Soft actuators that execute diverse motions have recently been proposed to improve the usability of soft robots. Nature-inspired actuators, in particular, are emerging as a means of accomplishing efficient motions based on the flexibility of natural creatures. In this research, we present an actuator capable of executing multi-degree-of-freedom motions that mimics the movement of an elephant’s trunk. Shape memory alloys (SMAs) that actively react to external stimuli were integrated into actuators constructed of soft polymers to imitate the flexible body and muscles of an elephant’s trunk. The amount of electrical current provided to each SMA was adjusted for each channel to achieve the curving motion of the elephant’s trunk, and the deformation characteristics were observed by varying the quantity of current supplied to each SMA. It was feasible to stably lift and lower a cup filled with water by using the operation of wrapping and lifting objects, as well as effectively performing the lifting task of surrounding household items of varying weights and forms. The designed actuator is a soft gripper that incorporates a flexible polymer and an SMA to imitate the flexible and efficient gripping action of an elephant trunk, and its fundamental technology is expected to be used as a safety-enhancing gripper that requires environmental adaptation.

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BackgroundTo date, much research has been conducted to measure needle manipulation quantitatively and objectively. This study was performed to quantitatively measure the differences in the amount of stimulation caused by various rotation frequencies and angles in twisting–rotating acupuncture needle manipulation.MethodsThe torque Z force exerted on a tissue was measured at various rotation frequencies and angles by rotating a needle with a needle force measurement system attached to a needle insertion tissue model.ResultsThe results show that with rotation frequency at 60°, the torque Z force increased significantly from 0.023 N mm to 0.118 N mm as the rotation angle increased (p < 0.05). In addition, the torque Z force was significantly increased from 0.082 N mm to 0.292 N mm when the rotation angle increased from 60° to 180° at 0.15 Hz. (p < 0.05). A strong linear positive relationship between the torque Z force and rotation angle or frequency was obtained [Pearson correlation coefficient (r) > 0.88; p < 0.001].ConclusionThe change in needle–tissue interaction force by rotating angles showed a tendency to be higher than those by rotation frequency. Further quantitative research on various manipulations will be required for a standardized education on manipulation and stimulation as well as on needle model development to become possible.

In recent years, many researchers have aimed to construct robotic soft grippers that can handle fragile or unusually shaped objects without causing damage. This study proposes a smart textile-composite actuator and its application to a soft robotic gripper. An active fiber and an inactive fiber are combined together using knitting techniques to manufacture a textile actuator. The active fiber is a shape memory alloy (SMA) that is wire-wrapped with conventional fibers, and the inactive fiber is a knitting yarn. A knitted textile structure is flexible, with an excellent structure retention ability and high compliance, which is suitable for developing soft grippers. A driving source of the actuator is the SMA wire, which deforms under heating due to the shape memory effect. Through experiments, the course-to-wale ratio, the number of bundling SMA wires, and the driving current value needed to achieve the maximum deformation of the actuator were investigated. Three actuators were stitched together to make up each finger of the gripper, and layer placement research was completed to find the fingers’ suitable bending angle for object grasping. Finally, the gripping performance was evaluated through a test of grasping various object shapes, which demonstrated that the gripper could successfully lift flat/spherical/uniquely shaped objects.