Silver-plated Nylon Research Articles

Supercoiled Polymer Sensors From Twisting and Coiling Silver-Plated Nylon Threads

Supercoiled Polymer Sensors From Twisting and Coiling Silver-Plated Nylon Threads

Parallel-Stranded Spiral Structure of Artificial Muscle Based on Polyethylene Fiber and Silver-Plated Nylon Wire

Parallel-Stranded Spiral Structure of Artificial Muscle Based on Polyethylene Fiber and Silver-Plated Nylon Wire

Study on a smart knee sleeve based on piezoresistive strain sensing for stride estimation

PurposeDevices for step estimation are body-worn devices used to compute steps taken and/or distance covered by the user. Even though textiles or clothing are foremost to come to mind in terms of articles meant to be worn, their prominence among devices and systems meant for cadence is overshadowed by electronic products such as accelerometers, wristbands and smart phones. Athletes and sports enthusiasts using knee sleeves should be able to track their performances and monitor workout progress without the need to carry other devices with no direct sport utility, such as wristbands and wearable accelerometers. The purpose of this study thus is to contribute to the broad area of wearable devices for cadence application by developing a cheap but effective and efficient stride measurement system based on a knee sleeve.Design/methodology/approachA textile strain sensor is designed by weft knitting silver-plated nylon yarn together with nylon DTY and covered elastic yarn using a 1 × 1 rib structure. The area occupied by the silver-plated yarn within the structure served as the strain sensor. It worked such that, upon being subjected to stress, the electrical resistance of the sensor increases and in turn, is restored when the stress is removed. The strip with the sensor is knitted separately and subsequently sewn to the knee sleeve. The knee sleeve is then connected to a custom-made signal acquisition and processing system. A volunteer was employed for a wearer trial.FindingsExperimental results establish that the number of strides taken by the wearer can easily be correlated to the knee flexion and extension cycles of the wearer. The number of peaks computed by the signal acquisition and processing system is therefore counted to represent stride per minute. Therefore, the sensor is able to effectively count the number of strides taken by the user per minute. The coefficient of variation of over-ground test results yielded 0.03%, and stair climbing also obtained 0.14%, an indication of very high sensor repeatability.Research limitations/implicationsThe study was conducted using limited number of volunteers for the wearer trials.Practical implicationsBy embedding textile piezoresistive sensors in some specific garments and or accessories, physical activity such as gait and its related data can be effectively measured.Originality/valueTo the best of our knowledge, this is the first application of piezoresistive sensing in the knee sleeve for stride estimation. Also, this study establishes that it is possible to attach (sew) already-knit textile strain sensors to apparel to effectuate smart functionality.

Warp-knitted strain sensors: impact of loop parameters on sensing performance under biaxial stretching

This paper explores the sensing performance displayed by warp-knitted strain sensors under biaxial stretching. These sensors were knitted using silver-plated nylon to be interlooped on a tricot warp-knitting machine. Eight types of warp-knitted sensing fabrics with different loop parameters were prepared and, afterward, electro-mechanical tests were conducted on a biaxial tensile testing machine. These specimens offered similar ground structures but differed in conductive yarn configuration in terms of linear density, number of underlapping wales, open/closed loop type, and guide-bar lapping sequence. Experimental results showed that the loop parameters significantly played a fundamental role in determining sensing performance. It is therefore possible to improve the sensing performance of warp-knitted sensors and engineer them by differing the loop parameters based on certain applications.

Chemical Resistant Yarn with Hierarchical Core–Shell Structure for Safety Monitoring and Tunable Thermal Management in High-Risk Environments

Chemical resistant textiles are vital for safeguarding humans against chemical hazards in various settings, such as industrial production, chemical accidents, laboratory activities, and road transportation. However, the ideal integration of chemical resistance, thermal and moisture management, and wearer condition monitoring in conventional chemically protective textiles remains challenging. Herein, the design, manufacturing, and use of stretchable hierarchical core–shell yarns (HCSYs) for integrated chemical resistance, moisture regulation, and smart sensing textiles are demonstrated. These yarns contain helically elastic spandex, wrapped silver-plated nylon, and surface-structured polytetrafluoroethylene (PTFE) yarns and are designed and manufactured based on a scalable fabrication process. In addition to their ideal chemical resistance performance, HCSYs can function as multifunctional stretchable electronics for real-time human motion monitoring and as the basic element of intelligent textiles. Furthermore, a desirable dynamic thermoregulation function is achieved by exploiting the fabric structure with stretching modulation. Our HCSYs may provide prospective opportunities for the future development of smart protective textiles with high durability, flexibility, and scalability.

Bifunctional Smart Textiles with Simultaneous Motion Monitoring and Thermotherapy for Human Joint Injuries.

The motion detection and thermotherapy provides a convenient strategy for the diagnosis and rehabilitation assessment of joint injuries. However, it is still challenging to simultaneously achieve accurate joint motion monitoring and on-demand thermotherapy. Herein, core-sheath sensing yarns (CSSYs) is proposed and fabricated for excellent electrical and photothermal heating, which consists of carbon black (CB)-coated nylon (sheath layer), silver-plated nylon and elastic spandex yarns (core layer). The CSSYs demonstrates great joule heating performance, which reaches 75°C at 2V applied voltage. The good thermal management performance can be well maintained when weaving these yarns into bifunctional smart textile. Further, the optimized double-ply CSSYs (DPCSSYs) with helically twisted structure possess several appealing sensing performance, including preferable strain sensitivity (0.854), excellent linearity (0.962), and superior durability (over 5000 cycles). The as-woven bifunctional smart textile can provide instant and convenient thermotherapy to the injured joints, and simultaneously monitor the injury and recovery conditions of the joint. Therefore, the designed bifunctional smart textile can provide a promising route for developing next-generation healthcare smart textile.

Wireless CardioS framework for continuous ECG acquisition

A first-level textile-based electrocardiogram (ECG) monitoring system referred to as “CardioS” (cardiac sensor) for continuous health monitoring applications is proposed in this study to address the demand for resource-constrained environments. and the signal quality assessment of a wireless CardioS was studied. The CardioS consists of a Lead-I ECG signal recorded wirelessly using silver-plated nylon woven (Ag-NyW) dry textile electrodes to compare the results of wired wearable Ag-NyW textile electrode-based ECG acquisition system and CardioS. The effect of prolonged usage of Ag-NyW dry electrodes on electrode impedance was tested in the current work. In addition, electrode half-cell potential was measured to validate the range of Ag-NyW dry electrodes for ECG signal acquisition. Further, the quality of signals recorded by the proposed wireless CardioS framework was evaluated and compared with clinical disposable (Ag–AgCl Gel) electrodes. The signal quality was assessed in terms of mean magnitude coherence spectra, signal cross-correlation, signal-to-noise-band ratio (S band/N band), crest factor, low and high band powers and power spectral density. The experimental results showed that the impedance was increased by 2.5–54.6% after six weeks of continuous usage. This increased impedance was less than 1 MΩ/cm2, as reported in the literature. The half-cell potential of the Ag-NyW textile electrode obtained was 80 mV, sufficient to acquire the ECG signal from the human body. All the fidelity parameters measured by Ag-NyW textile electrodes were correlated with standard disposable electrodes. The cardiologists validated all the measurements and confirmed that the proposed framework exhibited good performance for ECG signal acquisition from the five healthy subjects. As a result of its low-cost architecture, the proposed CardioS framework can be used in resource-constrained environments for ECG monitoring.

Enabling High‐Performance Artificial Muscles via a High Strength Fiber Reinforcement Strategy

AbstractCoiled‐polymer‐fiber‐based artificial muscles can provide large contractile actuation stroke. However, it is a challenge to achieve high actuation load and high actuation stroke for artificial muscle simultaneously. Herein, a powerful coiled‐polymer‐fiber‐based artificial muscle with a “rigid‐and‐flexible” structure is fabricated by cotwisting rigid heterocyclic aramid (HA) fibers with flexible silver‐plated nylon (SPN) fibers. The artificial muscle based on coiled HA@SPN fibers can lift a load over 108 MPa with a fast response time of 0.6 s, which is 309 times heavier than the load that human muscle can lift, and generate a work density per temperature of 41.3 J (kg °C)−1. The coiled HA@SPN fiber muscle exhibits high actuation stability of over 30 000 cycles. The coiled HA@SPN fiber muscle can provide a contractile actuation stroke of up to 8.2% and generate an average gravimetric mechanical energy density of 702 J kg−1, which is 18.1 times that of human skeletal muscle (≈38.8 J kg−1). An average contractile power density of 1168 W kg−1 is obtained for coiled HA@SPN fiber muscle, which is 23.4 times that of human skeletal muscle (≈50 W kg−1).

Size Prediction and Electrical Performance of Knitted Strain Sensors.

Benefitting from the multifunctional properties of knitted fabrics with elasticity, flexibility, and high resilience, knitted strain sensors based on structure and strain performance are widely utilized in sports health due to their adaptability to human movements. However, the fabrication process of common strain sensors mainly relies on experienced technicians to determine the best sensor size through repeated experiments, resulting in significant size errors and a long development cycle. Herein, knitted strain sensors based on plain knit were fabricated with nylon/spandex composite yarn and silver-plated nylon yarn using a flat knitting process. A size prediction model of knitted strain sensors was established by exploring the linear relationship between the conductive area size of samples and knitting parameters via SPSS regression analysis. Combined with stable structures and high performance of good sensitivity, stability, and durability, the knitted strain sensors based on size prediction models can be worn on human skin or garments to monitor different movements, such as pronunciation and joint bending. This research indicated that the reasonable size control of the knitted strain sensor could realize its precise positioning in intelligent garments, exhibiting promising potential in intelligent wearable electronics.

Surface microstructural engineering of continuous fibers as one-dimensional multifunctional fiber materials for wearable electronic applications

The rapid progress in advanced functional fibers (AFFs) offers unique superiorities in wearable electronics, artificial intelligence, and healthcare monitoring. However, there remain considerable challenges for AFFs to fulfill specific requirements of advanced applications due to their low electrical outputs, limitation in materials selection, and difficulty in regulating microstructures on narrow and curved surface of the fibers. In this study, fabricating and regulating honeycomb porous microstructures (HPMs) on one-dimensional nonplanar fiber surfaces were proposed and systematically studied for developing AFFs with customized functionalities. As a demonstration of application, multifunctional silver-plated nylon fibers surface-engineered with HPMs (SNF@HPMs) were developed with the assistance of the BF method and were further fabricated into SNF@HPMs-based triboelectric nanogenerator (SNF@HPMs-TENG). The SNF@HPMs-TENG showed considerable electrical performances with a power density of 390.8 mW/m2 and good long-term stability, which can power portable electronics as capacitors, calculator, watch, and light up 150 LEDs. Moreover, a self-powered wearable sensor based on SNF@HPMs was also developed for monitoring the bending, tactile, and frictional stimuli in a real-time manner. The comprehension of HPMs mechanism on nonplanar fiber surface and demonstrated capability of the SNF@HPMs-TENG provide insights and guidance in regulating microstructures of fiber materials for developing AFFs with customizable functionalities.

The electrical conductivity and interlaminar fracture toughness of composite laminate interleaved with silver-plated nylon mesh

A composite laminate with high conductivity and high mode I fracture toughness was prepared by using a silver-plated nylon mesh as the interleaf. Through in-depth comparison with the silver-plated non-woven veil interleaved composites, the mechanisms of the conductivity improvement and interlaminar toughening were discussed. The conductivities along the fiber direction, in transverse to fiber direction and through thickness direction reached 739 S/cm, 734 S/cm, and 5.4 S/cm, respectively, which increased by 196%, 344,500%, and 4326%, respectively, and are much higher than these of the other modified systems. At the same time, the mode I interlaminar fracture toughness increased by 112%. Mechanism study shows that the conductivities along the fiber direction and in transverse to fiber direction are greatly affected by the interleaf conductivity, while the conductivity through thickness direction is little affected. The toughening mechanism of the plain or silver-plated nylon mesh is much different from that of the non-woven veils. Both of the composites interleaved with the plain or silver-plated nylon mesh have higher mode I interlaminar fracture toughness, but less improved mode II toughness. The effect of silver-plating on the mode I and mode II fracture toughness was studied.

Wide-range sensitive all-textile piezoresistive sensors assembled with biomimetic core-shell yarn via facile embroidery integration

Emerging of flexible high-performance pressure sensor has recently led to the development and flourish of wearable intelligent systems. However, a recurring challenge restricting the performances and large-scale applications is the incorporation of high flexibility, wide working pressure range, and facile integration into flexible pressure sensor. In this paper, cytoskeleton-inspired core–shell yarns (CCSY), containing internal silver-plated nylon electrode and external sensing layer with bridge-binder cell (BBC) structures, have been prepared by a modified immersing coating process. Due to the great flexibility and knittability of CCSY, integrated sensors array, as well as pressure sensors, has been inserted into traditional textiles with expected location and resolution via a facile embroidery technique. The obtained pressure sensor shows a wide working pressure range (up to 25 N, ∼148.017 MPa), a high sensitivity (up to 5.15 N−1) and a short response time (∼11.2 ms) with the help of BBC structures. Moreover, the pressure sensor can monitor physiological signals of human body accurately and swiftly, such as pulses, joints movements, and plantar pressure. The scalable and high-performance CCSY-based pressure sensors pave a pass for the next generation wearable intelligent system, fulfilling the sophisticated demands of intelligent life, personalized health care and human–machine interface.

An Alternative Method to Develop Embroidery Textile Strain Sensors

In this paper, a method to develop embroidered textile strain resistive sensors is presented. The method is based on two overlapped zigzag conductive yarn patterns embroidered in an elastic textile. To demonstrate the functionality of the proposed configuration, a textile sensor embroidered with a conductor yarn composed of 99% pure silver-plated nylon yarn 140/17 dtex has been experimentally characterised for an elongation range from 0% to 65%. In order to show the sensor applicability, a second test with the sensor embroidered in a knee-pad has been done to evaluate the flexion knee angle from 180° to 300°. The experimental results show the usefulness of the proposed method to develop fabric strain sensors that can help to manufacture commercial applications on the healthcare sector.

Scalable core–spun coating yarn-based triboelectric nanogenerators with hierarchical structure for wearable energy harvesting and sensing via continuous manufacturing

With rapid advancement in wearable electronics, textile-based triboelectric nanogenerators (T-TENGs) have attracted great attention for energy harvesting and bio-motion sensing because of their softness, lightweight, and comfort properties. However, the interface bonding between functional materials and textile substrate, and the compatibility with manufacturing still face considerable challenges. Herein, a kind of scalable core–spun coating yarn-based triboelectric nanogenerators (CSCY-TENGs) with a hierarchical architecture is designed and developed via continuous manufacturing which integrates yarn spinning, coating and braiding technologies to achieve fully continuous production. In this method, spinning technology was used to spin a kind of conductive core-spun yarns with silver-plated nylon yarn (SNY) as core and insulating cotton fibers as shell, where SNY serves as electrode and cotton fibers serve as base materials for absorbing/coating with triboelectric materials. Then multiple core-spun yarns coated with nylon and doped polydimethylsiloxane are used as positive and negative triboelectric materials to realize hierarchical CSCY-TENGs by braiding technology. The CSCY-TENGs can be washed and compatible with industrial-scale manufacturing. Besides, it can achieve an output voltage of 174 V, and a peak power density and an average power density of 275 mW/m2 and 57 mW/m2 respectively. As demonstration, the CSCY-TENG can charge various commercial capacitors and power low-power electronics. It can also be used as an anti-theft alarm carpet and energy harvesting shoes for bio-motion detection and energy harvesting.

Full-Textile Human Motion Detection Systems Integrated by Facile Weaving with Hierarchical Core-Shell Piezoresistive Yarns.

The tremendous progress of the wearable intelligent system has brought an urgent demand for flexible pressure sensors, especially for those possessing high sensing performances, simple manufacture technology, and efficient integration. In this work, hierarchical core-shell piezoresistive yarns (HCPYs), which contain internal silver-plated nylon electrodes and surface microporous structured carbon nanotubes (CNTs)/thermoplastic polyurethane (TPU) sensing layer, are designed and manufactured via facile wet-spinning accompanied by a water vapor coagulating bath. The obtained HCPY can either be inserted into traditional textiles to assemble a single-pressure sensor, or be woven into a textile-based flexible pressure sensors array with expected size and resolution, without compromising their comfort, breathability, and three-dimensional (3D) conformability. Simultaneously, to further enhance the sensing performance, the surface microporous structures of HCPYs are optimized by altering the treatment humidity and exposure time during the process of water vapor-induced phase separation. The wearable pressure sensors assembled by the optimal HCPY achieved a high sensitivity up to 84.5 N-1, a good durability over 5000-cycle tests, a fast response time of 2.1 ms, and a recovery time of 2.4 ms. Moreover, the wearable pressure sensors have been successfully used to monitor physical signals and human motions. The textile-based flexible pressure sensors array has also been seamlessly integrated with sportswear to detect movements of the elbow joint and map spatial pressure distribution, which makes HCPY a promising candidate for constructing next-generation wearable electronics.

A Fabric-Based Integrated Sensor Glove System Recognizing Hand Gesture

Abstract The research on wearable glove sensor system has been increasing over recent years because of the need for portability and comfort. This study presents a fabric-based integrated sensor glove system with five sensing zones. Five sensors are knitted by silver-plated nylon yarn and embedded into glove directly using intarsia technology. Various parameters including sensor elasticity, sizes of embedded sensor as well as glove are discussed, respectively. Further, selected or chosen integrated sensor glove is manufactured and tested for recognizing gestures. Results show that elasticity affects effective sensing range of knitted sensors, size has significant influence on sensors’ sensitivity, and appropriate glove size helps avoiding nonlinear sensing phenomenon. Finally, the glove system, by extracting feature data, can distinguish Chinese number gestures very well and has also the potential to recognize more hand gestures in the future.

Comparison of the efficacy of silver-based antimicrobial burn dressings in a porcine model of burn wounds

PurposeA variety of silver-based antimicrobial dressings are available on the market and are commonly used to prevent infection. Such prophylaxis is particularly important in treating burns, yet there is a paucity of evidence confirming the efficacy of commercially available dressingsin vivo. We describe here an in vivo porcine model of burns, which we use to test the antimicrobial efficacy of three common wound dressings and a control. ProceduresDomestic Yorkshire-cross pigs were medicated for pain management before inflicting burns with a heated brass rod. The wounds were artificially challenged with a mixture of two pathogens commonly associated with burn wound infection:Staphylococcus aureus and Pseudomonas aeruginosa. The following dressing materials were sutured in place: gauze, nanocrystalline silver, silver-plated nylon, and polyethylene/polyester coated with high-oxidation silver salts. After 1 and 3 days, the wounds were assessed for erythema, swelling, and re-epithelialization, tissue was biopsied to determine the recovery of the challenge microorganisms, and histology was performed. We also examined the number of microorganisms present on the dressings themselves. ResultsHistology indicated that 30 s was sufficient to produce burns extending into the deep dermal layer. After 3 days, nanocrystalline silver and silver-plated nylon led to slightly reduced swelling relative to simple gauze, although none of the dressings significantly affected erythema or wound re-epithelialization. All the dressings led to decreased recovery of the challenge organisms from the burn tissue, relative to simple gauze. However, the magnitude of the reduction was greatest for nanocrystalline silver (log10 reduction = 4–5); additionally, only nanocrystalline silver gave a statistically significant decrease (P = 0.02). Notably, the antimicrobial effect for all dressings was reduced by Day 3 relative to Day 1. Similar trends were observed for microbial retention on the dressings themselves. ConclusionNanocrystalline silver-based wound dressings generally outperformed silver-plated nylon and high-oxidation silver salts in thisin vivo model of burn wounds. Relative to prophylactic use, it may be advisable to change the dressings more frequently when treating an infected wound.

Quantification of the silver content of a silver-plated nylon electrode according to the nature of the laundering detergent

In this study, the loss of the silver content was determined accurately when silver plated nylon electrodes dedicated to a measurement of human physiological parameters are washed with detergents containing bleaching agents. Thermogravimetric analysis and morphological observations based on SEM images have been conducted to determine the quantity of remaining silver on the electrodes. This loss of the conductive silver content is critical for the electrodes as it reduces their electrical conductivity and therefore their capacity to be used to measure either low voltages from the skin generated by ECG (electrocardiograph), EMG (electromyograph) or even EEG (electroencephalograph) or to determine the bioimpedance of human body or specific organs. The reduced surface conductivity leads also to a very complex contact impedance between the electrodes and the skin and therefore to their high sensitivity to any movement. This also results in noisy signals that are not useful to monitoring of physiological parameters and the concept of predictive medicine.

Toward Flexible and Wearable Embroidered Supercapacitors from Cobalt Phosphides-Decorated Conductive Fibers

HighlightsThe conductive silver-plated nylon yarns fully fit the demand for wearable supercapacitor skeleton, owing to the advantages of high conductivity and flexibility.The computerized programming embroidering technique was firstly applied for realizing standardized batch processing of the flexible supercapacitor skeleton in various patterns.Cobalt phosphides were properly electrodeposited on the conductive embroidery as the pseudocapacitive materials, providing remarkable electrochemical performance.

Design of an Active Cooling System for Thermally Activated Soft Actuators.

A new type of actuator made from twisting a silver-plated nylon thread presents new possibilities for the way wearable mechatronic rehabilitation devices are designed. The twisted coiled actuator (TCA) has been previously shown to provide a power density up to 100 times that of biological muscles, while also encompassing biomimetic characteristics. However, since TCAs require heat to contract, the main drawbacks preventing this type of actuator are its inherent low efficiency and slow reaction times. To combat both of these issues, a simple tube enclosure was designed to provide active cooling using forced air. The two main parameters affecting the efficiency and bandwidth are the cooling air pressure and tube diameter. This study presents a two-way repeated measures test to compare these parameters on the cooling and heating rates of the TCA system, as well as the thermal capacitance with three pressure levels (10, 15, and 20 psi) and three tube diameters (4, 4.5, and 5 mm). The results show that an increase in pressure significantly improves the rate of cooling, while a decrease in tube diameter has negative effects on the efficiency and cooling rate of the system. The mean values of the cooling time $(\tau_{\text {cool}})$ were 2.972, 2.210, and 2.682 seconds for 4, 4.5, and 5 mm diameters, respectively. These results indicate that a decrease in diameter improves the cooling rate up to the point at which the walls of the tube become so close to the TCA strand, that they prevent rapid heat transfer while cooling.