Design and characterization of additive manufactured pressure-driven extensile soft actuators with a stackable bistable architecture

Soft materials and structures enable large motions and complex stability profiles through careful geometric designs that are useful for many soft robotics applications. Advancements in additive manufacturing have simplified the fabrication of novel structures with complex geometries, continuing the path to unlocking the full potential of soft structures. In this work, we develop and characterize single print pressure-driven linear extensile soft robotic actuators with a stackable bistable architecture. The actuators are designed through a two-step design process consisting of physical iterations and simulations. Force-displacement characterizations quantify the stackable bistable response of the actuators. The effects of the number of segments with blocked and free-displacement boundaries are discussed in detail for different starting states. Actuator performance is compared to actuators of similar morphologies from the literature. This work provides a recipe for the simple design and fabrication of stackable bistable soft actuators for improved functionality in soft robotic systems.