Embedded Conductive Fiber for Pumpless Liquid–Gas Phase Transition Soft Actuation

Soft pneumatic actuators are widely used in diverse robotic applications due to their dexterous deformation and conspicuous performance. However, the control and operation of these actuators were restricted by bulky, noisy, and vibrating pneumatic systems. This work introduces a pumpless pneumatic actuator design based on liquid-gas phase transition, named electroconductive fiber-reinforced phase transition actuators (E-FPTAs). Conductive fibers are embedded into the elastomer matrix as flexible heating circuits and morphing programming elements. The E-FPTA generates a high actuation strain of 120% with a low power input of 12 W, showing comparable performance to pump-driven pneumatic actuators. By mechanically programming fiber patterns, the motion type of the E-FPTA can be changed to extending, contracting, twisting, bending, and helical motion, which can be applied for various application scenarios. The E-FPTA is integrated into an octopus-inspired soft gripper and demonstrates multimode grasping in diverse objects. A pumpless robotic glove with eight independent finger joint motions without any pneumatic components is also prototyped. The E-FPTA combines the large deformation of soft pneumatic actuators and the concise structures of the electroactive polymer actuator, which provides a design insight for soft actuations.