Transforming Commercial Textiles and Threads into Sewable and Weavable Electric Heaters

Advances in Printed Electronic Textiles

Electronic textiles (e-textiles) have emerged as a revolutionary solution for personalized healthcare, enabling the continuous collection and communication of diverse physiological parameters when seamlessly integrated with the human body. Among various methods employed to create wearable e-textiles, printing offers unparalleled flexibility and comfort, seamlessly integrating wearables into garments. This has spurred growing research interest in printed e-textiles, due to their vast design versatility, material options, fabrication techniques, and wide-ranging applications. Here, a comprehensive overview of the crucial considerations in fabricating printed e-textiles is provided, encompassing the selection of conductive materials and substrates, as well as the essential pre- and post-treatments involved. Furthermore, the diverse printing techniques and the specific requirements are discussed, highlighting the advantages and limitations of each method. Additionally, the multitude of wearable applications made possible by printed e-textiles is explored, such as their integration as various sensors, supercapacitors, and heated garments. Finally, a forward-looking perspective is provided, discussing future prospects and emerging trends in the realm of printed wearable e-textiles. As advancements in materials science, printing technologies, and design innovation continue to unfold, the transformative potential of printed e-textiles in healthcare and beyond is poised to revolutionize the way wearable technology interacts and benefits.

Easy-To-Wear Auxetic SMA Knot-Architecture for Spatiotemporal and Multimodal Haptic Feedbacks

Wearable haptic interfaces prioritize user comfort, but also value the ability to provide diverse feedback patterns for immersive interactions with the virtual or augmented reality. Here, to provide both comfort and diverse tactile feedback, an easy-to-wear and multimodal wearable haptic auxetic fabric (WHAF) is prepared by knotting shape-memory alloy wires into an auxetic-structured fabric. This unique meta-design allows the WHAF to completely expand and contract in 3D, providing superior size-fitting and shape-fitting capabilities. Additionally, a microscale thin layer of Parylene is coated on the surface to create electrically separated zones within the WHAF, featuring zone-specified actuation for conveying diverse spatiotemporal information to users with using the WHAF alone. Depending on the body part it is worn on, the WHAF conveys either cutaneous or kinesthetic feedback, thus, working as a multimodal wearable haptic interface. As a result, when worn on the forearm, the WHAF intuitively provides spatiotemporal information to users during hands-free navigation and teleoperation in virtual reality, and when worn on the elbow, the WHAF guides users to reach the desired elbow flexion, like a personal exercise advisor.

Rapid In Situ Thermal Decontamination of Wearable Composite Textile Materials

Pandemics stress supply lines and generate shortages of personal protective equipment (PPE), in part because most PPE is single-use and disposable, resulting in a need for constant replenishment to cope with high-volume usage. To better prepare for the next pandemic and to reduce waste associated with disposable PPE, we present a composite textile material capable of thermally decontaminating its surface via Joule heating. This material can achieve high surface temperatures (>100 °C) and inactivate viruses quickly (<5 s of heating), as evidenced experimentally with the surrogate virus HCoV-OC43 and in agreement with analytical modeling for both HCoV-OC43 and SARS-CoV-2. Furthermore, it does not require doffing because it remains relatively cool near the skin (<40 °C). The material can be easily integrated into clothing and provides a rapid, reusable, in situ decontamination method capable of reducing PPE waste and mitigating the risk of supply line disruptions in times of need.

Multifunctional MoSe2 @MXene Heterostructure-Decorated Cellulose Fabric for Wearable Thermal Therapy

A booming demand for wearable electronic devices urges the development of multifunctional smart fabrics. However, it is still facing a challenge to fabricate multifunctional smart fabrics with satisfactory mechanical property, excellent Joule heating performance, highly efficient photothermal conversion, outstanding electromagnetic shielding effectiveness, and superior anti-bacterial capability. Here, a MoSe₂ @MXene heterostructure-based multifunctional cellulose fabric is fabricated by depositing MXene nanosheets onto cellulose fabric followed by a facile hydrothermal method to grow MoSe₂ nanoflakes on MXene layers. A low-voltage Joule heating therapy platform with rapid Joule heating response (up to 230 °C in 25 s at a supplied voltage of 4 V) and stable performance under repeated bending cycles (up to 1000 cycles) is realized. Besides, the multifunctional fabric also exhibits excellent photothermal performance (up to 130 °C upon irradiation for 25 s with a light intensity of 400 mW cm^-2 ), outstanding electromagnetic interference shielding effectiveness (37 dB), and excellent antibacterial performances (>90% anti-bacterial rate toward Escherichia coli, Bacillus subtilis, and Staphylococcus aureus). This work offers an efficient avenue to fabricate multifunctional wearable thermal therapy devices for mobile healthcare and personal thermal management.

High-strength, low infrared-emission nonmetallic films for highly efficient Joule/solar heating, electromagnetic interference shielding and thermal camouflage

High-strength nonmetallic materials with low infrared (IR) emission are rare in nature, yet highly anticipated especially in military and aerospace fields for thermal camouflage, IR stealth, energy-saving heating. Here, we reported a high-strength (422 MPa) nonmetallic film with very low IR emissivity (12%), realized by constructing alternating multilayered structures consisting of successive MXene functionalized outer layers and continuous GO reinforced inner layers. This nonmetallic film is capable of competing with typical stainless steel (415 MPa, 15.5%), and exhibits remarkable thermal camouflage performance (ΔT = 335 °C), ultrahigh Joule heating capability (350 °C at 2 V), excellent solar-to-thermal conversion efficiency (70.2%), and ultrahigh specific electromagnetic interference shielding effectiveness (83 429 dB cm^-1). Impressively, these functionalities can be maintained well after prolonged outdoor aging, and even after undergoing harsh application conditions including strong acid/alkali and boiling water immersion, and cryogenic (-196 °C) temperature.

Portable Heating and Temperature-Monitoring System with a Textile Heater Embroidered on the Facemask

Personal heating systems are getting increasing interest because of the need to reduce the negative impact of cold weather on the health of people and animals. Heating the air before inhalation is of great importance as it can reduce the probability of various diseases. In this paper, we present a textile-based heater composed of commercial conductive threads, embroidered on an ordinary protective facemask. We also present the design and implementation details of the temperature monitoring and controlling circuit. Air temperature inside the facemask was monitored by a thermocouple placed in close proximity to the nose (nostrils). Preliminary testing revealed that the difference among temperatures in repeated heating cycles is in the range of ±1.5 °C. The response time for temperature increase from 29.9 to 40.5 °C was about 4 min, while the recovery time from 40.5 to 31.3 °C was about 4.3 min. Safety for human use and wireless data transmission to an application installed on a mobile phone are also demonstrated.

Flexible stretchable electrothermally/photothermally dual-driven heaters from nano-embedded hierarchical CuxS-Coated PET fabrics for all-weather wearable thermal management

The multifunctional photoelectronic devices are recently attracting much more attention due to their potential enlarged applications. The flexible stretchable electrothermally/photothermally dual-driven heaters for all-weather wearable thermal management are presented in this work with nano-embedded hierarchical Cu_xS-coated PET fabrics. Herein, the hierarchical nano-embedded Cu_xS film is fabricated via a simple chemical bath method for high electrical conductivity and highly efficient inelastic collision of electro/photo-generated carriers. The hierarchical nano-embedded Cu_xS morphology produces the low sheet resistance of 1.26 Ω sq^-1 and the super low total heat transfer coefficient of 3.256 × 10^-5 W/^oC·mm², which lead to the high-efficient electro/photo-dual-driven heating effect in the Cu_xS@PET fabrics. The saturated temperature on the as-fabricated flexible wearable heaters reaches up to 172 °C. The thermal conversion devices also bear the excellent stability, reproducibility, stretchability, controllability and corrosion-resistant characteristics. Interestingly, their excellent thermal conversion performance could be achieved by freely exchanging the driving power sources, such as electricity-supplying equipment, 635-nm laser, infrared physiotherapy lamp and solar simulator, which provides a necessary precondition for the all-weather applications of flexible wearable heaters. The as-fabricated electro/photo-dual-driven heaters on the Cu_xS@PET fabrics have the promising applications in wearable electronics, all-weather self-heating facilities, out/in-vivo physiotherapy, and so on.

Joule-Heating Effect of Thin Films with Carbon-Based Nanomaterials

Smart textiles have become a promising area of research for heating applications. Coatings with nanomaterials allow the introduction of different functionalities, enabling doped textiles to be used in sensing and heating applications. These coatings were made on a piece of woven cotton fabric through screen printing, with a different number of layers. To prepare the paste, nanomaterials such as graphene nanoplatelets (GNPs) and multiwall carbon nanotubes (CNTs) were added to a polyurethane-based polymeric resin, in various concentrations. The electrical conductivity of the obtained samples was measured and the heat-dissipating capabilities assessed. The results showed that coatings have induced electrical conductivity and heating capabilities. The highest electrical conductivity of (9.39 ± 1.28 × 10⁻¹ S/m) and (9.02 ± 6.62 × 10⁻² S/m) was observed for 12% (w/v) GNPs and 5% (w/v) (CNTs + GNPs), respectively. The sample with 5% (w/v) (CNTs + GNPs) and 12% (w/v) GNPs exhibited a Joule effect when a voltage of 12 V was applied for 5 min, and a maximum temperature of 42.7 °C and 40.4 °C were achieved, respectively. It can be concluded that higher concentrations of GNPs can be replaced by adding CNTs, still achieving nearly the same performance. These coated textiles can potentially find applications in the area of heating, sensing, and biomedical applications.

In Vitro and In Vivo Biocompatibility Studies on Engineered Fabric with Graphene Nanoplatelets

To produce clothes made with engineered fabrics to monitor the physiological parameters of workers, strain sensors were produced by depositing two different types of water-based inks (P1 and P2) suitably mixed with graphene nanoplatelets (GNPs) on a fabric. We evaluated the biocompatibility of fabrics with GNPs (GNP fabric) through in vitro and in vivo assays. We investigated the effects induced on human keratinocytes by the eluates extracted from GNP fabrics by the contact of GNP fabrics with cells and by seeding keratinocytes directly onto the GNP fabrics using a cell viability test and morphological analysis. Moreover, we evaluated in vivo possible adverse effects of the GNPs using the model system Caenorhabditis elegans. Cell viability assay, morphological analysis and Caenorhabditis elegans tests performed on smart fabric treated with P2 (P2GNP fabric) did not show significant differences when compared with their respective control samples. Instead, a reduction in cell viability and changes in the membrane microvilli structure were found in cells incubated with smart fabric treated with P1. The results were helpful in determining the non-toxic properties of the P2GNP fabric. In the future, therefore, graphene-based ink integrated into elastic fabric will be developed for piezoresistive sensors.

Porous and Ultra-Flexible Crosslinked MXene/Polyimide Composites for Multifunctional Electromagnetic Interference Shielding

Lightweight, ultra-flexible, and robust crosslinked transition metal carbide (Ti₃C₂ MXene) coated polyimide (PI) (C-MXene@PI) porous composites are manufactured via a scalable dip-coating followed by chemical crosslinking approach. In addition to the hydrophobicity, anti-oxidation and extreme-temperature stability, efficient utilization of the intrinsic conductivity of MXene, the interfacial polarization between MXene and PI, and the micrometer-sized pores of the composite foams are achieved. Consequently, the composites show a satisfactory X-band electromagnetic interference (EMI) shielding effectiveness of 22.5 to 62.5 dB at a density of 28.7 to 48.7 mg cm^-3, leading to an excellent surface-specific SE of 21,317 dB cm² g^-1. Moreover, the composite foams exhibit excellent electrothermal performance as flexible heaters in terms of a prominent, rapid reproducible, and stable electrothermal effect at low voltages and superior heat performance and more uniform heat distribution compared with the commercial heaters composed of alloy plates. Furthermore, the composite foams are well attached on a human body to check their electromechanical sensing performance, demonstrating the sensitive and reliable detection of human motions as wearable sensors. The excellent EMI shielding performance and multifunctionalities, along with the facile and easy-to-scalable manufacturing techniques, imply promising perspectives of the porous C-MXene@PI composites in next-generation flexible electronics, aerospace, and smart devices.

A Combination of Synthetic Molecules Acts as Antifreeze for the Protection of Skin against Cold-Induced Injuries

Seasonal and occupational exposure of the human body to extreme cold temperatures can result in cell death in the exposed area due to the formation of ice crystals. This leads to superficial or deep burn injury and compromised functionality. Currently available therapeutics can be ineffective in extreme cases, and thus, it is necessary to develop prophylactic strategies. In this study, we have devised a combination of known synthetic cryopreservative agents (termed SynAFP) and evaluated their potential antifreeze applications on skin. The prophylactic activity of SynAFP in vitro is indicated by improved cellular revival and cell viability, retention of the cytoskeleton, and normal cell cycle progression even after cold stress. A comprehensive whole-cell proteomic approach revealed that in the presence of SynAFP, cold-induced downregulation of proteins involved in cell-cell adhesion and upregulation of those related to mitochondrial stress were ameliorated. Pre-application of SynAFP in mice facing a frostbite challenge prevents their skin from incurring significant injury as confirmed through macroscopic and histological examination. Moreover, multiple applications of SynAFP on mouse skin at room temperature did not compromise skin integrity. SynAFP was also formulated in anAloe vera-based cream (referred to as fSynAFP), which offered similar protection under cold stress conditions. Thus, SynAFP can be considered as a potential candidate for formulating a topical intervention for protection from cold-induced injuries to skin.

Progress in Flexible Electronic Textile for Heating Application: A Critical Review

Intelligent textiles are predicted to see a 'surprising' development in the future. The consequence of this revived interest has been the growth of industrial goods and the improvement of innovative methods for the incorporation of electrical features into textiles materials. Conductive textiles comprise conductive fibres, yarns, fabrics, and finished goods produced using them. Present perspectives to manufacture electrically conductive threads containing conductive substrates, metal wires, metallic yarns, and intrinsically conductive polymers. This analysis concentrates on the latest developments of electro-conductivity in the area of smart textiles and heeds especially to materials and their assembling processes. The aim of this work is to illustrate a potential trade-off between versatility, ergonomics, low energy utilization, integration, and heating properties.

Advanced Functional Materials for Intelligent Thermoregulation in Personal Protective Equipment

The exposure to extreme temperatures in workplaces involves physical hazards for workers. A poorly acclimated worker may have lower performance and vigilance and therefore may be more exposed to accidents and injuries. Due to the incompatibility of the existing standards implemented in some workplaces and the lack of thermoregulation in many types of protective equipment that are commonly fabricated using various types of polymeric materials, thermal stress remains one of the most frequent physical hazards in many work sectors. However, many of these problems can be overcome with the use of smart textile technologies that enable intelligent thermoregulation in personal protective equipment. Being based on conductive and functional polymeric materials, smart textiles can detect many external stimuli and react to them. Interconnected sensors and actuators that interact and react to existing risks can provide the wearer with increased safety, protection, and comfort. Thus, the skills of smart protective equipment can contribute to the reduction of errors and the number and severity of accidents in the workplace and thus promote improved performance, efficiency, and productivity. This review provides an overview and opinions of authors on the current state of knowledge on these types of technologies by reviewing and discussing the state of the art of commercially available systems and the advances made in previous research works.

Wash-Durable Conductive Yarn with Ethylene Glycol-Treated PEDOT:PSS for Wearable Electric Heaters

Recently, wearable electric heaters with high durability and low-power operation have attracted much attention due to their potential to change traditional approaches for personal heating management and thermal therapy systems. Here, we report textile-based wearable heaters based on highly durable conductive yarns, which were transformed from traditional cotton yarns through a facile dyeing process of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) and ethylene glycol (EG). With the EG post-treatment, the conductive yarns exhibited an electrical conductivity of ∼76 S cm^-1 and good stability under repeated cycles of washing and drying. The heating elements made from the conductive yarns showed an excellent distribution of temperature and could be heated up to 150 °C at a sufficiently low driving voltage of 5 V. Also, the heating elements showed stable Joule heating performance under repeated bending stress and 2000 cycles of stretching and releasing. To demonstrate its practical use for on-body heating systems, a lightweight and air-breathable thermal wristband was demonstrated by sewing the conductive yarns onto a fabric with a simple circuit structure. From these results, we believe that our strategy to obtain highly conductive and durable yarns can be utilized in various applications, including medical heat therapy and personal heating management systems.

Textile-Based Triboelectric Nanogenerators for Wearable Self-Powered Microsystems

In recent years, wearable electronic devices have made considerable progress thanks to the rapid development of the Internet of Things. However, even though some of them have preliminarily achieved miniaturization and wearability, the drawbacks of frequent charging and physical rigidity of conventional lithium batteries, which are currently the most commonly used power source of wearable electronic devices, have become technical bottlenecks that need to be broken through urgently. In order to address the above challenges, the technology based on triboelectric effect, i.e., triboelectric nanogenerator (TENG), is proposed to harvest energy from ambient environment and considered as one of the most promising methods to integrate with functional electronic devices to form wearable self-powered microsystems. Benefited from excellent flexibility, high output performance, no materials limitation, and a quantitative relationship between environmental stimulation inputs and corresponding electrical outputs, TENGs present great advantages in wearable energy harvesting, active sensing, and driving actuators. Furthermore, combined with the superiorities of TENGs and fabrics, textile-based TENGs (T-TENGs) possess remarkable breathability and better non-planar surface adaptability, which are more conducive to the integrated wearable electronic devices and attract considerable attention. Herein, for the purpose of advancing the development of wearable electronic devices, this article reviews the recent development in materials for the construction of T-TENGs and methods for the enhancement of electrical output performance. More importantly, this article mainly focuses on the recent representative work, in which T-TENGs-based active sensors, T-TENGs-based self-driven actuators, and T-TENGs-based self-powered microsystems are studied. In addition, this paper summarizes the critical challenges and future opportunities of T-TENG-based wearable integrated microsystems.

Vapor phase polymerized conducting polymer/MXene textiles for wearable electronics

Multifunctional electronic textiles hold great potential applications in the wearable electronics field. However, it remains challenging to seamlessly integrate the multiple functions on the textile substrates without sacrificing their intrinsic properties. Herein, we report a novel and facile vapor phase polymerization (VPP) and spray-coating strategy towards the construction of a laminated film containing a PEDOT film and Ti3C2Tx MXene sheets on the fiber surface. The fabricated PEDOT/MXene decorated cotton fabrics are integrated with excellent electrochemical performance, joule heating performance, good electromagnetic interference (EMI) shielding, and strain sensing performance. The resultant multifunctional textiles have a low sheet resistance of 3.6 Ω sq-1, and the assembled all-solid-state fabric supercapacitors exhibit an ultrahigh specific capacitance of 1000.2 mF cm-2, which exceeds the state-of-the-art MXene-based fabric supercapacitors. In addition, the PEDOT/MXene modified fabrics exhibit an exceptional joule heating performance of 193.1 °C at the applied voltage of 12 V, high EMI shielding effectiveness of 36.62 dB, and high sensitivity as strain sensors for human motion detection. This work provides a novel strategy for the structure design of multifunctional textiles and will lay the foundation for the development of multifunctional wearable electronics.

Design of Electro-Thermal Glove with Sensor Function for Raynaud's Phenomenon Patients

Raynaud’s phenomenon (RP) is a disease that mainly affects human fingertips during cold weather. It is difficult to treat this disease using medicine, apart from keeping the body in a warm environment. In this research, conductive knitted fabrics were fabricated to help relax the vessels of the patient’s fingertips by providing proper heat, and also serving as a sensor to detect finger motion after relaxation of the blood vessels of patients. Four different structures, termed plain, purl, interlock, and rib were produced using conductive silver/PE (polyethylene) yarn and wool yarn, with a computerized flat knitting machine. The effect of knitted structure on the electro-thermal behavior, sensitivity, and stability of resistance change (∆R/R) under different tensile forces was investigated. By comprehensive comparison, the purl structure was identified as the preferred structure for the heating glove for RP patients, owing to superior electro-thermal behavior. Additionally, the purl structure had a greater capacity to detect different motions with stable resistance change. This potential electro-thermal glove could be used for functional, as well as aesthetic (fashion) purposes, and could be worn at any time and occasion with complete comfort.

An anisotropic layer-by-layer carbon nanotube/boron nitride/rubber composite and its application in electromagnetic shielding

Multifunctional polymer composites with anisotropic properties are attracting interest as they fulfil the growing demand of multitasking materials. In this work, anisotropic polymer composites have been fabricated by combining the layer-by-layer (LBL) filtration method with the alternative assembling of carbon nanotubes (CNTs) and hexagonal boron nitride flakes (hBN) on natural rubber latex particles (NR). The layered composites exhibit anisotropic thermal and electrical conductivities, which are tailored through the layer formulations. The best composite consists of four layers of NR modified with 8 phr (parts per Hundred Rubber) CNTs (∼7.4 wt%) and four alternate layers with 12 phr hBN (∼10.7 wt%). The composites exhibit an electromagnetic interference (EMI) shielding effectiveness of 22.41 ± 0.14 dB mm^-1 at 10.3 GHz and a thermal conductivity equal to 0.25 W m^-1 K^-1. Furthermore, when the layered composite is used as an electrical thermal heater the surface reaches a stable temperature of ∼103 °C in approx. 2 min, with an input bias of 2.5 V.

Flexible MXene-Decorated Fabric with Interwoven Conductive Networks for Integrated Joule Heating, Electromagnetic Interference Shielding, and Strain Sensing Performances

Although flexible and multifunctional textile-based electronics are promising for wearable devices, it is still a challenge to seamlessly integrate excellent conductivity into textiles without sacrificing their intrinsic flexibility and breathability. Herein, the vertically interconnected conductive networks are constructed based on a meshy template of weave cotton fabrics with interwoven warp and weft yarns. The two-dimensional early transition metal carbides/nitrides (MXenes), with unique metallic conductivity and hydrophilic surfaces, are uniformly and intimately attached to the preformed fabric via a spray-drying coating approach. Through adjusting the spray-drying cycles, the degree of conductive interconnectivity for the fabrics is precisely tuned, thereby affording highly conductive and breathable fabrics with integrated Joule heating, electromagnetic interference (EMI) shielding and strain sensing performances. Interestingly, triggered by the interwoven conductive architecture, the MXene-decorated fabrics with a low loading of 6 wt % (0.78 mg cm^-2) offer an outstanding electrical conductivity of 5 Ω sq^-1. The promising electrical conductivity further endows the fabrics with superior Joule heating performance with a heating temperature up to 150 °C at a supply voltage of 6 V, excellent EMI shielding performance, and highly sensitive strain responses to human motion. Consequently, this work offers a novel strategy for the versatile design of multifunctional textile-based wearable devices.

Highly Flexible, Efficient, and Sandwich-Structured Infrared Radiation Heating Fabric

Controlling thermal energy is one of the biggest concerns along with the progress of human civilization for thousands of years. Current thermal comfort devices are mainly based on materials that are bulky, rigid, and heavy, largely limiting their widespread practical applications. It still remains a challenge to develop highly lightweight, flexible, and efficient electrical heaters for personal thermal management and local climate control. In this work, we present a high-performance composite infrared radiation heating fabric (IRHF), which mainly consists of two layers of poly(ethylene terephthalate) (PET) fabrics and one sandwiched layer of carbon nanofibers embedded with different inorganic nanoparticles. A copper electrode sheet was connected with the carbon nanofibers to form a conductive heating circuit. The permanent spontaneous polarization of both carbon nanofibers and infrared radiation nanoparticles can facilitate an enhanced current in the heater by creating an additional electrical field, which results in a fast electrothermal response and favorable heat preservation. The constructed IRHF could achieve an increase in the temperature to 43 °C from room temperature in 1 min under a voltage of 30 V, with an electrothermal conversion efficiency up to 78.99%. With a collection of compelling features such as good thermal stability, excellent flexibility and breathability, and high electrical conductivity and energy conversion efficiency, the fabricated sandwich-structured IRHF can open up new opportunities to develop smart heating textiles and wearable heating clothes in many fields.

Flexible, portable and heatable non-woven fabric with directional moisture transport functions and ultra-fast evaporation

Compared with previous textiles possessing a hierarchical roughness structure for accelerating moisture evaporation, the use of Joule-heating to prepare heatable textiles is a more novel and useful way to achieve ultra-fast evaporation. Herein, we report an assembly strategy to create a functional non-woven (NW) fabric for directional moisture transportation and ultra-fast evaporation, ameliorating previous shortcomings. The resulting functional NW fabric reaches a sheet resistance of 1.116 Ω □⁻¹, and the increased surface temperature (76.1 °C) induced by a low voltage (5 V) further results in an excellent ultra-fast evaporation rate (3.42 g h⁻¹). Also, the moisture is transported to the outer surface of the designed fabric and spreads onto this surface. This desirable property can expand the contact area between sweat and the heatable fabric, further improving the evaporation efficiency, while maintaining the dry state of human skin. Generally, this functional textile with remarkable moisture management capabilities could be applied in winter outdoor sportswear to maintain human comfort.

Functional non-woven fabric with directional moisture transport and ultra-fast evaporation properties is demonstrated.

Simultaneous PAN Carbonization and Ceramic Sintering for Fabricating Carbon Fiber-Ceramic Composite Heaters

In this study, a single firing was used to convert stabilized polyacrylonitrile (PAN) fibers and ceramic forming materials (kaolin, feldspar, and quartz) into carbon fiber/ceramic composites. For the first time, PAN carbonization and ceramic sintering were achieved simultaneously in one thermal cycle and the microscopic morphologies and physical features of the obtained carbon fiber/ceramic composites were characterized in detail. The obtained carbon fiber/ceramic composite showed comparable flexural strength as commercial ceramic tiles. Meanwhile, the composite showed exceptional electro-thermal performance based on the electro-thermal performance of the carbonized PAN fibers, which could reach 108 ℃ after 15 s, 204 ℃ after 90 s, and 292 ℃ after 450 s at 5 V (2.6 A), thereby making the ceramic composite a good candidate as an indoor climate control heater, defogger device, kettle, and other heating element.

Printed fabric heater based on Ag nanowire/carbon nanotube composites

The increasing demand for smart fabrics has inspired extensive research in the field of nanomaterial-based wearable heaters. However, existing stretchable heaters employ polymer substrates, and hence require additional substrate-fabric bonding that can result in high thermal contact resistance. Moreover, currently used stretchable fabric heaters suffer from high sheet resistance and require complex fabrication processes. In addition, conventional fabrication methods do not allow for patternability, thus hindering the fabrication of wearable heaters with diverse designs. Herein, we propose an improved spray coating method well suited for the preparation of patternable heaters on commercial fabrics, combining the structural stability of carbon nanotubes with the high electrical conductivity of Ag nanowires to fabricate a stretchable fabric heater with excellent mechanical (stretchability ≈ 50%) and electrical (sheet resistance ≈ 22 Ω sq^-1) properties. The fabricated wearable heater reaches typical operating temperatures of 35 °C-55 °C at a low driving voltage of 3-5 V with a proper surface power density of 26.6-72.2 [Formula: see text] (heater area: [Formula: see text]) and maintains a stable heating temperature for more than 30 h. This heater shows a stable performance even when folded or rolled, thus being well suited for the practical wearable applications.

Selection of Immiscible Polymer Blends Filled with Carbon Nanotubes for Heating Applications

In many application fields, such as medicine or sports, heating textiles use electrically conductive multifilaments. This multifilament can be developed from conductive polymer composites (CPC), which are blends of an insulating polymer filled with electrically conductive particles. However, this multifilament must have filler content above the percolation threshold, which leads to an increase of the viscosity and problems during the melt spinning process. Immiscible blends between two polymers (one being a CPC) can be used to allow the reduction of the global filler content if each polymer is co-continuous with a selective localization of the fillers in only one polymer. In this study, three immiscible blends were developed between polypropylene, polyethylene terephthalate, or polyamide 6 and a filled polycaprolactone with carbon nanotubes. The morphology of each blend at different ratios was studied using models of co-continuity and prediction of fillers localization according to viscosity, interfacial energy, elastic modulus, and loss factor of each polymer. This theoretical approach was compared to experimental values to find out differences between methods. The electrical properties (electrical conductivity and Joule effect) were also studied. The co-continuity, the selective localization in the polycaprolactone, and the Joule effect were only exhibited by the polypropylene/filled polycaprolactone 50/50 wt.%.

An integrated smart heating control system based on sandwich-structural textiles

Integrated fabrics with a smart heating control system (HCS) are attractive in warming and thermotherapy for human healthcare management. Metal nanofibers (NFs) networks with high flexibility, conductivity and gas permeability are ideal functional materials for wearable electronics. Herein, a novel sandwich-structural (Ag NFs/fabrics/Pt NFs) textile for a HCS is constructed, where a Ag NF network film was functioned as a wearable heater and Pt NF network arrays were functioned as wearable temperature sensors. Conductivity and mechanical stability of the metal NFs were enhanced by crosslinking the free-standing fiber networks, resulting in high thermo-stability, thermal resistance (163.5 °C W^-1 cm²) and temperature sensitivity (0.135% °C^-1) of the HCS. The HCS can simultaneously realize heating and temperature distribution detection, demonstrating only 0.57% average error between the simulated resistance-to-temperature diagram of Pt NF arrays and actual temperature mapping. In addition, the HCS can be stuck on the skin for thermochromic fabrics, real-time heating and temperature detection/control through a Bluetooth device in a smartphone wirelessly.

High-Performance and Rapid-Response Electrical Heaters Based on Ultraflexible, Heat-Resistant, and Mechanically Strong Aramid Nanofiber/Ag Nanowire Nanocomposite Papers

High-performance and rapid response electrical heaters with ultraflexibility, superior heat resistance, and mechanical properties are highly desirable for the development of wearable devices, artificial intelligence, and high-performance heating systems in areas such as aerospace and the military. Herein, a facile and efficient two-step vacuum-assisted filtration followed by hot-pressing approach is presented to fabricate versatile electrical heaters based on the high-performance aramid nanofibers (ANFs) and highly conductive Ag nanowires (AgNWs). The resultant ANF/AgNW nanocomposite papers present ultraflexibility, extremely low sheet resistance (minimum R_s of 0.12 Ω/sq), and outstanding heat resistance (thermal degradation temperature above 500 °C) and mechanical properties (tensile strength of 285.7 MPa, tensile modulus of 6.51 GPa with a AgNW area fraction of 0.4 g/m²), benefiting from the partial embedding of AgNWs into the ANF substrate and the extensive hydrogen-bonding interactions. Moreover, the ANF/AgNW nanocomposite paper-based electrical heaters exhibit satisfyingly high heating temperatures (up to ∼200 °C) with rapid response time (10-30 s) at low AgNW area fractions and supplied voltages (0.5-5 V) and possess sufficient heating reliability, stability, and repeatability during the long-term and repeated heating and cooling cycles. Fully functional applications of the ANF/AgNW nanocomposite paper-based electrical heaters are demonstrated, indicating their excellent potential for emerging electronic applications such as wearable devices, artificial intelligence, and high-performance heating systems.

Three-Dimensional Textile Platform for Electrochemical Devices and its Application to Dye-Sensitized Solar Cells

The demand for easy-to-use portable electric devices that are combined with essential items in everyday life, such as apparel, has increased. Hence, significant research has been conducted into the development of wearable technology by fabrication of electronic devices with a textile structure based on fiber or fabric. However, the challenge to develop a fabrication method for wearable devices based on weaving or sewing technology still remains. In this study, we have proposed and fabricated a 3-D textile with two electrodes and one spacer in a single sheet of fabric, utilizing a commercial weaving machine. The two electrodes fulfil the role of electron transfer and the spacer between the electrodes circulates electrons and prevents electrical shorting. Hence, the 3-D textile could be applied to a wide range of electrochemical devices. In addition, it is possible to control the textile structure, size and quantity and change the electrode or spacer materials by replacing the thread. We applied the 3-D textile to dye-sensitized solar cells (DSSCs) which has distinctive advantages such as low manufacturing cost, esthetic appearance for interior or exterior application and high power output under relatively weak light illuminations. The 3-D textile DSSCs were fabricated through a continuous process, from manufacturing to encapsulation, using a non-volatile electrolyte and demonstrated a specific power of 1.7% (1 sun, 1.5 A.M.). The 3-D textile DSSCs were electrically connected in parallel and series by twisting, stainless steel wires, which were used as the weft, and a light-emitting diode lamp was turned on using 3-D textile DSSCs connected in series. This study represents the first stage in the development and application of wearable textile devices.

Significance of Nanomaterials in Wearables: A Review on Wearable Actuators and Sensors

Together with the evolution of digital health care, the wearable electronics field has evolved rapidly during the past few years and is expected to be expanded even further within the first few years of the next decade. As the next stage of wearables is predicted to move toward integrated wearables, nanomaterials and nanocomposites are in the spotlight of the search for novel concepts for integration. In addition, the conversion of current devices and attachment-based wearables into integrated technology may involve a significant size reduction while retaining their functional capabilities. Nanomaterial-based wearable sensors have already marked their presence with a significant distinction while nanomaterial-based wearable actuators are still at their embryonic stage. This review looks into the contribution of nanomaterials and nanocomposites to wearable technology with a focus on wearable sensors and actuators.

Solvent-Free Reactive Vapor Deposition for Functional Fabrics: Separating Oil–Water Mixtures with Fabrics

A facile, solvent-minimized approach to functionalize commercial raw fabrics is described. Reactive vapor deposition of conjugated polymers followed by post-deposition functionalization transforms common, off-the-shelf textiles into distinctly hydrophobic or superhydrophilic materials. The fabric coatings created by reactive vapor deposition are especially resistant to mechanical and solvent washing, as compared to coatings applied by conventional, solution-phase silane chemistries. Janus fabrics with dissimilar wettability on each face are also easily created using a simple, three-step vapor coating process, which cannot be replicated using conventional solution phase functionalization strategies. Hydrophobic fabrics created using reactive vapor deposition and post-deposition functionalization are effective, reusable, large-volume oil–water separators, either under gravity filtration or as immersible absorbants.

Machine-Washable Smart Textiles with Photothermal and Antibacterial Activities from Nanocomposite Fibers of Conjugated Polymer Nanoparticles and Polyacrylonitrile

Smart textiles based on conjugated polymers have been highlighted as promising fabrics that can intelligently respond to environmental stimuli based on the electrical properties of polymer semiconductors. However, there has been limited interest in the photothermal properties of conjugated polymers that can be applied to smart textiles. We prepared nanoparticles by assembling a conjugated polymer with a fatty acid via an emulsion process and nanocomposite fibers by distributing the conjugated polymer nanoparticles in a polyacrylonitrile matrix. We then fabricated the textiles using the fibers. The resulting fabrics based on nanocomposite fibers show a temperature increase to 50 °C in 10 min under white light irradiation because of efficient photothermal conversion by the conjugated polymer light harvester, while the temperature of a pristine polyacrylonitrile fabric increases to only 35 °C. In addition, excellent antimicrobial activity was confirmed by a 99.9% decrease in the populations of Staphylococcus aureus and Escherichia coli over 24 h because of the effect of the fatty acid in the nanocomposite films and fabrics. Furthermore, the fabric showed efficient durability after a laundry test, suggesting the usefulness of these smart textiles based on conjugated polymer nanoparticles for practical applications.

High Energy Density, Super-Deformable, Garment-Integrated Microsupercapacitors for Powering Wearable Electronics

Lightweight energy storage technologies are integral for powering emerging wearable health monitors and smart garments. In-plane, interdigitated microsupercapacitors (MSCs) hold the greatest promise to be integrated into wearable electronics because of their miniaturized footprint, as compared to conventional, multilayered supercapacitors and batteries. Constructing MSCs directly on textiles, while retaining the fabric's pliability and tactile quality, will provide uniquely wearable energy storage systems. However, relative to plastic-backed or paper-based MSCs, garment-integrated MSCs are underreported. The challenge lies in creating electrochemically active fiber electrodes that can be turned into MSCs. We report a facile vapor deposition and sewing sequence to create rugged textile MSCs. Conductive threads are vapor-coated with a stably p-doped conducting polymer film and then sewn onto a stretchy textile to form three-dimensional, compactly aligned electrodes with the electrode dimensions defined by the knit structure of the textile backing. The resulting solid-state device has an especially high areal capacitance and energy density of 80 mF/cm² and 11 μW h/cm² with a polymer gel electrolyte, and an energy density of 34 μW h/cm² with an ionic liquid electrolyte, sufficient to power contemporary iterations of wearable biosensors. These textile MSCs are also super deformable, displaying unchanging electrochemical performance after fully rolling-up the device.

Melding Vapor-Phase Organic Chemistry and Textile Manufacturing To Produce Wearable Electronics

Body-mountable electronics and electronically active garments are the future of portable, interactive devices. However, wearable devices and electronic garments are demanding technology platforms because of the large, varied mechanical stresses to which they are routinely subjected, which can easily abrade or damage microelectronic components and electronic interconnects. Furthermore, aesthetics and tactile perception (or feel) can make or break a nascent wearable technology, irrespective of device metrics. The breathability and comfort of commercial fabrics is unmatched. There is strong motivation to use something that is already familiar, such as cotton/silk thread, fabrics, and clothes, and imperceptibly adapt it to a new technological application. (24) Especially for smart garments, the intrinsic breathability, comfort, and feel of familiar fabrics cannot be replicated by devices built on metalized synthetic fabrics or cladded, often-heavy designer fibers. We propose that the strongest strategy to create long-lasting and impactful electronic garments is to start with a mass-produced article of clothing, fabric, or thread/yarn and coat it with conjugated polymers to yield various textile circuit components. Commonly available, mass-produced fabrics, yarns/threads, and premade garments can in theory be transformed into a plethora of comfortably wearable electronic devices upon being coated with films of electronically active conjugated polymers. The definitive hurdle is that premade garments, threads, and fabrics have densely textured, three-dimensional surfaces that display roughness over a large range of length scales, from microns to millimeters. Tremendous variation in the surface morphology of conjugated-polymer-coated fibers and fabrics can be observed with different coating or processing conditions. In turn, the morphology of the conjugated polymer active layer determines the electrical performance and, most importantly, the device ruggedness and lifetime. Reactive vapor coating methods allow a conjugated polymer film to be directly formed on the surface of any premade garment, prewoven fabric, or fiber/yarn substrate without the need for specialized processing conditions, surface pretreatments, detergents, or fixing agents. This feature allows electronic coatings to be applied at the end of existing, high-throughput textile and garment manufacturing routines, irrespective of dye content or surface finish of the final textile. Furthermore, reactive vapor coating produces conductive materials without any insulating moieties and yields uniform and conformal films on fiber/fabric surfaces that are notably wash- and wear-stable and can withstand mechanically demanding textile manufacturing routines. These unique features mean that rugged and practical textile electronic devices can be created using sewing, weaving, or knitting procedures without compromising or otherwise affecting the surface electronic coating. In this Account, we highlight selected electronic fabrics and garments created by melding reactive vapor deposition with traditional textile manipulation processes, including electrically heated gloves that are lightweight, breathable, and sweat-resistant; surface-coated cotton, silk, and bast fiber threads capable of carrying large current densities and acting as sewable circuit interconnects; and surface-coated nylon threads woven together to form triboelectric textiles that can convert surface charge created during small body movements into usable and storable power.