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Novel electrode-elastomer combinations for improved performance and application of dielectric elastomers.

机译：新型电极-弹性体组合可改善介电弹性体的性能和应用。

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摘要

Dielectric elastomers are the most promising technology for mimicking human muscles in terms of strain, stress, and work density, etc. Actuators have been fabricated based on different design concepts and configurations for applications in robotics, prosthetic devices, medical implants, pumps, and valves. However, to date these actuators have experienced high rates of failure caused by electrical shorting of the compliant electrodes through the elastomer film during electrical breakdown, which has prevented their practical application.;In this thesis, single walled carbon nanotube (SWNT) thin films were employed as compliant electrodes for dielectric elastomers to reduce the rate of failure. Thanks to the high aspect ratio of the SWNTs, the electrodes maintain substantial conductance at high biaxial strains. 3M VHB acrylics can be actuated up to 200% area strain with SWNT electrodes, this matches the performance of actuators with carbon grease electrodes. During uni-directional stretching, SWNT electrodes can maintain surface conductivity up to 700% linear strain.;SWNT electrodes can experience a self-clearing process under high voltage discharging and electrically isolate the electrodes around the breakdown sites when breakdown events happen. With conventional dielectric elastomer electrode materials such as carbon grease and carbon black, a single breakdown event results in a permanent loss in the actuator's functionality. In contrast, for SWNT electrodes, the SWNTs around the breakdown site will be degraded and become non-conductive. The non-conductive area expands outward until the high voltage discharging stops. As such, the opposing electrodes are prevented from coming into contact with each other and forming an electrical short and the breakdown site is electrically isolated from the remainder of the active area. Despite the existence of the breakdown sites, the dielectric elastomer will resume its functionality and avoid permanent failure. Thus, dielectric elastomers with self-clearable SWNT electrodes will be self-healable.;Due to the non-uniform surface morphology of SWNT thin films as well as their low turn-on voltage for field emission, corona discharging tends to occur on the electrode surface, even without the presence of a breakdown site through the film. The corona discharging will damage the SWNT electrodes, especially in the regions where the nanotube density is low. This in turn causes the dielectric elastomer to gradually lose its function. By applying a thin coating of dielectric oil on the SWNT electrodes, the corona discharging will be quenched. Dielectric elastomers with self-clearable SWNT electrodes combined with a dielectric oil coating show much longer lifetime and more stable operation.;Thus, the SWNT self-clearable electrodes endow dielectric elastomers with fault-tolerance, high dielectric breakdown strength and long lifetime actuation. For examples, VHB acrylic elastomer can achieve 340 V/mum dielectric strength and 20x longer actuation. A dielectric strength of 270 V/mum and longer than 300 minutes of continuous actuation with 50% area strain have also obtained with silicone elastomers. This addition of self-clearable fault-tolerant electrodes to dielectric elastomers transducers improves the manufacturing yield and operational reliability of these artificial muscles and pushes them closer to commercialization.
机译：介电弹性体是在应变，应力和工作密度等方面模仿人体肌肉的最有前途的技术。执行器是根据不同的设计概念和配置制造的，用于机器人技术，修复设备，医疗植入物，泵和阀门。然而，迄今为止，这些致动器经历了很高的故障率，这是由于在电击穿过程中柔性电极通过弹性体膜的电短路引起的，这阻碍了它们的实际应用；在本论文中，单壁碳纳米管（SWNT）薄膜被用于用作介电弹性体的顺应性电极，以降低故障率。由于SWNT的高长宽比，电极在高双轴应变下保持了相当大的电导率。 3M VHB丙烯酸树脂可通过SWNT电极驱动高达200％的面积应变，这与碳脂电极的驱动器性能相匹配。在单向拉伸过程中，SWNT电极可保持高达700％的线性应变的表面电导率。SWNT电极在高压放电下会经历自清除过程，并在发生击穿事件时将击穿部位周围的电极电隔离。使用传统的介电弹性体电极材料（例如碳脂和碳黑），一次击穿事件将导致执行器功能的永久性丧失。相反，对于SWNT电极，击穿部位周围的SWNT将退化并变得不导电。非导电区域向外扩展，直到高压放电停止。这样，防止了相对的电极彼此接触并形成电短路，并且击穿部位与有源区域的其余部分电隔离。尽管存在击穿部位，电介质弹性体仍将恢复其功能并避免永久性故障。因此，具有自清除SWNT电极的介电弹性体将具有自修复性；由于SWNT薄膜的表面形态不均匀以及用于场发射的导通电压低，电极上容易发生电晕放电表面，即使没有贯穿薄膜的击穿部位。电晕放电将损坏SWNT电极，尤其是在纳米管密度较低的区域。这进而导致介电弹性体逐渐失去其功能。通过在SWNT电极上涂一层薄薄的绝缘油，电晕放电将被终止。带有自清除SWNT电极的电介质弹性体与电介质油涂层相结合，显示出更长的使用寿命和更稳定的操作;因此，SWNT自清除电极赋予电介质弹性体以容错性，高介电击穿强度和较长的使用寿命。例如，VHB丙烯酸弹性体可以达到340 V / um的介电强度，并且驱动时间延长20倍。硅氧烷弹性体还获得了270 V / m2的介电强度，并且连续致动时间超过300分钟，且面积应变为50％。在介电弹性体换能器中增加了可自我清除的容错电极，从而提高了这些人造肌肉的制造良率和操作可靠性，并使它们更接近于商业化。

著录项

  • 作者

    Yuan, Wei.;

  • 作者单位

    University of California, Los Angeles.;

  • 授予单位 University of California, Los Angeles.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 124 p.
  • 总页数 124
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:36:55

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