Search Results (77)

Functionalized hydrogels represent an emerging class of smart materials being explored for advancing next-generation wearable technologies, owing to their flexibility, biocompatibility, stimuli-responsiveness, and tunable properties. This review provides an overview of recent developments in hydrogel-based wearables, highlighting their potential to enhance adaptive, multifunctional, and environmentally sustainable devices and textiles. It begins by examining progress in wearable sensors, energy storage and harvesting, biosignal monitoring, and smart textiles, as well as the associated challenges, including limited battery life, inadequate skin adhesion, user discomfort, and constrained functionality. The review further explores the synthesis, fabrication techniques, properties, and types of hydrogels tailored for wearable technologies, followed by a detailed discussion of their applications in smart batteries, supercapacitors, sensors, nanogenerators, fabrics and hybrid systems. It also highlights integrating artificial intelligence (AI) and the Internet of Things (IoT) to improve designs; enhance performance through real-time monitoring, data analytics, and user interaction; and expand functionality. Also, it analyzes key limitations of current hydrogels—particularly in energy density, dehydration resistance, fatigue behaviour, and large-scale reproducibility—and outlines strategies based on hierarchical material design, sustainable and biodegradable formulations, and standardized testing and regulatory alignment. The review concludes by affirming the role of hydrogel-based technologies in shaping the future of wearable innovations across healthcare, lifestyle, and beyond and outlines promising research directions. Full article

This paper presents results on the preparation of thermoelectric composite materials for flexible and wearable electronics applications. Composite materials in the form of pastes for screen printing or stencil printing were made from a mixture of PEDOT:PSS paste and Bi₂Te₃ powder. The pastes showed good adhesion both to polyimide foil (Kapton) and polyester fabric substrates. Depending on the composition and the substrate used, the pastes had a sheet resistance of 26–264 Ω/sq, a Seebeck coefficient of 14–45 μV/K and a power factor of 0.05–0.8 μW/mK². The obtained pastes enabled the fabrication of textile thermopiles using Ag and PEDOT:PSS/Bi₂Te₃ materials for both arms. The output voltage of the obtained thermopiles on textile and foil substrates was 6–8 mV at a temperature gradient of 100 °C, and the output power was 0.01–0.12 μW. Energy harvesting from the human–ambient temperature gradient using the developed generators yielded promising results, with output voltages around 0.3 mV. Full article

Water scarcity is an escalating global challenge, driven by climate change and population growth. With only 2.5% of Earth’s freshwater readily accessible, there is an urgent need to explore sustainable alternatives. Textile-based fog collectors are advanced tools which have shown great potential and have gained remarkable attention across the world. This review critically evaluates emerging technologies for freshwater generation, including desalination (thermal and reverse osmosis (RO)), fog and dew harvesting, atmospheric water extraction, greywater reuse, and solar desalination systems, e.g., WaterSeer and Desolenator. Key performance metrics, e.g., water yield, energy input, and water collection efficiency, are summarized. For instance, textile-based fog harvesting devices can yield up to 103 mL/min/m², and modern desalination systems offer 40–60% water recovery. This work provides a comparative framework to guide future implementation of water-scarcity solutions, particularly in arid and semi-arid regions. Full article

Wearable and implantable Lab-on-Chip (LoC) biosensors are revolutionizing healthcare by enabling continuous, real-time monitoring of physiological and biochemical parameters in non-clinical settings. These miniaturized platforms integrate sample handling, signal transduction, and data processing on a single chip, facilitating early disease detection, personalized treatment, and preventive care. This review comprehensively explores recent advancements in LoC biosensing technologies, emphasizing their application in skin-mounted patches, smart textiles, and implantable devices. Key innovations in biocompatible materials, nanostructured transducers, and flexible substrates have enabled seamless integration with the human body, while fabrication techniques such as soft lithography, 3D printing, and MEMS have accelerated development. The incorporation of nanomaterials significantly enhances sensitivity and specificity, supporting multiplexed and multi-modal sensing. We examine critical application domains, including glucose monitoring, cardiovascular diagnostics, and neurophysiological assessment. Design considerations related to biocompatibility, power management, data connectivity, and long-term stability are also discussed. Despite promising outcomes, challenges such as biofouling, signal drift, regulatory hurdles, and public acceptance remain. Future directions focus on autonomous systems powered by AI, hybrid wearable–implantable platforms, and wireless energy harvesting. This review highlights the transformative potential of LoC biosensors in shaping the future of smart, patient-centered healthcare through continuous, minimally invasive monitoring. Full article

This systematic review explores recent advancements in antenna and rectifier systems for radio frequency (RF) energy harvesting within the gigahertz frequency range, aiming to support the development of sustainable and efficient low-power electronic applications. Conducted under the PRISMA methodology, our review filtered 2465 initial records down to 80 relevant studies, addressing three research questions focused on antenna design, operating frequency bands, and rectifier configurations. Key variables such as antenna type, resonant frequency, gain, efficiency, bandwidth, and physical dimensions were examined. Antenna designs including fractal, spiral, bow-tie, slot, and rectangular structures were analyzed, with fractal antennas showing the highest efficiency, while array antennas exhibited lower performance despite their compact dimensions. Frequency band analysis indicated a predominance of 2.4 GHz and 5.8 GHz applications. Evaluation of substrate materials such as FR4, Rogers, RT Duroid, textiles, and unconventional composites highlighted their impact on performance optimization. Rectifier systems including Schottky, full-wave, half-wave, microwave, multi-step, and single-step designs were assessed, with Schottky rectifiers demonstrating the highest energy conversion efficiency. Additionally, correlation analyses using boxplots explored the relationships among antenna area, efficiency, operating frequency, and gain across design variables. The findings identify current trends and design considerations crucial for enhancing RF energy harvesting technologies. Full article

Stretchable display technology has rapidly evolved, enabling a new generation of flexible electronics with applications ranging from wearable healthcare and smart textiles to implantable biomedical devices and soft robotics. This review systematically presents recent advances in stretchable displays, focusing on intrinsic stretchable materials, wavy surface engineering, and hybrid integration strategies. The paper highlights critical breakthroughs in device architectures, energy-autonomous systems, durable encapsulation techniques, and the integration of artificial intelligence, which collectively address challenges in mechanical reliability, optical performance, and operational sustainability. Particular emphasis is placed on the development of high-resolution displays that maintain brightness and color fidelity under mechanical strain, and energy harvesting systems that facilitate self-powered operation. Durable encapsulation methods ensuring long-term stability against environmental factors such as moisture and oxygen are also examined. The fusion of stretchable electronics with AI offers transformative opportunities for intelligent sensing and adaptive human–machine interfaces. Despite significant progress, issues related to large-scale manufacturing, device miniaturization, and the trade-offs between stretchability and device performance remain. This review concludes by discussing future research directions aimed at overcoming these challenges and advancing multifunctional, robust, and scalable stretchable display systems poised to revolutionize flexible electronics applications. Full article

Nanomaterials (NMs) have gained tremendous attention in various applications in the modern era. The most significant challenge associated with NMs is their strong propensity to aggregate. The chemical surface modification of NMs has garnered notable attention in managing NM dispersion and aggregation. Among the modification approaches, the silane modification of NMs has generated great interest among researchers as a versatile approach to tailoring the surface characteristics of NMs. This review comprehensively examined the recent advancements in silane modification techniques with a focus on triboelectric nanogenerator (TENG) applications. It provides an overview of silane chemistry and its interaction with diverse NMs, elucidating the underlying mechanisms governing the successful surface functionalization process. This review emphasized the silane modification, such as improved mechanical properties of composites, enhanced electrical and thermal conductivity, functional coatings, water treatment, textile industries, catalysis, membrane applications, and biomedical applications, of various NMs. In particular, the role of silane-modified NMs in advancing energy harvesting technologies was highlighted, showcasing their potential to enhance the performance and stability of next-generation devices. Full article

Virginia mallow or Sida hermaphrodita (L.) Rusby (SH) is a perennial plant from the Malvaceae family (mallows) that is used for medicinal purposes, reducing soil erosion, cleaning soil, and most recently for energy production. The potential of sustainable lignocellulosic agro-waste is immense as it represents Earth’s most abundant organic compound. This paper explores fibers isolated from SH stems, a plant with significant industrial application potential, including technical textiles and biocomposites. The fibers were harvested in January, March, and November of 2020 and in January and March of 2021, and their yield, mechanical properties, moisture content, and density were thoroughly analyzed. The fiber yield showed slight variations depending on the harvest time, with consistent results observed across different years, suggesting stable productivity. The SH fibers demonstrated a favorable moisture content, making them suitable for storage and processing, and their density ranged between 1.52 and 1.58 g/cm³, comparable to that of other natural fibers. According to this research, the best mechanical properties were observed in the winter harvest. Furthermore, the high percentage of solid residue left after fiber extraction shows promise for sustainable utilization, primarily for biofuel production. This study underscores the versatility and sustainability of SH fibers, positioning them as a valuable resource for a wide range of industrial applications. Full article

The integration of flexible electronics into textiles and smart products has revolutionized industries, enabling innovations such as wearable health monitors, interactive clothing, and energy-harvesting fabrics. However, the rapid growth of these technologies poses significant challenges for sustainability and circularity. This paper explores the concept of circular economy in the context of smart textiles and products containing flexible electronics. It highlights the technical, environmental, and economic challenges associated with their end-of-life management and proposes strategies to enhance circularity, including design for disassembly, advanced recycling technologies, and policy frameworks. The paper concludes with a discussion of future research directions to achieve a sustainable lifecycle for these advanced materials. Full article

Wearable photovoltaic (PV) cells offer a sustainable and lightweight solution for energy-harvesting applications, including safety gear and protective textiles. Despite their growing adoption, the application of PV cells in marine environments is limited due to the corrosive conditions that can degrade performance. This study evaluates the impact of corrosion on commercially sourced PV cells by analyzing maximum current and electrical resistance. This study used eight samples of two types of PV panel cells and tested them in corrosion conditions, and current and electrical resistance values were recorded. A paired sample t-test was used to assess variations in current and electrical resistance, while a repeated MANOVA compared the performance of two sample types during corrosion. The results reveal that corrosion significantly reduced current values and increased electrical resistance in Sample Type (1), while Sample Type (2) remained relatively stable. The MANOVA findings show a significant decrease in current for both samples, though the magnitude of reduction is similar between types. However, when combining both sample types, corrosion has no significant effect on electrical resistance. These results highlight the need for developing more durable, corrosion-resistant PV cells suitable for marine applications, emphasizing their potential for sustainable and practical use in harsh environments. Full article

This review provides a comprehensive analysis of the design, materials, fabrication techniques, and applications of flexible wearable antennas, with a primary focus on their roles in Wireless Body Area Networks (WBANs) and healthcare technologies. Wearable antennas are increasingly vital for applications that require seamless integration with the human body while maintaining optimal performance under deformation and environmental stress. Return loss, gain, bandwidth, efficiency, and the SAR are some of the most important parameters that define the performance of an antenna. Their interactions with human tissues are also studied in greater detail. Such studies are essential to ensure that wearable and body-centric communication systems perform optimally, remain safe, and are in compliance with regulatory standards. Advanced materials, including textiles, polymers, and conductive composites, are analyzed for their electromagnetic properties and mechanical resilience. This study also explores innovative fabrication techniques, such as inkjet printing, screen printing, and embroidery, which enable scalable and cost-effective production. Additionally, solutions for SAR optimization, including the use of metamaterials, electromagnetic band gap (EBG) structures, and frequency-selective surfaces (FSSs), are discussed. This review highlights the transformative potential of wearable antennas in healthcare, the IoT, and next-generation communication systems, emphasizing their adaptability for real-time monitoring and advanced wireless technologies, such as 5G and 6G. The integration of energy harvesting, biocompatible materials, and sustainable manufacturing processes is identified as a future direction, paving the way for wearable antennas to become integral to the evolution of smart healthcare and connected systems. Full article

We review recent results on textile triboelectric nanogenerators (T-TENGs), which function both as harvesters of mechanical energy and self-powered motion sensors. T-TENGs can be flexible, breathable, and lightweight. With a combination of traditional and novel manufacturing methods, including nanofibers, T-TENGs can deliver promising power output. We review the evolution of T-TENG device structures based on various textile material configurations and fabrication methods, along with demonstrations of self-powered systems. We also provide a detailed analysis of different textile materials and approaches used to enhance output. Additionally, we discuss integration capabilities with supercapacitors and potential applications across various fields such as health monitoring, human activity monitoring, human–machine interaction applications, etc. This review concludes by addressing the challenges and key research questions that remain for developing viable T-TENG technology. Full article

Multifunctional composites and smart textiles are an important advancement in material science, offering a variety of capabilities that extend well beyond traditional structural functions. These advanced materials are poised to revolutionize applications across a wide range of industries, including aerospace, healthcare, military, and consumer electronics, by embedding functionalities such as structural health monitoring, signal transmission, power transfer, self-healing, and environmental sensing. This review, which draws on insights from various disciplines, including material science, engineering, and technology, explores the manufacturing techniques employed in creating multifunctional composites, focusing on modifying textiles to incorporate conductive fibers, sensors, and functional coatings. The various multifunctional capabilities that result from these modifications and manufacturing techniques are examined in detail, including structural health monitoring, power conduction, power transfer, wireless communication, power storage, energy harvesting, and data transfer. The outlook and potential for future developments are also surveyed, emphasizing the need for improved durability, scalability, and energy efficiency. Key challenges are identified, such as ensuring material compatibility, optimizing fabrication techniques, achieving reliable performance under diverse conditions, and modeling multifunctional systems. By addressing these challenges through ongoing research and further innovation, we can significantly enhance the performance and utility of systems, driving advancements in technology and improving quality of life. Full article

With the increasing application of electrospun PVDF webs in piezoelectric sensors and energy-harvesting devices, it is crucial to understand their responses under complex mechanical excitations. However, the dependence of the piezoelectric effect on mechanical excitation properties is not fully comprehended. This study aims to investigate the piezoelectric output of randomly oriented electrospun PVDF nanofiber webs fabricated through different electrospinning processes at various mechanical excitation frequencies. The electrospun PVDF web was sandwiched between two textile electrodes, and its piezoelectric output as a full-textile sensor was measured across a frequency range from 0.1 Hz to 10 Hz. The experimental results revealed that the piezoelectric output of the electrospun PVDF web exhibited a nearly linear increase at excitation frequencies below 1.0 Hz and then reached an almost constant value thereafter up to 10 Hz, which is different from the hybrid PVDF or its copolymer web. Furthermore, the dependency of the piezoelectric output on the excitation frequency was found to be influenced by the specific electrospinning process employed, which determined the crystalline structure of electrospun PVDF nanofibers. These findings suggest that determining an appropriate working frequency for randomly oriented electrospun PVDF nanofiber webs is essential before practical implementation, and the piezoelectric response mode in different mechanical activation frequency ranges can be used to detect different human physiological behaviors. Full article

Triboelectric nanogenerators (TENGs) are devices that efficiently transform mechanical energy into electrical energy by utilizing the triboelectric effect and electrostatic induction. Embroidery triboelectric nanogenerators (ETENGs) offer a distinct prospect to incorporate energy harvesting capabilities into textile-based products. This research work introduces an embroidered triboelectric nanogenerator that is made using polyester and nylon 66 yarn. The ETENG is developed by using different embroidery parameters and its characteristics are obtained using a specialized tapping and friction device. Nine ETENGs were made, each with different stitch lengths and line spacings for the polyester yarn. Friction and tapping tests were performed to assess the electrical outputs, which included measurements of short circuit current, open circuit voltage, and capacitor charging. One sample wearable embroidered energy harvester collected 307.5 μJ (24.8 V) of energy under a 1.5 Hz sliding motion over 300 s and 72 μJ (12 V) of energy through human walking over 120 s. Another ETENG sample generated 4.5 μJ (3 V) into a 1 μF capacitor using a tapping device with a 2 Hz frequency and a 50 mm separation distance over a duration of 520 s. Measurement of the current was also performed at different pressures to check the effect of pressure and validate the different options of the triboelectric/electrostatic characterization device. In summary, this research explains the influence of embroidery parameters on the performance of ETENG (Embroidery Triboelectric Nanogenerator) and provides valuable information for energy harvesting applications. Full article