Design and development of soft active material based actuator

Abstract

Soft active materials have emerged as an increasingly important category of functional engineering materials due to their ability to undergo large, reversible deformations in response to external stimuli such as pneumatic pressure, temperature change, and applied electric fields. Among the various classes of soft active materials, silicone-based elastomers have found widespread application in soft pneumatic actuators owing to their excellent flexibility, biocompatibility, chemical inertness, and ability to recover from large strains without permanent deformation. These properties make silicone-based soft pneumatic actuators particularly attractive for soft robotic systems that must interact safely and adaptively with humans, biological tissues, and irregularly shaped objects.

In the present work, a soft pneumatic actuator is designed, fabricated, and numerically analyzed as the fundamental building unit of a soft robotic gripper. The actuator consists of 11 identical pneumatic chambers (each 7 mm x 15 mm x 15 mm) embedded within a flexible silicone body with 2 mm thick chamber walls and a 2.5 mm x 2.5 mm central air channel. The bending motion of the actuator is driven by geometric asymmetry between the expandable upper chamber layer and the relatively inextensible base layer, which contains an embedded paper layer to restrict elongation on the lower surface. When internal air pressure is applied, this asymmetry generates differential strain across the cross-section of the actuator, resulting in a well-controlled bending motion toward the constrained side.