Ultrathin and Highly-Stable rubber electrodes based on Island-Bridge Multi-Filler conductive network for Multilayer-Stacked dielectric elastomer artificial muscles

Dielectric elastomer actuators (DEAs) have shown great promise in applications ranging from millimeter-sized haptic feedback to centimeter-scaled soft robots. However, past progress has been focused on the soft dielectric elastomers, and little attention has been paid to the compliant electrodes. Being stable to maintain conductive while enduring repeated large deformations and compliant to avoid stiffness increasing remains challenging. Moreover, the complex fabrication of multilayer DEAs is hindering their practicality. Herein, an ultrathin (similar to 500 nm, after pre-stretching) and highly stable acrylate rubber electrode based on a unique island-bridge multi-filler conductive network is developed with outstanding electrical conductivity of 2.7 S cm(-1), excellent stretchability of over 1200 %, and superior cycling stability of 500,000 cycles at 30 % uniaxial strain. An efficient stacking method based on a conductive and dielectric layer co-stretching (CDCS) approach is proposed for assembling multilayer-stacked DEAs. The 5-layer DEA reaches a large actuation strain of > 17 % for lifting a 1-kg load and can serve as biceps muscle to drive an artificial lower arm by a maximum rotation angle of 8 degrees, demonstrating its potential in actuating humanoid robot in an essentially soft way. This conductive rubber electrode and CDCS method are promising for developing muscle-like actuators and soft robotics.