Zero‐Power Shape Retention in Soft Pneumatic Actuators with Extensional and Bending Multistability

Abstract

Power‐free shape retention enables soft pneumatic robots to reduce energy cost and avoid unexpected collapse due to burst or puncture. Existing strategies for pneumatic actuation cannot attain motion locking for trajectories combining extension and bending, one of the most common modes of operation. Here, a design paradigm is introduced for soft pneumatic actuators to enable zero‐power locking for shape retention in both extension and bending. The underpinning mechanism is the integration of a pneumatic transmitter and a multistable guider, which are programmed to interact for balanced load transfer, flexural and extension steering, and progressive snapping leading to state locking. Through theory, simulations, and experiments on proof‐of‐concept actuators, the existence of four distinct regimes of deformation is unveiled, where the constituents first interact during inflation to attain locking in extension and bending, and then cooperate under vacuum to enable fully reversible functionality. Finally, the design paradigm is demonstrated to realize a soft robotic arm capable to lock at desired curvature states at zero‐power, and a gripper that safely operates with puncture resistance to grasp and hold objects of various shapes and consistency. The study promises further development for zero‐power soft robots endowed with multiple deformation modes, sequential deployment, and tunable multistability.

Triple-Responsive Soft Actuator with Plastically Retentive Deformation and Magnetically Programmable Recovery

“…1−3 Different from traditional rigid actuators, the softness and high deformability of soft actuators enable them to morph the body, easily reconfiguring and deforming around object contours. 4,5 Thus far, substantial efforts have been devoted to developing the driving methods of actuators, including temperature, 6 light, 7 pH, 8 humidity, 9 and electric 10 and magnetic fields. 11 Among various types of stimulation, magnetically controlled soft actuators possess great potential for biomedical applications due to their fast response and contactless control performance.…”

“…Soft actuators have attracted much attention due to their effective applications in biomedicine, long-distance transportation, underwater detection, camouflage, and perception technology. − Different from traditional rigid actuators, the softness and high deformability of soft actuators enable them to morph the body, easily reconfiguring and deforming around object contours. , Thus far, substantial efforts have been devoted to developing the driving methods of actuators, including temperature, light, pH, humidity, and electric and magnetic fields . Among various types of stimulation, magnetically controlled soft actuators possess great potential for biomedical applications due to their fast response and contactless control performance. − However, traditional magnetically responsive soft robots require the use of three-dimensional magnetic fields to control their motion, which greatly limits their practical applications.…”