their growth, development and disease. However, current techniques for molecular imaging of living plants often lack spatial information or require tedious pre‐labelling. Here, we proposed a novel molecular imaging platform that combines sliver nanowire‐doped Ti3C2 MXene (Ag NWs@MXene) flexible film substrate with laser desorption/ionization mass spectrometry imaging (AMF‐LDI‐MSI) to study the spatial distribution of biomolecules on the surface of living plants. This platform overcomes the MSI challenges posed by difficult‐to‐slice plant tissues (e.g., tough or water‐rich roots and fragile flowers) and enables precisely transfer and visualize the molecule. Comparisons of the measurement results to those from matrix‐assisted LDI‐MSI (MALDI‐MSI) technology demonstrate the accuracy and reliability of the platform. Biocompatibility evaluations indicated that the platform without observable adverse effects on the health of living plants. The distribution of growth and disease‐associated signalling molecules, such as choline, organic acids and carbohydrates, can be in situ non‐destructively detected on the surfaces of living plants, which is important for tracking the health of plants and their diseased areas. AMF‐LDI‐MSI platform can serve as a promising tool for label‐free, in situ and non‐destructive monitoring of functional biomolecules and plant growth from a spatial perspective. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study of hydrogenated amorphous silicon (a-Si)-based detectors, utilizing electrical characterization, Raman spectroscopy, photoemission, and inverse photoemission techniques. The unique properties of a-Si have sparked interest in its application for radiation detection in both physics and medicine. Although amorphous silicon (a-Si) is inherently a highly defective material, hydrogenation significantly reduces defect density, enabling its use in radiation detector devices. Spectroscopic measurements provide insights into the intricate relationship between the structure and electronic properties of a-Si, enhancing our understanding of how specific configurations, such as the choice of substrate, can markedly influence detector performance. In this study, we compare the performance of a-Si detectors deposited on two different substrates: crystalline silicon (c-Si) and flexible Kapton. Our findings suggest that detectors deposited on Kapton exhibit reduced sensitivity, despite having comparable noise and leakage current levels to those on crystalline silicon. We hypothesize that this discrepancy may be attributed to the substrate material, differences in film morphology, and/or the alignment of energy levels. Further measurements are planned to substantiate these hypotheses. [ABSTRACT FROM AUTHOR]

Abstract BiFeO3 (BFO) application in flexible wearable devices is garnering interest because of its unique ferroelectric and magnetic properties. However, the integration of high-quality BFO films onto flexible substrates presents significant technical challenges. Here, we successfully fabricated high-quality BFO films on mica substrates by using pulsed laser deposition, and report the fatigue characteristics of BFO films on flexible substrates for the first time. The results demonstrated that, after 108 bipolar switching cycles, the polarization only degraded by 0.28%, indicating superior fatigue characteristics compared to previously reported BFO films. Additionally, the device ferroelectric properties remained largely unchanged, with a bending radius of 3.5 mm. The fabricated flexible Pt/BFO/La0.65Sr0.35MnO3(LSMO)/SrTiO3(STO)/mica non-volatile memory devices exhibited mechanical flexibility and fatigue resistance. These findings not only highlight the potential of flexible BFO films for wearable electronic devices and flexible memory devices, they also provide valuable insight for the future development of high-performance flexible ferroelectric materials.

Flexible pressure sensors can be attached to the human skin to sense external pressure signals， and have the characteristics of wide sensing range， short response time， high sensitivity， and durability. Therefore， they are widely used in the fields of electronic skin and human-computer interaction. Flexible pressure sensors are usually composed of flexible substrates， active materials and conductive electrodes. Among them， one or more of the active materials form a sensing material by compounding with a flexible substrate， and its deformation under external excitation will cause changes in parameters such as resistance， thereby achieving sensing function.In addition， by introducing microstructure， the compressibility and sensitivity to small pressure of the sensing material can be increased， and its sensing performance can be improved. In this paper， the research progress in flexible pressure sensors doped with carbon-based， metal-based， and black phosphorus-based active materials on film and fabric substrates was reviewed. The preparation methods， electromechanical properties and application scenarios of different sensors were discussed， and the advantages and disadvantages of various sensors were summarized. On this basis， the research on how to achieve wide-range pressure detection， commercialization， non-toxicity of the production process and long-term biocompatibility experiments of smart wearable flexible pressure sensors in the future is prospected.

A novel stress suppression design for flexible RF MEMS switches has been presented and demonstrated through theoretical and experimental research to isolate the stress caused by substrate bending. An RF MEMS switch with an S-shaped microspring structure was fabricated by the two-step etching process as a developmental step toward miniaturization and high reliability. The RF MEMS switches with an S-shaped microspring exhibited superior microwave performance and stable driving voltage under different substrate curvatures compared to the conventional non-microspring switches, demonstrating that the bending stress is successfully suppressed by the S-shaped microspring and the island structure. Furthermore, this innovative design could be easily extended to other flexible devices. [ABSTRACT FROM AUTHOR]

This study aims to establish and optimize a process for the fabrication of 3D microstructures of the biocompatible polymer Parylene C using hot embossing techniques. The different process parameters such as embossing temperature, embossing force, demolding temperature and speed, and the usage of a release agent were optimized, utilizing adhesive micropillars as a use case. To enhance compatibility with conventional semiconductor fabrication techniques, hot embossing of Parylene C was adapted from conventional stainless steel substrates to silicon chip platforms. Furthermore, this adaptation included an investigation of the effects of the hot embossing process on metal layers embedded in the Parylene C, ensuring compatibility with the ultra-thin Parylene printed circuit board (PCB) demonstrated previously. To evaluate the produced microstructures, a combination of characterization methods was employed, including light microscopy (LM) and scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). These methods provided comprehensive insights into the morphological, chemical, and structural properties of the embossed Parylene C. Considering the improved results compared to existing patterning techniques for Parylene C like plasma etching or laser ablation, the developed hot embossing approach yields a superior structural integrity, characterized by increased feature resolution and enhanced sidewall smoothness. These advancements render the method particularly suitable for diverse applications, including but not limited to, sensor optical components, adhesive interfaces for medical wearables, and microfluidic systems. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Miniaturization and flexibility are becoming the trend in the development of electronic products. These key features are driving new methods in the manufacturing of such products. Printed electronics technology is a novel additive manufacturing technique that uses active inks to print onto a diverse set of substrates, realizing large-area, low-cost, flexible and green manufacturing of electronic products. These advantageous properties make it extremely compatible with flexible electronics fabrication and extend as far as offering revolutionary methods in the production of flexible electronic devices. In this paper, the details of a printing process system are introduced, including the materials that can be employed as inks, common substrates, and the most recently reported printing strategies. An assessment on future setbacks and developments of printed flexible electronics is also presented. [ABSTRACT FROM AUTHOR]

In order to realize advanced flexible devices, it is critical to simultaneously ensure the flexibility and robustness of bonded joints in the electronic packages for the mechanical and electrical reliability. Flexible bonded joints of thin polymer substrates should be developed because the flexible substrates inevitably undergo extensive mechanical loads, including tension, bending, and twisting. While epoxy resins have been used to bind plastic substrates, they often exhibit inferior flexibility and poor fatigue resistance, which are caused by increased bonding thickness and inherent brittleness, respectively. To solve this problem, we adopted microwave heating of carbon nanotubes (CNTs) for bonding thin polymer substrates for flexible applications. Multiwalled carbon nanotubes are spray-coated onto flexible substrates with a thickness of less than 100 μm. Microwave irradiation was controlled to induce rapid thermal fusion bonding of a pair of thin polymer substrates, where glass plates were attached to prevent thermal distortion. To investigate the bonding mechanism, the polymer-CNT bonding interface was analyzed by using a scanning electron microscope. The mechanical robustness of the bonded joint was evaluated for different microwave power and irradiation times with a fixed frequency of 2.45 GHz. Flexibility of the bonded assembly was characterized by using a three-point bending test and a cross-sectional digital image correlation method with microscopic images. In addition, the bending endurance of a CNT electrode on a flexible substrate assembly was tested under static and dynamic bending. This work provides a concept for realizing flexible interconnections between electronic components, including flexible substrates and electrodes. [ABSTRACT FROM AUTHOR]

This study proposes a flexible MIMO antenna with improved isolation and connected ground designed on a flexible substrate that makes it compatible with various shapes and surfaces, including curved, irregular, or non-planar structures. The suggested single unit consists of a slotted rectangular radiator on the front layer with a partial ground connected to a circular stub on the other side. As well it is created on a flexible substrate (Rogers RO3003) that has a dielectric constant (εr) of 3 and a thickness of 1.52 mm. The Four copies of the single unit with orthogonal orientation are added to improve the system performance. The antenna units are connected through their ground to introduce the connected ground antenna. The size of the proposed design is compact (50 × 50 × 1.524 mm3). The simulating and testing results demonstrate that the antenna operates within a frequency range of 3–12 GHz and achieves a high isolation of ≥ 17 dB over most frequency range. The MIMO parameters and the radiation patterns are analyzed to evaluate the performance of the MIMO antenna. Finally, the four elements of the flexible antenna are fabricated and tested under flat and bending conditions. The simulation and testing results demonstrate that the suggested design exhibits excellent performance, such as broad bandwidth, high isolation, simple structure, and decreased correlation coefficient, which suggest it for the UWB applications and its flexibility allows it for integration into a wide range of devices, such as wearable technology, Internet of Things (IoT) devices, and curved surfaces of vehicles or aircraft. [ABSTRACT FROM AUTHOR]

Medical devices have progressed from their initial bulky forms to smart devices. However, their rigidity hampers their seamless integration into everyday life. The fields of stretchable, textile, and flexible electronics are emerging research areas with the potential to drive significant technological progress. This research presents a laboratory-based technique to produce highly sensitive and flexible biosensors for detecting the chikungunya virus. These biosensors are based on 0D nanomaterials and demonstrate significant advancements in voltammetry. The electrochemical platform was created utilizing the stencil printing (StPE) technique. Adapting the biosensor setup involved the selection of aptamer as the biorecognition element bound with silver nanoparticles (AgNPs). This biosensor was employed in the voltammetric identification of the Chikungunya virus antigen (CHIKV-Ag) within a solution containing 0.5 mM potassium ferro/ferri cyanide, a redox pair. The biosensor was employed to evaluate CHIKV-Ag within a human serum sample. It demonstrated a linear detection span ranging from 0.1 ng/mL to 1 μg/mL, with a detection limit of 0.1 ng/mL for CHIKV-Ag. The proposed approach, due to its flexibility in production and the electrocatalytic attributes displayed by the zero-dimensional nanostructure, presents innovative opportunities for cost-effective and tailored aptamer-based bioelectronics, thereby broadening the scope of this domain. [ABSTRACT FROM AUTHOR]

Summary: This article demonstrates a novel type of series‐fed planar antenna array for a W‐band (70 GHz) application. The proposed architecture is a 5‐element antenna array with 10 numbers of gap‐coupled parasitic patches in microstrip configuration over a thin, flexible and bio‐compatible substrate named LCP (liquid crystal polymer). A detailed design methodology with all fabrication constraints has been elaborated on here. Full wave analysis of the whole structure has been carried out in the FEM‐based 3D electromagnetic (EM) solver ANSYS HFSS Suite V.19.2. Parametric simulations were studied to achieve the optimized values of all design parameters. Further, an empirical electrical equivalent circuit model is proposed for the antenna array, and it was validated with the simulation results obtained from the FEM solver. Two prototypes have been fabricated, and measurements were carried out to fetch all the designed antenna parameters. The proto version of the antenna offers peak directive gain of about 19 dBi with better than 22 dB of return loss and 80% radiation efficiency for the frequency range of 67–85 GHz. Experimental and simulated results closely match each other. Small deviations are attributed to practical imperfections incurred by fabrication tolerances, measurement inaccuracies, testing, assembly‐related issues and so forth. Finally, the current research work is compared with the recently reported literature. [ABSTRACT FROM AUTHOR]

A compact CaxCo(0.90-x)Zn0.10Fe2O4 based nanoparticles synthesized flexible microwave substrate with single negative (SNG) metamaterial is being successfully fabricated for industrial chemical contamination sensing applications. The unit cell dimensions of the MTM are 0.114λ × 0.114 λ × 0.017 λ. The nanoparticles, derived from the CaxCo(0.90-x)Zn0.10Fe2O4 material with varying Ca concentrations (Ca25, Ca50, and Ca75), have been synthesized using a sol-gel method, and their structural, morphological, and dielectric properties have been comprehensively characterized. Dielectric constants and loss tangents have been measured over the frequency range of 2–20 GHz. Simulation of the S21 response at 3.43 GHz, 6.50 GHz, 11.49 GHz, and 16.46 GHz has yielded maximum magnitudes of −52.78 dB, −48.07 dB, −52.16 dB, and −39.37 dB, respectively. Experimental verification on an FR-4 rigid substrate at 3.28 GHz, 6.58 GHz, 11.76 GHz, and 16.33 GHz has revealed magnitudes of −25.67 dB, −24.56 dB, −31.13 dB, and −25.17 dB. Finally, when fabricated on the flexible microwave substrate, the MTM displayed S21 responses of −48.31 dB, −43.12 dB, −61.80 dB, and −24.70 dB at 3.19 GHz, 6.62 GHz, 11.58 GHz, and 16.65 GHz, respectively. The MTM has exhibited SNG properties in distinct frequency bands and near-zero index (NZI) characteristics. The sensitivity, figure of merit (FOM), and Q-factor have been achieved at 0.096 GHz/RIU, 0.152 GHz/RIU, 0.846 (RIU−1), 0.846 (RIU−1), and 8.430, 29.801, respectively. Its performance has been validated through simulation, VNA measurements, and advanced design system (ADS) software analysis, showcasing promise for diverse applications in S-, C-, X-, and Ku-bands. The anticipated structure performs well in terms of its small size, flexibility, sensitivity, and lightweight, making it suitable for wireless communications and methanol and ethanol contamination sensing in industrial applications.

A flexible wipe paper for rapid nondestructive detection of ferbam residues on the surface of fruits and vegetables by surface-enhanced Raman scattering (SERS) was prepared using filter paper as the substate by a simple soaking method. The synthesis and storage conditions were optimized to ensure that the SERS method has excellent performance. The results showed that concentration factor of silver nanoparticles (AgNPs), soaking time in AgNP solution and drying method greatly affected the performance of the SERS wipe paper. The performance under the condition of soaking for 8 h in a 5-fold concentrate of AgNP solution was significantly better than that under other conditions. The SERS wipe paper prepared by vacuum drying had better performance that those prepared by other drying methods. After 9 days of storage at −20 ℃, the optimized substrate retained approximately 50% of the original peak value. Besides, it exhibited good sensitivity, uniformity, and repeatability. The limit of detection (LOD) for ferbam on a glass plate was 4.07 × 10-6 mg/mL, and the LOD for ferbam on the surface of spinach and nectarine were 0.043 and 0.062 mg/kg, respectively. This study provides an excellent basis for the development and utilization of SERS wipe paper.

Wearable antennas are important in many areas of our lives, including the Internet of Things (IoT), health care, sports, the automobile industry, security, and entertainment. Wearable antennas should be designed with a compact size in order to be readily integrated and conform to the body shape, as well as a high performance to withstand mechanical and environmental changes. 5 G and 6 G technologies offer sufficient solutions for wearable antennas utilized for wireless body area networks (WBANs) and IoT applications in terms of high reliability, high gain, compactness, low cost, and high performance. In this work, we present for the first time a comprehnsive review of 5 G and 6 G wearable antennas discussing their significance, types, applications, and design issues in detail. A state-of-the-art for the recent 5 G wearable antenna reviews is also outlined. The main contribution of this work is explaining the compactness and performance enhancement methods at both bands in ascending order starting from low frequency, sub 6 GHz, 5 G mmWave, up to 6 G (high mmWavw and THz wave), so the reader will differentiate between the antennas' design requirements and challenges for different bands easily. The impacts of flexibility, bending, and on-body/off-body on antenna performance as well as specific absorption rate (SAR) calculation are also taken into account. This review can be considered a valuable tool for designers and researchers in designing many types of wearable antennas at 5 G and 6 G frequency bands for various applications by understanding the antenna's design problems, topologies, and types of substrate and conductive materials. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nanocomposite represents the backbone of many industrial fabrication applications and exerts a substantial social impact. Among these composites, metal nanostructures are often employed as the active constituents, thanks to their various chemical and physical properties, which offer the ability to tune the application scenarios in thermal management, energy storage, and biostable materials, respectively. Nanocellulose, as an emerging polymer substrate, possesses unique properties of abundance, mechanical flexibility, environmental friendliness, and biocompatibility. Based on the combination of flexible nanocellulose with specific metal fillers, the essential parameters involving mechanical strength, flexibility, anisotropic thermal resistance, and conductivity can be enhanced. Nowadays, the approach has found extensive applications in thermal management, energy storage, biostable electronic materials, and piezoelectric devices. Therefore, it is essential to thoroughly correlate cellulose nanocomposites' properties with different metallic fillers. This review summarizes the extraction of nanocellulose and preparation of metal modified cellulose nanocomposites, including their wide and particular applications in modern advanced devices. Moreover, we also discuss the challenges in the synthesis, the emerging designs, and unique structures, promising directions for future research. We wish this review can give a valuable overview of the unique combination and inspire the research directions of the multifunctional nanocomposites using proper cellulose and metallic fillers. [ABSTRACT FROM AUTHOR]

Using a stainless shadow mask combined with a magnetron-ion-assisted deposition (IAD) sputtering system, we investigate the surface morphologies and optical properties of microfilms. Optimal color-filter (CF) coating microfilms with niobium pent-oxide (Nb2O5)/silicon dioxide (SiO2) multilayers on a hard polycarbonate (HPC) substrate, grown at 85 °C and 50 SCCM oxygen flow, can obtain a fairly uniform thickness (with an average roughness of 0.083 and 0.106 nm respectively for Nb2O5 and SiO2 films) through all positions. On a flexible HPC substrate with the Nb2O5/SiO2 microfilms, meanwhile, the peak transmittances measured in the visible range are 95.70% and 91.47%, respectively, for coatings with and without a shadow mask for this new-tech system. For the optimal CF application with a shadow mask, transmittance on each 100 nm band-pass wavelength is enhanced by 4.04% absolute (blue), 2.96% absolute (green), and 2.12% absolute (red). Moreover, the developed new-tech system not only enhances the quality of the films by achieving smoother and uniform surfaces but also reduces deposition time, thereby improving overall process efficiency. For the with-shadow-mask condition, there is little shift at 50% transmittance (T50%), and high transmittance (~97%) is maintained after high-temperature (200 °C) baking for 12 h. These results are well above the commercial CF standard (larger than 90%) and demonstrate reliability and good durability for flexible optical applications. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, a flexible and fully printable four element patch antenna array bent on a cylindrical-shaped surface for main beam steering is proposed. The individual phases of the microstrip patches in the array are varied by using novel planar phase shifters constituted of microstrip composite right/left-handed (CRLH) lines ingrained with microparticles. The reinforcement of newly introduced microparticles in the CRLH transmission line structure makes it a variable phase shifter, which is fabricated on a flexible substrate in completely planar and conformal configurations. The magnetic particles-based CRLH-TL phase shifter (MP-CRLH) consists of multiple cavities in the substrate filled with micron-sized silver-coated ferrite particles. These particles in the cavity are magnetically aligned by a small magnet placed beneath the cavity. A particular phase shift can be achieved by activating particles in multiple cavities in the MP-CLRH phase shifter. The optimum locations of the cavities partially filled with magnetic particles for a particular phase shift have been explored after extensive 3D simulations in the frequency domain using CST Studio Suite. The main advantage of using the MP-CRLH phase shifter is that it can be conformed to non-planar surfaces, such as cylindrical-shaped in this scenario. As compared to conventional IC/discrete components-based phase shifters, the working of the novel MP-CRLH phase shifter is independent of external SMT and lumped circuit components for its biasing. The four unit-cell cascaded MP-CRLH phase shifter is then integrated with a four-element patch array on a cylindrical-shaped surface with radii of 30 cm and 10 cm. The main pattern of the array has been successfully scanned at 0°, −15°, and +30° using the integrated MP-CRLH phase shifter at.2.45 GHz. The full-wave simulation results are validated with the measured radiation patterns in a fully anechoic chamber facility. The conformal phased array integrated with MP-CRLH phase shifters on a flexible substrate can be used for applications like on-body communication systems, wearable devices, flexible electronics, and aircraft communication systems.

This article presents a flexible four-element MIMO antenna designed on a thin polyimide substrate to operate at 30.50 GHz for wearable applications. The antenna element structure is a combination of circular rings combined with T-shape stubs. The MIMO antenna isolation is enhanced through a novel decoupling structure consisting of a rectangular stub, four open-ended horizontal strip lines, and two vertical strip lines connecting the ground plane. It provides 22.5 dB isolation, even with conformal orientation. A metamaterial (MTM) reflective surface of $9\times9$ unit cells is designed and placed below the antenna to improve its radiation characteristics, bandwidth, gain, and specific absorption rate (SAR). The metamaterial unit cell provides a double negative property with a wide stop-band range of 26.27–36.49 GHz. With an MTM surface, the measured bandwidth is 25.2–33 GHz with a maximum broadside gain of 8.90 dBi. The resulting SAR is reduced from 1.71 W/kg to 0.86 W/kg by incorporating MTM reflective surface. The MIMO antenna with MTM improves the bandwidth by 56%, gain by 32.5%, and radiation from bidirectional to broadside, compared to the MIMO antenna without MTM. Also, the antenna is measured and validated for diversity parameters such as Envelope correlation coefficient (ECC), Diversity gain (DG), Channel coefficient loss (CCL), Total active reflection coefficient (TARC), and Mean effective gain (MEG). The reduced SAR and improved antenna performance suggest the proposed MIMO antenna with an MTM reflective surface is suitable for on-body wearable applications in IoT devices, smart watches, headwear, and footwear devices.

Quantum dot light‐emitting diodes (QLEDs) have garnered significant attention due to their outstanding optical and electrical properties. Furthermore, there have been many attempts to fabricate QLEDs on the flexible substrates for the application of wearable devices. However, flexible QLEDs face the challenge of instability under thermal heat, due to the low thermal conductivity of the substrates. In this study, we present the InP‐based QLEDs on 1 µm thick polyethylene naphthalate substrates, coated with aluminum for the heat dissipation. The coated Al layer can effectively dissipate the generated heat due to its high conductivity, while maintaining the flexibility of the substrates. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study of hydrogenated amorphous silicon (a-Si)-based detectors, utilizing electrical characterization, Raman spectroscopy, photoemission, and inverse photoemission techniques. The unique properties of a-Si have sparked interest in its application for radiation detection in both physics and medicine. Although amorphous silicon (a-Si) is inherently a highly defective material, hydrogenation significantly reduces defect density, enabling its use in radiation detector devices. Spectroscopic measurements provide insights into the intricate relationship between the structure and electronic properties of a-Si, enhancing our understanding of how specific configurations, such as the choice of substrate, can markedly influence detector performance. In this study, we compare the performance of a-Si detectors deposited on two different substrates: crystalline silicon (c-Si) and flexible Kapton. Our findings suggest that detectors deposited on Kapton exhibit reduced sensitivity, despite having comparable noise and leakage current levels to those on crystalline silicon. We hypothesize that this discrepancy may be attributed to the substrate material, differences in film morphology, and/or the alignment of energy levels. Further measurements are planned to substantiate these hypotheses.

Semiconductor materials have become a competitive candidate for surface-enhanced Raman scattering (SERS) substrate. However, powdered semiconductors are difficult to execute a fast in situ detection for trace analytes. Here, we developed a new flexible semiconductor SERS substrate by in situ densely growing anatase TiO2 nanoparticles on the surface of cotton fabric through a filtration-hydrothermal method, in which TiO2 exhibits excellent controllability in size and distribution by regulating the ratio of water to alcohol in synthesis and the number of filtration-hydrothermal repetitive cycle. Cotton fabric/TiO2 (Cot/TiO2) substrate exhibits a high SERS activity and excellent spectral repeatability. The developed substrate has an ultra-high stability that can withstand long-term preservation; it can even resist the corrosions of strong acid and alkali, as well as high temperature up to 100 °C and low temperature down to − 20 °C. The flexible substrate can be used to carry out a rapid in situ detection for quinolone antibiotic (enrofloxacin and enoxacin) residues on the fish body surface by using a simple swabbing method, with high quantitative detection potential (up to an order of magnitude of 10−7 M), and even for the simultaneous detection of both drug residues. The flexible substrate also exhibits an excellent recyclability up to 6 recycles in the actual SERS detection. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering (SERS) has been recognized as one of the most sensitive analytical methods by adsorbing the target of interest onto a plasmonic surface. Growing attention has been directed towards the fabrication of various substrates to broaden SERS applications. Among these, flexible SERS substrates, particularly paper-based ones, have gained popularity due to their easy-to-use features by full contact with the sample surface. Herein, we reviewed the latest advancements in flexible SERS substrates, with a focus on paper-based substrates. Firstly, it begins by introducing various methods for preparing paper-based substrates and highlights their advantages through several illustrative examples. Subsequently, we demonstrated the booming applications of these paper-based SERS substrates in abiotic and biological matrix detection, with particular emphasis on their potential application in clinical diagnosis. Finally, the prospects and challenges of paper-based SERS substrates in broader applications are discussed. [ABSTRACT FROM AUTHOR]

With the demand for healthy life and the great advancement of flexible electronics, flexible sensors are playing an irreplaceably important role in healthcare monitoring, wearable devices, clinic treatment, and so on. In particular, the design and application of polyimide (PI)-based sensors are emerging swiftly. However, the tremendous potential of PI in sensors is not deeply understood. This review focuses on recent studies in advanced applications of PI in flexible sensors, including PI nanofibers prepared by electrospinning as flexible substrates, PI aerogels as friction layers in triboelectric nanogenerator (TENG), PI films as sensitive layers based on fiber Bragg grating (FBG) in relative humidity (RH) sensors, photosensitive PI (PSPI) as sacrificial layers, and more. The simple laser-induced graphene (LIG) technique is also introduced in the application of PI graphitization to graphene. Finally, the prospect of PIs in the field of electronics is proposed in the review. [ABSTRACT FROM AUTHOR]

This study investigates the crystal structure, epitaxial relation, and magnetic properties in CoFe thin films deposited on a flexible mica substrate. The epitaxial growth of CoFe thin films was successfully achieved by DC magnetron sputtering, forming three CoFe(002) domains exhibiting four-fold symmetry on the mica substrate. A notable achievement of this work was the attainment of the highest anisotropic magnetoresistance (AMR) value reported to date on a flexible substrate. Additionally, it was observed that the magnetic characteristics of the CoFe films on the flexible mica substrate display reversibility upon strain release. More importantly, the AMR effect of epitaxial CoFe films on flexible mica shows lesser dependence on the crystalline orientation and remains the same under different bending states. These findings demonstrate the potential of utilizing CoFe films on flexible substrates to develop wearable magnetoresistance sensors with diverse applications. [ABSTRACT FROM AUTHOR]

Copper oxide (CuO) is an abundant and low-cost material, which is active as a photocatalyst under visible light due to its narrow band gap (1.3 eV). In the present work, CuO thin films at different Ni doping amounts (5, 10, and 30 % mol) were prepared using two different techniques: dip-coating and electrodeposition of Cu precursors over glass and PET substrates. X-Ray analysis results indicate the presence of Cu2O, CuO and Cuo phases in PET substrate films, while only CuO phase in Glass-substrate films. Glass substrate films presented a higher formic acid production performance reaching 50,000 μmol/g·h using 5% Ni doping on CuO. This higher activity was associated with a lower ratio between the adsorbed oxygen and the oxygen located in the crystal lattice, attributing this to the oxygen species adsorbed over the surface that could hinder the active sites of the material. Finally, PET substrate samples present a higher ratio between adsorbed oxygen and lattice oxygen, however, the Cu2O phase presents less affinity to adsorb CO2 molecules than CuO monoclinic phase reducing the photoactivity of the CO2 photoreduction. Majority charge carrier mobility of 4 cm2/Vs and 35 cm2/Vs for Cu2O and CuO respectively, with the charge carrier concentration of ∼1 × 1019 order was achieved switching the conducting type.

A novel stress suppression design for flexible RF MEMS switches has been presented and demonstrated through theoretical and experimental research to isolate the stress caused by substrate bending. An RF MEMS switch with an S-shaped microspring structure was fabricated by the two-step etching process as a developmental step toward miniaturization and high reliability. The RF MEMS switches with an S-shaped microspring exhibited superior microwave performance and stable driving voltage under different substrate curvatures compared to the conventional non-microspring switches, demonstrating that the bending stress is successfully suppressed by the S-shaped microspring and the island structure. Furthermore, this innovative design could be easily extended to other flexible devices.

Medical devices have progressed from their initial bulky forms to smart devices. However, their rigidity hampers their seamless integration into everyday life. The fields of stretchable, textile, and flexible electronics are emerging research areas with the potential to drive significant technological progress. This research presents a laboratory-based technique to produce highly sensitive and flexible biosensors for detecting the chikungunya virus. These biosensors are based on 0D nanomaterials and demonstrate significant advancements in voltammetry. The electrochemical platform was created utilizing the stencil printing (StPE) technique. Adapting the biosensor setup involved the selection of aptamer as the biorecognition element bound with silver nanoparticles (AgNPs). This biosensor was employed in the voltammetric identification of the Chikungunya virus antigen (CHIKV-Ag) within a solution containing 0.5 mM potassium ferro/ferri cyanide, a redox pair. The biosensor was employed to evaluate CHIKV-Ag within a human serum sample. It demonstrated a linear detection span ranging from 0.1 ng/mL to 1 μg/mL, with a detection limit of 0.1 ng/mL for CHIKV-Ag. The proposed approach, due to its flexibility in production and the electrocatalytic attributes displayed by the zero-dimensional nanostructure, presents innovative opportunities for cost-effective and tailored aptamer-based bioelectronics, thereby broadening the scope of this domain.

Due to their excellent properties, Zinc oxide nanowires (ZnO NW) have been attractive and considered as a promising electron-transporting layer (ETL) in flexible Perovskite Solar Cells (FPSCs). Since the first report on ZnO NWs-based FPSCs giving 2.6 % power conversion efficiency (in 2013), great improvements have been made, allowing to reach up to∼15 % nowadays. However, some issues still need to be addressed, especially on flexible substrates, to achieve uniform and well-aligned ZnO NWs via low-cost chemical solution techniques. Several parameters, such as the growing method (time, temperature, precursors concentration), addition of seed layer (thickness, roughness, annealing temperature) and substrate (rigid or flexible), play a crucial role in ZnO NWs properties (i.e., length, diameter, density and aspect ratio). In this review, these parameters allowing to control the properties of ZnO NWs, like the growth techniques, utilization of seed layers and the growing method (time or precursors concentration) have been summarized. Then, a particular focus on the ZnO NW's role in FPSCs as well as the use of these results on the development of ZnO NWs-based FPSCs have been highlighted.

Extensively employed antibiotics in livestock cause residue in food products that would threaten public health safety. In this work, we have developed a flexible, sensitive, cost-effective graphene oxide (GO)/silver–polyester fibrous membrane (PFM) flexible SERS substrate (GO–Ag–PFM) which is suitable for in situ food safety detection. PFMs built nanoporous networks as a flexible template, while GO–Ag nanomaterials were precipitated on the crossed fibers by self-assembly techniques, providing a density "hot-spot" that significantly increased electromagnetic fields. The lowest distinguishable level of rhodamine 6G is 10−9 mol/L, and the flexible SERS substrates also exhibit good uniformity and reproducibility. The sensitive GO–Ag–PFM flexible SERS substrates achieve low-level SERS detection of florfenicol (FF). The estimated LOD is low to 2.46 × 10−9 mol/L for FF. The proposed method can be applied to the determination of FF residues in milk. The recoveries were 89–98% with a relative standard deviation of 4.5–9.1%, which is expected to show great potential in food safety testing. [ABSTRACT FROM AUTHOR]

In this paper, novel chipless radio frequency identification (RFID) tags are designed by using asymmetrical triple mode resonators constructed by an open loop resonator with two open stubs in different lengths. Three transmission zeros (bits) can be obtained by coupling a proposed resonator to a straight feeding line that connects input/output ports. Five frequency codes can be achieved with respect to the existence of the open stubs and the open loop resonator. By coupling eight asymmetrical triple mode resonators to the feeding line, a multi-resonant circuit is developed on a flexible substrate of Rogers 5870. Totally 24 bit frequencies can be achieved and it is possible to identify 58 different items. For the chipless RFID tags, two monopole wideband antennas in vertical/horizontal polarizations are integrated instead of the input/output ports. Two tags have been fabricated and tested to demonstrate the identification of different codes under smoothed and curved positions successfully. [ABSTRACT FROM AUTHOR]

Metallic nanogaps have been studied for many years in the context of a significant amount of field enhancements. Nanogaps of macroscopic lengths for long-wave applications have attracted much interest, and recently one dimensional tunable nanogaps have been demonstrated using flexible PET substrates. For nanogaps on flexible substrates with applied tensile strain, large stress is expected in the vicinity of the gap, and it has been confirmed that several hundred nanometer-deep trenches form beneath the position of the nanogap because of this stress singularity. Here, we studied trench formation under nanogap structures using COMSOL Multiphysics 6.1. We constructed a 2D nanogap unit cell, consisting of gold film with a crack on a PDMS substrate containing a trench beneath the crack. Then, we calculated the von Mises stress at the bottom of the trench for various depths and spatial periods. Based on it, we derived the dependence of the trench depth on the strain and periodicity for various yield strengths. It was revealed that as the maximum tensile strain increases, the trench deepens and then diverges. Moreover, longer periods lead to larger depths for the given maximum strain and larger gap widths. These results could be applied to roughly estimate achievable gap widths and trench depths for stretchable zerogap devices. [ABSTRACT FROM AUTHOR]

Self-polarized energy harvesting materials have seen increasing research interest in recent years owing to their simple fabrication method and versatile application potential. In this study, we systematically investigated self-polarized P(VDF-TrFE)/carbon black (CB) composite thin films synthesized on flexible substrates, with the CB content varying from 0 to 0.6 wt.% in P(VDF-TrFE). The presence of –OH functional groups on carbon black significantly enhances its crystallinity, dipolar orientation, and piezoelectric performance. Multiple characterization techniques were used to investigate the crystalline quality, chemical structure, and morphology of the composite P(VDF-TrFE)/CB films, which indicated no significant changes in these parameters. However, some increase in surface roughness was observed when the CB content increased. With the application of an external force, the piezoelectrically generated voltage was found to systematically increase with higher CB content, reaching a maximum value at 0.6 wt.%, after which the sample exhibited low resistance. The piezoelectric voltage produced by the unpoled 0.6 wt.% CB composite film significantly exceeded the unpoled pure P(VDF-TrFE) film when subjected to the same applied strain. Furthermore, it exhibited exceptional stability in the piezoelectric voltage over time, exceeding the output voltage of the poled pure P(VDF-TrFE) film. Notably, P(VDF_TrFE)/CB composite-based devices can be used in energy harvesting and piezoelectric strain sensing to monitor human motions, which has the potential to positively impact the field of smart wearable devices. [ABSTRACT FROM AUTHOR]

After more than ten years of development, organic inorganic hybrid perovskite solar cells have become candidate devices with great industrialization prospects in the photovoltaic yield. However, the perovskite solar cells based hard substrate are heavy and not easy to carry, and the flexible perovskite so' cells can be well used in various portable wearable electronic products, with good development prospects. In this work, flexible TiO2 Nano rods were prepared on traditional hard substrates by electrospinning, and the effect of Lexie TiO2 Nano rods on the intrinsic properties of was studied. The surface roughness, morphology, structure and spectral performance of flexing TiO2 Nano rods on perovskite thin films were studied by using advanced defect evaluation microsystem, scanning electron microscope, X-ray diffractometer, ultravioletviribie spectrophotometer and fluorescence spectrometer, respectively. The results show that the perovskite thin films based on flexing TiO2 Nano rods have good spectral absorption and electron extraction cape- blitzes. This has certain guiding significance for the large-scale promotion and commercial application of flexible proves- kite photovoltaic devices. [ABSTRACT FROM AUTHOR]

Printed electronic technologies have sparked interest worldwide because of their capacity to transcend the limitations of existing high-cost electronics based on the fabrication of various devices deploying flexible substrates. Fabricating electrodes on stretchable, bendable, and soft substrates plays a vital role in flexible electronics. Hence this study demonstrates an electrochemical flexible substrate-based aptamer sensor for the Chikungunya virus (CHIKV) antigen over an extensive range of concentrations. In brief, ZnO nanorods were chemically synthesised and characterised by Field emission scanning electron microscopy (FESEM), UV-Vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and X-Ray Diffraction (XRD), providing biocompatibility to the aptamer, a biorecognition element. The aptasensor showed a wide linearity (1 ng/ml-10 μg/ml), deploying a voltammetric identification in the presence of 10 mM methylene blue act as a redox-transition substance, with an estimated limit of detection of 1 ng/ml and 25 s as its optimal response time. The applicability of the sensor was further demonstrated by introducing CHIKV-Antigen into commercial serum samples. The built-in sensor has a shelf-life of approximately a month. CHIKV-Antigen can be detected rapidly on a portable platform. As a result, CHIKV can be diagnosed more quickly, allowing for more effective treatment choices. [Display omitted] • In-house, a flexible glove based three electrode system was developed. • Chemically synthesized and thoroughly characterized zinc oxide nanorods were utilized. • The built electrochemical sensor performed in human serum efficiently. • This sensor could be used to diagnose Chikungunya virus antigen. • The application of the Dengue Virus protein confirmed cross-reactivity. [ABSTRACT FROM AUTHOR]

Ga-doped zinc oxide (GZO) has been used as material to apply to touch sensing. In addition, the touch sensing properties of the GZO thin films have been further improved by depositing different GZO layers with nitrogen-mediated crystallization (NMC) as buffer layers. First, GZO thin films of different thicknesses, 200 nm, 300 nm, and 400 nm, were grown and their touch-sensing properties were measured to find out the optimum thickness with the best sensitivity and stability. GZO thin films with an NMC structure of different thicknesses (100–300 nm) as the buffer layer were processed, then the influence of the thin film with different NMC GZO structures on their sensitivity and stability has been analyzed. Finally, nitrogen/argon (N2/Ar) flow ratios for the deposition of NMC GZO thin films were designed to be 1/8, 1/10, and 1/12, respectively, and the various structures of the NMC GZO thin films further enhanced their touch-sensing properties. The electrical properties of the GZO thin films have been measured by the Hall effect measurement system. Observations of the GZO thin films' surface structure and roughness were carried out by field-emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), respectively. An x-ray diffractometer (XRD) was used to analyze the thin films' crystallinity, crystallite size, and lattice strain. Finally, the thin-film structure of the GZO (200 nm)/NMC GZO (100 nm)/PC plastic substrate deposited in the N2/Ar flow ratio of 1/8 had an optimum touch sensitivity, and was enhanced by 6.12% from 1.046 to 1.110 compared to a pure GZO (300 nm) thin film. It is thus confirmed that GZO thin films have a better potential in touch sensor applications after the optimum nitrogen-mediated crystallization process. [ABSTRACT FROM AUTHOR]

This article reports the preparation of MgxZn(1-x)Fe2O4 ferrite-based flexible substrate using the sol–gel synthesis method. A stove-shaped metamaterial unit cell is designed and fabricated on a flexible substrate, and the microwave performance of the structure is investigated. The developed flexible composite substrate is built using PVA glue and a micro-scale of Mg–Zn ferrite nanoparticle powder, while this powder is used as filler. The structural (XRD) and morphological (FESEM) investigation allows for being used as a flexible substrate. The dielectric and loss tangent properties of the substrate are manipulated using different weight ratios of filler, while PVA keeps the flexibility features. The substrate achieved a dielectric constant (Td), and loss tangent (T) of 6.101 and 0.00899 are measured using DAK 3.5 Kit while the bending performance is investigated for 0°, 30°, 60°, and 90°, respectively. The suggested structure exhibited SNG properties within the frequency range of 4.77–5.65 GHz, 8.75–10.60 GHz, and 16.86–17.66 GHz, respectively, and near-zero index is exhibited within the frequency range of 5.216–6.388 GHz, 9.626–12.617 GHz, and 17.277–18.276 GHz, respectively. The measured response of S21 achieved a bandwidth of 4.88–5.76 GHz, 8.26–10.69 GHz, and 15.87–17.93 GHz with a maximum magnitude of −40.57 dB, −39.41 dB, and −27.63 dB at 5.31 GHz, 9.77 GHz, and 17.123 GHz resonance frequency. The proposed flexible substrate-based MTM structure can be a potential candidate for wireless communications in the S-, C-, and Ku-bands, especially as the SNG material that can increase the antenna bandwidth and gain enhancement.

Using a stainless shadow mask combined with a magnetron-ion-assisted deposition (IAD) sputtering system, we investigate the surface morphologies and optical properties of microfilms. Optimal color-filter (CF) coating microfilms with niobium pent-oxide (Nb2O5)/silicon dioxide (SiO2) multilayers on a hard polycarbonate (HPC) substrate, grown at 85 °C and 50 SCCM oxygen flow, can obtain a fairly uniform thickness (with an average roughness of 0.083 and 0.106 nm respectively for Nb2O5 and SiO2 films) through all positions. On a flexible HPC substrate with the Nb2O5/SiO2 microfilms, meanwhile, the peak transmittances measured in the visible range are 95.70% and 91.47%, respectively, for coatings with and without a shadow mask for this new-tech system. For the optimal CF application with a shadow mask, transmittance on each 100 nm band-pass wavelength is enhanced by 4.04% absolute (blue), 2.96% absolute (green), and 2.12% absolute (red). Moreover, the developed new-tech system not only enhances the quality of the films by achieving smoother and uniform surfaces but also reduces deposition time, thereby improving overall process efficiency. For the with-shadow-mask condition, there is little shift at 50% transmittance (T50%), and high transmittance (~97%) is maintained after high-temperature (200 °C) baking for 12 h. These results are well above the commercial CF standard (larger than 90%) and demonstrate reliability and good durability for flexible optical applications.

Zinc oxide ultra-thin films doping with aluminum (AZO) were produced through radio frequency (rf) sputtering at a fixed pressure of 10 mTorr while varying the rf power between 80 and 140 W. The crystal structure of hexagonal Wurtzite was consistent throughout, with improved crystallinity observed at higher rf powers due to optimal diffusivity of the sputtered particles during nucleation and growth. The size of the crystallite was increased from 10.37 to 16.58 nm with increasing the rf power from 80 to 140 W. The Raman spectra provided evidence of the formation of ultra-thin AZO films, with discernable changes in morphology due to the influence of rf power. The value of optical band gap fluctuated between 3.49 and 3.58 eV as a function of rf power, a basis of the Burstein–Moss effect. The resistivity of the ultra-thin AZO films declined while augmenting rf power. A bilayer structure of intrinsic ZnO (i-ZnO) and AZO was fabricated and exhibited good transmittance, well-crystalline morphology, and excellent electrical conductivity. The optimized window layer (i-ZnO and AZO) was used to produce flexible Cu(In,Ga)Se2(CIGSe) solar cells with a photo conversion efficiency of 9.53%. Therefore, ultra-thin ZnO films exhibit potential as a favorable option for a window layer in the production of high-efficient flexible solar cells in cost effective way.

The detection of polycyclic aromatic hydrocarbons (PAHs) on fruit and vegetable surfaces is important for protecting human health and ensuring food safety. In this study, a method for the in situ detection and identification of PAH residues on fruit and vegetable surfaces was developed using surface-enhanced Raman spectroscopy (SERS) based on a flexible substrate and lightweight deep learning network. The flexible SERS substrate was fabricated by assembling β-cyclodextrin-modified gold nanoparticles (β-CD@AuNPs) on polytetrafluoroethylene (PTFE) film coated with perfluorinated liquid (β-CD@AuNP/PTFE). The concentrations of benzo(a)pyrene (BaP), naphthalene (Nap), and pyrene (Pyr) residues on fruit and vegetable surfaces could be detected at 0.25, 0.5, and 0.25 μg/cm2, respectively, and all the relative standard deviations (RSD) were less than 10%, indicating that the β-CD@AuNP/PTFE exhibited high sensitivity and stability. The lightweight network was then used to construct a classification model for identifying various PAH residues. ShuffleNet obtained the best results with accuracies of 100%, 96.61%, and 97.63% for the training, validation, and prediction datasets, respectively. The proposed method realised the in situ detection and identification of various PAH residues on fruit and vegetables with simplicity, celerity, and sensitivity, demonstrating great potential for the rapid, nondestructive analysis of surface contaminant residues in the food-safety field. [ABSTRACT FROM AUTHOR]

A wideband flexible coplanar microstrip patch (CPW) antenna is developed on a felt substrate to radiate from 1.4 to 3 GHz. The dimension of the antenna is 0.37λ × 0.37λ × 0.007λ, developed on felt, which is a flexible textile material with a 1.38 dielectric constant. The patch and ground are printed on the same side of the substrate, where a semi‐circular slot is etched on the patch, and symmetric slots are etched on the ground to achieve wide bandwidth (73%). CPW feed impedance is matched with the connector impedance using the modified feed line. The felt antenna has a measured peak gain of 4.7 dB at 2.45 GHz. Moreover, the performance of the textile antenna under different bending conditions are experimentally carried out. The antenna bandwidth is reduced due to a decrease in bending angle, but still, the antenna operates at the required bandwidth of 1.8–2.9 GHz (upto 80 mm radius). [ABSTRACT FROM AUTHOR]