基于介电弹性体的风力发电机理及性能分析

设计并研究分析了一种基于介电弹性体发电机的新型风力发电装置，它可以从风能收集装置叶片中嵌入的介电弹性体膜中获取能量。介绍了该系统的能量采集过程，从理论上建立了风致旋转下该系统的电力学模型，然后推导了该系统在旋转运动下的输出电压和电能增量。通过测量所提出系统的输出电压和电能增量，实验验证了理论分析的可操作性。在此基础上，通过Design Expert中的响应面法分析了该系统在模拟环境下的电能增量，研究了激励参数、外内半径比、输入电压参数对能量采集的影响。结果表明，在较大的激励参数和输入电压下，系统表现出较好的能量收集性能，同时增大外内半径比也可提高系统的能量收集性能。在给定激励参数60 mm、输入电压1 000 V和外内半径比为2时，实验结果表明，单个周期内的发电量可达26.61 mJ。研究结果可为介电弹性体的能量收集和发电机设计提供参考。     

一种基于介电弹性体阵列的能量转换装置

设计了一种基于介电弹性体阵列的风力能量转化装置,装置包括风车、曲轴、介电弹性体薄膜、外壳、轴承、夹具、电刷、高压发生器、电缆等。其中,风车的转轴与曲柄连杆的主轴颈连接,连杆轴颈上安装轴承,轴承外侧180°对向设置固定介电弹性体的夹具;介电弹性体另一侧同样使用夹具固定在外壳内表面,设置多段连杆轴颈,始终处于相同拉伸状态的介电弹性体发电单元并联组成一组发电阵列,提高单次发电量。本装置基于单个介电弹性体组成介电弹性体阵列,在1个周期内依次进行电能的转化。实验结果表明,在材料应变量达230%,充电电压为925 V时,单个周期内的发电量可达到17.06 mJ,为介电弹性体阵列大规模发电的应用提供参考。     

EAP换能单元发电量的影响因素分析

电活性聚合物(EAP)作为一种新型电活性软体功能材料,具有多种优点,用于能量收集具有巨大的应用潜力。该文从宏观和微观两个层面阐述了介电材料用于能量收集的机电转化原理,以EAP换能单元为例,说明了EAP换能单元怎样将机械能转化为电能,并阐述了介电弹性体发电机理,为后面EAP换能单元的发电提供理论依据。以其他学者研究得到影响EAP换能单元发电量的因素为基础,通过正交试验得到EAP换能单元发电特性和最佳工作条件,并对试验的可靠性进行了分析。实验结果表明,各因素对EAP材料发电的影响大小顺序为:EAP膜面积>拉伸位移>预加电压>预拉伸率>EAP膜厚度。换能单元最佳工作条件为预加电压1 000 V,预拉伸率400%,拉伸位移4 cm,膜面积62.41 cm~2,EAP膜厚度1 mm。     

基于介电弹性体的海洋能发电装置的研究进展

介电弹性体是一种新型功能材料,其能量收集作用主要应用在低频、大变形的能量源场合,与海洋能发电十分契合。该文描述了介电弹性体发电的基本原理及其材料特性和发电装置电极材料的研究进展。针对目前介电弹性体海洋能发电装置成本高,种类少,能量转换效率低等问题,该文总结了国内外不同类型的基于介电弹性体的海洋能发电装置及研究方案,对不同类型的发电机特点及适用场合进行了分析。结果表明,浮标式和管状水动力式发电机应用前景广。最后阐述了当前介电弹性体在海洋能应用上亟待解决的问题,并对进一步解决上述问题提出了建议。     

介电弹性体驱动器柔性电极技术发展动态

对介电弹性体柔性电极相关研究进行了总结和分析。柔性电极是介电弹性体发电或驱动材料的重要组成部分,其性能直接影响介电弹性体发电机的发电效率以及驱动器的驱动性能。目前,对柔性电极的研究处于起步阶段。本文基于介电弹性体材料的不同用途,分析了碳基电极、碳纳米管电极等几种典型的柔性电极材料的性能、制备工艺及方法。并针对其应用条件的不同,分析了电极材料的应用领域。经过研究分析发现,柔性电极材料需要具备柔性大、导电性高这两点特性,但是目前柔性电极在柔性与导电性上不能兼具,存在贴合度不足、导电性差等问题,需要对柔性电极的材料以及制备工艺进行更加深入的研究。     

基于新型介电弹性体平行板电容器的研究

为了研究具有传感功能的可变电容器,采用新型介电弹性体材料制成平行板电容器。研究了该电容器充放电前后的外形变化及影响电容大小的因素。结果表明:在高压充放电前后,电容器的极板面积和两电极板间距离都发生了明显的变化;电容随着外加电压的增大而增大;在外加电压为6 000 V的条件下,电容随着材料预拉伸的增大出现一极大值,随后又减小,即在变化过程中存在拐点;另外,电容器的电极材料用石墨粉时要比用导电胶时电容大。     

一种双极板结构数字微流控芯片研制

基于介电润湿研制了一种将零电极布局为介电层表面的双极板结构数字微流控芯片.为了降低驱动电压并提高介电层的抗击穿能力,将介电层设计为Si3N4-SiO2层状复合结构.30 V直流电压作用下,成功实现了对0.5 μL去离子水微液滴的连续输运操控;且在100 V以内电压作用时,均未出现介电层击穿.实验结果表明所研制数字微流控芯片可行.     

电活性聚合物发电基本原理及应用研究

剖析了电活性聚合物在静电场中机械能和电能相互转换的内部机理,主要针对电活性聚合物发电原理进行分析研究.在不考虑能量损耗的理想前提下,探讨电活性聚合物在发电过程中3种能量循环过程.最后,采用丹佛斯生产的电活性聚合物(DEAP)材料,建立了电活性聚合物发电机实验装置平台,分析恒电荷状态下收集能量过程.试验验证了电活性聚合物发电原理.实验结果表明,作为新型智能材料的电活性聚合物在发电应用领域前景广阔.     

50Hz交流电控制的可变焦液体透镜

研究了采用"金属导电基底/Parylene介电层/Teflon疏水层"透镜内芯材料的介电上电润湿(EWOD)特性。实验获得了导电液滴分别在直流电(DC)和50Hz交流电(AC)控制下的接触角随电压变化的曲线。实验结果表明,为达到DC电源控制下的液滴的EWOD相同效果,使用低频的AC电压应考虑其瞬时最大值而不是有效值(均方根值)。目前已经制作出基于50Hz交流电控制的可变焦液体透镜并进行加电压变焦实验。给出了该液体透镜的焦距与电压之间的变化曲线,实验结果与上述分析一致。     

基于介电润湿效应的微液滴操控

基于介电润湿的微液滴操控已被众多学者实现,但微液滴接触角在饱和阶段随电压变化的数学关系仍未得到较好解决,为此,基于能量最小化原理对Young-Lippmann方程进行了补充和改进.结合理论计算和数值仿真设计了一种叉齿状驱动电极单元数字微流控芯片,并加工出介电层分别为SiO2及SiO2-Si3N4-SiO2两种结构的芯片.实验结果表明,在接触角饱和阶段,所改进的Young-Lippmann方程能在一定程度上反映微液滴接触角的变化趋势.此外,SiO2-Si3N4-SiO2复合介电层结构中的微液滴操控电压低于SiO2单一介电层中微液滴操控电压.     

Maximizing the Energy Density of Dielectric Elastomer Generators Using Equi‐Biaxial Loading

Dielectric elastomer generators (DEGs) for harvesting electrical energy from mechanical work have been demonstrated but the energy densities achieved are still small compared with theoretical predictions. In this study, significant improvements in energy density (560 J/kg with a power density of 280 W/kg and an efficiency of 27%) are achieved using equi‐biaxial stretching, a mechanical loading configuration that maximizes the capacitance changes. The capacitance of dielectric elastomers subjected to equi‐biaxial stretches is demonstrated to be proportional to the fourth power of the stretch. Quantification of the individual energy contributions indicates that attaining higher conversion efficiencies is limited by viscous losses within the acrylic elastomer, suggesting that still higher conversion efficiencies with other elastomers should be attainable with our novel mechanical loading design.     

Electrical and Mechanical Self‐Healing in High‐Performance Dielectric Elastomer Actuator Materials

Dielectric elastomers are of interest for actuator applications due to their large actuation strain, high bandwidth, high energy density, and their flexible nature. If future dielectric elastomers are to be used reliably in applications that include soft robotics, medical devices, artificial muscles, and electronic skins, there is a need to design devices that are tolerant to electrical and mechanical damage. In this paper, the first report of self‐healing of both electrical breakdown and mechanical damage in dielectric actuators using a thermoplastic methyl thioglycolate–modified styrene–butadiene–styrene (MGSBS) elastomer is provided. The self‐healing functions are examined from the material to device level by detailed examination of the healing process, and characterization of electrical properties and actuator response before and after healing. It is demonstrated that after dielectric breakdown, the initial dielectric strength can be recovered by up to 67%, and after mechanical damage, a 39% recovery can be achieved with no degradation of the strain–voltage response of the actuators. The elastomer can also heal a combination of mechanical and electrical failures. This work provides a route to create robust and damage tolerant dielectric elastomers for soft robotic and other applications related to actuator and energy‐harvesting systems.     

Skin-Mountable Vibrotactile Stimulator Based on Laterally Multilayered Dielectric Elastomer Actuators

Skin-stimulation technology has attracted intense attention for virtual/augmented reality applications and tactile-feedback systems. However, bulky, heavy, and stiff characteristics of existing skin-stimulating devices limit their wearability and comfort, thus disturbing the immersive experience of users. This study presents a new type of thin and lightweight dielectric elastomer actuator for developing a skin-mountable vibrotactile stimulator. A new methodology is suggested to enhance the operating efficiency of dielectric elastomer actuators based on a laterally aligned dielectric multilayer structure (≈900 layer) with short dielectric distance (≈10 µm) and a soft elastomer/ionic liquid composite with low modulus and high dielectric constant. With the improved structural/material properties, the flexible actuator exhibits high displacements at low operating voltage (<200 V) over a wide frequency range (≈800 Hz). Therefore, the finger-band type vibrotactile stimulator based on the laterally multilayered dielectric elastomer actuators can exert indentations that have the ability of stimulating all mechanoreceptors in human skin over the full perception frequency/amplitude range. In addition, the actuator shows a high electromechanical stability for long-term operation due to time-efficient and precise fabrication process using sophisticated photolithography and secondary sputtering. Therefore, this vibrotactile stimulator shows high promise for use in tactile-assistive devices, tactile communications, haptic feedback, and beyond.     

Electric Field-Driven Dielectrophoretic Elastomer Actuators

Dielectrophoresis is the electro-mechanical phenomenon where a force is generated on a dielectric material when exposed to a non-uniform electric field. It has potential to be exploited in smart materials for robotic manipulation and locomotion, but to date it has been sparsely studied in this area. Herein, a new type of dielectrophoretic actuator exploiting a novel electroactive polymer is described, termed as dielectrophoretic elastomer (DPE), which undergoes electric field-driven actuation through dielectrophoresis. Unique deflection and morphing behavior of the elastomer induced by controlling the dielectrophoretic phenomenon, such as out-of-plane deformation and independence of electric field polarity, are illustrated. The dielectric and mechanical properties of the DPE are studied to gain insight into the influence of materials composition on deformation. Actuation performance using different electrode parameters is experimentally investigated with supplementary analysis through finite element simulation, revealing the relationship between electric field inhomogeneity and deflection. The applications of DPE actuators in a range of robotic devices is demonstrated, including a pump, an adjustable optical lens, and a walking robot. This diverse range of applications illustrates the wide potential of these new soft-and-smart electric field-driven materials for use in soft robotics and soft compliant devices.     

Stable and High-Strain Dielectric Elastomer Actuators Based on a Carbon Nanotube-Polymer Bilayer Electrode

Dielectric elastomer actuators (DEAs) have shown promises in numerous applications such as bio-inspired robotics, tactile displays, tunable optics, and microfluidics, owing to their unique combination of large actuation strain, high energy density, and light weight. However, the practical applications of the DEAs have been hindered partly due to their poor reliability and durability under high-strain actuation. A major failure mechanism is from the localized electrical breakdown. Compliant electrodes with self-clearing capability have been studied to prevent premature failures. Here, an interpenetrating bilayer compliant electrode comprising a thin layer of a water-based polyurethane (WPU) overcoated on an ultrathin single-walled carbon nanotube (SWNT) layer is reported. The thin polyurethane layer serves as the dielectric barrier to suppress corona discharges of the nanotubes in air. The SWNT+WPU bilayer electrode has the capability to self-clear at the breakdown sites, enhancing the fault tolerance and mendability of the DEA at a large-strain actuation. Stable actuation at 150% area strain for 1000 cycles under square-wave voltage and 5.5-h continuous actuation at a constant voltage have been achieved for acrylic elastomer-based DEAs.     

双晶片压电材料微型驱动系统研究

在微型机器人应用中,双晶片压电材料作为执行器将电势能转化为机械变形。通常,此类执行器使用庞大而笨重的电源进行激励,因此限制了其应用范围。该文采用级联型抽头变压器(CTI)升压级与高电压驱动级进行级联,设计并研制了具有高能效、高增益双晶片压电材料微型驱动系统。该微型驱动系统能量转换效率峰值为68.5%,升压增益为162倍,且具备输出频率为4Hz,输出电压为600V的驱动能力。实验表明,该微型驱动系统可驱动双晶片压电材料,使其能在微型机器人领域中得到广泛应用。     

Development,characterization, and processing of thin and thick inkjet-printed dielectric films

This work introduces the material and electrical characterization of two dielectric inks for use with inkjet printing fabrication and the realization of fully-printed multilayer electronic structures. The dielectric inks are categorized by the thickness of their per-layer profiles, where SU-8 polymer and poly(4-vinylphenol)-based solutions are utilized to realize thick (>4 μm) and thin (< 400 nm) inkjet-printed dielectric films, respectively. The material formulations for each ink are outlined in detail in order to achieve the desired viscosity and surface tension for optimal printing with a Dimatix inkjet printing system. Once printability and processing techniques are tuned and established, various material and electrical characterizations are performed, including printed profile measurement, multilayer profile tendencies, thermal reflow processing, UV-ozone surface energy modification, relative permittivity extraction, leakage current density, and dielectric breakdown voltage. Finally, the demonstration of fully-printed post-processed on-chip capacitors utilizing both thin and thick dielectric inks in conjunction with a silver nanoparticle-based metallic ink is presented and compared with other inkjet-printed capacitors.     

Stimulating Acrylic Elastomers by a Triboelectric Nanogenerator – Toward Self‐Powered Electronic Skin and Artificial Muscle

Dielectric elastomers are a type of actuator materials that exhibit excellent performance as artificial muscles, but a high driving voltage is required for their operation. By using the amazingly high output voltage generated from a triboelectric nanogenerator (TENG), a thin film dielectric elastomer actuator (DEA) can be directly driven by the contact‐separation motion of TENG, demonstrating a self‐powered actuation system. A TENG with a tribo surface area of 100 cm² can induce an expansion strain of 14.5% for the DEA samples (electrode diameter of 0.6 cm) when the system works stably within the contact‐separation velocity ranging from 0.1 to 10 cm s^?1. Finally, two simple prototypes of an intelligent switch and a self‐powered clamper based on the TENG and DEA are demonstrated. These results prove that the dielectric elastomer is an ideal material to work together with TENG and thereby the fabricated actuation system can potentially be applied to the field of electronic skin and soft robotics.