At high electric fields, the electrical energy stored in a soft elastomer dielectric can be comparable to the mechanical deformation energy it produces. This has led to the development of a class of electrically controlled, large strain dielectric elastomer actuators for soft robotics and energy harvesting devices. At large electric fields, the electro-mechanically induced deformation can lead to pseudo-periodic surface morphological instabilities which then grow with increasing field into stable pre-breakdown defects prior to final, irreversible electrical breakdown. Under these extremes of combined large electrical and mechanical deformations, the morphological evolution of the pre-breakdown defects has not hitherto been reported. In contrast to the filamentary breakdown of much stiffer dielectrics, fluorescence confocal microscopy reveals an array of defects that evolve through a complex, reversible series of morphologies, transitioning from axi-symmetric “pits” to “crack-like” shapes that can “twist” and deflect, and finally open to form an array of holes. The observations suggest that the transitions, from axi-symmetric pits to flat, slit-like defects and then to an array of holes, are geometric instabilities. The implications for using a soft elastomer layer to increase the dielectric breakdown of a stiffer dielectric are discussed.

在高电场下，储存在软弹性体电介质中的电能与其产生的机械变形能相当。这导致开发了一类用于软机器人和能量收集设备的电控大应变介电弹性体致动器。在大电场下，机电诱发的变形会导致伪周期表面形态不稳定性，然后随着场的增加，在最终的不可逆电击穿之前变成稳定的预击穿缺陷。在这些极端的大电气和机械变形组合下，击穿前缺陷的形态演变迄今尚未报道。与更硬的电介质的丝状击穿相反，荧光共聚焦显微镜揭示了一系列缺陷，这些缺陷通过一系列复杂的、可逆的形态演变，从轴对称的“凹坑”转变为可以“扭曲”和偏转的“裂纹状”形状，最后打开形成一系列孔。观察结果表明，从轴对称凹坑到平坦的狭缝状缺陷，然后到一系列孔的转变是几何不稳定性。讨论了使用软弹性体层来增加较硬电介质的介电击穿的影响。狭缝状缺陷，然后形成一系列孔洞，是几何不稳定性。讨论了使用软弹性体层来增加较硬电介质的介电击穿的影响。狭缝状缺陷，然后形成一系列孔洞，是几何不稳定性。讨论了使用软弹性体层来增加较硬电介质的介电击穿的影响。