Conductive Fabrics Research Articles

Development of customizable conductive thermal woven textile for ready-to-wear functional collections

With the emergence of conductive materials and the development of textile technologies, various wearable smart textiles have been created and their application has been greatly expanded. Among them, thermal textiles using thermal woven technology have been the subject of limited research but offer promising application potential. Unlike the traditional development procedure, the integrated design-driven strategy of thermal woven textiles mainly contains a yarn phase, fabric phase and apparel phase. This article introduces a design-driven approach to develop thermal functional garments for ready-to-wear collections applying thermal woven textiles. The fabric development procedure includes design, test, evaluation, simulation model setup and modification. The apparel development procedure aims to guide commercial production. Since there is almost no systematic guidance for thermal woven product development so far, this study will fill the gap and provide practical instruction.

A Conductive Bamboo Fabric with Controllable Resistance for Tailoring Wearable Sensors.

Force-sensitive textile sensors are becoming a research hotspot as a part of wearable devices. The core research topic is the method to obtain the sensing property, which decides the sensitivity and service performance of the sensors. Here, we introduce a new sensing mechanism based on a statistical change of contact resistance that exhibits an exponential decay upon strain or pressure, where a novel conductive bamboo fabric is prepared and the dependence of electric conductivity on the fabric structure is discovered. The fabric surface resistivity (ρs) is anisotropic with respect to the measuring directions and the warp, weft, and linear densities. The surface resistance (Rs) decreases rapidly under pulling force, especially in diagonal directions, making it available in designing strain sensors. The volume resistivity (ρv) decreases with increasing weft and linear densities, too. The vertical resistance (Rv) decays exponentially under pressure, and the rule is retained even if the fabric is coated with a polymer, leading to diverse possible pressure sensors with a good service performance (e.g., waterproof). Finally, the conductive fabric could be facilely tailored to various wearable sensors with a fast response time, e.g., sensing finger sleeves and sensing insole, which could be used to operate the manipulator's fingers or to monitor human walking gestures, respectively.

Achieving Highly Conductive, Stretchable, and Washable Fabric from Reactive Silver Ink and Increased Interfacial Adhesion

Achieving Highly Conductive, Stretchable, and Washable Fabric from Reactive Silver Ink and Increased Interfacial Adhesion

Silicone-incorporated nanoporous cobalt oxide and MXene nanocomposite-coated stretchable fabric for wearable triboelectric nanogenerator and self-powered sensing applications

Triboelectric nanogenerators (TENGs) provide a desirable solution to alleviate the expanding energy supply concerns in the development of self-powered wearable devices and sensors. Herein, a novel wearable, stretchable multifunctional double-layered TENG is fabricated by using a metal-organic framework-derived nanoporous cobalt oxide (NPCO)/silicone and MXene/silicone nanocomposite. The excellent nanoporosity of NPCO induces high charge accumulations that promote the electronegativity of the nanocomposite by fourfold. In addition, MXene/silicone with bifunctionality (charge trapping and charge transport) is incorporated into the intermediate layer to improve the charge trapping capability and electronegativity of the nanocomposite by nine times. Facile, hierarchical fabric-assisted micro/nanostructures on the nanocomposite are conceived to increase hydrophobicity and water resistivity. Conductive knitted fabric is employed as a flexible electrode to obtain high stretchability (230 %) and robustness. Owing to the synergistic effect of the optimized nanocomposite, the fabricated TENG delivers a high power density (10.4 W/m2), which is approximately 23 times higher than the pure silicone-based TENG. By exploiting the outstanding sensitivity (5.82 V/kPa), the TENG reveals an extraordinary self-powered biomotion sensor, and its practical applications in a foot pressure distribution sensor array and a self-powered wearable keyboard. This work provides new insights into the design of high-performance TENGs with high sensitivity and durability and facilitates their applications in biomechanical energy harvesting and self-powered wearable sensors.

Eco-Technologies for Immobilizing Redox Enzymes on Conductive Textiles, for Sustainable Development

Enzyme immobilization on electrically conductive supports is necessary to improve their bioactivity and stability, for use and re-use in applications depending on bio-electrochemical response, such ...

A Proprioceptive Soft Robot Module Based on Supercoiled Polymer Artificial Muscle Strings.

In this paper, a multi-functional soft robot module that can be used to constitute a variety of soft robots is proposed. The body of the soft robot module made of rubber is in the shape of a long strip, with cylindrical chambers at both the top end and bottom end of the module for the function of actuators and sensors. The soft robot module is driven by supercoiled polymer artificial muscle (SCPAM) strings, which are made from conductive nylon sewing threads. Artificial muscle strings are embedded in the chambers of the module to control its deformation. In addition, SCPAM strings are also used for the robot module’s sensing based on the linear relationship between the string’s length and their resistance. The bending deformation of the robot is measured by the continuous change of the sensor’s resistance during the deformation of the module. Prototypes of an inchworm-like crawling robot and a soft robotic gripper are made, whose crawling ability and grasping ability are tested, respectively. We envision that the proposed proprioceptive soft robot module could potentially be used in other robotic applications, such as continuum robotic arm or underwater robot.

Textile-based pressure sensor arrays: A novel scalable manufacturing technique

Soft pressure sensors have sparked a lot of interest over the last decade because of their applications in human motion recognition, object detection, and human–computer interaction. However, their mass production and availability to end users are limited due to the complex and time-consuming steps. The scalability of working range for various applications is also a critical challenge. Therefore, a laborless, rapid, and scalable manufacturing technique for capacitive-based soft pressure sensors with high sensitivity and high working range is proposed in this work. The novel manufacturing method enables manipulation of sensor properties by varying production parameters based on specific application needs. The proposed sensor's electrode is made of conductive knit fabric, and the dielectric layers are made of thermoplastic polyurethane (TPU) sheets. As a result of the novel approach, it is possible to generate scalable air gaps between electrodes and dielectric layers to capture low pressures of less than 1 kPa. The usage of multi-layer TPU sheets also increases the working range of sensors up to 1000 kPa. Here, the proposed technology is successfully applied to create several sensor mats for different purposes such as improved gesture and shape recognition, and interactive gaming mats for children. • Simple and fast manufacturing of a novel textile pressure sensor. • Scalable with desired pattern of the sensor mat. • Adjustable sensitivity and wide working range from 1 kPa to 1000 kPa. • Pressure mapping for e-textiles, interactive software and human gesture recognition.

Green preparation of PEDOT-based composites with outstanding electrothermal heating and durable rapid-response sensing performance for smart healthcare textiles

Wearable electronics have attracted tremendous interest owing to their potential applications on rehabilitation training treating, and human health monitoring. Poly(3,4-ethylenedioxythiophene)@Cotton/spandex fabric (PEDOT@CSF) was developed for flexible, multifunctional, and smart healthcare textiles via high efficiency and environmentally friendly in situ enzymatic polymerization. PEDOT@CSF shows the good UV resistance, outstanding electrothermal heating, and excellent sensing performance. In detail, surface temperature rapidly reached to 130.6 °C for PEDOT@CSF, when the supply voltage at 10 V. The heater could carry out thermal therapy in any designated body part for patients. Meanwhile, the required temperature could easily be obtained by varying the supplied voltages. The motion of human joints (such as fingers, wrist, and elbow) and respiratory condition were recognize and monitor by PEDOT@CSF that easily attached to clothes and accessories. PEDOT:p-toluenesulfonic acid (PEDOT:TsOH) give the textiles a smart sensing ability with fast response, and excellent durability. Furthermore, electrical resistance of PEDOT@CSF exhibited better stability under heating conditions, long time storage, multiple bending, and washing cycles. In summary, we have developed an environment-friendly and general method and obtained a high-performance multifunctional conductive textile, which provide a new path for the green synthesis and improvement of conductive polymer-based materials and development of flexible thermotherapy.

High-performance hybrid biofuel cells using amphiphilic assembly based enzyme electrodes

Biofuel cells, which convert chemical energy into electrical energy at mild temperature and over moderate pH ranges, have been considered some of the most promising candidates for powering biomedical devices. However, most biofuel cells provide low power output and short-term operational stability due to their poor electron transfer. To address these issues, we use a unique amphiphilic assembly method to generate hybrid biofuel cells with high power output and good operational stability. This approach can induce favorable interfacial interactions between electrocatalysts and significantly improve the electron transfer kinetics of electrodes. In this study, glucose oxidase (in aqueous media) is repeatedly assembled with hydrophobic metal nanoparticles (in nonpolar media) on a conductive textile. The formed biofuel cell exhibits remarkably high power output (7.3 mW cm−2) and good operational durability. We believe that our assembly approach can provide a basis for preparing a variety of high-performance bioelectrochemical devices, including biofuel cells.

Silicone-Textile Composite Resistive Strain Sensors for Human Motion-Related Parameters.

In recent years, soft and flexible strain sensors have found application in wearable devices for monitoring human motion and physiological parameters. Conductive textile-based sensors are good candidates for developing these sensors. However, their robust electro-mechanical connection and susceptibility to environmental factors are still an open challenge to date. In this work, the manufacturing process of a silicone-textile composite resistive strain sensor based on a conductive resistive textile encapsulated into a dual-layer of silicone rubber is reported. In the working range typical of biomedical applications (up to 50%), the proposed flexible, skin-safe and moisture resistant strain sensor exhibited high sensitivity (gauge factor of −1.1), low hysteresis (maximum hysteresis error 3.2%) and ease of shaping in custom designs through a facile manufacturing process. To test the developed flexible sensor, two applicative scenarios covering the whole working range have been considered: the recording of the chest wall expansion during respiratory activity and the capture of the elbow flexion/extension movements.

Ionofibers: Ionically Conductive Textile Fibers for Conformal i‐Textiles

AbstractWith the rise of ion‐based devices using soft ionic conductors, ionotronics show the importance of matching electronic and biological interfaces. Since textiles are conformal, an essential property for matching interfaces, light‐weight and comfortable, they present as an ideal candidate for a new generation of ionotronics, i‐textiles. As fibers are the building blocks of textiles, ionically conductive fibers, named ionofibers, are needed. However, ionofibers are not yet demonstrated to fulfill the fabric manufacturing requirements such as mechanical robustness and upscaled production. Considering that ionogels are known to be conformal films with high ionic conductivity, ionofibers are produced from commercial core yarns with specifically designed ionogel precursor solution via a continuous dip‐coating process. These ionofibers are to be regarded as composites, which keep the morphology and improve the mechanical properties from the core yarns while adding the (ionic) conductive function. They keep their conductivity also after their integration into conformal fabrics; thus, an upscaled production is a likely outlook. The findings offer promising perspectives for i‐textiles with enhanced textile properties and in‐air electrochemical applications.

Influence of woven fabric construction parameters on electromagnetic shielding effectiveness: Part I – weave influence

The development of textiles with the ability to shield an electromagnetic field is still of great interest, and the influences of the construction parameters of woven fabric (weave, input fibrous material composition, three-dimensional (3D) construction) on the resulting electromagnetic shielding efficiency have still not been sufficiently investigated. The main goal of this study is therefore to analyze the weaves of special electrically conductive woven fabrics and evaluate their impact on electromagnetic shielding effectiveness (SE) using statistical methods. Here, the interlacing structure cells of woven fabric are newly used to describe the weave. The results confirmed that the proposed theory of the interlacing of woven fabric is satisfactory for evaluating and, especially, for prediction of the SE of electromagnetic shielding woven fabrics. For this study, the input yarn (made from a mixture of traditional and extremely thin discrete stainless steel fibers) is used for the production of 21 types of dobby woven fabrics with different weaves and its SE was analyzed using the coaxial transmission-line technique. This contribution can be used as theoretical guidance for the construction, design, and production of special woven fabrics (dobby and jacquard pattern) with controlled SE.

Multicomponent Composite Membrane with Three-Phase Interface Heterostructure as Photocatalyst for Organic Dye Removal.

A multicomponent composite membrane (P-S-T/C) with three-phase interface heterostructure is ingeniously designed. A polydopamine (PDA)-modified conductive carbon fiber cloth (CFC) is used as the substrate. Activated poly(vinylidene fluoride) (PVDF) with titanium dioxide (TiO2) and a silicon dioxide (SiO2) aerogel are electrospun as the top layer. The three-phase interface heterostructure was formed by TiO2, conductive CFC, and the SiO2 aerogel. Its photocatalytic performance is validated by photodegradation of organic dyes in a low-oxygen (O2) water environment. On combining with the capillary condensation of a bilayer structure, P-S-T/C exhibits excellent removal capability for anionic and cationic dyes. Moreover, P-S-T/C exhibits excellent stability and recyclability under simulated sunlight. The mechanism study indicates that the separated photogenerated carriers diffuse to the composite membrane surface rapidly on the three-phase interface of P-S-T/C. The abundant O2 adsorbed on the porous SiO2 aerogel surface acts as an electron (e–)-trapping agent, which can also decrease the work function of the composite materials. Superoxide radicals (•O2–) play a dominant role in the reaction of photodegradation supported by a free radical-trapping experiment. This work paves a way to design a membrane with photocatalytic performance by constructing the interface heterostructure.

Sleeping Heart Monitoring Using Hydrogel-Textile Capacitive ECG Electrodes

In the application on sleeping heart monitoring by using capacitive electrocardiogram (cECG), a raw cECG signal with high quality is usually difficult to be obtained due to the low coupling capacitance composed of human skin, pajamas, bed sheet and sensing electrodes. This is mainly caused by a low relative dielectric constant of bed sheet and pajamas. In order to overcome this challenge, this study proposed a cECG system containing hydrogel-textile electrode for sleeping heart monitoring. The hydrogel layer was applied in an array pattern onto conductive textile to become a sensitive electrode in order to increase the coupling capacitance and lower the equivalent impedance as well, which was helpful to improve the quality of raw cECG signals. The reference electrode was linked to the circuit of the signal acquisition circuit to decrease the common-mode noises. The system incorporates eight membrane pressure sensors to capture the body’s sleep postures and detect the cECG signals from different sleep postures. The experimental results on tests with three different human sleep postures showed that the signal-noise ratio of the proposed system was close to the wet-electrode based ECG system. The sleeping heart monitoring experiments were conducted involving eight subjects with no constraint conditions through a period of two hours, the R-wave of the cECG signal was analyzed using RR interval extraction algorithms and the heart rate (HR) was calculated. The results showed that all subjects’ HRs during sleep state falls into a normal range, indicating that no signs of tachycardia and bradycardia can be observed.

Chitosan fabrics with synergy of silver nanoparticles and silver nanowires for enhanced conductivity and antibacterial activity

Wearable electronic textiles with high conductivity and excellent antibacterial activity are very desirable to minimize health risks and deteriorated performance of the electronic textiles in application. In this work, conductive fabrics were prepared with chitosan nonwovens with inherent antibacterial activity as the substrate. Silver nanoparticles (AgNPs) were synthesized in situ on the surface of chitosan fabric without any additional reducing agent, and silver nanowires (AgNWs) were adhered to the surface of AgNPs-coated chitosan fabrics by simple dip-coating cycles. The synergy of AgNPs and AgNWs enhances the conductivity of the fabric and the stability of AgNPs on the surface of the fabric. According to the analysis of scanning electron microscope and fourier transform infrared spectroscopy spectra, AgNPs were reduced in situ on the fabric. With synergy of AgNPs and AgNWs, the electrical resistance of the fabric is as low as low as 0.93 Ω/sq and 0.20 Ω/sq after one and four dip-coating cycles of AgNWs respectively. Thermogravimetric analysis and inhibition zone assay showed that combination of AgNPs and AgNWs enhanced the thermal stability and antibacterial activity of chitosan fabrics. The chitosan fabrics with conductivity, thermal stability and antibacterial activity can be used in electronic textiles for different applications.

Designing of Unit EBG Cell Using Conductive Textile for Dual Band Operation

Background/Objectives: Flexible electronics have paved the way for Wireless Body Area Networks (WBAN). The main challenge in accommodating such applications is reducing the impact of radiation on the human body. The presence of body tissues may affect WBAN devices such as wearable sensors and wearable antennas, so reducing back radiations becomes an important task. Methodology: When a microstrip patch antenna is placed on a human body, the artificially formed Electromagnetic Band Gap (EBG) surface mimics the property of a Perfect Magnetic Conductor (PMC) rather than the conventional Perfect Electrical Conductor (PEC). Findings: In this work, the unique property of the EBG surface beneath the patch antenna creates a zero phase shift at the resonance, which improves the antenna’s performance and reduces back radiations as well. The proposed EBG surface structure is the simplest square-shaped structure with no conductor connections Via patch (Via-less). Novelty: The EBG structure designed and presented in this paper has zero reflections for the dual-band of operations. The resonance frequency of 2.45GHz and 5.5 GHz has been designed for the absorption of 80% and 65% respectively. This level of absorption has not yet been reported in the literature. The newly formed EBG cell integrated with the patch antenna and its performance improvements has been shown. The analysis shows that the EBG enhances the return loss by 20.35 % and gain enhances by 16.44 %, on textile materials with the advantage of most simplex EBG cell construction. Keywords: EBG; PMC; PEC; Wearable Microstrip Patch Antenna; WBAN

Overview of the Influence of Silver, Gold, and Titanium Nanoparticles on the Physical Properties of PEDOT:PSS-Coated Cotton Fabrics.

Metallic nanoparticles have been of interest to scientists, and they are now widely used in biomedical and engineering applications. The importance, categorization, and characterization of silver nanoparticles, gold nanoparticles, and titanium nanoparticles have been discussed. Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) is the most practical and reliable conductive polymer used in the manufacturing of conductive textiles. The effects of metallic nanoparticles on the performance of PEDOT:PSS thin films are discussed. The results indicated that the properties of PEDOT:PSS significantly depended on the synthesis technique, doping, post-treatment, and composite material. Further, electronic textiles known as smart textiles have recently gained popularity, and they offer a wide range of applications. This review provides an overview of the effects of nanoparticles on the physical properties of PEDOT:PSS-coated cotton fabrics.

Conductive Chitosan Nonwoven Fabrics by Electroless Plating with Excellent Laundering Durability for Wearable Electronics

ABSTRACT Silver-plated chitosan fabrics with excellent conductivity and launderability were obtained via the electroless plating method. Due to the high content of amino and hydroxyl groups, chitosan can provide active sites for the formation of complexes with silver ions which can be further reduced to a silver layer on the surface of chitosan fibers. Scanning electron microscopy (SEM) results showed that chitosan/Ag nanocomposite fabrics displayed a uniform and continuous layer of silver on the chitosan fiber surface. The hydrophilic surface of chitosan fabrics became hydrophobic due to the plated silver. Thermogravimetric analysis displayed that the initial decomposition temperature of silver-plated fabrics increased slightly. The treated fabrics exhibited a very low electrical resistance of 20.23 mΩ/sq. After 40 washing cycles, the electrical resistance was still below 1 Ω/sq. It is expected that such novel conductive fabrics have promising applications in the field of wearable electronics materials.

In Situ Construction of ZIF-67-Derived Hybrid Tricobalt Tetraoxide@Carbon for Supercapacitor.

The Co3O4 electrode is a very promising material owing to its ultrahigh capacitance. Nevertheless, the electrochemical performance of Co3O4-based supercapacitors is practically confined by the limited active sites and poor conductivity of Co3O4. Herein, we provide a facile synthetic strategy of tightly anchoring Co3O4 nanosheets to a carbon fiber conductive cloth (Co3O4@C) using the zeolitic imidazolate framework-67 (ZIF-67) sacrificial template via in situ impregnation and the pyrolysis method. Benefiting from the enhancement of conductivity and the increase in active sites, the binder-free porous Co3O4@C supercapacitor electrodes possess typical pseudocapacitance characteristics, with an acceptable specific capacitance of ~251 F/g at 1 A/g and long-term cycling stability (90% after cycling 5000 times at 3 A/g). Moreover, the asymmetric and flexible supercapacitor composed of Co3O4@C and activated carbon is further assembled, and it can drive the red LED for 6 min.

Embroidered Textile Frequency-Splitting Sensor Based on Stepped-Impedance Resonators

This paper presents an embroidered textile frequency-splitting microwave sensor based on a pair of identical stepped-impedance resonators (SIRs) loading a microstrip transmission line. The sensor is implemented by means of conductive threads. The sensing region of the proposed structure is the capacitive square patch of one of the SIRs. If such region is kept unaltered, the structure is symmetric, and the frequency response (transmission coefficient) exhibits a single transmission zero. However, if symmetry is broken (e.g., through liquid absorption in the sensing region), the frequency response of the proposed sensor exhibits two transmission zeros (frequency splitting). The difference (in frequency and magnitude) between such zeros (or notches) is intimately related to the dielectric properties of the absorbed liquids to be sensed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$/$ </tex-math></inline-formula> detected. The proposed sensing structure is applied to the detection of deionized (DI) water absorption, and to the quantification of the number of DI water drops. The maximum measured sensitivity is found to be 2.70 MHz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$/ \mu \text{l}$ </tex-math></inline-formula> and 0.03 dB <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$/ \mu \text{l}$ </tex-math></inline-formula> for the incremental frequency and incremental magnitude of the notches.