Reliability analysis of silicone-based high-frequency dielectric elastomer actuators: Intrinsic breakdown and carbon nanotube electrode degradation

Abstract This work investigates the reliability of dielectric elastomer actuators (DEAs) based on silicone elastomers and carbon nanotube (CNT) electrodes from two key perspectives: intrinsic dielectric breakdown and long-term reliability associated with CNT electrode stability, particularly under high-frequency actuation. Experimental results reveal that the breakdown behavior is strongly influenced by voltage polarity, waveform, frequency, and material thickness, while high-frequency bipolar voltages result in significant insulation degradation. To facilitate systematic testing, a multi-channel reliability testing platform was developed, enabling continuous monitoring of voltage, current, and breakdown events for multiple DEAs under various conditions. It is found that high-frequency mechanical vibrations can cause CNT detachment from the silicone surfaces, reducing the overlapping area of the top and bottom electrodes to nearly zero. Furthermore, it is demonstrated that actuation current plays a critical role in accelerating DEA performance decline through CNT degradation. Coating encapsulation layers and using relatively higher-areal-density CNT electrodes can substantially enhance long-term reliability. In addition, self-healing current waveforms in the milliamperes range were observed, regardless of whether the electrodes have coated layers or CNT areal densities. These insights offer fundamental guidance for the design and control of DEA systems under sustained high-frequency electrical stress.