Design, Fabrication, and Characterization of a Temperature-Sensitive Fluid-Driven Soft Actuator

Typical soft actuators can perform unidirectional bending between pressurized and loose states. Multidirectional motion commonly requires multiple chambers or the bundling of multiple unidirectional actuators. If multidirectional motion can be achieved with a simple mechanism, it will provide considerable flexibility in designing objects such as grippers or wearable devices. Here, we present a new design for a multidirectional soft actuator that uses a combination of a temperature-sensitive material (TSM) and a non-temperature-sensitive material (NTSM). The actuator consists of a fluid chamber, and the bending is controlled by the temperature and pressure of the working fluid to balance the stiffness between the TSM and NTSM. In this study, the concept, design, and fabrication method are introduced, and the basic characteristics are discussed through experiments and modeling using a prototype actuator. The results of the static analysis of the curvature and curve fitting based on the model show that actuator bending in a static state can be represented by a simple linear-spring model. We also discuss the features, potential, and applications of the actuator by demonstrating its grasping capabilities.