Design, 3D printing and characterization of a soft actuator with embedded strain sensor

In this paper, one of the most common and inexpensive additive manufacturing, or 3D printing, technology named fused filament fabrication (FFF) has been used to manufacture a sensing soft actuator which in future could be used for hands and fingers rehabilitation. The innovative element of the proposed soft actuator consists of an embedded strain sensor which, as shown during the characterization phase, provides an electrical resistance change when the actuator is actuated by compressed air. The strain sensor has been embedded into the soft actuator during the manufacturing process: the printing process has been stopped, a 3D printed channel has been filled by means of a silver paste and after its solidification, the manufacturing process has been resumed. In this way a smart soft actuator has been fabricated in a single-step printing cycle by taking advantage from the stop-and-go method.