Design and Characterization of Purely Textile Patch Antennas

In this paper, we present four purely textile patch antennas for Bluetooth applications in wearable computing using the frequency range around 2.4 GHz. The textile materials and the planar antenna shape provide a smooth integration into clothing while preserving the typical properties of textiles. The four antennas differ in the deployed materials and in the antenna polarization, but all of them feature a microstrip line as antenna feed. We have developed a manufacturing process that guarantees unaffected electrical behavior of the individual materials when composed to an antenna. Thus, the conductive textiles possess a sheet resistance of less than 1Omega/squarein order to keep losses at a minimum. The process also satisfies our requirements in terms of accuracy meeting the Bluetooth specifications. Our investigations not only characterize the performance of the antennas in planar shape, but also under defined bending conditions that resemble those of a worn garment. We show that the antennas can withstand clothing bends down to a radius of 37.5 mm without violating specifications     

Textile Technology for Soft Robotic and Autonomous Garments

Textiles have emerged as a promising class of materials for developing wearable robots that move and feel like everyday clothing. Textiles represent a favorable material platform for wearable robots due to their flexibility, low weight, breathability, and soft hand-feel. Textiles also offer a unique level of programmability because of their inherent hierarchical nature, enabling researchers to modify and tune properties at several interdependent material scales. With these advantages and capabilities in mind, roboticists have begun to use textiles, not simply as substrates, but as functional components that program actuation and sensing. In parallel, materials scientists are developing new materials that respond to thermal, electrical, and hygroscopic stimuli by leveraging textile structures for function. Although textiles are one of humankind's oldest technologies, materials scientists and roboticists are just beginning to tap into their potential. This review provides a textile-centric survey of the current state of the art in wearable robotic garments and highlights metrics that will guide materials development. Recent advances in textile materials for robotic components (i.e., as sensors, actuators, and integration components) are described with a focus on how these materials and technologies set the stage for wearable robots programmed at the material level.     

Wearable sweat biosensors on textiles for health monitoring

With the rapid technological innovation in materials engineering and device integration, a wide variety of textile-based wearable biosensors have emerged as promising platforms for personalized healthcare, exercise monitoring, and pre-diagnostics. This paper reviews the recent progress in sweat biosensors and sensing systems integrated into textiles for wearable body status monitoring. The mechanisms of biosensors that are commonly adopted for biomarkers analysis are first introduced. The classification, fabrication methods, and applications of textile conductors in different configurations and dimensions are then summarized. Afterward, innovative strategies to achieve efficient sweat collection with textile-based sensing patches are presented, followed by an in-depth discussion on nanoengineering and system integration approaches for the enhancement of sensing performance. Finally, the challenges of textile-based sweat sensing devices associated with the device reusability, washability, stability, and fabrication reproducibility are discussed from the perspective of their practical applications in wearable healthcare.     

All-Organic Smart Textile Sensor for Deep-Learning-Assisted Multimodal Sensing (Adv. Funct. Mater. 30/2023)

Smart textile for sensor is identified as a superior platform with greatly improved convenience and comfort for wearable bioelectronics. However, most reported textile-based sensors cannot fully demonstrate the inherent advantages of textiles, such as comfortability, breathability, biocompatibility, and environmental friendliness, mainly due to the intrinsic limitation of non-textile or inorganic components. Here, an all-textile, all-organic, washable, and breathable sensor with discriminable pressure, proximity, and temperature sensing function is first reported. Multiple sensing functions and outstanding washability are demonstrated. The all-textile sensor can also be seamlessly integrated into diverse types of fabrics to realize wide-range sensing of human activities and noncontact stimuli without sacrificing biocompatibility and comfortability. Additionally, by combining with the deep-learning technique, an all-textile sensing system is established to recognize object shape, contactless trajectory, and even environmental temperature. These results open a new avenue for designing low-cost, washable, comfortable, and biocompatible green textile electronics, providing a meaningful guideline in intelligent textiles.     

Piezoelectric Nylon-11 Fibers for Electronic Textiles,Energy Harvesting and Sensing

Electronic textiles and functional fabrics are among the key constituents envisioned for wearable electronics applications. For e-textiles, the challenge is to process materials of desired electronic properties such as piezoelectricity into fibers to be integrated as wefts or wraps in the fabrics. Nylons, first introduced in the 1940s for stockings, are among the most widely used synthetic fibers in textiles. However, realization of nylon-based e-textiles has remained elusive due to the difficulty of achieving the piezoelectric phase in the nylon fibers. Here, piezoelectric nylon-11 fibers are demonstrated and it is shown that the resulting fibers are viable for applications in energy harvesting from low frequency mechanical vibrations and in motion sensors. A simulation study is presented that elucidates on the sensitivity of the nylon-11 fibers toward external mechanical stimuli. Moreover, a strategy is proposed and validated to significantly boost the electrical performance of the fibers. Since a large fraction of the textile industry is based on nylon fibers, the demonstration of piezoelectric nylon fibers will be a major step toward realization of electronic textiles for applications in apparels, health monitoring, sportswear, and portable energy generation.     

Hybrid Smart Fiber with Spontaneous Self‐Charging Mechanism for Sustainable Wearable Electronics

Smart wearable electronics that are fabricated on light‐weight fabrics or flexible substrates are considered to be of next‐generation and portable electronic device systems. Ideal wearable and portable applications not only require the device to be integrated into various fiber form factors, but also desire self‐powered system in such a way that the devices can be continuously supplied with power as well as simultaneously save the acquired energy for their portability and sustainability. Nevertheless, most of all self‐powered wearable electronics requiring both the generation of the electricity and storing of the harvested energy, which have been developed so far, have employed externally connected individual energy generation and storage fiber devices using external circuits. In this work, for the first time, a hybrid smart fiber that exhibits a spontaneous energy generation and storage process within a single fiber device that does not need any external electric circuit/connection is introduced. This is achieved through the employment of asymmetry coaxial structure in an electrolyte system of the supercapacitor that creates potential difference upon the creation of the triboelectric charges. This development in the self‐charging technology provides great opportunities to establish a new device platform in fiber/textile‐based electronics.     

Rapid Fabrication of Soft,Multilayered Electronics for Wearable Biomonitoring

Soft integrated electronics are key components for emerging applications in wearable biomonitoring, soft co‐robotics, and physical human–machine interaction. They are composed of soft and elastically deformable circuits and sensors that are combined with packaged microelectronics for signal processing, power regulation, and communication. While promising, widespread use of soft wearable electronics is currently limited by the lack of robust fabrication techniques to rapidly, efficiently, and precisely assemble soft and rigid components into multilayered systems. Here, an efficient digital fabrication approach is presented to create highly customizable wearable electronics through rapid laser machining and adhesion controlled soft materials assembly. Well aligned, multilayered materials are created from 2D and 3D elements that stretch and bend while seamlessly integrating with rigid components such as microchip integrated circuits, discrete electrical components, and interconnects. These techniques are applied using commercially available materials and components and the fabrication of thin, lightweight, customized sensor skins is demonstrated in under an hour. These fully integrated wireless devices conformably bond to the hand and are successfully used for monitoring hand gesture, pulse rate, and blood oxygenation. These materials and methods enable custom wearable electronics while offering versatility in design and functionality for a variety of applications through material selection and construction.     

Textile Resistance Switching Memory for Fabric Electronics

A new type of wearable electronic device, called a textile memory, is reported. This is created by combining the unique properties of Al‐coated threads with a native layer of Al₂O₃ as a resistance switching layer, and carbon fiber as the counter‐electrode, which induces a fluent redox reaction at the interface under a small electrical bias (typically 2–3 V). These two materials can be embroidered into an existing cloth or woven into a novel cloth. The electrical resistance of the contacts is repeatedly switched by the bias polarity, as observed in the recently highlighted resistance switching memory. The devices with different structure from the solid metal‐insulator‐metal devices show reliable resistance switching behaviors in textile form by single stitch and in array as well that would render this new type of material system applicable to a broad range of emerging wearable devices. Such behavior cannot be achieved in other material choices, revealing the uniqueness of this material system.     

Robust planar textile antenna for wireless body LANs operating in 2.45 GHz ISM band

A single-feed rectangular-ring textile antenna is proposed for wireless body area networks operating in the 2.45 GHz ISM band. The conductive parts of the planar antenna consist of FlecTron/spl reg/, whereas fleece fabric is used as non-conductive antenna substrate. This results in a highly efficient, flexible and wearable antenna to be integrated in garments. The robustness of the antenna characteristics with respect to bending is proven.     

Smart Textile Optoelectronics for Human-Interfaced Logic Systems

Textiles with a freedom of form factor, unlimited scalability, and high programmability provide an ideal platform for constructing wearable optoelectronic systems. The emerging wearable technologies, like artificial intelligence and Internet of Things, have driven the development of textile optoelectronics from simple functional blocks to sophisticated logic systems, offering a seamless, breathable, and programmable on-body platform to synergistically sense, analyze, store, and feedback information in response to complex commands. In the past few years, the creation of such smart textile optoelectronics-based logic systems is boosted by nanomaterial science and manufacturing integration technologies and has revolutionized human–machine interaction paradigms in numerous emerging fields. Herein, in this review, the recent progress of smart textile optoelectronics for human-interfaced logic systems is timely summarized. This review begins with a concise discussion about the wearability evaluation and integration consideration of textile optoelectronic devices. Then, important breakthroughs in human-interfaced logic systems based on smart textile optoelectronics are demonstrated by highlighting their representative device, working principle, and application scenarios. Finally, the existing challenges and potential directions in the field of textile optoelectronics-integrated logic systems are analyzed.     

Integrating Flexible Ultralight 3D Ni Micromesh Current Collector with NiCo Bimetallic Hydroxide for Smart Hybrid Supercapacitors

Flexible and lightweight supercapacitors with superior mechanical flexibility and outstanding capacity are regarded as an ideal power source for wearable electronic devices. Meanwhile, incorporating additional novel characters such as transparency and electrochromism can further benefit the development of smart supercapacitors. Nevertheless, the application of the commonly used planar-structural current collectors is seriously restricted by their intrinsic properties such as poor rigidity, large thickness, and limited loading surface area. Flexible and ultralight current collectors with 3D architecture, high conductivity, and easy integration are believed to be the most appropriate alternatives to build high-performance supercapacitors. In this study, a novel and scalable manufacturing technique is developed to produce a flexible and ultralight 3D Ni micromesh (3D NM) current collector for supercapacitor. Flexible smart supercapacitor integrated by 3D NM and high active Ni–Co bimetallic hydroxide (3D NM@NiCo BH) delivers a considerable rate performance (60.6% capacity retention from 1 to 50 mA cm⁻²). Furthermore, the fabricated hybrid supercapacitor device integrated with electrochromic functionality can visually indicate the energy level by a color display. This flexible electrochromic supercapacitor based on ultralight 3D Ni micromesh provides a novel insight into multifunctional energy storage systems for smart wearable electronic devices.     

Muscle Fibers Inspired High-Performance Piezoelectric Textiles for Wearable Physiological Monitoring

The next-generation wearable biosensors with highly biocompatible, stretchable, and robust features are expected to enable the change of the current reactive and disease-centric healthcare system to a personalized model with a focus on disease prevention and health promotion. Herein, a muscle-fiber-inspired nonwoven piezoelectric textile with tunable mechanical properties for wearable physiological monitoring is developed. To mimic the muscle fibers, polydopamine (PDA) is dispersed into the electrospun barium titanate/polyvinylidene fluoride (BTO/PVDF) nanofibers to enhance the interfacial-adhesion, mechanical strength, and piezoelectric properties. Such improvements are both experimentally observed via mechanical characterization and theoretically verified by the phase-field simulation. Taking the PDA@BTO/PVDF nanofibers as the building blocks, a nonwoven light-weight piezoelectric textile is fabricated, which hold an outstanding sensitivity (3.95 V N⁻¹) and long-term stability (<3% decline after 7,400 cycles). The piezoelectric textile demonstrates multiple potential applications, including pulse wave measurement, human motion monitoring, and active voice recognition. By creatively mimicking the muscle fibers, this work paves a cost-effective way to develop high-performance and self-powered wearable bioelectronics for personalized healthcare.     

Textile‐Based Triboelectric Nanogenerators for Self‐Powered Wearable Electronics

Wearable smart electronic devices based on wireless systems use batteries as a power source. However, recent miniaturization and various functions have increased energy consumption, resulting in problems such as reduction of use time and frequent charging. These factors hinder the development of wearable electronic devices. In order to solve this energy problem, research studies on triboelectric nanogenerators (TENGs) are conducted based on the coupling of contact‐electrification and electrostatic induction effects for harvesting the vast amounts of biomechanical energy generated from wearer movement. The development of TENGs that use a variety of structures and materials based on the textile platform is reviewed, including the basic components of fibers, yarns, and fabrics made using various weaving and knitting techniques. These textile‐based TENGs are lightweight, flexible, highly stretchable, and wearable, so that they can effectively harvest biomechanical energy without interference with human motion, and can be used as activity sensors to monitor human motion. Also, the main application of wearable self‐powered systems is demonstrated and the directions of future development of textile‐based TENG for harvesting biomechanical energy presented.     

4D Printing of Shape Memory Materials for Textiles: Mechanism,Mathematical Modeling,and Challenges

Shape memory materials (SMMs) in 3D printing (3DP) technology garnered much attention due to their ability to respond to external stimuli, which direct this technology toward an emerging area of research, “4D printing (4DP) technology.” In contrast to classical 3D printed objects, the fourth dimension, time, allows printed objects to undergo significant changes in shape, size, or color when subjected to external stimuli. Highly precise and calibrated 4D materials, which can perform together to achieve robust 4D objects, are in great demand in various fields such as military applications, space suits, robotic systems, apparel, healthcare, sports, etc. This review, for the first time, to the best of the authors’ knowledge, focuses on recent advances in SMMs (e.g., polymers, metals, etc.) based wearable smart textiles and fashion goods. This review integrates the basic overview of 3DP technology, fabrication methods, the transition of 3DP to 4DP, the chemistry behind the fundamental working principles of 4D printed objects, materials selection for smart textiles and fashion goods. The central part summarizes the effect of major external stimuli on 4D textile materials followed by the major applications. Lastly, prospects and challenges are discussed, so that future researchers can continue the progress of this technology.     

Waterproof,Breathable, and Antibacterial Self‐Powered e‐Textiles Based on Omniphobic Triboelectric Nanogenerators

Multifunctional electronic textiles (e‐textiles) incorporating miniaturized electronic devices will pave the way toward a new generation of wearable devices and human–machine interfaces. Unfortunately, the development of e‐textiles is subject to critical challenges, such as battery dependence, breathability, satisfactory washability, and compatibility with mass production techniques. This work describes a simple and cost‐effective method to transform conventional garments and textiles into waterproof, breathable, and antibacterial e‐textiles for self‐powered human–machine interfacing. Combining embroidery with the spray‐based deposition of fluoroalkylated organosilanes and highly networked nanoflakes, omniphobic triboelectric nanogenerators (R^F‐TENGs) can be incorporated into any fiber‐based textile to power wearable devices using energy harvested from human motion. R^F‐TENGs are thin, flexible, breathable (air permeability 90.5 mm s^?1), inexpensive to fabricate (<0.04$ cm^?2), and capable of producing a high power density (600 µW cm^?2). E‐textiles based on R^F‐TENGs repel water, stains, and bacterial growth, and show excellent stability under mechanical deformations and remarkable washing durability under standard machine‐washing tests. Moreover, e‐textiles based on R^F‐TENGs are compatible with large‐scale production processes and exhibit high sensitivity to touch, enabling the cost‐effective manufacturing of wearable human–machine interfaces.     

Recent Progress of Flexible Photodetectors Based on Low-Dimensional II–VI Semiconductors and Their Application in Wearable Electronics

Flexible photodetectors exhibit many advantages such as a good bendability, foldability, and even stretchability as well as weight light, which have triggered a widely concerned in wearable electronics including wearable monitoring, wearable image sensing, self-powered integrated electronics, etc. Recently, various II–VI semiconductor nanostructures have become promising candidates in flexible photodetectors due to their unique characteristics, such as direct bandgap semiconductors, excellent optical and electric properties, high quantum efficiency, and inherent mechanical flexibility. Herein, the most recent progress on low-dimensional (0D, 1D, 2D, and related heterostructures) II–VI semiconductors based flexible photodetectors and their application in wearable electronic is reviewed. First, a brief introduction of the main sensing mechanisms and key figures of merits for photodetectors is presented. Then, the recent progresses on flexible photodetectors are provided, in which the functional materials synthesis methods are also discussed. More importantly, the applications of the flexible photodetectors are summarized, including wearable monitoring sensors, image sensors, and self-powered integrated wearable electronics. Finally, the challenges and the future research direction of the flexible photodetectors are discussed, meanwhile the outlook for the development of flexible photodetectors in the future integration of wearable electronic is also provided.     

Enzymatic sensing with laccase-functionalized textile organic biosensors

Herein we present a textile wearable electrochemical transistor by functionalizing a single cotton yarn with semiconducting polymer. The organic electrochemical transistor (OECT), which is low cost and completely integrated e-textile, is decorated by adsorption of the fungal laccase POXA1b, and is used as biosensor for the direct detection of Tyrosine (L-Tyr) without the use of electron mediators. The detection of Tyr in real-case scenario such as human physiological fluids would own a paramount importance in noninvasive analysis of the patient's condition, monitoring and preventing several pathologies. To assess the reaction progression, the redox process is studied by UV–visible absorption with test reference molecule of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS): the results confirmed that the oxidation reaction is driven by the presence of laccase enzyme and direct electron transfer occurred. The modulation of the signal response and the kinetic of the signal is used to detect Tyr molecule in aqueous solution and the role of the enzyme adsorption on the textile is analyzed. A kinetic analysis of the characteristic modulation times of the sensing curves, confirm the sensing properties of the textile device. The textile-based biosensor is demonstrated to monitor human health biomarkers through wearable applications in a non-invasive way, finding potential application in sport, healthcare and working safety.     

Healable Transparent Electronic Devices

With the advent of the digital era, healable electronic devices are being developed to alleviate the propagation of breakdown in electronics due to the mechanical damage caused by bending, accidental cutting or scratching. Meanwhile, flexible transparent electronics, exhibiting high transmittance and robust flexibility, are drawing enormous research efforts due to their potential applications in various integrated wearable electronics. However, the breakdown of flexible transparent electronics seriously limits their reliability and lifetime. Therefore, transparent healable electronics are desired to tackle these problems, yet most of the healable electronics are not transparent nowadays. The combination of high performance, healability, and transparency into electronics is often mutually exclusive. Herein, after a brief introduction of self‐healing materials, healable electronics, and flexible transparent electronics, the recent progress in the healable electronic devices without transparency is reviewed in detail. Then, healable transparent electronic devices with high transparency, robust portability, and reliable flexibility are summarized. They are drawing great attention owing to their potential application in optical devices as well as smart wearable and integrated optoelectronic devices. Following that, the critical challenges and prospects are highlighted for the development of healable transparent electronic devices.     

Multifunctional and Water‐Resistant MXene‐Decorated Polyester Textiles with Outstanding Electromagnetic Interference Shielding and Joule Heating Performances

Although multifunctional, flexible, and wearable textiles with integrated smart electronics have attracted tremendous attention in recent years, it is still an issue to balance new functionalities with the inherent performances of the textile substrates. 2D early transition metal carbides/nitrides (MXenes) are considered as ideal nanosheets for fabricating multifunctional and flexible textiles on the basis of their superb intrinsic electrical conductivity, tunable surface chemistry, and layered structure. Herein, highly conductive and hydrophobic textiles with exceptional electromagnetic interference (EMI) shielding efficiency and excellent Joule heating performance are fabricated by depositing in situ polymerized polypyrrole (PPy) modified MXene sheets onto poly(ethylene terephthalate) textiles followed by a silicone coating. The resultant multifunctional textile exhibits high electrical conductivity of ≈1000 S m^?1 in conjunction with an exceptional EMI shielding efficiency of ≈90 dB at a thickness of 1.3 mm. The thin silicone coating renders the hydrophilic PPy/MXene‐decorated textile hydrophobic, leading to an excellent water‐resistant feature while retaining a satisfactory air permeability of the textile. Interestingly, the multifunctional textile also exhibits an excellent moderate voltage‐driven Joule heating performance. Thus, the deposition of PPy‐modified MXene followed by silicone coating creates a multifunctional textile that holds great promise for wearable intelligent garments, EMI shielding, and personal heating applications.     

Wearable and Implantable Triboelectric Nanogenerators

Triboelectric nanogenerators (TENGs) are a promising technology to convert mechanical energy to electrical energy based on coupled triboelectrification and electrostatic induction. With the rapid development of functional materials and manufacturing techniques, wearable and implantable TENGs have evolved into playing important roles in clinic and daily life from in vitro to in vivo. These flexible and light membrane‐like devices have the potential to be a new power supply or sensor element, to meet the special requirements for portable electronics, promoting innovation in electronic devices. In this review, the recent advances in wearable and implantable TENGs as sustainable power sources or self‐powered sensors are reviewed. In addition, the remaining challenges and future possible improvements of wearable and implantable TENG‐based self‐powered systems are discussed.