Functional Materials and Innovative Strategies for Wearable Thermal Management Applications

Thermal management is essential in our body as it affects various bodily functions,ranging from thermal discomfort to serious organ failures,as an example of the worst-case scenario.There have been extensive studies about wearable materials and devices that augment thermoregulatory functionalities in our body,employing diverse materials and systematic approaches to attaining thermal homeostasis.This paper reviews the recent progress of functional materials and devices that contribute to thermoregulatory wearables,particularly emphasizing the strategic methodology to regulate body temperature.There exist several methods to promote personal thermal management in a wearable form.For instance,we can impede heat transfer using a thermally insulating material with extremely low thermal conductivity or directly cool and heat the skin surface.Thus,we classify many studies into two branches,passive and active thermal management modes,which are further subdivided into specific strategies.Apart from discussing the strategies and their mechanisms,we also identify the weaknesses of each strategy and scrutinize its potential direction that studies should follow to make substantial contributions to future thermal regulatory wearable industries.

Rational Design of Cellulosic Triboelectric Materials for Self‑Powered Wearable Electronics

With the rapid development of the Internet of Things and flexible electronic technologies,there is a growing demand for wireless,sustainable,multifunctional,and independently operating self-powered wearable devices.Nevertheless,structural flexibility,long operating time,and wearing comfort have become key requirements for the widespread adoption of wearable electronics.Triboelectric nanogenerators as a distributed energy harvesting technology have great potential for application development in wearable sensing.Compared with rigid electronics,cellulosic self-powered wearable electronics have significant advantages in terms of flexibility,breathability,and functionality.In this paper,the research progress of advanced cellulosic triboelectric materials for self-powered wearable electronics is reviewed.The interfacial characteristics of cellulose are introduced from the top-down,bottom-up,and interfacial characteristics of the composite material preparation process.Meanwhile,the modulation strategies of triboelectric properties of cellulosic triboelectric materials are presented.Furthermore,the design strategies of triboelectric materials such as surface functionalization,interfacial structure design,and vacuum-assisted self-assembly are systematically discussed.In particular,cellulosic self-powered wearable electronics in the fields of human energy harvesting,tactile sensing,health monitoring,human–machine interaction,and intelligent fire warning are outlined in detail.Finally,the current challenges and future development directions of cellulosic triboelectric materials for self-powered wearable electronics are discussed.

Recent progress in solution assembly of 2D materials for wearable energy storage applications

Wearable energy storage devices are desirable to boost the rapid development of flexible and stretchable electronics. Two-dimensional (2D) materials, e.g., graphene, transition metal dichalcogenides and oxides, and MXenes, have attracted intensive attention for flexible energy storage applications because of their ultrathin 2D structures, high surface-to-volume ratio, and unique physical/chemical properties. To achieve commercialization of 2D material-based wearable energy storage devices (2DM-WESDs), scalable and cost-efficient manufacturing is a critical challenge. Among existing manufacturing technologies, solution-based assembly strategies show strong potential to achieve low-cost and scalable production. A timely review of the recent progress in solution-based assembly strategies and the resultant 2DM-WESDs will be meaningful to guide the future development of 2DM-WESDs. In this review, first, a brief introduction of exfoliation and solution preparation of 2D material species from bulk materials is discussed. Then, the solution-based assembly strategies are summarized, and the advantages and disadvantages of each method are compared. After that, two major categories of 2DM-WESDs, supercapacitor and battery, are discussed, emphasizing their state-of-the-art energy storage performances and flexibilities. Finally, insights and perspectives on current challenges and future opportunities regarding the solution assembly of 2DM-WESDs are discussed.

A Comprehensive Review of Wearable Applications and Material Construction

Wearable electronic systems are able to monitor and measure multiple biophysical, biochemical signals to help researchers develop further understandings of human health and correlation between human performance and diseases. Driven by increasing demand for need in sports training, health monitoring and disease diagnose, bio-integrated systems are developing at a significant speed based on recent advances in material science, structure design and chemical techniques. A wide range of wearable systems are created and feature unique measuring targets, methods and soft, transparent, stretchable characters. This review summarizes the recent advances in wearable electronic technologies that also include material science, chemical science and electronic engineering. The introduction to basic wearable fundamentals covers subsequent consideration for materials, system integration and promising platforms. Detailed classification towards their functions of physical, chemical detection is also mentioned. Strategies to achieve stretchability and promising material, AgNW, are fully discussed. This paper concludes with consideration of main challenging obstacles in this emerging filed and promises in materials that possess excellent potentials for predicted progress.

The Selection and Application of Non-Conventional Decoration Materials in Indoor Design

In indoor design innovation, the material role can not be ignored. In indoor design, using non-conventional decoration materials can make space more personalized and charming. This is one of the material innovation modes and also one of the indoor design innovation modes. The design method should obtain more attention.

A Thermoregulatory Flexible Phase Change Nonwoven for All‑Season High‑Efficiency Wearable Thermal Management

Phase change materials have a key role for wearable thermal management,but suffer from poor water vapor permeability,low enthalpy value and weak shape stability caused by liquid phase leakage and intrinsic rigidity of solid–liquid phase change materials.Herein,we report for the first time a versatile strategy for designed assembly of high-enthalpy flexible phase change nonwovens(GB-PCN)by wet-spinning hybrid grapheneboron nitride(GB)fiber and subsequent impregnating paraffins(e.g.,eicosane,octadecane).As a result,our GB-PCN exhibited an unprecedented enthalpy value of 206.0 J g^(−1),excellent thermal reliability and anti-leakage capacity,superb thermal cycling ability of 97.6%after 1000 cycles,and ultrahigh water vapor permeability(close to the cotton),outperforming the reported PCM films and fibers to date.Notably,the wearable thermal management systems based on GB-PCN for both clothing and face mask were demonstrated,which can maintain the human body at a comfortable temperature range for a significantly long time.Therefore,our results demonstrate huge potential of GB-PCN for human-wearable passive thermal management in real scenarios.

Functionalized Fiber-Based Strain Sensors:Pathway to Next-Generation Wearable Electronics

Wearable strain sensors are arousing increasing research interests in recent years on account of their potentials in motion detection,personal and public healthcare,future entertainment,man-machine interaction,artificial intelligence,and so forth.Much research has focused on fiber-based sensors due to the appealing performance of fibers,including processing flexibility,wearing comfortability,outstanding lifetime and serviceability,low-cost and large-scale capacity.Herein,we review the latest advances in functionalization and device fabrication of fiber materials toward applications in fiber-based wearable strain sensors.We describe the approaches for preparing conductive fibers such as spinning,surface modification,and structural transformation.We also introduce the fabrication and sensing mechanisms of state-of-the-art sensors and analyze their merits and demerits.The applications toward motion detection,healthcare,man-machine interaction,future entertainment,and multifunctional sensing are summarized with typical examples.We finally critically analyze tough challenges and future remarks of fiber-based strain sensors,aiming to implement them in real applications.

Mechanically strong,flexible,and multi-responsive phase change films with a nacre-mimetic structure for wearable thermal management

Phase change materials(PCMs)are a highly promising candidate for thermal energy storage owing to their large latent heat and chemical stability.However,their intrinsic brittle induces poor flexibility and low mechanical strength,which limits them use for wearable thermal management.And,the electrical insulation and weak solar absorption make them lack multi-responsive capability.Herein,we report a facile strategy to synthesize mechanically strong and flexible multi-responsive phase change films by stirring an aqueous dispersion of cellulose nanofibrils(CNFs),MXene(Ti_(2)C_(3))nanosheets,and polyethylene glycol(PEG),followed by air-drying self-assembly and coating with hydrophobic fluorocarbon.The hydrogen bonds and nacre-mimetic synergistic toughening networks formed by ternary CNFs,Ti_(2)C_(3)nanosheets,and PEG endow films with high mechanical strength(16.7 MPa)and strain(10.4%),which are 18.6 and 8.7 times higher than those of pure PEG film,respectively.The films exhibit outstanding flexibility and do not crack or fracture even when bent,twisted,and folded into a complex small boat.Meanwhile,the laminar structure formed by the self-assembly Ti_(3)C_(2)nanosheets enhances electrical conductivity(3.95 S/m)and solar absorption,affording excellent electro-thermal(68.3%–81.0%)and solarthermal(85.6%–90.6%)conversion efficiency,thus achieving multi-response to external stimuli(electron/solar radiation).In addition,the as-prepared films also deliver large latent heat(136.1 J/g),outstanding cyclic and shape stability,leak-free encapsulation even under compressed at above 5000 times its weight,excellent hydrophobicity(131.4°),and self-cleaning function.This work paves the way for developing flexible,mechanically strong,and self-cleaning phase change film with multi-responsive function for wearable thermal management devices under high humidity condition.

Investigation and Comparison of 2.4 GHz Wearable Antennas on Three Textile Substrates and Its Performance Characteristics

In this paper, two different methods were used for investigating the RF characteristics of three types of textile materials. Goch, Jeans and Leather substrates were studied. A microstrip ring resonator method and DAK (Dielectric Assessment Kit) method were used. Bluetooth antennas were designed and fabricated using these substrates. The results were compared for the two methods. The bending effect of these antennas on its impedance characteristics due to human body movements was also studied. Finally, all antennas were simulated by CST simulator version 2016, fabricated using folded cupper and measured by Agilent 8719ES VNA. The measured results agree well with the simulated results.

Health and safety perspectives of graphene in wearables and hybrid materials

The growing demand for smart wearables, coupled with the omnipresence of graphene due to its array of outstanding thermal, electrical, and mechanical properties, have driven the industry-led initiatives to develop lightweight, smart, and robust graphene-based wearable technologies. The substantial research and the increase in technology readiness levels (TRLs) of graphene-based technologies have led to the adoption of graphene in many industries. Graphene-based wearables are one such technology that involves closer interaction of graphene by the end-user. Despite this, understanding the toxicological risks associated with using graphene-based wearables is still in the fundamental stage. Herein, graphene-based wearables and industrial-scale fabrication techniques for the development of graphene-based wearables are reviewed. The main goal of the review is to initially evaluate the likelihood of user exposure to graphene from the wearable device and the potential health effects. The subsequent health risks based on graphene's physicochemical characteristics are also discussed. A framework to elucidate the risk is presented in terms of crucial exposure routes, possible graphene interactions, recent exposure assessments, detection removal techniques from the human body, and risk management protocols. It is hoped that this review may aid towards establishing a reasonable practice concerning the safe integration of graphene materials into wearables and facilitate their commercialization.

银纳米线导电纺织品制备及应用研究进展

银纳米线具有优异的长径比、导电、透光、柔性、抗菌等特性,是制备导电纺织品最有前途的纳米材料之一。介绍银纳米线导电纺织品的常用制备方法,即共混纺丝法、后整理法,综述银纳米线导电纺织品在空气过滤、饮用水过滤、电磁屏蔽、个人热管理、柔性压力传感器等领域的应用进展。最后对银纳米线导电纺织品的未来发展趋势进行展望,为下一代智能纺织品的研发提供思路。

电致变色材料在智能运动服装中的应用

为实现电致变色材料与柔性器件的集成,设计出高性能、低成本和舒适性的智能运动服装。采用文献综述和比较分析的研究方法,对电致变色材料的基本原理、分类以及优越性进行了论述;分析了电致变色材料在智能运动服装中的温度调节功能和运动状态监测功能等功能与应用。电致变色材料在智能运动服装领域展现巨大潜力,但电致变色材料在智能运动服装实际应用中仍面临一些挑战问题,如能耗高、响应速度慢和循环稳定性差等,提出针对性的解决方案,可为电致变色材料在智能运动服装中的应用提供可行性参考。

智能可穿戴柔性压力传感器的研究进展

柔性压力传感器可以附着在人体皮肤感知外界压力信号,且具有传感范围广、响应时间短、灵敏度和耐久性高等特点,因此被广泛应用于电子皮肤和人机交互等领域。柔性压力传感器通常由柔性基底、活性材料、导电电极组成。其中,一种或多种活性材料通过与柔性基底复合形成传感材料,其受外界刺激产生的变形会引起阻值等变化,进而实现传感功能。此外,通过引入微结构可增加传感材料的可压缩性以及对微小压力的敏感度,提升传感性能。本文围绕薄膜和织物两类基底,综述了在其中掺杂碳基、金属基与黑磷基等活性材料的柔性压力传感器的研究,重点论述了不同传感器的制备方法、机电性能与应用场景,总结了各类传感器的优缺点。在此基础上,对未来智能可穿戴柔性压力传感器如何实现宽范围压力检测、商业化以及制作流程无毒化与长时期生物相容性实验等方面的研究做出了展望。

钆-钡/天然皮革复合可穿戴X射线屏蔽材料的制备及性能

为了不明显增加材料厚度的同时提升屏蔽性能,通过等体积浸渍法将钡(Ba^(2+))负载到天然皮革(NL)的多层级结构中得到钡/天然皮革(Ba/NL),并将分散有纳米氧化钆(Gd_(2)O_(3))的水性聚氨酯涂饰剂均匀涂覆于Ba/NL的粒面,得到钆-钡/天然皮革复合X射线屏蔽材料(Gd-Ba/NL)。X射线屏蔽性能研究表明,施加含钆涂层后,1.5 mm厚的Gd_(1.80)-Ba_(2.32)/NL具有与2.6 mm的Ba_(2.32)/NL相近的屏蔽效率;得益于Gd和Ba的协同作用,Gd_(1.80)-Ba_(2.32)/NL对能量为16~48 keV的X射线的屏蔽效率达到70%以上,对能量为65和83 keV的X射线的质量衰减系数与0.25 mm铅板的作用相当。此外,Gd_(1.80)-Ba_(2.32)/NL具有穿戴舒适度高、力学性能佳的优势,其密度仅为铅衣的1/3,透水汽性是铅衣的12倍,抗张强度和撕裂强度分别是国家标准要求的2倍和3倍,是一种可用于替代铅衣的有潜力的可穿戴X射线屏蔽材料。

蚕丝基柔性可穿戴传感器在人体健康监测中的研究进展

传感器是智能可穿戴器件的关键组成部分之一,通过信号转换机制能够全天候、实时连续采集人体生命体征和生理信息,被广泛应用于实时健康监测、医疗诊断及科学化运动训练领域。蚕丝材料具有易再生成型、富含功能化基团、结构可控及生物相容等特点,被广泛研究并应用在柔性可穿戴传感器中。本文结合蚕丝的组成、结构与性能特点,聚焦蚕丝基可穿戴传感器的构筑及在健康监测领域的应用,围绕其构筑方法及应用领域,系统地阐述了蚕丝基柔性可穿戴传感器的研究进展,并对蚕丝基可穿戴传感器面临的挑战和未来的发展趋势进行了探讨。

柔性电子材料在可穿戴设备中的研究进展

在电子技术与现代纺织技术融合的背景下,更加柔性、传输信号更加灵敏精准、监控范围更加广泛的可穿戴设备成为研究热点,为此,研究人员着力于开发新型柔性电子材料。文章简要总结了可穿戴设备中所用新型柔性电子材料的研究进展,重点介绍了柔性传感材料、导电材料、供电材料的研究现状及发展方向,同时指出了目前柔性电子材料在制备过程及成品性能方面存在的不足及未来研究趋势。

离子凝胶可穿戴传感器研究与应用进展

离子凝胶可穿戴传感器具有高灵敏度、快响应性以及极好耐用性等独特优势,这类传感器将受刺激过程中的载荷信号转化为电信号输出到智能端从而达到人机交互,用来智能监测人体各类活动状态,如日常状态、运动状态和健康状态等。也能复合各类电子元件,在诸多领域得以广泛应用,如智能电池、压力传感器、人体组织工程、医疗器械和药物制备等。文章综述离子凝胶可穿戴传感器研究进展,并结合应用实例讨论该类传感器在传感基材或工艺方面优缺点,最后从为大数据时代提供辅助信息角度出发,提出离子凝胶可穿戴传感器未来将要面对的挑战,并对其进行展望。

凝胶复合材料柔性可穿戴传感器研究

水凝胶和离子凝胶具有高可拉伸性和优异透明度,是一种理想柔性传感器制备原料,与导电材料复合后导电性能大大提高。凝胶复合材料具有较强形状可塑性,可通过改变表面微结构提高传感器件灵敏度。综述水凝胶和离子凝胶及复合材料研究现状,列举其在柔性可穿戴力学传感器、电化学生物传感器及温、湿度传感器等方面的应用,为后续在柔性通信设备、生物医疗监护等领域的应用提供参考。

一种超宽带双陷波可穿戴天线设计

基于牛仔布柔性材料,设计了一种小型化双陷波超宽带可穿戴天线。天线由牛仔布料基板、开槽单极子辐射贴片和缺陷地平面构成,具有超宽带特性,能覆盖3.1~10.6GHz的超宽带频段范围。通过在天线接地板刻蚀两条新型蜿蜒形槽和在单极子辐射贴片上添加对称枝节以实现双陷波特性。该天线结构紧凑,尺寸仅为24mm×28mm×0.84mm。仿真的-10dB天线工作带宽为143.7%(2.95~18GHz),并且天线在3.24~3.87GHz和5.11~5.91GHz频段内具有双陷波特性,能有效抑制全球微波互联接入系统(WiMAX)和无线局域网(WLAN)频段的干扰。此外,对天线的可弯曲性、辐射性能以及人体安全性能进行了分析。测试与仿真结果基本一致,表明该天线可用于可穿戴系统中。

面向柔性外骨骼机器人的纺织材料研究现状

基于纺织材料的柔性外骨骼机器人有效解决了刚性外骨骼机器人顺应性差、笨重、穿戴舒适性差等问题。文章介绍了柔性外骨骼机器人的发展现状,重点介绍了主要的驱动结构(包括线驱动、气动肌肉和液压驱动等),柔性外骨骼机器人主要采用的纺织材料(形状记忆材料、电活性聚合物、碳纤维和水凝胶材料等),并剖析了纺织材料在柔性外骨骼领域应用所面临的困难,并提出了今后的发展方向。