Wearable Textiles Research Articles

A bio-inspired, green, and universal preparation method to develop textile-based solar energy storage heater and ammonia leakage monitor sensor

Flexible and smart devices, especially wearable textiles, play a significant role in constantly upgrading modern healthcare and safety management. Poly(3,4-ethylenedioxythiophene) (PEDOT) has attracted much attention because of its outstanding performance, for instance, high stability, conductivity, and biocompatibility. However, PEDOT is not adaptable to the current textile industry because PEDOT has no functional groups that react with the fabrics. Herein, we have reported a facile in situ enzymatic polymerization method to prepare conductive and flexible PEDOT textiles. Polydopamine (PDA) serves as a universal adhesive to enhance the combined force of PEDOT and any fabrics, providing a secondary reaction platform for the assembly of PEDOT particles. We have polymerized conductive PEDOT on polyester-latex mesh, knitted cotton, woven wool, and polyester nonwoven fabrics with PDA treatment successfully. It should be noted that the surface temperature of the solar energy-thermal storage heater can rapidly reach 57.9 °C with 1 sun under the synergistic effect of PEDOT and PDA. In addition, PEDOT-coated ammonia gas sensor has outstanding anti-wet interference, wide detection limit, reusability, and excellent selectivity for common volatile organic compounds. This method of preparing durable coated fabrics has the potential to be widely applied in the development and design of next-generation wearable devices.

Fluids transmission and thermal durability analysis of Miura-ori auxetic relief knits; the next generation wearable materials

Knitted materials with superior thermal comfort attributes and cheap production costs are primarily utilized in leisurewear. Auxetic materials having biaxial stretch capabilities increase the propensity of knitted auxetic fabrics for size-changing clothing applications, such as maternity wear and growing kids' apparel, consequently supporting the sustainable development goal of responsible material consumption. Knitted auxetic fabrics based on Miura-ori fold geometries have been engineered with typically targeted clothing fibrous assemblies/yarns (polyester, cotton, and acrylic) and assorting different knitting parameters. Diagonal relief and hybrid square relief patterns with variable structural knitted cell (SKC) size proved to be a solution towards size and shape-changing clothing materials. Fluid transmission, heat retention, and durability evaluations were undertaken to determine the efficacy towards wearability of such auxetic materials. Varying structural porosities and the number of folds per unit area created properties discrepancy, governing different Poisson’s ratios and thermal attributes. Engineered foldable geometries exhibited about 10% to 40% increase in fluids transmissions than control plain rib fabrics. Quadratic thermal resistance enhancements of above 100% were noticed for auxetic fabrics and increasing SKC size enhanced thermal insulation. Influence of studied input variables was found statistically significant; fluid transmission had a p-value<0.05 for all material, SKC, and structure factors; heat retention was also significantly affected by material and SKC variation. The SKC size expansion promoted auxeticity up to optimum size of 9×9. Corresponding associations estimation using bubble plot analysis revealed positive correlations between fluid transmissions and durability attributes; however, an increase in fluid transmission compromised the heat retention of materials.

Double-network polyimide/silica aerogel fiber for thermal insulation under extremely hot and humid environment

Aerogel fibers display good flexibility, low density and high porosity, making them highly promising as wearable thermal-insulating textiles. However, the inferior thermal insulating property in hot and humid environment resulting from the poor thermal stability and water penetration hampers their use in harsh environments. Herein, we report a double-network organic/inorganic aerogel fiber for thermal insulation under extremely hot and humid environment prepared by co-gelation and freezing-spinning technique. Through the co-gelation strategy, a homogeneous organic/inorganic poly(amic acid)/SiO2 (PAA/SiO2) gels can be obtained, benefiting for the stable spinning process. The resultant polyimide/silica (PI/SiO2) aerogel fibers with unique organic/inorganic double-network structure display good mechanical strength, exceptional thermal stability (up to 500 °C) and low thermal conductivity (75.6 mW m−1 K−1 at 350 °C). Furthermore, the PI/SiO2 aerogel fabrics reveal hydrophobicity and can effectively prevent thermal transfer in hot and humid environment with thermal conductivity of 58.8 mW m−1 K−1 at 80 °C and relative humidity of 100%, about 60% lower than that of silica aerogels. It is expected that such PI/SiO2 aerogel fibers/fabrics will be applied as a novel textile for thermal insulation in hot and humid environments.

Recent Trends in Wearable Electronic Textiles (e-Textiles): A Mini Review

Wearable electronic textiles (e-textiles) have the ability to sense, respond, and adjust in multiple environmental stimuli, which can interact with the human brain's capability for cognition, reasoning, and activation. Moreover, they have the ability to generate and store energy, keep track of the wearer's health, and react to varying situations. Conductive polymers, metal-wrapped yarns, as well as, carbon nanotubes with silver, copper, and gold nanoparticles are used in a variety of yarn structures to design circuits, switches, and fabrics directly. Knitting, stitching, embroidery, and other integration techniques are used to combine electronic components and electrical interconnects to develop flexible electronic clothing and smart wearables. For this purpose, controlled sensors, actuators, conductive embroidered or printed fabric, planer yarn, data transfer devices, conductive inks, electromagnetic shielding, power supply, and other components are incorporated in e-textiles design. Despite the progress made so far, wearable e-textiles still, lack the required performance and device features along with the issues related to complex fabrication techniques, end-of-life processing and sustainability. Hence, this review aims to discuss the recent developments, which address the future challenges concerning electronic (e-textiles).

Hybrid cross-linked sodium carboxymethyl starch/polyacrylamide flexible sensing hydrogels with adhesion, antimicrobial properties and multiple responses

Ionic hydrogels used as ideal and flexible strain sensor materials should have excellent mechanical, adhesive and antimicrobial properties. However, it is challenging to achieve these multifunctional requirements simultaneously. Herein, we designed and prepared a multifunctional ionic hydrogel with a multi-length tentacle bentonite backbone to initiate the free radical polymerization of acrylic acid bentonite (AABT) and acrylamide (AAm). The interactions of covalent cross-linking, hydrogen bonding cross-linking, charge interactions and physical entanglement between hybrid polyacrylamide-AABT (PAAm-AABT), sodium carboxymethyl starch (SCMS) and PAAm form an multi-in-one hybrid supramolecular network hydrogel (CABZ). This CABZ ion-conductive hydrogel is capable of detecting weak deformation with a detection limit of 1 % strain, high tensile properties of 995 %, excellent strength of 254.5 kPa, fast response (≈0.21 s), high sensitivity of 0.86 and high conductivity of 0.37 S/m. In addition, this CABZ ion-conductive hydrogel has impressive adhesion properties with shear adhesion strength up to 50.78 kPa and broad-spectrum antibacterial properties achieved by AABT-loaded ZnO nanoparticles. Through special AABT hybrid cross-linking, the CABZ ion-conductive hydrogel achieves stable mechanical properties, highly sensitive signal response and antimicrobial properties, which will make it a good choice for flexible wearable sensor materials.

Upcycling of surgical facemasks into carbon based thin film electrode for supercapacitor technology

Polypropylene (PP), a commonly used plastic, is used for making the outer layers of a surgical face mask. In 2020, around 3 billion surgical face masks were disposed into the environment, causing a huge threat to wildlife, aquatic life, and ecosystems. In this work, we have reported the sulfonation technique for stabilizing the surgical face masks and their conversion into carbon nanoparticles for application as a supercapacitor electrode. The electrode is fabricated by preparing a slurry paste of carbon nanoparticles and pasting it on a conductive wearable fabric. To investigate the performance of the carbon thin film electrode, electrochemical techniques are employed. The Cyclic Voltammetry (CV) analysis performed at different scan rates in a 6 molar KOH electrolyte reveals that the carbon thin film acts as a positive electrode. At 4 A g−1, the electrode shows a specific capacitance of 366.22 F g−1 and 100% retention of specific capacitance for 8000 cycles. A two-electrode asymmetric device is fabricated using carbon thin film as the positive electrode, NiO thin film as the negative electrode, and a KOH separator between two electrodes. The device shows a specific capacitance of 113.73 F g−1 at 1.3 A g−1 and glows a red LED for 6 min. This work is a step towards upcycling the waste produced from surgical face masks used during the COVID-19 pandemic and its application for energy storage.

MXene Fibers for Flexible and Wearable Electronics: Recent Progress and Future Perspectives.

With the impetus of flexible electronics and micro-nano fabrication technology, the human demand for flexible intelligent wearable devices is on an upsurge. In recent years, new functional fibers have undergone rapid development and emerged as an indispensable carrier of flexible wearable e-textiles. However, to achieve their functional applications and durability, new functional fibers must possess good electrical and mechanical properties. As an emerging two-dimensional material, MXenes have attracted immense attention for their high electrical conductivity, mechanical strength, specific surface area, adjustable surface properties, and exceptional processability. As such, MXenes have become an ideal candidate for the primary functional component of functional fibers. This paper presents a comprehensive review of research progress on MXene-based fibers in the construction of flexible wearable electronic textiles. Firstly, we briefly outline the preparation methods of MXenes materials. Next, we summarize the processing types of MXene-based fibers and highlight their performance parameters. Lastly, we summarize the primary application scenarios of MXene-based fibers and anticipate the future development of flexible wearable e-textiles.

A biocompatible and antibacterial all-textile structured triboelectric nanogenerator for self-powered tactile sensing

With the rapid development of cutting-edge technologies, self-powered breathable wearable electronic textiles have received significant attention because of portable and convenient power sources. In this work, a biocompatible and antibacterial all-textile structured triboelectric nanogenerator was designed for self-powered tactile sensing, constructed by the MXene doped PVDF (P/M) nanofibers and the antibacterial Ag nanoparticles modified nylon 6,6 (Ag@nylon 6/6) nanofibers as the triboelectric negative and positive materials, respectively. The effect of MXenes in PVDF nanofibers for its mutual interaction, surface potential, breathability, tensile strength, biocompatibility, and triboelectric performance was evaluated thoroughly through experimental and theoretical investigations. As developed P/M nanofiber film was paired with tribopositive Ag@nylon 6/6 nanofibers to fabricate the TENG, exhibiting a high output voltage of 362 V and an output current of 38.5 μA. The triboelectric harvesting properties were further demonstrated by capacitor charging and the operation of low power devices such as the clock, 95 commercial LEDs. In addition, a self-powered tactile sensor based on the Ag@nylon 6,6 and P/M fibrous membranes realizes ultrasensitive motion and pulse detection from different arteries, and the fabricated tactile sensor array shows a great potential in the application of smart wearable keyboard as well as high-resolution tactile mapping.

Flexible and strain conductive cotton yarn enabled by low-temperature sintering of silver paste with multifunctional sensing capability in human motion detection and wearable applications

Flexible wearable textiles have attracted increasing attention, due to their potential applications in human motion detection, electric heating and humidity monitoring. However, the rigidity of metal materials contradicts the flexibility of textiles, and the complex preparation process and unfriendly environment hinder the development of metal materials as conductive materials of smart textiles. This study proposed a simple and environmentally friendly solution for smart textile preparation. Drawing on the bionic design principle of long-horned beetle’s exocuticle, the conductive layer on the surface of cotton yarn (CY) was formed by sintering the silver paste under low temperature of 200 ˚C. Silver Paste (SP) mainly composed with silver particles, terpineol (TE) and ethyl cellulose (EC). The resultant conductive yarn was characterized with high flexibility and high conductivity (4.08 × 103 S/cm). The conductivity of the yarn increases under tensile force, while decreases under non-tensile bending action. The strain sensor prepared by the yarn has a wide working range and high sensitivity, with distinguish performances of signal output according to the motion of different human body parts. The sensing behavior was also highlighted with the capability of micro-vibration strain of the human body, such as response to the pulse and throat. Furthermore, the conductive property of sintered silver paste cotton yarn (SSP-CY) has the capability of electric heating. The electric heating device based on SSP-CY can realize wired and radio heating, which resulted a maximum temperature of about 41 ℃. Therefore, the novel conductive cotton yarn has great potential in the application of high-sensitive wearable electronic devices.

High-performance flexible pressure sensor based on ordered double-level nanopillar array films: Design, development, and modeling

To improve the sensitivity and broaden the range of flexible pressure sensors, we proposed a high-performance flexible pressure sensor based on ordered double-level nanopillar array films. In this work, polypyrrole/multi-walled carbon nanotube/polyurethane (PPy/MWCNT/PU) conductive films with double-level nanopillar array microstructures were prepared by continuously adjusting the oxidation and pore expansion parameters of a porous anodic alumina template (AAO), where the high pillar height was 1243.0 ± 7.0 nm, and the low pillar height was 868.0 ± 4.70 nm. We studied the influence of the structural characteristics of ordered double-level nanopillar array conductive films and a flexible pressure sensor on the sensing performance using finite element simulations, the establishment of sensing mechanism, and sensor performance measurements. The results showed that the pressure was positively correlated with the change rate of strain and the surface microstructure contact area of the ordered double-level nanopillar array films. The sensor sensitivity reached 208.353 kPa−1, and its range was extended by 267%. In addition, the sensor, which could monitor vocalization, drinking pulse and finger movements, could be used in a wide range of applications, including wearable medical monitoring and smart sign language textiles.

Homogeneous wet-spinning construction of skin-core structured PANI/cellulose conductive fibers for gas sensing and e-textile applications

Fiber-based wearable electronic textiles have broad applications, but non-degradable substrates may contribute to electronic waste. The application of cellulose-based composite fibers as e-textiles is hindered by the lack of fast and effective preparation methods. Here, we fabricated polyaniline (PANI)/cellulose fibers (PC) with a unique skin-core structure through a wet-spinning homogeneous blended system. The conductive network formation was enabled at a mere 1 wt% PANI. Notably, PC15 (15 wt% PANI) shows higher electrical conductivity of 21.50 mS cm−1. Further, PC15 exhibits excellent ammonia sensing performance with a sensitivity of 2.49 %/ppm and a low limit of detection (LOD) of 0.6 ppm. Cellulose-based composite fibers in this work demonstrate good gas sensing and anti-static properties as potential devices for smart e-textiles.

Flexing the Spectrum: Advancements and Prospects of Flexible Electrochromic Materials.

The application potential of flexible electrochromic materials for wearable devices, smart textiles, flexible displays, electronic paper, and implantable biomedical devices is enormous. These materials offer the advantages of conformability and mechanical robustness, making them highly desirable for these applications. In this review, we comprehensively examine the field of flexible electrochromic materials, covering topics such as synthesis methods, structure design, electrochromic mechanisms, and current applications. We also address the challenges associated with achieving flexibility in electrochromic materials and discuss strategies to overcome them. By shedding light on these challenges and proposing solutions, we aim to advance the development of flexible electrochromic materials. We also highlight recent advances in the field and present promising directions for future research. We intend to stimulate further innovation and development in this rapidly evolving field and encourage researchers to explore new opportunities and applications for flexible electrochromic materials. Through this review, readers can gain a comprehensive understanding of the synthesis, design, mechanisms, and applications of flexible electrochromic materials. It serves as a valuable resource for researchers and industry professionals looking to harness the potential of these materials for various technological applications.

Design of Intelligent Protective Composite Material with Stress Rate Sensititivity, Strong Interface Adhesion and Recyclability.

Poly(dimethyl siloxane) (PDMS) elastomers play a significant role in smart materials, actuators, and flexible electronics. However, current PDMS lacks adhesion abilities and intelligent responsive properties, which limit its further application. In this study, the polydimethylsiloxane-ureidopyrimidinone impact hardening polymer (PDMS-UI) composites are manufactured by a dual cross-linking compositing tactic. PDMS, a chemically stable cross-linked network, acts as a framework owing to its excellent mechanical strength, whereas UI, a reversible dynamic physically cross-linked network with quadruple hydrogen bonding, endows the PDMS-UI with excellent self-healing ability (efficiency > 90%) and energy absorption (75.23%). Impressively, owing to multivalent hydrogen bonds, the PDMS-UI exhibits superior adhesion performance: the adhesion strength on various substrates exceed 150kPa and that on the Ferrum substrate reaches 570kPa. These outstanding properties make the PDMS-UI a potential candidate for application in both well-developed fields, such as, wearable protective materials, artificial skin and soft robotics. This article is protected by copyright. All rights reserved.

A reversibly flame-retardant thermal regulation material inspired by leaf transpiration

The demand for advanced fire-retardant wearable materials has increased with a rise in fire disasters in modern society. However, traditional fabrics have some drawbacks including non-temperature regulation, non-recyclability and contaminated products. Here, inspired by leaf transpiration, we prepared a reversibly flame-retardant thermal regulation material (LPWH). Wood cellulose skeleton is expected to be a reinforced mechanical scaffold by imitating the role of leaf vein for water collection and transportation. In parallel, to mimic the mesophyll cells around leaf vein, a hydrophilic and porous phase-change hydrogel aggregation is prepared by anchoring polyethyleneglycoldiacrylate-co-sodium vinylsulfonate copolymer on cellulose fibers and subsequent in-situ assembly of sodium alginate. This precise combination creates an artificial transpiration tissue, achieving effective heat dissipation and temperature regulation via water transpiration and phase-change behavior of hydrogel aggregation. LPWH shows a longer ignited time of 150 s (71% extension), a lower total smoke release of 22.3 m2/m2 (76% reduction), together with an ultralow fire growth index of 2.4 compared to commercial fire-retardant cotton fabric. Moreover, reversible fire retardancy (30 cycles) and great mechanical property (351 times higher than pure phase-change hydrogel) are demonstrated, suggesting LPWH can be the next generation of the pollution-free, recyclable temperature-regulated fireproof suit.

Highly Flexible All-Solid-State Supercapacitors Based on MXene/CNT Composites

MXene, a promising electrode material for supercapacitors, has excellent mechanical properties, hydrophilicity, metallic conductivity, and rich surface chemistry. However, the self-restacking of MXene nanosheets due to the strong van der Waals force makes it difficult to assemble them into electrodes. Here, continuous, ultrathin carbon nanotube (CNT) films are introduced as interlayers between MXene layers to prevent self-restacking during the assembly process, and freeze-drying is used to obtain composite films with a layered porous structure. The MXene/CNT composite films exhibit excellent electrochemical performance, and the film asymmetric device based on them delivers an energy density of 7.34 Wh kg–1 at a power density of 50 W kg–1. Moreover, these composite films demonstrate good flexibility and can be spun into fibers to assemble symmetric supercapacitors, showing good cyclic stability with a capacitance retention up to 99% over 5000 cycles. These MXene/CNT composite film electrodes can work under different forms (films or fibers) and have potential applications as flexible and wearable energy storage devices and textiles.

Fabrication of coral tentacle-like ZIF-67 derived NiCo-LDH/Ag nanowires on cotton fibers for wearable supercapacitor electrode materials

Wearable flexible electronic devices suitable for the human body have promising prospects in areas such as health monitoring and smart communication. Therefore, rational design and fabrication of flexible electrode materials is of great importance for efficient energy storage in wearable electronic devices. In this work, a unique coral tentacle-like interconnected network structured nickel-cobalt layered double hydroxide/silver nanowires/cotton (NiCo-LDH/AgNWs/Cotton) flexible electrode material is developed by a facile three-step method: (ⅰ) AgNWs are adsorbed on cotton fibers to form a conductive network by dipping, (ⅱ) ZIF-67 precursors grow on AgNWs/Cotton by in-situ, and (ⅲ) ZIF-67 precursors are converted into interconnected NiCo-LDH nanosheets by hydrothermal. The NiCo-LDH/AgNWs/Cotton electrode material exhibits an ultra-high areal capacitance (823.9 mF cm−2 at 1 mA cm−2), and decent cycling performance (77.7 % after 1000 cycles). The assembled symmetrical supercapacitor exhibits 8.63 μWh cm−2 energy density at a power density of 0.26 mW cm−2. In addition, NiCo-LDH/AgNWs/Cotton electrode material also have excellent flexibility, mechanical properties, and electromagnetic shielding. This study achieves high-value utilization of cotton fibers and provides fresh ideas for the development of flexible supercapacitors.

Highly Sensitive, Wide-Range Pressure Sensor Based on Negative Poisson’s Ratio for Human Motion Detection

Flexible wearable materials can be attached to human skin to collect a range of health information, such as wrist rotation, finger joint movement, knee flexion, and so on. Moreover, facial muscle-based signal monitoring can infer people’s emotional expressions, which has a wide range of applications. At present, it is difficult for one sensor to realize the interactive information monitoring of multiple parts of the human body, which is caused by the contradiction between sensitivity and range. In this work, an innovative method of mechanical structure is proposed. A PDMS elastomer with negative Poisson’s ratio (NPR) is embedded in the graphene–silicon rubber foam composite (rGO-PDMS/SR) in a simple and low-cost process, which improves the mechanical performance and resistance variation range effectively. The performance test results show that compared with ordinary graphene–silicon rubber composites (rGO-SR), the resistance variation range of the rGO-PDMS/SR has expanded by six times, which has high linear sensitivities of 7.0838 kPa−1 at 0–50 kPa and 0.0168 kPa−1 at 50–250 kPa. In addition, the composite shows reliable stability during cyclic compression. By analyzing the resistance change mechanism of the sensor, the explicit expression between the composite material performance parameters and the resistance is obtained. The results of human interaction experiments show that the sensor can meet the requirements of signal detection at nine different positions of the human body, including facial expression judgment, motion state monitoring, and other fields, which indicates good human interaction performance.

How Practical Are Fiber Supercapacitors for Wearable Energy Storage Applications?

Future wearable electronics and smart textiles face a major challenge in the development of energy storage devices that are high-performing while still being flexible, lightweight, and safe. Fiber supercapacitors are one of the most promising energy storage technologies for such applications due to their excellent electrochemical characteristics and mechanical flexibility. Over the past decade, researchers have put in tremendous effort and made significant progress on fiber supercapacitors. It is now the time to assess the outcomes to ensure that this kind of energy storage device will be practical for future wearable electronics and smart textiles. While the materials, fabrication methods, and energy storage performance of fiber supercapacitors have been summarized and evaluated in many previous publications, this review paper focuses on two practical questions: Are the reported devices providing sufficient energy and power densities to wearable electronics? Are the reported devices flexible and durable enough to be integrated into smart textiles? To answer the first question, we not only review the electrochemical performance of the reported fiber supercapacitors but also compare them to the power needs of a variety of commercial electronics. To answer the second question, we review the general approaches to assess the flexibility of wearable textiles and suggest standard methods to evaluate the mechanical flexibility and stability of fiber supercapacitors for future studies. Lastly, this article summarizes the challenges for the practical application of fiber supercapacitors and proposes possible solutions.

Exploring the intersection of equipment design and human physical ability: Leveraging biomechanics, ergonomics/anthropometry, and wearable technology for enhancing human physical performance

This perspective article highlights the development of sports equipment design and development. The impact of ergonomics/anthropometry and biomechanics on sports equipment design is discussed, focusing on the need for physical enhancement, and accommodating equipment for a diverse range of users. The use of innovative materials in sports equipment design, which has led to increased energy return and power output during sports performance, is also highlighted. Further, the article emphasizes the importance of interdisciplinary collaboration among various academic disciplines to examine past problem-solving approaches, develop new methods, and identify future research directions. Additionally, the article discusses four generations of sports equipment design, each characterized by specific design and engineering approaches that have significantly improved athletic performance. The fourth/current generation is expected to focus on biologically altering or modifying human physical capabilities to enhance athletic performance, with wearable technology identified as a key tool in this endeavor. Overall, the article provides a comprehensive overview of the evolution of sports equipment design and the role of interdisciplinary collaboration in enhancing human physical ability in sports. The article encourages further research in this area, particularly in the use of wearable technology and material innovation to enhance athletic performance in the future.

A wideband flexible electro-textiles material linear-to-circular polarizing metasurface for S-band CubeSat

In this paper, a flexible linear-to-circular polarizer FSS-based surface made from a single layer of cloth is introduced. Two orthogonal strips serve as the foundation for the proposed structure's architecture, with a central aperture in the unit cell for the pico-satellites aimed towards the S-Band. A wearable material called Shieldit Super serves as the conducting fabric in the unit cell, while Felt serves as the substrate. For the working center frequency of 2.41 GHz, the unit cell size is 0.32λ × 0.26λ × 0.02λ. It has a 3 dB axial ratio bandwidth (ARBW) of 42.90% and an axial ratio of 0.08 dB at 2.41 GHz, which is very close to zero. In addition, the FSS metasurface provides a bandwidth of up to 56.84% with 90% conversion efficiency. The polarizing surface is then created by multiplying this unit cell by a 6 × 6 array. The proposed structure's performance is proven by placing it in front of a patch antenna operating at 2.41 GHz. In addition to efficiently converting linearly polarized waves into circularly polarized waves, the antenna's performance improved when paired with the polarizing surface, as measured by the realized gain, which went from 3.14 dBi to 7.33 dBi.