PVDF压电薄膜的应变传感特性研究

PVDF压电薄膜是一种重要的智能材料。本文理论分析了智能材料——PVDF压电薄膜的应变传感机理；研究了PVDF应变传感器的制作与布设工艺；试验研究了PVDF传感元件在准静态和动态响应下的传感特性．得到了PVDF传感元件的电压灵敏度，并分析了PVDF压电薄膜的尺寸对灵敏度的影响。研究结果表明：PVDF传感器具有灵敏度高、线性度好、制作与布置工艺简单、面监测等优点．适用于土木工程结构的健康监测。     

聚丙烯腈纤维导电填料的制备与性能研究

研究了采用化学镀法和电镀法制备的聚丙烯腈（ＰＡＮ）纤维导电填料，对导电纤维填料的导电性、镀层结合强度以及与树脂复合中的填料量、纤维表面处理、混炼时间等做了较深入的研讨。     

PVA/EG导电水凝胶及其应变传感性能

作为柔性传感器的优良材料,导电水凝胶在人体可穿戴设备领域具有广泛的应用前景。将水凝胶基底聚乙烯醇(PVA)与乙二醇(EG)混合,制备了几种不同PVA质量比的PVA/EG导电水凝胶。针对10%、20%、30%PVA/EG水凝胶进行了结构和形态的表征,其中20%PVA/EG水凝胶的相对背景强度和晶体含量较高,且表面孔隙最多。通过万能材料试验机对20%PVA/EG导电水凝胶试样进行拉伸和压缩,测试了灵敏度、线性度、响应时间、稳定性和温度可靠性等传感性能。结果表明,导电水凝胶灵敏度系数最高达到0.74,线性相关系数达到0.987,响应时间低至80 ms, 50次15%循环拉伸时的相对电阻变化基本恒定,且试样在-20℃低温下仍可正常工作。最后,将导电水凝胶试样粘贴在手指、脊椎和足部等人体不同部位,进行了运动试验,验证了该导电水凝胶在各类人体运动监测中的可行性。     

3D打印聚吡咯纳米管/聚二甲基硅氧烷应变传感复合材料的制备与性能

柔性电阻式应变传感器作为柔性传感器中重要的一类,具有柔性好、结构简单、数据读取便捷等优点,在多个领域中已有广泛应用。现有研究中,用于填充型应变传感器复合材料的导电填料多以金属导电粉末和碳系导电粉末为主,较少有单独使用导电聚合物的报道。本文以甲基橙（MO）为掺杂剂,无水三氯化铁（FeCl3）为氧化剂,通过化学氧化法聚合制得聚吡咯纳米管（PPy-N）,电导率高达121.70 S·cm^-1。以PPy-N为导电填料和增稠剂,聚二甲基硅氧烷（PDMS）为基体,通过机械共混制成打印墨水,采用直写式3D打印机和智能流变仪表征墨水的可打印性和流变性能;采用SEM、智能拉伸机、数字万用表、DSC等仪器对3D打印固化后的试样进行表征和性能测试,研究PPy-N的浓度对PPy/PDMS复合材料微观形貌、电学性能、力学性能、差热性能、动态热力学性能和应变传感性能的影响。结果表明：PPy-N浓度达到5.98wt%～7.56wt%时,墨水具有良好的打印能力。其中5.98wt%的墨水在连续20层打印测试中表现出优异的打印性能,所打印哑铃型拉伸试样在单一拉伸测试中的抗拉强度和断裂伸长率可达3.02 MPa和178.64%,敏感因子（GF）高达36.14;在100次循环拉伸测试中具有较低的电阻信号峰值稳定系数（α=1.714）和肩峰比例（Psp=9.8%）,在1 000次循环拉伸测试中表现出较好的耐久性和稳定性。用该墨水所制备的人体皮肤传感贴片在对手指、手腕、手肘和膝盖关节的运动监测中具有良好的信号稳定性和可重复性,证明了3D打印PPy-N/PDMS复合材料在柔性电子、可穿戴设备和人体运动监测领域中具有一定的应用前景。     

压阻式柔性应变传感器研究进展

在信息时代,传感器已渗透到各个领域。压阻式柔性应变传感器因其优良的柔韧性、可拉伸/弯曲性以及在异形物体表面的“随形”贴合性,在智能穿戴、人机交互、结构服役过程监测等领域发挥了重要作用。压阻式柔性应变传感器一般有填充式、夹层式和吸附式三种结构,三种结构在制备复杂程度、重复性及传感性能等方面均有差异。研究者们多采用传统方法实现结构构筑,但传统方法普遍存在操作复杂、成本高、重复性差等问题,而采用新兴的3D打印技术可以高效、高精度、可重复地构筑传感结构,赋予了传感器更大的发展空间。在构筑压阻式柔性应变传感器时需采用柔性基体材料和导电填料,构筑得到的传感器主要有裂纹扩展、导电网络断开和隧穿效应三种传感机制,传感机制的形成与传感器的微观结构和材料有关。另外,压阻式柔性应变传感器的传感性能通常通过灵敏度、传感范围、耐久性等参数来表征,而如何兼具多项优异性能是目前的研究热点。同时,压阻式柔性应变传感器的配套器件和技术是限制其发展的主要因素,尤其是在供电和信号传输方面。本文归纳了压阻式柔性应变传感器在材料选择、结构构筑、机理探索、性能优化、应用开发等方面的研究进展,分析了压阻式柔性应变传感器目前所面临的...     

柔性可拉伸硅橡胶@多壁碳纳米管/硅橡胶可穿戴应变传感纤维

基于核-壳结构设计,采用简便、低成本的浸涂-固化法制得柔性、可拉伸、高灵敏且稳定的聚二甲基硅氧烷硅橡胶@多壁碳纳米管/聚二甲基硅氧烷硅橡胶(PDMS@MWCNTs/PDMS)压阻式应变传感纤维。通过FTIR、XRD、TG、TEM对硅烷偶联剂改性多壁碳纳米管(MWCNTs-KH570)的化学结构、热稳定性和微观形貌进行了分析,深入研究了核-壳结构与MWCNTs-KH570质量分数对PDMS@MWCNTs/PDMS复合纤维导电性能、传感性能及力学性能的影响规律与机制。结果表明:羟基化MWCNTs(MWCNTs—OH)表面接枝KH570使其在壳层PDMS基体中具有良好的分散性和界面相互作用;核-壳结构的设计使PDMS@MWCNTs/PDMS复合纤维在低填充下具有高电导率和传感性能;PDMS@MWCNTs/PDMS复合纤维的导电性能与传感性能随着MWCNTs-KH570质量分数增加而提高,且在人体关节运动监测中表现出良好的可重复性和工作稳定性。     

光纤布拉格光栅应变与温度传感特性及其实验分析

对光纤布拉格光栅应变与温度传感特性进行了分析,理论计算了波长变化对传感系数的影响,提出了光纤光栅应变传感的温度补偿方法,并理论分析了光纤光栅温度和应变传感的耦合作用,最后,通过材料实验与等强度梁实验研究与分析了光纤光栅的应变与温度传感特性。理论分析与实验结果表明,两者吻合很好,光纤光栅的波长变化与应变和温度存在很好的线性关系,波长变化对传感系数的影响很小。     

纳米碳纤维复合材料的电阻-应变传感性能研究

制备了不同含量的纳米碳纤维，环氧树脂复合材料试样，采用三点弯曲法测试了复合材料的电阻．应变行为．结果表明，纳米碳纤维，环氧树脂复合材料具有良好的电阻．应变行为，且当纳米碳纤维含量为4％～6％（质量分数）时，电阻．应变呈线性变化，复合材料的传感性能最为优异．     

ABS/不锈钢纤维/石墨导电复合材料的导电特性?

以丙烯腈/丁二烯/苯乙烯共聚物(ABS)为基体,不锈钢纤维(SSF)和石墨为混杂导电介质制备了ABS/不锈钢纤维/石墨0-1-3复合体系。采用动态机械分析(DMA)、数字万用表和旋转流变仪等研究了复合材料的导电渗流行为、流变渗流特性的关联性及在DMA多频应变模式-动态微力场下的阻温特性与导电机理。结果表明,石墨的加入可明显提高复合体系的渗流导电能力;复合体系的导电渗流与流变渗流的渗滤阀值相近,均约为15％;在动态交变微载荷下,电阻率强烈的依赖于振动频率和温度,随着温度的升高,出现电阻正温度效应(PTC)和电阻负温度效应(NTC);且频率越高,SSF含量越低,复合体系的 PTC转变温度越高。     

TiO_2/PA纤维的导电性能研究

设计制备了导电TiO2材料,使用(NaPO3)6对其进行表面活性处理,并与聚酰胺(PA)混合造粒,再经熔融纺丝制备了一种白色导电纤维。测试表明经处理的导电TiO2材料可以很好地分散于PA基体中且相容性良好,纺出的纤维具有良好的导电性能。对其导电机理进行了研究,结果表明当导电TiO2含量7%时属于隧道导电,含量为10%~13%时属于隧道导电和欧姆导电组合导电,含量13%时以欧姆导电为主。     

Strain sensing behavior of electrically conductive fibers under large deformation

Electrically conductive fiber/yarn/fabric is one of the promising materials as flexible conductive sensors because of their sensitivity to strain, temperature and humidity. Aiming at developing of effective flexible sensors, this study investigates experimentally the strain sensing behavior of PPy (polypyrrole)-coated Lycra fibers, showing that the electrically resistance of the conductive fibers changes with the deformation of fibers. The variation in electrically resistance is mainly related to the micro-cracks appearing on the fiber surface during deformation. Then, the effects of the characteristic parameters of the micro-cracks are studied statistically by means of image processing functions in MATLAB, and the governing parameters are determined. Based on the results, a model is built to describe the variation of electrical resistance by the parameters of the micro-cracks. The analytical results are compared with the experimental results, showing an acceptable agreement.     

Layer-by-layer assembly of chitosan and carbon nanotube on cotton fabric for strain and temperature sensing

Layer-by-layer(LBL)assembly shows great potential in fabrication of flexible conductive cotton fabrics(FCCF)with carbon nanotubes(CNT)as conductive components but is limited because complicated chem-ical modification of CNT is usually required.Herein,we reported a facile and eco-friendly LBL approach to fabricating FCCF by dipping in chitosan(CS)aqueous solution and poly(sodium 4-styrenesulfonate)(PSS)wrapped CNT aqueous dispersion alternately.The FCCF with electrical conductivity higher than 30 S/m was achieved when 4 layers of CNT were coated on the cotton fabric(CF).The obtained FCCF possessed outstanding mechanical stability with electrical resistivity almost unchanged after exposure to 500 times mechanical abrasion and 500 circles of tape peeling.The FCCF showed excellent strain sensing perfor-mance with high sensitivity(with a gauge factor up to 35.1)and a fast response time(70 ms).It can be used as a strain sensor to accurately detect various human deformations such as finger bending and joint movements.The FCCF could be used as a temperature sensor in that it exhibited stable and reproducible negative temperature sensing behavior in the temperature range of 30-100 ℃.     

基于激光直写的柔性天线传感器研究

激光直写是一种高效、可规模化制备柔性电子器件的技术。本文采用激光直写技术在具有良好介电性能的聚酰亚胺薄膜上制备了一种可用于应变传感和湿度传感的柔性环形天线传感器。利用激光碳化聚酰亚胺获得的材料表面呈现多孔及堆叠片层碳结构,当施加于天线上的应变和环境湿度改变时,天线的谐振频率会发生规律变化,进而实现应变和湿度感知。制备的环形天线传感器的应变响应灵敏度为?8.943 kHz/με,湿度响应灵敏度为?6.45 MHz/RH%。采用激光直写技术制备的天线传感器可以广泛应用于结构健康监测等领域。     

Aramid fibers; a multifunctional sensor for monitoring stress/strain fields and damage development in composite materials

A multifunctional non-destructive technique, based on the Raman response of aramid fibers, is employed for (a) assessing the interface integrity and the overall stress distribution in a unidirectional Kevlar 29^®/epoxy composite (b) measuring the stress concentration and its development with applied load in Kevlar 49^®/epoxy composites incorporating a circular notch and finally, (c) determining the strain arising in 0° plies due to partial and full crack growth within the θ° plies in multidirectional 0°/θ°/0° composites. It is shown that this technique can be used effectively to study the damage development in composite materials that arise from the presence of different length scale discontinuities.     

分布式光纤传感技术应变测量试验研究

基于布里渊散射原理的布里渊光时域反射技术利用布里渊散射光的光谱技术和光时域测量技术,可对光纤沿线的温度、应变进行分布式监测。通过试验研究了分布式光纤传感技术在应变测量中的空间分辨率、应变分辨率、应变测量精度。研究结果表明,分布式光纤传感技术应变测量能够较准确地测得被测量结构上任何一点的应变,空间最小分辨率0.1m,应变测量分辨率和精度满足工程监测要求,可以在工程监测中作为一种新型分布式应变监测技术加以推广。     

Comparative study on early stages of film growth for transparent conductive oxide films deposited by dc magnetron sputtering

Early stages of film growth were investigated on three different kinds of representative transparent conductive oxide films including tin doped indium oxide (ITO), indium zinc oxide (IZO) and gallium doped zinc oxide (GZO) films deposited on unheated alkali free glass substrates by dc magnetron sputtering. The variations in sheet resistance, film coverage and average surface roughness showed clearly that ITO and GZO films possessed Volmer-Weber growth mode. In contrast, the evolution of islands is not clearly observed for IZO film. The nucleation density of IZO film is considered to be much higher than that of ITO and GZO films.     

Comparative study of nanoparticle effects on feedstock behavior for injection molding

Rheological properties of bimodal feedstocks containing nano- and micro-particles were studied. To examine nanoparticle effects, five feedstocks were prepared with the nanoparticle contents from 0 to 75 vol. %. Each feedstock was formulated with the optimal amounts of the powders, determined from the critical solids loadings of the powders. Viscosity measurement of the feedstocks was performed using a capillary rheometer. From the result, the flow behavior index and flow activation energy were obtained as representative rheological parameters. The moldability index for each feedstock was also calculated and compared. Some bimodal feedstocks showed lower viscosity than microfeedstock due to the roller bearing effect of the nanoparticles. The rheological parameters indicated the bimodal feedstocks were more desirable for mold filling except for 75% nano-bimodal feedstock. The results revealed 25% nano-bimodal feedstock showed the highest moldability index and was the most desirable feedstock to prepare a green body via nano/micro-bimodal powder injection molding.     

Comparative study of strain rate effects on mechanical properties of glass fibre-reinforced thermoset matrix composite

The tensile dynamic behaviour of glass fibre-reinforced phenolic and polyester resins has been determined in order to find the influence of strain rate on the mechanical properties of composite materials produced by the resin transfer moulding (RTM) and pultrusion processes. Data and experimental test systems from the literature are analysed. A new specimen design is created and validated using drop-weight dynamic tests. The dynamic elastic modulus and strength tend to increase in an important ratio for the majority of the materials studied. The shear modulus measured with off-axis and ±45° coupons produces different effects as a function of strain rate. The influence of the reinforcement structure is emphasized and shown to be effective.     

多点感温式液位传感器的研究

液位测量的方法很多,针对传统液位传感器难以实现准确可靠的液位测量,提出了一种多点感温式液位传感器。它是基于发热体在气(汽)体和液体中放热系数差异显著的特点,设计的一种变液位测量为温差测量的传感器。实验表明,研制的多点感温式液位传感器原理正确,结构可行,性能可靠,可承受高温、高压,能够准确地判断出液气(汽)界面,有必要推广到压力容器内应用。