Dielectric oil coated single-walled carbon nanotube electrodes for stable, large-strain actuation with dielectric elastomers

Abstract

Dielectric elastomers have shown remarkably large actuation strain and energy density. A wide range of novel applications have been conceptualized, but commercial devices have not materialized due to the high rates of failure during high-strain actuation. We report that the use of single-walled carbon nanotube (SWNT) layers with thicknesses in the tens of nanometers as the compliant electrodes in combination with dielectric oil can prolong the actuation durability by at least one order of magnitude. Even though the ultrathin SWNT electrodes can undergo localized self-clearing in the event of electrical breakdown, effectively deactivating the fault and enabling self-healing of the device, extended duration actuation at strains larger than 100% in area cannot be achieved. This is due to corona discharge of the highly porous SWNT electrodes that have sharp tips that amplify the electric field. We show that by applying a dielectric oil coating on the SWNT electrodes, the corona discharging is quenched and continuous actuation at larger than 150% strain for longer than 1500 min can be achieved. The combination of self-clearable SWNT electrodes with dielectric oil coating should improve the manufacturing yield and operational reliability of dielectric elastomer artificial muscles and push them closer to commercialization.