Electronic Textile Applications Research Articles

High‐Energy Asymmetric Supercapacitor Yarns for Self‐Charging Power Textiles

AbstractRapid growth of electronic textile increases the demand for textile‐based power sources, which should have comparable lightweight, flexibility, and comfort. In this work, a self‐charging power textile interwoven by all‐yarn‐based energy‐harvesting triboelectric nanogenerators (TENG) and energy‐storing yarn‐type asymmetric supercapacitors (Y‐ASC) is reported. Common polyester yarns with conformal Ni/Cu coating are utilized as 1D current collectors in Y‐ASCs and electrodes in TENGs. The solid‐state Y‐ASC achieves high areal energy density (≈78.1 µWh cm−2), high power density (14 mW cm−2), stable cycling performance (82.7% for 5000 cycles), and excellent flexibility (1000 cycles bending for 180°). The TENG yarn can be woven into common fabrics with desired stylish designs to harvest energy from human daily motions at high output (≈60 V open‐circuit voltage and ≈3 µA short‐circuit current). The integrated self‐charging power textile is demonstrated to power an electronic watch without extra recharging by other power sources, suggesting its promising applications in electronic textiles and wearable electronics.

Graphene electronic fibres with touch-sensing and light-emitting functionalities for smart textiles

The true integration of electronics into textiles requires the fabrication of devices directly on the fibre itself using high-performance materials that allow seamless incorporation into fabrics. Woven electronics and opto-electronics, attained by intertwined fibres with complementary functions are the emerging and most ambitious technological and scientific frontier. Here we demonstrate graphene-enabled functional devices directly fabricated on textile fibres and attained by weaving graphene electronic fibres in a fabric. Capacitive touch-sensors and light-emitting devices were produced using a roll-to-roll-compatible patterning technique, opening new avenues for woven textile electronics. Finally, the demonstration of fabric-enabled pixels for displays and position sensitive functions is a gateway for novel electronic skin, wearable electronic and smart textile applications.

Highly Sensitive Multifilament Fiber Strain Sensors with Ultrabroad Sensing Range for Textile Electronics.

Highly stretchable fiber strain sensors are one of the most important components for various applications in wearable electronics, electronic textiles, and biomedical electronics. Herein, we present a facile approach for fabricating highly stretchable and sensitive fiber strain sensors by embedding Ag nanoparticles into a stretchable fiber with a multifilament structure. The multifilament structure and Ag-rich shells of the fiber strain sensor enable the sensor to simultaneously achieve both a high sensitivity and largely wide sensing range despite its simple fabrication process and components. The fiber strain sensor simultaneously exhibits ultrahigh gauge factors (∼9.3 × 105 and ∼659 in the first stretching and subsequent stretching, respectively), a very broad strain-sensing range (450 and 200% for the first and subsequent stretching, respectively), and high durability for more than 10 000 stretching cycles. The fiber strain sensors can also be readily integrated into a glove to control a hand robot and effectively applied to monitor the large volume expansion of a balloon and a pig bladder for an artificial bladder system, thereby demonstrating the potential of the fiber strain sensors as candidates for electronic textiles, wearable electronics, and biomedical engineering.

“Drop-on-textile” patternable aqueous PEDOT composite ink providing highly stretchable and wash-resistant electrodes for electronic textiles

We demonstrate a direct-write patternable water-based poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) composite ink which is capable of providing highly stretchable and washing-resistant electrodes on a fabric substrate for electronic textile applications. An aqueous composite ink consisting of PEDOT:PSS, graphene oxide nanosheets and anionic polyurethane does readily not permeated into hygroscopic fabric, which facilitate direct drawing of fine PEDOT electrode on the fabric without undesired blur effect. This limited permeation of aqueous PEDOT composite ink on the hygroscopic fabric is mainly originated from the intermolecular interactions of anionic polyurethane including hydrogen bonding with water molecules, and charge balancing interactions with PEDOT chains. Furthermore, addition of the graphene oxide nanosheets contributes to enhance the electrical conductivity of the composite by improving crystallization of PEDOT molecules. The PEDOT composite film shows unique structure of the PEDOT nanofibril network embedded by the polyurethane matrix, which resulted in an enough electrical pathway for charge carriers even though only 2.9 wt% of PEDOT:PSS existed in the composite film. The PEDOT composite film exhibited electrical conductivity of 4.6 S/cm, extremely high stretchability of 375% rupture strain, and high durability for repeated washing process with strong bleaching agent. Light emitting diode incorporated on the stretchable spandex with interconnects of the PEDOT composite pattern showed that LED light intensity was almost maintained even with stretching of PEDOT interconnects to 290%.

Stretchable and waterproof elastomer-coated organic photovoltaics for washable electronic textile applications

Textile-compatible photovoltaics play a crucial role as a continuous source of energy in wearable devices. In contrast to other types of energy harvester, they can harvest sufficient electricity (on the order of milliwatts) for wearable devices by utilizing the cloth itself as the platform for photovoltaics. Three features are important for textile-compatible photovoltaics, namely environmental stability, sufficient energy efficiency and mechanical robustness. However, achieving these simultaneously remains difficult because of the low gas barrier properties of ultrathin superstrates and substrates. Here, we report on ultraflexible organic photovoltaics coated on both sides with elastomer that simultaneously realize stretchability and stability in water whilst maintaining a high efficiency of 7.9%. The efficiency of double-side-coated devices decreases only by 5.4% after immersion in water for 120 min. Furthermore, the efficiency of the devices remains at 80% of the initial value even after 52% mechanical compression for 20 cycles with 100 min of water exposure. Organic solar cells can be thin, bendable and strechable. Now, Jinno et al. develop flexible organic photovoltaic devices that can also be washed in water and detergent, opening future integration routes into everyday objects such as fabric.

Fundamental Aspects on Conductive Textiles Implemented in Intelligent System

Conductive fibers, which are electrically conductive elements having the structure of a fiber, have a fairly long history and have been used for applications in electronic textiles as well as for aesthetics, anti-static and shielding purposes. Electrically conducting textile fibers, such as gold-coated threads, were produced in antiquity for aesthetic purposes, before the discovery of electricity, using various manufacturing methods. The textile intelligent systems, which comprise conducting textile structures (electroconducting wires or structures), present a dynamic behavior which favors the self regulation of the thermal insulation and vapor permeability with the purpose to maintain the thermo-physiological balance; the clothing assembly aims at monitoring the biologic potential, used only in critical situation (ex. accidents, falling down in a precipice etc.).

Research progress on fiber-shaped dye-sensitized solar cells

As the increasingly serious problems of fossil energy depletion and environmental pollutions, exploiting the clean renewable energy resources has become the urgency. Solar energy is one of the important renewable energy resources, and its effective utilization will exert a great influence on solving energy and environmental problems. Solar cells, which convert solar energy to electrical energy, represent a promising candidate to use renewable energies. In the past 20 years, the dye-sensitized solar cells (DSSCs) have drawn much attention from both academia and industry due to its low cost, environment-friendliness and high efficiency. It was reported that the efficiency of traditional DSSCs using fluorine- doped tin oxide (FTO) glass as the working electrode substrate exceeded 12% (100 mW/cm2). But rigid flat-shaped DSSCs are unfavorable for installation, transportation, and application as a result of their extreme brittleness and heaviness. Therefore, the development of flexible cells has become a challenge. Fiber-shaped dye-sensitized solar cells (F-DSSCs) are flexible DSSCs that fabricated by assembling the photovoltaic function on the surface of fiber-shaped conductive substrate with high curvature structure. The fiber cells show unique and promising advantages: (1) Since they have a three-dimensional structure and very low dependence on incident light angle, they can catch more photons from all directions and gather diffused/reflected light to improve the power output of the cell. (2) The fiber cell has smaller package area ratio. A larger area cell can be assembled by simply increasing the length of the cell. The characteristic of F-DSSCs is that when the cells go up to some extent, the package area of the cell remains basically unchanged, which has a great significance in maintaining the stability of F-DSSCs with larger size. (3) F-DSSCs can directly adopt traditional preparation technology, even under milder processing conditions, such as low temperature. (4) F-DSSCs are lightweight so that they are easy to be woven into clothes or integrated into other structures by existing textile techniques, which enables applications in electronic textiles and various complex devices. Therefore, extensive attention has recently been paid to develop F-DSSCs photovoltaic devices, and the maximum energy conversion efficiencies have exceeded 8%. However, a few critical scientific issues still need to be addressed. Firstly, it is necessary to make further and deeper research on solid-state electrolytes to improve the stability of F-DSSCs. Secondly, more efforts are required to explore new photoactive materials and electrodes. Meanwhile, optimizing the F-DSSCs structures and developing the scale-up technologies will enhance the conversion efficiencies which are currently much lower than traditional planar DSSCs counterparts. Thirdly, F-DSSCs may be integrated with other energy storage parts to produce more efficient devices. To accomplish this, much more efforts should be made to optimize the structure and improve the performance of the integrated fiber. In this review, the basic structure and working principle of F-DSSCs are briefly introduced. The related researches in recent years are reviewed in detail, including working electrodes, counter electrodes and electrolytes. At the same time, future development trends are forecasted.

Metal–Insulator–Semiconductor Coaxial Microfibers Based on Self‐Organization of Organic Semiconductor:Polymer Blend for Weavable, Fibriform Organic Field‐Effect Transistors

With the increasing importance of electronic textiles as an ideal platform for wearable electronic devices, requirements for the development of functional electronic fibers with multilayered structures are increasing. In this paper, metal–polymer insulator–organic semiconductor (MIS) coaxial microfibers using the self‐organization of organic semiconductor:insulating polymer blends for weavable, fibriform organic field‐effect transistors (FETs) are demonstrated. A holistic process for MIS coaxial microfiber fabrication, including surface modification of gold microfiber thin‐film coating on the microfiber using a die‐coating system, and the self‐organization of organic semiconductor–insulator polymer blend is presented. Vertical phase‐separation of the organic semiconductor:insulating polymer blend film wrapping the metal microfibers provides a coaxial bilayer structure of gate dielectric (inside) and organic semiconductor (outside) with intimate interfacial contact. It is determined that the fibriform FETs based on MIS coaxial microfiber exhibit good charge carrier mobilities that approach the values of typical devices with planar substrate. It additionally exhibits electrical property uniformity over the entire fiber surface and improved bending durability. Fibriform organic FET embedded in a textile is demonstrated by weaving MIS coaxial microfibers with cotton and conducting threads, which verifies the feasibility of MIS coaxial microfiber for use in electronic textile applications.

(Invited) Opportunities in Atomic Layer Deposition for Electronic Textile and Hydrophobic Coating Applications

Atomic layer deposition (ALD) has been widely applied for high technology applications from semiconductor industry to energy devices since it has several superior properties in nanoscale device fabrications, such as excellent conformality, large area uniformity, and process compatibility, over the conventional thin film deposition methods. In this work, we extended ALD researches to two novel applications, electronic textile (e-textile) and hydrophobic coating applications. We developed a Pt ALD process capable of low temperature deposition down to 80 °C using a new Pt precursor and O2 counter reactant. Pt was deposited on organic textile substrates, such as cotton and Nylon. The ALD-Pt-coated textiles showed high electrical conductivity and high mechanical durability even after mechanical wrinkling test. Fabrications of pressure sensor arrays using ALD-Pt-coated textile were demonstrated. For the hydrophobic coating, we developed rear earth oxides (REOs) ALD including Y2O3, La2O3, CeO2, Dy2O3 and Er2O3 by using new rare earth precursors All the ALD REOs showed hydrophobic property over 100 ° of water contact angles. In addition, the hydrophobicity of ALD REOs showed high durability even after high temperature process over 500 °C. A superhydrophobic surface was fabricated by using ALD REOs and nanostructured Si surface. The nanostructured Si coated by ALD REOs showed very high water contact angle as high as 158 °.

Printable elastic conductors with a high conductivity for electronic textile applications.

The development of advanced flexible large-area electronics such as flexible displays and sensors will thrive on engineered functional ink formulations for printed electronics where the spontaneous arrangement of molecules aids the printing processes. Here we report a printable elastic conductor with a high initial conductivity of 738 S cm−1 and a record high conductivity of 182 S cm−1 when stretched to 215% strain. The elastic conductor ink is comprised of Ag flakes, a fluorine rubber and a fluorine surfactant. The fluorine surfactant constitutes a key component which directs the formation of surface-localized conductive networks in the printed elastic conductor, leading to a high conductivity and stretchability. We demonstrate the feasibility of our inks by fabricating a stretchable organic transistor active matrix on a rubbery stretchability-gradient substrate with unimpaired functionality when stretched to 110%, and a wearable electromyogram sensor printed onto a textile garment.

Failure modes of conducting yarns in electronic-textile applications

Integration of electronic functionalities into textiles adds to the value of textiles. It allows measuring, detecting, actuating and treating or communicating with a body or object. These added values can render the smart textiles very useful, fun, supporting, protecting or even lifesaving. It is, however, important for the comfort, acceptance and functionality to have integration of electronics as unobtrusive as possible. One elegant unobtrusive method of integration is to have circuitry included in the textile and mount components to this circuitry. Conducting yarns introduced by weaving, knitting or embroidery are attractive candidates to compose the circuitry as they do not disturb the textile nature of the system and are processable by the mentioned conventional textile technologies. In the case that these smart textiles are worn by humans under dynamic circumstances, the system is exposed to mechanical stress. In this paper we report the results of studies on the failure modes of Ag-coated nylon yarns, which are applied on textile carriers by means of stitching or soutache embroidery. The test methods varied in combinations of mechanical stress, such as shearing, bending and tension, and support to better understand the process of deterioration of the yarns when these are mechanically stressed. The delamination of the Ag coating from the yarns leads to unstable resistance values in non-static conditions. The mechanical forces, such as shearing, bending and tension, cause progressively more damage to the filaments of the yarns. This leads to a reduction of the electrical conductivity.

Flexible and Stretchable Lithium‐Ion Batteries and Supercapacitors Based on Electrically Conducting Carbon Nanotube Fiber Springs

AbstractThe construction of lightweight, flexible and stretchable power systems for modern electronic devices without using elastic polymer substrates is critical but remains challenging. We have developed a new and general strategy to produce both freestanding, stretchable, and flexible supercapacitors and lithium‐ion batteries with remarkable electrochemical properties by designing novel carbon nanotube fiber springs as electrodes. These springlike electrodes can be stretched by over 300 %. In addition, the supercapacitors and lithium‐ion batteries have a flexible fiber shape that enables promising applications in electronic textiles.

Flexible and Stretchable Lithium‐Ion Batteries and Supercapacitors Based on Electrically Conducting Carbon Nanotube Fiber Springs

The construction of lightweight, flexible and stretchable power systems for modern electronic devices without using elastic polymer substrates is critical but remains challenging. We have developed a new and general strategy to produce both freestanding, stretchable, and flexible supercapacitors and lithium-ion batteries with remarkable electrochemical properties by designing novel carbon nanotube fiber springs as electrodes. These springlike electrodes can be stretched by over 300 %. In addition, the supercapacitors and lithium-ion batteries have a flexible fiber shape that enables promising applications in electronic textiles.

ChemInform Abstract: Novel Solar Cells in a Wire Format

AbstractReview: 48 refs.

Ultrafast charge and discharge biscrolled yarn supercapacitors for textiles and microdevices

Flexible, wearable, implantable and easily reconfigurable supercapacitors delivering high energy and power densities are needed for electronic devices. Here we demonstrate weavable, sewable, knottable and braidable yarns that function as high performance electrodes of redox supercapacitors. A novel technology, gradient biscrolling, provides fast-ion-transport yarn in which hundreds of layers of conducting-polymer-infiltrated carbon nanotube sheet are scrolled into ~20 μm diameter yarn. Plying the biscrolled yarn with a metal wire current collector increases power generation capabilities. The volumetric capacitance is high (up to ~179 F cm(-3)) and the discharge current of the plied yarn supercapacitor linearly increases with voltage scan rate up to ~80 V s(-1) and ~20 V s(-1) for liquid and solid electrolytes, respectively. The exceptionally high energy and power densities for the complete supercapacitor, and high cycle life that little depends on winding or sewing (92%, 99% after 10,000 cycles, respectively) are important for the applications in electronic textiles.

Novel solar cells in a wire format

Photovoltaic devices in a wire format have recently attracted increasing attention as, compared with the conventional planar structure, they show unique and promising advantages. For instance, they are light-weight and can be easily woven into clothes or integrated into other structures, which enable applications in electronic textiles and various complex devices. In this tutorial review, the recent advancement in photovoltaic wires including both dye-sensitized and polymer solar cells are described. Two main architectures based on a single core-sheath fiber and twisted fibers are carefully illustrated with an emphasis on the comparison of various substrates which have been focused in past development. The current challenge including low energy conversion efficiency and low stability and future direction of the wire-shaped cell have been finally summarized.

Nanofibrous p-n Junction and Its Rectifying Characteristics

Randomly oriented tin oxide (SnO2) nanofibers and poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate)/polyvinylpyrrolidone (PEDOT:PSS/PVP) nanofibers were prepared by a two‐step electrospinning technique to form a layered fibrous mat. The current‐voltage measurement revealed that the fibrous mat had an obvious diode‐rectifying characteristic. The thickness of the nanofiber layers was found to have a considerable influence on the device resistance and rectifying performance. Such an interesting rectifying property was attributed to the formation of a p‐n junction between the fibrous SnO2 and PEDOT:PSS/PVP layers. This is the first report that a rectifying junction can be formed between two layers of electrospun nanofiber mats, and the resulting nanofibrous diode rectifier may find applications in sensors, energy harvest, and electronic textiles.

Applications of Low Pressure Plasma in High-tech Textiles

The textile and clothing industries especially in developed countries are facing now-a-days some big challenges largely because of the globalization process. Therefore, the market of a high-functional, added value and technical textiles is deemed to be essential for their sustainable growth. The growing environmental and energy-saving concerns will also lead to the gradual replacement of many traditional wet chemical-based textile processing by various forms of low liquor and dry-finishing processes. The main reason for the increasing interest is that industrially well-established surface finishing processes suffer considerably from environmental demands such as large amount of water, energy and effluents. Plasma technology, when developed at a commercially viable level, has strong potential to offer in an attractive way to obtain new functionalities in textiles. The synthetic fibres such as polypropylene (PP), polyester (PES), Aramid (AR) etc. are widely used in apparel and home furnishings due to their good physical and chemical properties. The demand of these fibres increases greatly for high performance applications such as smart textiles, technical textiles, operation clothing etc. and more recently, for their potential applications in electronic textiles. But these fibres often reveal hydrophobic nature due to the lack of polar functional groups. The hydrophobic nature of such fabrics limits their application to the above mentioned areas. In addition, adhesion is fundamentally a surface property, often governed by a layer of molecular dimensions, which necessarily required for coating, bonding and printing of synthetic textiles. The low surface energy of hydrophobic polymeric materials results in intrinsically poor adhesion. On the other hand, some natural fibres (e.g. cotton, wool, linen) and synthetic fibres (e.g. rayon, viscose, acetate, spun nylon) exhibit to be hydrophilic in nature due to their polar functionalities. Hydrophilicity of such fibres may act as a barrier for their applications in many areas where liquids repellent is necessary. It is a wide-reaching technical effect that is sought after in several industry sectors, from biosciences, healthcare and electronics to industrial filtration, sports and active wear. In addition to water repellency, other liquids such as oils, inks and alcohols repellency often required. Liquids are constantly in use around us, in the majority of cases in the form of rain water and food and beverages. Arguably, the most noticeable, unfavorable interactions of these liquids are with textile products such as clothing, carpets and upholstery, so added value can be provided by protecting these items from interacting with the liquids, enabling the liquids to roll off or be dabbed away, leaving the underlying material unchanged. Furthermore, hydrophobicity of textiles is frequently associated with self-cleaning properties. When a water droplet rolls off the surface, the surface impurities such as dust get carried away by the droplet resulting in a self-cleaning effect. Using plasma technology to modify textile surfaces with precision cleaning, etching, chemical priming for lowering or raising surface energy can be used to obtain a desirable property of an end product. The plasma technology, a dry and eco-friendly technique, avoids waste water production which is a unique advantage over the wet-chemical processes. This benefit extends into all market areas, where the end product can undergo the plasma enhancement process to provide properties such as adhesion, hydrophilic, liquid-repellent etc. However, to transfer this technology from laboratory into industry, both the scale-up and economic aspects have to be regarded. Main objective of this work is to study the possibility of substituting plasma processes for the traditional wet chemical methods using an industrial plasma reactor aiming to produce wash permanent super-hydrophilic, super hydrophobic textile surfaces.

Electronic Textiles: Atomic Layer Deposition of Conductive Coatings on Cotton, Paper, and Synthetic Fibers: Conductivity Analysis and Functional Chemical Sensing Using “All‐Fiber” Capacitors (Adv. Funct. Mater. 11/2011)

Electronic functionalization of complex fiber systems is important for new applications in energy systems and electronic textiles. The cover image shows a natural fibrous material with and without conductive coating. Atomic layer deposition (ALD) of conductive coatings on natural and synthetic fibrous materials show high conductivity, and the values scale as expected with film thickness and bulk-material conductance. On page 1993, Jesse S. Jur and co-workers present an all-fiber-based capacitor formed by ALD on textiles that shows good sensing performance in several liquid media.

Effect of synthesis conditions on the properties of wet spun polypyrrole fibres

High molecular weight doped polypyrrole (PPy) has been synthesized by the incorporation of the di(2-ethylhexyl) sulfosuccinate dopant anion which renders the polymer soluble in various organic solvents. The intrinsic viscosity of PPy solutions show that the molecular weight of PPy is very sensitive to the polymerization temperature. A significant increase in molecular weight was achieved by reducing the polymerization temperature from 0 to −15°C. The resultant solutions were amenable to a wet-spinning process that produced continuous, doped polypyrrole fibres. The ultimate tensile strength, elastic modulus and elongation at break of the higher molecular weight fibres were 136MPa, 4.2GPa and 5%, respectively. These values were 500%, 250% and 280% higher than obtained from the lower molecular weight fibers. X-ray diffraction showed that the low temperature PPy powder exhibited a similar degree of ordering to the standard PPy powder. UV and FT-IR spectroscopy showed that the conjugation length of PPy could be increased significantly depending on the polymerization conditions. Cyclic voltammetry demonstrated the electroactivity of the polypyrrole fibres. These fibres are likely to be important for bionic, electronic textile, artificial muscles, battery and sensor applications.