Knittable and Washable Multifunctional MXene‐Coated Cellulose Yarns

Textile‐based electronics enable the next generation of wearable devices, which have the potential to transform the architecture of consumer electronics. Highly conductive yarns that can be manufactured using industrial‐scale processing and be washed like everyday yarns are needed to fulfill the promise and rapid growth of the smart textile industry. By coating cellulose yarns with Ti₃C₂T_x MXene, highly conductive and electroactive yarns are produced, which can be knitted into textiles using an industrial knitting machine. It is shown that yarns with MXene loading of ≈77 wt% (≈2.2 mg cm^?1) have conductivity of up to 440 S cm^?1. After washing for 45 cycles at temperatures ranging from 30 to 80 °C, MXene‐coated cotton yarns exhibit a minimal increase in resistance while maintaining constant MXene loading. The MXene‐coated cotton yarn electrode offers a specific capacitance of 759.5 mF cm^?1 at 2 mV s^?1. A fully knitted textile‐based capacitive pressure sensor is also prepared, which offers high sensitivity (gauge factor of ≈6.02), wide sensing range of up to ≈20% compression, and excellent cycling stability (2000 cycles at ≈14% compression strain). This work provides new and practical insights toward the development of platform technology that can integrate MXene in cellulose‐based yarns for textile‐based devices.     

Highly Conductive Carbon Nanotube‐Graphene Hybrid Yarn

An efficient procedure for the fabrication of highly conductive carbon nanotube/graphene hybrid yarns has been developed. To start, arrays of vertically aligned multi‐walled carbon nanotubes (MWNT) are converted into indefinitely long MWNT sheets by drawing. Graphene flakes are then deposited onto the MWNT sheets by electrospinning to form a composite structure that is transformed into yarn filaments by twisting. The process is scalable for yarn fabrication on an industrial scale. Prepared materials are characterized by electron microscopy, electrical, mechanical, and electrochemical measurements. It is found that the electrical conductivity of the composite MWNT‐graphene yarns is over 900 S/cm. This value is 400% and 1250% higher than electrical conductivity of pristine MWNT yarns or graphene paper, respectively. The increase in conductivity is asssociated with the increase of the density of states near the Fermi level by a factor of 100 and a decrease in the hopping distance by an order of magnitude induced by grapene flakes. It is found also that the MWNT‐graphene yarn has a strong electrochemical response with specific capacitance in excess of 111 Fg^?1. This value is 425% higher than the capacitance of pristine MWNT yarn. Such substantial improvements of key properties of the hybrid material can be associated with the synergy of MWNT and graphene layers in the yarn structure. Prepared hybrid yarns can benefit such applications as high‐performance supercapacitors, batteries, high current capable cables, and artificial muscles.     

Fast and High-Strain Electrochemically Driven Yarn Actuators in Twisted and Coiled Configurations

Commercially available yarns are promising precursor for artificial muscles for smart fabric-based textile wearables. Electrochemically driven conductive polymer (CP) coated yarns have already shown their potential to be used in smart fabrics. Unfortunately, the practical application of these yarns is still hindered due to their slow ion exchange properties and low strain. Here, a method is demonstrated to morph poly-3,4-ethylenedioxythiophene:poly-styrenesulfonate (PEDOT:PSS) coated multifilament textile yarns in highly twisted and coiled structures, providing > 1% linear actuation in < 1 s at a potential of + 0.6 V. A potential window of + 0.6 V and –1.2 V triggers the fully reversible actuation of a coiled yarn providing > 1.62% strain. Compared to the untwisted, regular yarns, the twisted and coiled yarns produce > 9 ×  and > 20 ×  higher strain, respectively. The strain and speed are significantly higher than the maximum reported results from other electrochemically operated CP yarns. The yarn's actuation is explained by reversible oxidation/reduction reactions occurring at CPs. However, the helical opening/closing of the twisted or coiled yarns due to the torsional yarn untwisting/retwisting assists the rapid and large linear actuation. These PEDOT:PSS coated yarn actuators are of great interest to drive smart textile exoskeletons.     

基于红外传感器的环锭纺断纱在线检测装置

为了解决环锭纺纱在纺纱过程中细纱断头难以及时发现的问题,提高纺织企业的生产效能,设计了基于红外传感器的环锭纺断纱在线检测装置,装置包括红外传感器、双运算放大器和单片机控制模块。在环锭细纱机上试纺18.2 tex棉纱,利用环锭纺断纱检测装置对纺纱过程中的细纱气圈信号进行在线检测。实验结果表明,装置将细纱气圈信号转换成电信号,再经过单片机控制模块处理判断,准确实现了细纱断纱在线检测。为了验证装置对棉纱的品种适应性,对5.8 tex、9.7 tex、18.2 tex三种纱支的棉纱进行检测。结果表明,装置能够实现对市场上大部分棉纱的断纱在线检测。     

Evaporation-Induced Closely-Packing of Core–Shell PDMS@Ag Microspheres Enabled Stretchable Conductor with Ultra-High Conductance

Stretchable conductors are indispensable building blocks for stretchable electronic devices that are used in next-generation wearable electronics, on-skin electronics, and soft robotics. Whereas, the ability to realize synergy high conductance and sufficient conductivity under high strain remains challenging. Herein, a stretchable conductor made from tightly assembled core–shell polydimethylsiloxane@silver microspheres (PDMS@Ag MPs) is elaborated. By judiciously using evaporation-induced capillary effect, 3D interconnected conductive paths consisting of closely packed conductive PDMS@Ag MPs are constructed inside the elastic matrix. The spatially selective distributed Ag-shell enables conductor metallic conductivity (67185 S cm⁻¹) at ultralow Ag fraction (19.5 wt.%), and well-maintained conductance over wide strain (820 S cm⁻¹ at 400%). Due to the suppressed Ag content, both the rapture strain and Young's modulus (613%, 0.79 MPa for CPSC4) of the conductor are largely retained. Besides, the synergy hierarchical surface topology and low surface energy endow conductors with high water-repellent properties. The fabricated conductors with remarkably high conductivity, well-retained conductance under large strain, and robust hydrophobicity are of great significance for advanced stretchable electronics.     

Gallium-Based Liquid–Solid Biphasic Conductors for Soft Electronics

Soft and stretchable electronics have diverse applications in the fields of compliant bioelectronics, textile-integrated wearables, novel forms of mechanical sensors, electronics skins, and soft robotics. In recent years, multiple material architectures have been proposed for highly deformable circuits that can undergo large tensile strains without losing electronic functionality. Among them, gallium-based liquid metals benefit from fluidic deformability, high electrical conductivity, and self-healing property. However, their deposition and patterning is challenging. Biphasic material architectures are recently proposed as a method to address this problem, by combining advantages of solid-phase materials and composites, with liquid deformability and self-healing of liquid phase conductors, thus moving toward scalable fabrication of reliable stretchable circuits. This article reviews recent biphasic conductor architectures that combine gallium-based liquid-phase conductors, with solid-phase particles and polymers, and their application in fabrication of soft electronic systems. In particular, various material combinations for the solid and liquid phases in the biphasic conductor, as well as methods used to print and pattern biphasic conductive compounds, are discussed. Finally, some applications that benefit from biphasic architectures are reviewed.     

双频带柔性人工磁导体结构研究

人工磁导体能够减小人体生物组织对人体通信天线性能的影响。根据等效电路模型以及软件优化仿真明确3*3人工磁导体结构单元形状和尺寸参数。结合人体手臂生物组织模型进行仿真,以0.05 mm 厚度聚酰亚胺为基底材料、铜为导电材料,加工制作正方形人工磁导体结构辐射单元和天线并在人体手臂进行实测。仿真与测试结果表明辐射单元结构尺寸设计为S1 =24 mm,S2 =23 mm,S3 = 12 mm,S4 = 7 mm,能够确保天线工作在2.45GHz 和5.80 GHz 双频段,将人体SAR值在2.45 GHz 时降低了86%,在5.8 GHz 降低了64%,AMC 结构和天线相距5 mm 时,实测天线回波损耗S11参数曲线与理论结果相符,可以满足双频带安全人体通信的应用需求。     

Wearable Energy Generating and Storing Textile Based on Carbon Nanotube Yarns

The challenges of textiles that can generate and store energy simultaneously for wearable devices are to fabricate yarns that generate electrical energy when stretched, yarns that store this electrical energy, and textile geometries that facilitate these functions. To address these challenges, this research incorporates highly stretchable electrochemical yarn harvesters, where available mechanical strains are large and electrochemical energy storing yarns are achieved by weaving. The solid‐state yarn harvester provides a peak power of 5.3 W kg^?1 for carbon nanotubes. The solid‐state yarn supercapacitor provides stable performance when dynamically deformed by bending and stretching, for example. A textile configuration that consists of harvesters, supercapacitors, and a Schottky diode is produced and stores as much electrical energy as is needed by a serial or parallel connection of the harvesters or supercapacitors. This textile can be applied as a power source for health care devices or other wearable devices and be self‐powered sensors for detecting human motion.     

3D Interconnected Conductive Graphite Nanoplatelet Welded Carbon Nanotube Networks for Stretchable Conductors

Stretchable conductors with stable electrical conductivity under harsh mechanical deformations are essential for developing next generation portable and flexible wearable electronics. To achieve both high stretchability and conductivity with electromechanical stability, highly stretchable conductors based on 3D interconnected conductive graphite nanoplatelet welded carbon nanotube (GNP-w-CNT) networks are fabricated by welding the junctions of CNTs using GNPs followed by infiltrating with poly(dimethylsiloxane) (PDMS). It is observed that GNPs can weld the adjacent CNTs to facilitate the formation of continuous conductive pathways and avoid interfacial slippage under repetitive stretching. The enhanced interfacial bonding enables the conductor both high electrical conductivity (>132 S m⁻¹) and high stretchability (>150% strain) while ensuring long-term stability (1000 stretching-releasing cycles under 60% tensile strain). To demonstrate the outstanding flexibility and electrical stability, a flexible and stretchable light-emitting diode circuit with stable performance during stretching, bending, twisting, and pressing conditions is further fabricated. The unique welding mechanism can be easily extended to other material systems to broaden the application of stretchable conductors to a myriad of new applications.     

Effect of process variables on the microwave conductivity of thick-film conductors

This letter presents the preliminary results of an investigation into the effect of process variables on the microwave conductivity of thick-film conductors. The quality factor Q0 of 50 ? closed resonators has been measured as a function of the firing temperature of the conductor and the mesh printing size. The results show that fine-mesh screens can be used without increasing the conductor losses, and that a high peak-firing temperature reduces the losses. The radio-frequency conductivity of the films as a fraction of bulk metal ranges from 0.45 at 1 GHz to 0.65 at 12 GHz.     

Niobium Nanowire Yarns and their Application as Artificial Muscles

Metal nanowires are twisted to form yarns that are strong (0.4 to 1.1 GPa), pliable, and more conductive (3 × 10⁶ S m^?1) than carbon nanotube yarns. Niobium nanowire fibers are extracted by etching a copper‐niobium nano‐composite material fabricated using the severe plastic deformation process. When impregnated with paraffin wax, the niobium (Nb) nanowire yarns produce fast rotational actuation as the wax is heated. The heated wax expands, untwisting the yarn, which then re‐twists upon cooling. Normalized to yarn length, 12 deg mm^?1 of torsional rotation was achieved along with twist rates in excess of 1800 rpm. Tensile modulus of 19 ± 5 GPa was measured for the Nb yarns, which is very similar to those of carbon multiwalled nanotubes.     

Transposing conductors in signal buses to reduce nearest-neighborcrosstalk

A conductor layout technique is described that reduces nearest-neighbor crosstalk for multiconductor signal buses with applications in high-speed digital and microwave pulse integrated circuits. Periodic transposition of conductors in a bus increases the average spacing of formerly nearest neighbors and thus decreases their capacitive and inductive coupling compared with ordinary parallel conductors. A conductor transposition pattern is evaluated for crosstalk, propagation delay, and chip area. SPICE simulations demonstrate that conductor transposition reduces, in certain situations, near- and far-end nearest-neighbor crosstalk by roughly 40% compared with parallel conductors. Quantitative guidelines are developed for reducing nearest-neighbor crosstalk in a transposed five-conductor bus, including effects of signal rise time, source resistance, load capacitance, and bus length     

Slow-Wave Propagation Along Variable Schottky-Contact Microstrip Line

Schottky-contact microstrip lines (SCML) are a special type of transmission line on the semiconducting substrate: the metallic-strip conductor is specially selected to form a rectifying metal-semiconductor transition while the ground plane exhibits an ohmic metallization. Thus the cross section of SCML is similar to that of a Schottky-barrier diode. The resulting voltage-dependent capacitance per unit length causes the nonlinear behavior of such lines. In this paper a detailed analysis of the, slow-wave propagation on SCML is presented, including the effect of metallic losses. Formulas for the propagation constant and characteristic impedance are derived and an equivalent circuit is presented. Conditions for slow-mode behavior are given, particularly taking into account the influence of imperfect conductors and defining the range of many interesting applications. Experimental results performed on Si-SCML are compared with theory.     

Novel SPICE Compatible Partial-Element Equivalent-Circuit Model for 3-D Structures

This paper presents a novel SPICE compatible partial-element equivalent-circuit (PEEC) model for general linear medium. In this new model, the magnetized current in conductive magnet and fictitious magnetized current through the magnetic interface are considered, as well as conduction current in conductor and polarization currents in a dielectric, to model the magnetization and conduction loss effect of a conductive magnet. Corresponding equivalent circuits are derived. The magnetic field couplings between inductive cells are taken into account as current controlled current sources to avoid the time-consuming calculation of time derivatives. The new model was applied in 3-D magnetically enhanced inductor structure analysis and antenna modeling. Obtained results are compared with those obtained from commercial numerical electromagnetic simulation software and show good agreement.      

High‐Performance Polypyrrole/Graphene/SnCl2 Modified Polyester Textile Electrodes and Yarn Electrodes for Wearable Energy Storage

Flexible supercapacitors have potential for wearable energy storage due to their high energy/power densities and long operating lifetimes. High electrochemical performance with robust mechanical properties is highly desired for flexible supercapacitor electrodes. Usually, the mechanical properties are improved by choosing high flexible textile substrates but at the much expense of electrochemical performance due to the nonideal contact between conductive materials and textile substrates. Herein, the authors present an efficient, scalable, and general strategy for the simultaneous fabrication of high‐performance textile electrodes and yarn electrodes. It is interesting to find that the conformal reduced graphene oxide (RGO) layer is uniformly and successively painted on the surface of SnCl₂ modified polyester fibers (M‐PEF) via a repeated “dyeing and drying” strategy. The large‐area textile electrodes and ultralong yarn electrodes are fabricated by using RGO/M‐PEF as substrate with subsequent deposition of polypyrrole. This work provides new opportunities for developing high flexible textile electrodes and yarn electrodes with further increased electrochemical performance and scalable production.     

A thermo-mechanical study on the electrical resistance of aluminum wire conductors

From the standpoint of electrical performance, the objective of a wire conductor is to transmit signals efficiently from one point to another. When the clock frequency trends faster, the high frequency signals on the wire conductor exhibit propagation delay, signal distortion and some symbiosis noise problems. These noises are related to the resistance, capacitance and inductance of the wire conductors. The major goal of this research is to propose a mathematical model to predict the unit change in resistance of aluminum wire conductors used in wire bonding technology in various surrounding temperatures and stress–strain states. The constitutive equation of wire conductors and the working principle of strain gages were used to derive the mathematical model. The experimental investigations involved three environmental temperatures (25, 50 and 80 °C) and two strain rates (1 and 3 mm/s) were employed to confirm the validity of the mathematical model. In the elastic range and the initiation of the plastic range, the variations in the electrical resistance of aluminum wire conductors are dominated by the thermal effect. The tensile strain replaces the thermal effect within the later half of the plastic range, however. We also proposed the electrical resistance charts of aluminum wire conductor that can be applied the variations into the electronic circuit and system simulation software (such as SPICE, PSPICE, etc.) to produce access simulations of the electrical circuits in package design.     

基于分段预留法的互连线二维电容提取技术

随着制造工艺的不断演进、电路规模的不断增大,集成电路逐渐进入后摩尔时代。如何准确快速地进行寄生电容参数提取,对于保证设计质量、减少成本和缩短设计周期变得越来越重要。文章提出了一种基于分段预留法的二维电容提取技术,该技术基于改进的有限差分法,采用非均匀网格划分和求解不对称系数矩阵方程,模拟互连结构横截面,可以高效计算出主导体的单位长度总电容以及主导体和相邻导体之间的单位长度耦和电容。为了验证提出方法的准确性和有效性,进行了一系列验证实验。实验结果表明,提出的互连线二维电容提取技术在寄生电容计算精度上平均提高了140倍,运行时间平均缩了10%。     

Identifying Migration Channels and Bottlenecks in Monoclinic NASICON-Type Solid Electrolytes with Hierarchical Ion-Transport Algorithms

Monoclinic natrium superionic conductors (NASICON; Na₃Zr₂Si₂PO₁₂) are well-known Na-ion solid electrolytes which have been studied for 40 years. However, due to the low symmetry of the crystal structure, identifying the migration channels of monoclinic NASICON accurately still remains unsolved. Here, a cross-verified study of Na⁺ diffusion pathways in monoclinic NASICON by integrating geometric analysis of channels and bottlenecks, bond-valence energy landscapes analysis, and ab initio molecular dynamics simulations is presented. The diffusion limiting bottlenecks, the anisotropy of conductivity, and the time and temperature dependence of Na⁺ distribution over the channels are characterized and strategies for improving both bulk and total conductivity of monoclinic NASICON-type solid electrolytes are proposed. This set of hierarchical ion-transport algorithms not only shows the efficiency and practicality in revealing the ion transport behavior in monoclinic NASICON-type materials but also provides guidelines for optimizing their conductive properties that can be readily extended to other solid electrolytes.     

Endurance behavior of conductive yarns

Various companies are industrializing ‘photonic’ textiles for medical and architectural applications. Here we report reliability testing of photonic textiles based on woven textiles with integrated copper-based conductive yarns used to drive attached LEDs. These textiles were subjected to cyclic mechanical stress tests and the cycle life was analyzed in terms of fatigue. Results show that failure is due to wire fractures at the transition from the rigid component to the compliant textile. The results are in good agreement with Cu-fatigue data from literature. This shows that it is possible to estimate the lifetime of electronic textiles under use conditions by the mechanical fatigue of the conducting yarn material properties.     

Design and Characterization of Purely Textile Patch Antennas

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