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.