A Skin-Inspired High-κ Self-Healing Polymer for Low-Voltage Dielectric Elastomer Actuators

Dielectric elastomer actuators (DEAs), known as a type of artificial muscles, are promising soft actuators with many applications including robotics and wearables due to their conformability, fast response, and large actuation. However, their usage remains constrained by high driving voltages needed to achieve substantial actuation. Here, we design a skin-inspired high-κ self-healing elastomer, poly-(acrylonitrile-co-butadiene)-co-thiourea (PABTU), that features a high dielectric constant (15 at 1 kHz), low Young's modulus (0.58 and 0.012 MPa upon pre-stretch), and ability to form pinhole-free thin films (∼ 3 µm). To mitigate relatively high dielectric loss of our PABTU, PABTU/PDMS-MPU_0.3-IU_0.7 bilayer structure (ULTRA) is used for actuators, increasing its breakdown strength from ∼33 to 43 V/µm. Our ULTRA actuators exhibit visible deformation at an unprecedented low voltage of 30 V and an areal strain exceeding 130% at 120 V, representing an order of magnitude reduction in voltage for actuation compared with previously reported DEAs while achieving similar actuation strain. As proof of concept, we demonstrate a low-voltage multipixel array with ULTRA DEA. Our molecular design concept provides a path for material systems toward low-voltage operating soft robotics.