二维导电材料/柔性聚合物复合材料基可穿戴压阻式应变传感器的研究进展

可穿戴应变传感器在人体运动检测、健康监测、可穿戴电子设备和柔性电子皮肤等新兴领域具有极大的应用前景.近年来,由二维(2D)导电材料和柔性聚合物基体组成的可穿戴压阻式应变传感器具有较高的灵敏度、良好的拉伸性和柔韧性、优异的耐久性、可调的应变传感性和易加工等特点,受到广泛关注.基于此,该文对基于2D导电材料/柔性聚合物复合材料(2D-CPC)的可穿戴压阻式应变传感器的类型、传感机理、性能指标、影响因素及应用等进行了综述,并对其未来发展趋势进行了展望.     

基于弹性聚合物复合材料的压阻式柔性应变传感器研究进展

综述了近年来基于弹性聚合物复合材料的压阻式柔性应变传感器的研究现状,包括压阻式柔性应变传感器的结构、传感机理、传感器基质,以及导电材料种类、结构控制方法及应用等。指出了现阶段压阻式柔性应变传感器研究面临的主要问题,并对其未来发展方向进行了展望。     

石墨烯/聚合物泡沫压阻式应变传感器研究进展

基于石墨烯和聚合物的三维多孔结构的导电聚合物基复合材料（CPCs）具有轻量化、高灵敏度、宽应变检测范围、低成本和可扩展性等优点，已成为可穿戴柔性应变传感器的理想选择。首先，总结了柔性压阻式泡沫应变传感器的裂纹扩展机制、重叠-断开机制和隧穿效应机制；其次，介绍了3种具有多孔结构的石墨烯/聚合物柔性应变传感器的构筑工艺，包括基于聚合物泡沫、基于石墨烯/聚合物混合分散液、基于石墨烯泡沫的方法；然后，综述了通过上述3种工艺制备的柔性多孔应变传感器的传感性能，并列举了其在人体运动监测领域中的应用实例；最后，对基于石墨烯和聚合物的柔性多孔应变传感器面临的挑战和发展前景进行了展望。     

基于高分子导电复合材料的柔性传感材料研究

随着智能机器人、电子皮肤和可穿戴电子器件等新兴领域的高速发展,人们对柔性传感材料需求大幅提升,从而促使柔性传感材料研究得到了迅速发展。基于高分子导电复合材料的柔性传感材料可用作应变、温度及湿度传感器,由于具有柔韧性好、灵敏度高、刺激响应迅速等特性,是柔性传感器的理想材料。系统回顾了基于高分子复合材料的柔性应变传感材料、温度传感材料的传感机理,研究进展及潜在应用,并对目前存在的问题及未来发展趋势进行了讨论。     

不同模式多功能柔性传感器研究进展

柔性传感器能够实现压力、应变、温度、湿度及气体等与人体健康相关信号多功能识别及监测,在可穿戴人工智能设备的开发中展现出巨大的应用前景。本文综述了具有多种模式监测功能的柔性电化学式传感器领域最新研究成果,包括双模式传感器、三模式传感器和多模式传感器;重点介绍了传感器实现多功能监测的途径和传感机理。研究表明,多模式传感性的实现方法主要包括结构设计和多功能材料制备两种。而基于先进功能材料(包括纳米金属、纳米碳及导电聚合物)和柔性基体材料(如水凝胶、气凝胶及弹性聚合物)所制造的柔性多功能复合材料可有效降低多模式传感器的复杂性。最后,对比并指出了不同类型的功能材料在制造多功能柔性传感器中的特点与优势,为多功能柔性传感器的研究提供借鉴意义。     

基于PDMS的柔性压阻式传感器的研究进展

近年来,以聚二甲基硅氧烷(PDMS)为主体材料的柔性压阻式传感器的发展十分迅速,在人体运动及健康监测、电子皮肤、智能机器人等领域中具有广阔的应用前景。本文首先介绍了柔性压阻式传感器的传感机理及主要性能指标,然后重点综述了基于PDMS的柔性压阻式传感器的研究进展,特别是在PDMS与不同导电填料结合制备传感器以及微结构构建两个方面进行了详细阐述,最后指出了当前该领域存在的一些问题,并对其发展方向进行了展望。     

聚氨酯表面形貌调控及其压力传感性能研究

为构筑具有优异传感性能和穿戴舒适性的压力传感器,利用超柔顺聚合物纤维材料制备柔性压力传感纱线与编织型压力传感器。利用水性聚氨酯（WPU）、氧化石墨烯（GO）、碳纳米管（CNTs）和正癸烷（DC）制备具有环状液滴结构的WPU/GO/CNTs/DC复合导电浆料;再制造皮芯型微褶皱结构压力传感纱线（WCPY）,其芯层为传输电极,皮层为导电浆料形成的传感层,组装成编织型柔性压力传感器。研究不同组分比下WCPY形貌、力学性能及器件传感性能。结果表明：在CNTs、GO、DC含量分别为100%、25%及20%时,环状液滴结构尺寸均一,微褶皱结构分布均匀,器件灵敏度最高为71.65 N-1。构筑表面微褶皱结构为制备高性能柔性压力传感器提供新的设计思路。     

基于夹心结构的碳纳米管/石墨烯复合柔性导电纤维的制备及其应用

具有较大检测区域的纤维状柔性导电材料是可穿戴电子产品和电子纺织品等多种柔性器件的重要组成部分。通过在氨纶复丝表面涂覆碳纳米管(CNT)/RGO导电层,继而在导电层外部涂覆弹性聚氨酯(TPU)保护层来制备夹心结构的高度可拉伸和高灵敏度的柔性导电纤维。1D CNT和2D RGO组成的多维导电网络使纤维在具有较大可拉伸性的同时又拥有较大的相对电阻变化(ΔR/R0),将其用作传感器可用工作范围达465%(GF为215. 0)。在与皮肤连接的可穿戴设备领域中具有广阔的应用前景。     

基于碳材料的柔性压力传感器研究进展

柔性压力传感器作为可穿戴电子技术的核心器件,近几年得到广泛的关注。本文综述了国内外高精度碳材料柔性压力传感器的研究进展,包括介绍其传感机理、主要材料(基底材料、活性材料、电极材料)、性能影响因素和优化方法以及在人体运动和健康监测等方面的最新应用。提出以碳基微纳米材料,如炭黑、石墨、碳纳米管、石墨烯等为感应活性材料的柔性压力传感器主要采用压阻和电容式传感机制,其具有高灵敏度和稳定性、宽线性和快速响应等特点,并能够通过控制碳材料的含量或结构来提高传感器性能。但低成本、高性能、低能耗和自驱动仍然是柔性传感器所面临的挑战,新型传感机制、新材料功能化以及柔性器件的整合技术将是未来发展方向。     

高灵敏、可穿戴生物质炭基柔性压力传感材料的制备与性能研究

杜仲残渣(EUR)是杜仲胶提取过程剩余的废弃物,是一种廉价、可再生、环境友好的资源,以其炭化物为导电材料、聚二甲基硅氧烷(PDMS)为柔性基质,制备了廉价、对人体友好的复合柔性压阻式传感材料,并对材料结构以及压敏性进行了表征,测试了该压力传感材料从0到14 k Pa的响应特性。结果表明,在0.3 k Pa应力下具有高的灵敏度(142.1 kPa-1),所制备的CEUR/PDMS材料对应力变化响应稳定并具有良好的耐久性;该复合传感材料对手持不同质量烧杯、手机振动以及书写信号具有良好的响应。该复合材料制备工艺简单、成本低、响应性能优异且对人体无害,在可穿戴和监测人体活动等领域具有广泛的应用前景。     

MXene Reinforced PAA/PEDOT:PSS/MXene Conductive Hydrogel for Highly Sensitive Strain Sensors

Conductive hydrogel has a vital application prospect in flexible electronic fields such as electronic skin and force sensors. Developing conductive hydrogel with significant toughness and high sensitivity is urgently needed for application research. In this work, a strong and sensitive strain sensor based on conductive hydrogel is demonstrated by introducing MXene (Ti3C2Tx) into the micelle crosslinked polyacrylic acid (PAA)/poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) hydrogel network. The functional polymer micelle crosslinkers can dissipate external stress by deformation, endowing the hydrogel with high strength. The combination of MXene both improves the polymer network structure and the conductive pathways, further enhancing the mechanical properties and sensing performance. Resultantly, the flexible strain sensor base on PAA/PEDOT:PSS/MXene conductive hydrogel exhibits excellent sensing performance with a high gauge factor of 20.86, a large strain detection range of 1000%, as well as good adhesion on different interfaces. Thus, it can be used to monitor various movements of the human body and identify all kinds of handwriting, showing great potential into wearable electronics.     

Durable and highly sensitive flexible sensors for wearable electronic devices with PDMS-MXene/TPU composite films

MXenes, as two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides, have very excellent electrical properties and surface activity and are increasingly used in supercapacitors, batteries, electromagnetic interference shielding, and composite materials. Still, the poor stability of MXene when exposed to aqueous oxygen and the poor ability to interact with the polymer matrix have become important factors limiting its’ practical applications. To enhance stability, highly conductive and stretchable Ti₃C₂MXene/TPU sensing elements were prepared by a simple spraying process using thermoplastic polyurethane (TPU) as a substrate, and the sensing elements were encapsulated by polydimethylsiloxane (PDMS) to obtain MXene-TPU/PDMS constructed flexible strain sensors with excellent performance. This strain sensor features low detection limits (less than 0.005%, 0.5 μm), a wide sensing range (0–90%), a short response time (120.1 ms), and excellent durability (>3000 cycles). This strain sensor can be applied to a range of applications such as health detection, motion signals, detection of robot movements, and wearable electronic devices.     

Double Network Hydrogel Sensors with High Sensitivity in Large Strain Range

Owing to their preferable flexibility and facilitation to integrate with various apparel products, flexible sensors with high sensitivity are highly favored in the fields of environmental monitoring, health diagnosis, and wearable electronics. However, great challenges still remain in integrating high sensitivity with wide sensing range in one single flexible strain sensor. Herein, a new stretchable conductive gel-based sensor exhibiting remarkable properties regarding stretchability and sensitivity is developed via improving the ionic conductivity of the PVA/P(AM-AANa) double network hydrogel. Specifically, the strain sensor developed exhibits an excellent elongation of 549%, good fatigue resistance, and recovery performance. Simultaneously, the hydrogel strain sensor shows a high conductivity of 25 mS cm⁻¹, fast response time of 360 ms, and a linear response (gauge factor = 4.75) to external strain (≈400%), which endow the sensor with accurate and reliable capacities to detect various human movements. Integrating the merits of flexibility, environment friendliness, and high sensitivity, the conductive gel-based sensor has promising application prospects in human–machine interfaces, touchpads, biosensors, electronic skin, wearable electronic devices, and so on.     

Flexible and high-sensitivity piezoresistive sensor based on MXene composite with wrinkle structure

Due to the portability, good flexibility and excellent sensing performance, flexible piezoresistive sensors have received great attention in the field of transient electronic skin, intelligent robots and human-machine interaction. However, achieving both high sensitivity and wide sensing range by low-cost and large-scale method still remains a key challenge for developing high performance piezoresistive sensors. Here, a flexible and highly sensitive piezoresistive sensor was designed and realized by combining the 2D MXene material with wrinkle structure. The MXene composite based sensor with wrinkle structure was fabricated by spraying the active material onto the surface of a pre-stretched polyacrylate tape, which is facile, efficient and low-cost. The MXene composite based sensor demonstrates high sensitivity (148.26 kPa⁻¹), wide pressure range (up to 16 kPa), short response time (120 ms) and excellent durability (>13000 cycles). Moreover, benefiting from the extraordinary sensing performance and flexibility, the sensor can detect human physiological signals, monitor intelligent robot postures and map spatial pressure distributions, thus exhibiting great potential in physiological analysis systems, humanoid robotics and biomedical prostheses.     

Highly Stretchable and Sensitive Flexible Strain Sensor Based on Fe NWs/Graphene/PEDOT:PSS with a Porous Structure

With the rapid development of wearable smart electronic products, high-performance wearable flexible strain sensors are urgently needed. In this paper, a flexible strain sensor device with Fe NWs/Graphene/PEDOT:PSS material added under a porous structure was designed and prepared. The effects of adding different sensing materials and a different number of dips with PEDOT:PSS on the device performance were investigated. The experiments show that the flexible strain sensor obtained by using Fe NWs, graphene, and PEDOT:PSS composite is dipped in polyurethane foam once and vacuum dried in turn with a local linearity of 98.8%, and the device was stable up to 3500 times at 80% strain. The high linearity and good stability are based on the three-dimensional network structure of polyurethane foam, combined with the excellent electrical conductivity of Fe NWs, the bridging and passivation effects of graphene, and the stabilization effect of PEDOT:PSS, which force the graphene-coated Fe NWs to adhere to the porous skeleton under the action of PEDOT:PSS to form a stable three-dimensional conductive network. Flexible strain sensor devices can be applied to smart robots and other fields and show broad application prospects in intelligent wearable devices.     

A Flexible and Multipurpose Piezoresistive Strain Sensor Based on Carbonized Phenol Formaldehyde Foam for Human Motion Monitoring

High‐performance flexible strain sensors are extensively studied for various applications including healthcare, robots, and human–computer interaction. In most of the reported research, the fabrication of these sensors involves conductive polymer composites containing expensive metallic or carbon nanomaterials. In this study, commercial phenol formaldehyde foam (PFF) is carbonized by a simple high‐temperature pyrolysis treatment and encapsulated by polydimethylsiloxane (PDMS) to fabricate a flexible and multipurpose piezoresistive strain sensor. The as‐fabricated PDMS‐cPFF strain sensor is capable of detecting various strain modes, including tension, compression, and three‐point bending. Furthermore, the sensor exhibits a high sensitivity with a gauge factor (GF) of ?20.5 under tension and stable signal responses in a frequency range of 0.01–0.5 Hz. The sensor is also capable of accurately monitoring a subtle bending strain of 0.05%. In addition, the sensor shows excellent durability in cyclic loading/unloading tests up to 1000 cycles. The applications of this strain sensor in both large‐ (finger bending and neck movement) and small‐scale human motion monitoring (facial micro‐expression and phonation) are demonstrated, showing its potential for applications in wearable electronics. This work also offers an alternative route to reuse waste thermosetting resins which would otherwise be difficult to recycle.     

Flexible Sandwich Structural Strain Sensor Based on Silver Nanowires Decorated with Self‐Healing Substrate

Flexible and stretchable conducting composites that can sense stress or strain are needed for several emerging fields including human motion detection and personalized health monitoring. Silver nanowires (AgNWs) have already been used as conductive networks. However, once a traditional polymer is broken, the conductive network is subsequently destroyed. Integrating high pressure sensitivity and repeatable self‐healing capability into flexible strain sensors represents new advances for high performance strain sensing. Herein, superflexible 3D architectures are fabricated by sandwiching a layer of AgNWs decorated self‐healing polymer between two layers of polydimethylsiloxane, which exhibit good stability, self‐healability, and stretchability. For better mechanical properties, the self‐healing polymer is reinforced with carbon fibers (CFs). The sensors based on self‐healing polymer and AgNWs conductive network show high conductivity and excellent ability to repair both mechanical and electrical damage. They can detect different human motions accurately such as bending and recovering of the forearm and shank, the changes of palm, fist, and fingers. The fracture tensile stress of the reinforced self‐healing polymer (9 wt% CFs) is increased to 10.3 MPa with the elongation at break of 8%. The stretch/release responses under static and dynamic loads of the sensor have a high sensitivity, large sensing range, excellent reliability, and remarkable stability.     

基于银/石墨烯纳米复合材料的柔性压力传感器——材料制备和微纳结构构建

柔性压力传感器是柔性可穿戴设备的核心部件,在医疗保健、运动健身、安全生产等领域极具应用潜力。二维材料石墨烯具有高载流子迁移率、超大比表面积和超高机械强度,被视为制备柔性压力传感器的优良敏感材料。然而石墨烯碎片引入晶界或堆叠等缺陷,用纯石墨烯制备柔性压力传感器存在灵敏度低、稳定性差、响应范围窄等问题。将零维银纳米颗粒或一维银纳米线与石墨烯构建复合材料,可有效跨越缺陷或搭接相邻片层,起到“桥梁”作用,石墨烯片层平铺到纳米银导电网络之间,起到“补丁”作用。本文综述了用于柔性电阻式压力传感器的银/石墨烯复合材料制备方法和工艺,并介绍了不同微纳结构的传感器构建方法。