Stretchable Yarns Research Articles

Influence of honeycomb structures on fluids transmission and heat retention properties; An initiative towards stretchable weaves

The aesthetics and functionality of honeycomb woven assemblies qualifies them for a range of applications expanding across home textiles, fashion, functional apparels, and technical products. Researchers have explored honeycomb assemblies with the focus on shrinkage, sound absorption, thermal conductivity, and heat protection properties analysis via variation in their cell sizes. However, very minimal research is found on analysis of honeycomb woven fabric assemblies’ thermal comfort characteristics by employing different weft insertion sequence and materials (cotton and stretchable yarns). This study reflects the thermal conductivity, dry fluid transmission (air permeability), wet fluid transmission (moisture management), and stiffness attributes of twelve stretchable honeycomb woven assemblies consisting of single ridge, double ridge, and brighton honeycomb weave structures along with different weft sequences of cotton and Type 400 (T-400) stretch yarns. Characterization data showed that single ridge honeycomb structure supports the highest dry fluid transmission property; however, brighton honeycomb offers the highest heat retention property. Double ridge honeycomb highlights the capability of the highest wet fluid transmission property, and brighton honeycomb has immense stiffness. Statistical analysis (ANOVA) also showed that honeycomb structures, weft yarn sequence and material have a statistically significant impact on thermal conductivity and fluid transmission behaviors with p-values less than 0.05.

A Review of Yarn-Based One-Dimensional Supercapacitors.

Energy storage in a one-dimensional format is increasingly vital for the functionality of wearable technologies and is garnering attention from various sectors, such as smart apparel, the Internet of Things, e-vehicles, and robotics. Yarn-based supercapacitors are a particularly compelling solution for wearable energy reserves owing to their high power densities and adaptability to the human form. Furthermore, these supercapacitors can be seamlessly integrated into textile fabrics for practical utility across various types of clothing. The present review highlights the most recent innovations and research directions related to yarn-based supercapacitors. Initially, we explore different types of electrodes and active materials, ranging from carbon-based nanomaterials to metal oxides and conductive polymers, that are being used to optimize electrochemical capacitance. Subsequently, we survey different methodologies for loading these active materials onto yarn electrodes and summarize innovations in stretchable yarn designs, such as coiling and buckling. Finally, we outline a few pressing research challenges and future research directions in this field.

Coaxial-helix MXene/PANI-based core-spun yarn towards strain-insensitive conductor and supercapacitor

Stretchable electrical conductors hold great promise in the wearable electronic devices, such as flexible display and human-machine interface. Stable conductivity is vital for wearable devices to maintain their stable performance. However, the electrical resistance of most reported yarns dramatically increases when they are deformed. Herein, we propose a design for a coaxial-helix structure by wrapping the polyaniline/MXene-based elastic core-spun yarn on itself in the form of coils. The fabricated coaxial-helix structured yarns (DCSs) exhibit excellent strain-insensitive properties, including low relative resistance change (25.4%), large strain (200%) and high quality factor (17.95). Moreover, the DCSs can be used as the stretchable electrodes for the supercapacitors, and delivers a linear specific capacitance of 256.7 mF cm−1, which is higher than most stretchable yarns. Therefore, the proposed coaxial-helix structure design creates a new approach for the strain-insensitive stretchable conductor, thereby paving the way for the development of stretchy electronics.

Hierarchically interlocked helical conductive yarn enables ultra-stretchable electronics and smart fabrics

Simultaneously achieving high mechanical elasticity and electrical conductivity is essentially required for wearable electronics and smart fabrics. However, great challenges still remain to achieve high electrical conductance under large mechanical deformations due to the “trade-off” effect between them. Herein, inspired by curling structure of climbing plants, hierarchically interlocked helical conductive yarn for ultra-stretchable electronics and smart fabrics was developed, via over-twisting silver nanowires (AgNWs)/MXene multi-dimensional synergistic conductive networks that hierarchically entangled with elastic thermoplastic polyurethanes (TPU) nanofiber networks. High-aspect-ratio 1D AgNWs bridged 2D MXene nanosheets into synergistic interconnected conductive network while interlocked with elastic 3D TPU nanofiber skeleton. Unique hierarchically interlocking effect between highly conductive networks and highly elastic nanofiber networks during the twisting process induced helical conductive yarn simultaneously exhibits excellent mechanical stretchability and electrical conductivity. Excellent intrinsic elasticity of TPU macromolecular chains coupled with its hierarchically helical structure enables the conductive yarn exhibits excellent mechanical stretchability. While the hierarchically interlocked conductive structure ensures the stretchable yarn possess high electrical conductivity which could resist large mechanical deformations during stretching process. The hierarchically interlocked helical conductive yarn could still exhibit high electrical conductivity (1.12 × 105 S/m) even under large mechanical deformations (300%), which effectively avoid the “trade-off” effect. Moreover, the ultra-stretchable conductive yarn exhibits smart responsiveness to multi stimuli (mechanical/electron/light). The helical strain sensor has excellent electromechanical performance with stable GF (1.7) in the 600%–1000% linear range. The hierarchically interlocked helical conductive yarn holds great promise for ultra-stretchable electronics and smart fabrics.

High-Strength and Extensible Electrospun Yarn for Wearable Electronics.

Stretchable conductive yarns have received significant consideration in the direction of wearable and flexible electronics. Wearable electronic structures need strong materials to assure stability, durability, and an extensive range of strain to develop their applications. Therefore, manufacturing high-performance yarn-based devices with ultrarobustness and great stretchability with a simple, cost-effective, and scalable method remains a great challenge for wearable electronics. Here, a highly stretchable yarn with high performance is fabricated, which comprises a core TPU nanoyarn, successively decorated with a liquid metal (LM) layer, and a protective outer nanofiber layer. The ultrarobust (40 MPa) and high-strain (548%) conducting yarn presents potential applications in assembling strain sensors. Moreover, such a unique conductive yarn can be used as a highly deformable, stretchable conductor to charge a mobile phone or for data transfer, a sensor to monitor human activities, and as an effective control for a hand robot as well as for smart thermal management textile application. This research gives promising applications in the field of flexible and wearable electronics.

Thermally Drawn Highly Conductive Fibers with Controlled Elasticity.

Electronic fabrics necessitate both electrical conductivity and, like any textile, elastic recovery. Achieving both requirements on the scale of a single fiber remains an unmet need. Here, two approaches for achieving conductive fibers (107 S m-1 ) reaching 50% elongation while maintaining minimal change in resistance (<0.5%) in embedded metallic electrodes are introduced. The first approach involves inducing a buckling instability in a metal microwire within a cavity of a thermally drawn elastomer fiber. The second approach relies on twisting an elastomer fiber to yield helical metal electrodes embedded in a stretchable yarn. The scalability of both approaches is illustrated in apparatuses for continuous buckling and twisting that yield tens of meters of elastic conducting fibers. Through experimental and analytical methods, it is elucidated how geometric parameters, such as buckling pre-strain and helical angle, as well as materials choice, control not only the fiber's elasticity but also its Young's modulus. Links between mechanical and electrical properties are exposed. The resulting fibers are used to construct elastic fabrics that contain diodes, by weaving and knitting, thus demonstrating the scalable fabrication of conformable and stretchable antennas that support optical data transmission.

Geometrically versatile triboelectric yarn-based harvesters via carbon nanotubes-elastomer composites

Recent advances in triboelectric nanogenerators (TENGs) have made such devices promising candidates for the independent operation of ongoing wearable electronics owing to their generic advantages, such as simple fabrication, light weight, and flexibility. However, their utilization for harvesting mechanical energy driven by human activities in daily life particularly has disadvantages when introduced to everyday use that requires various geometrical versatility under diverse environmental conditions. Here, we investigate a freestanding one-dimensional coaxial stretchable yarn TENG (1D CSY-TENG) with highly stretchable, water-resistant, and deformable characteristics. The integration of the 1D CSY-TENG into a scalable array-CSY-TENG (A-CSY-TENG) and textile-CSY-TENG (T-CSY-TENG) was tested to facilitate potential textile wearable products. The use of a highly stretchable 1D coaxial freestanding configuration provided the efficient energy conversion performance of the assembled T-CSY-TENG, despite being stretched over 100%, twisted, turned, and in strained states, along with maintaining performance even in water. Thus, suitable manipulation of geometrically versatile 1D freestanding coaxial configurations can aid the development of future TENG-integrated wearable applications.

Graphene-Coated Porous PDMS As a Gas Sensor for Potential Epidermal Electronics Applications

Introduction Epidermal electronics that can intimately integrate with human skin are getting much attention due to ultrathin, soft, and light-weight [1]. These capabilities create interesting opportunities for diverse wearable sensor applications such as sweat monitoring, multiple electrophysiological signal monitoring, subtle motion sensing, ultraviolet sensing, gas monitoring, etc [2]. The authors have been developed graphene-based gas sensors having various forms including electrospun fiber [3], commercially-available yarn [4], stretchable yarn [5], and fabric [6]. In this paper, we present the stretchable porous e-skin based gas sensor comprising of porous polydimethysiloxane (PDMS) as a stretchable substrate and reduced graphene oxide (RGO) as gas sensing materials showed high NO2 sensitivity under 30% strain at room temperature. Method Porous PDMS thin films with the average pore size of 10 um were achieved by breath figure method [7]. The porous PDMS film were functionalized with 3-aminopropyltriethoxysilane (APTES) via chemical vapor treatment, which induced positive charges on the surface of porous PDMS film. Spray coating was performed with a commercial spray coater system (Jinsung, Korea). GO dispersed solution of 1.0 mg/mL was deposited onto the amine functionalized periodic porous PDMS films. The prepared GO deposited porous PDMS films were chemically reduced by immersing them in a reduction agent of hydriodic acid solution at 50 °C for 20 min. To neutralize and remove any residual on the RGO porous PDMS films, the samples were repeatedly rinsed with a sodium bicarbonate solution and deionized water, and then dried in a chemical hood. The stretchable gas sensors were fabricated by deposition silver paste onto the tops of the RGO films to make electrodes by silk screening method. Results and Conclusions The RGO porous PDMS films exhibited distinctive wrinkles and ripples with high density on its surface, which was attributed to the successful coating of RGO sheets on the surface of porous PDMS film. We believe that numerous wrinkles make the RGO porous PDMS films more stable against several deformations. The Raman spectrum of RGO porous PDMS films exhibited typical RGO spectral features, such as the D peak at 1340 cm-1 (defects in graphene) and the G peak at 1580 cm-1 (a stretching mode of C-C bond of the sp2 structure of graphene).We also studied the electrical properties of porous PDMS films coated with RGO sheets using four probe method. A GO coated porous PDMS film yielded an electrical conductivity of about 10-8 S/cm. After chemical reduction, the conductivity of RGO porous PDMS increased by approximately seven orders of magnitude. Our RGO porous PDMS films could maintain stable electrical conductivity values upon about 30% strain deformation. The mechanical stability of the RGO porous PDMS films was evaluated by measuring the electrical conductivity under repeated stretching and releasing. The electrical resistance of the samples remains unchanged even after 5000 cycles. The as-prepared RGO porous films are mechanically robust and can be deformed without device performance degradation, making them very attractive candidates for epidermal electronic devices.Porous PDMS coated with reduced graphene oxide responded to NO2 gas with sensitive and selective manner. When we compare the response (Ra/Rg) of porous PDMS with that of non-porous PDMS, porous PDMS shows 20% stronger response to NO2 compared to non-porous PDMS. The porous nature is considered to contribute to strong response due to increase of reaction possibility with reduced graphene oxide and NO2 gas. We found that the response of gas sensor was increased around 20% upon elongation. We believe that the hidden area of pores in the PDMS matrix can be exposed to the gas molecules upon elongation. Finally, we found that the sensor shows reliability in terms of the response up to 5,000 times elongation-relaxation cycles. In the future, we expect that the thin porous PDMS can be attached to the skin and find the applications in healthcare by sensing gas molecules emitted from skin. Acknowledgement This research was supported the R&D Program (Development of a mobile diet-monitoring technology based on multiple biomarkers by the National Research Foundation of Korea under research projects, NRF-2017M3A9F1033056).

A Stretchable Yarn Embedded Triboelectric Nanogenerator as Electronic Skin for Biomechanical Energy Harvesting and Multifunctional Pressure Sensing.

Flexible and stretchable physical sensors capable of both energy harvesting and self-powered sensing are vital to the rapid advancements in wearable electronics. Even so, there exist few studies that can integrate energy harvesting and self-powered sensing into a single electronic skin. Here, a stretchable and washable skin-inspired triboelectric nanogenerator (SI-TENG) is developed for both biomechanical energy harvesting and versatile pressure sensing. A planar and designable conductive yarn network constructed from a three-ply-twisted silver-coated nylon yarn is embedded into flexible elastomer, endowing the SI-TENG with desired stretchability, good sensitivity, high detection precision, fast responsivity, and excellent mechanical stability. With a maximum average power density of 230 mW m-2 , the SI-TENG is able to light up 170 light-emitting diodes, charge various capacitors, and drive miniature electronic products. As a self-powered multifunctional sensor, the SI-TENG is adopted to monitor human physiological signals, such as arterial pulse and voice vibrations. Furthermore, an intelligent prosthetic hand, a self-powered pedometer/speedometer, a flexible digital keyboard, and a proof-of-concept pressure-sensor array with 8 × 8 sensing pixels are successively demonstrated to further confirm its versatile application prospects. Based on these merits, the developed SI-TENG has promising applications in wearable powering technology, physiological monitoring, intelligent prostheses, and human-machine interfaces.

Development of Textile Based Strain Sensor from Polypyrrole

The conducting polymers are polyconjugated, which possess electronic properties of metals, while retaining the mechanical properties and processability of conventional polymers. Conductive polymers can only withstand limited strain before breaking and cannot perform well in evaluating large strains. The aim of this study was to develop a low cost, small to large strain sensor using Polypyrrole and Latex/Polyamide 6 yarn. The stretchable yarn was chosen as the substrate due to its excellent resilience and elasticity. Polypyrrole was coated as thin film onto the substrate by means of vapour deposition technique. The response of resistance of the samples on 2% deformation and relaxation during 40 cycles was analysed. The sensitivity or the change in resistance per unit deformation was used as a tool to figure out the suitability of strain sensor. The high resistive sample gave better sensitivity as well as uniformity as compared to low resistive sample which made it suitable to use as a strain sensor.

Waterproof and Tailorable Elastic Rechargeable Yarn Zinc Ion Batteries by a Cross-Linked Polyacrylamide Electrolyte.

Emerging research toward next-generation flexible and wearable electronics has stimulated the efforts to build highly wearable, durable, and deformable energy devices with excellent electrochemical performances. Here, we develop a high-performance, waterproof, tailorable, and stretchable yarn zinc ion battery (ZIB) using double-helix yarn electrodes and a cross-linked polyacrylamide (PAM) electrolyte. Due to the high ionic conductivity of the PAM electrolyte and helix structured electrodes, the yarn ZIB delivers a high specific capacity and volumetric energy density (302.1 mAh g-1 and 53.8 mWh cm-3, respectively) as well as excellent cycling stability (98.5% capacity retention after 500 cycles). More importantly, the quasi-solid-state yarn ZIB also demonstrates superior knittability, good stretchability (up to 300% strain), and superior waterproof capability (high capacity retention of 96.5% after 12 h underwater operation). In addition, the long yarn ZIB can be tailored into short ones, and each part still functions well. Owing to its weavable and tailorable nature, a 1.1 m long yarn ZIB was cut into eight parts and woven into a textile that was used to power a long flexible belt embedded with 100 LEDs and a 100 cm2 flexible electroluminescent panel.

Influencing sheath type and core draft ratios on the physical properties of stretchable yarns

Influencing sheath type and core draft ratios on the physical properties of stretchable yarns

Properties of stretchable lyocell yarns developed using modified ring spinning frame

Stretchable fabrics provide a better fitting in addition to unhindered body movement. These stretchable fabrics are usually developed using composite yarns esp. core spun yarns having spandex as core. In the current research, stretchable yarns were developed using spandex and lyocell fibres. Spandex filaments were used as a core and lyocell fibres were used as a covering sheath. Two deniers of spandex were used in order to study the effect of deniers on the properties of yarns. Core spun yarns were developed by modified ring spinning frame at constant drawing ratio i.e. 3. Results of the study showed that presence of spandex, as well as change in its deniers, affected yarn count, tenacity, elongation and imperfection. However, breaking force and unevenness of yarns were remain unaffected by the presence of spandex as core in yarns.

Environmental Sensor Based on Stretchable Textile

Flexible and stretchable electronic devices have been widely studied because of various applications such as wearable devices and body-attachable devices based on facile human-machine interfaces. Research on this field has focused on the development of flexible, high-performance electronics devices ensures stability for physical/chemical stress and facile modification with various shapes. Chemical sensors, environmental sensors and biosensors along with physical sensors based on the flexible and stretchable devices have been reported through extensive investigations on various elastic substrates designs such as serpentine (P. Cutruf et al. Appl. Phys. Lett. 2014, 104, 021908), wavy (H. Fei et al. J. Vac. Sci. Technol. A 2009, 27, L9) and mogul (H.-B. Lee et al. Adv. Mater. 2016, DOI:10.1002/adma.201505218) patterns and sensing materials such as carbon nanotubes (S. Park et al. Nanoscale 2013, 5, 1727), reduced graphene oxides (N. O. Weiss et al. Adv. Mater. 2012, 24, 5782) and silver nanowires (P. Lee et al. Adv. Mater. 2012, 24, 3326). These sensors have been applied as tactile sensors, strain sensor, gas sensors, etc. The authors reported a method of graphene coating on electrospun fibers and commercially available yarns to convert them into conductive yarns (Y. J. Yun et al. Adv. Mater. 2013, 25, 5701) or chemical sensors (Y. J. Yun et al. Nanoscale 2014, 6, 6511; Y. J. Yun et al. Sci. Rep. 2015, 5, 10904) by utilizing molecular glues such as bovine serum albumin (BSA) and polydopamine, and found that the method was effective on increasing durability to mechanical and chemical stresses. The gas sensors coated with reduced graphene oxides on electrospun nylon fiber and commercial cotton yarn show 3 times higher responses to nitrogen dioxide (NO2) gas and durability to bending stress and washing treatment. We report a stretchable gas sensor by coating reduced graphene oxides on a stretchable yarn that can be elongated up to 400% compared to its original length without changing an electrical resistance. Optimal coating concentration of graphene oxide and its effective reducing condition were investigated to prepared stretchable and durable gas sensor using BSA as a molecular glue. We found that stretchable yarn showed no change of resistance upon 5000 times stretching treatments with 100% strain. Furthermore, the stretchable yarn showed 45% response to 1 ppm of NO2 gas under 45% relative humidity, which is 3 times higher response to what we obtained using cotton yarn coated with reduced graphene oxide (15% reponse@NO2 1.25 ppm). The stretchable yarn under 200% strain shows a similar response to the response of the yarn under no strain, which is one of the requirements for the stretchable electronic devices in order to find practical applications without limitation. The explanation of the sensitive response to NO2 gas and durability to mechanical stress will be covered through SEM (scanning electron microscope), Raman and TEM (transmission electron microscope) analyses. One of the advantages of reduced graphene oxides as a sensing material is the response selectivity to NO2 gas compared with other gases such as VOCs (volatile organic compounds). The stretchable yarn coated with reduced graphene oxides shows a selective response to NO2 gas rather than acetone, ethanol, carbon monoxide, carbon dioxide, ethylene, etc. NO2 is known as one of the most common exhausted gases from automobiles. The selective response to NO2 of the stretchable yarn can be considered as an environmental monitoring sensor. However, the sensor composed of reduced graphene oxide has a notorious slow recovery behavior that hinder an application of the sensor. Lastly, we found an effective recovery method of the sensor through UV irradiation for the practical application of the stretchable yarn as NO2gas sensor. (This work was supported by the Energy Efficiency & Resources Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted fi nancial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20142020500160))

High-performance stretchable yarn supercapacitor based on PPy@CNTs@urethane elastic fiber core spun yarn

Yarn supercapacitors, as knittable and weavable energy storage devices, are attracting more and more attention in recent years. Similar to various yarns with different physical and mechanical properties available in textile industry, different yarn supercapacitors should be developed as well. However, as a device, stretchable yarn supercapacitors suffer a lot from limited stretchability, complicated and high cost fabrication, which greatly restrict their wide adoptions. Here, we use urethane elastic fiber core spun yarns (UY) with intrinsic high stretchability for the first time, as a wearable scaffold for hosting conductive CNT and electrocapacitive PPy to fabricate large-scale highly stretchable yarn electrodes via a simple two-step process (CNTs dipping and PPy electrodeposition). The yarn supercapacitor keeps the excellent stretchability of the UY without using any extra stretchy substrate or wavy structure as most stretchable yarn supercapacitors used, and at the same time, exhibits a high areal capacitance of 69mFcm−2 (normalized to two electrodes) as well as a good rate capacity. Furthermore, the capacitive performance of the yarn supercapacitor remains nearly unchanged even at a high strain of 80%. The high-performance stretchable yarn supercapacitor with the use of intrinsically stretchable yarns paves a way for the production of large-size fabrics for wearable electronic applications.

Highly stretchable and wearable graphene strain sensors with controllable sensitivity for human motion monitoring.

Because of their outstanding electrical and mechanical properties, graphene strain sensors have attracted extensive attention for electronic applications in virtual reality, robotics, medical diagnostics, and healthcare. Although several strain sensors based on graphene have been reported, the stretchability and sensitivity of these sensors remain limited, and also there is a pressing need to develop a practical fabrication process. This paper reports the fabrication and characterization of new types of graphene strain sensors based on stretchable yarns. Highly stretchable, sensitive, and wearable sensors are realized by a layer-by-layer assembly method that is simple, low-cost, scalable, and solution-processable. Because of the yarn structures, these sensors exhibit high stretchability (up to 150%) and versatility, and can detect both large- and small-scale human motions. For this study, wearable electronics are fabricated with implanted sensors that can monitor diverse human motions, including joint movement, phonation, swallowing, and breathing.

Combined highly stretchable yarn using highly stretchable polyurethane fibre

The technology for manufacturing combined highly stretchable yarn by pneumomechanical spinning is examined. Regression models were obtained for Dorlastan V850 elastomeric fibre with 4.4 tex linear density. Examples of the dependence of the breaking load of the highly stretchable yarn on the twist and stretching value of the elastomeric component are reported.