A large-strain and ultrahigh energy density dielectric elastomer for fast moving soft robot.

Dielectric elastomer actuators (DEAs) with large actuation strain and high energy density are highly desirable for actuating soft robots. However, DEAs usually require high driving electric fields (>100 MV m -1 ) to achieve high performances due to the low dielectric constant and high stiffness of dielectric elastomers (DEs). Here, we introduce polar fluorinated groups and nanodomains aggregated by long alkyl side chains into DE design, simultaneously endowing DE with a high dielectric constant and desirable modulus. Our DE exhibits a maximum area strain of 253% at a low driving electric field of 46 MV m -1 . Notably, it achieves an ultrahigh specific energy of 225 J kg -1 at only‍‌ ‌‌40‍‌ MV m -1 , around 6 times higher than natural muscle and twice higher than the state-of-the-art DE. Using our DE, soft robots reach an ultrafast running speed of 20.6 BL s -1 , 60 times higher than that of commercial VHB 4910, representing the fastest DEA-driven soft robots ever reported.