Deformation and Locomotion of Untethered Small-Scale Magnetic Soft Robotic Turtle with Programmable Magnetization

Inspired by the way sea turtles rely on the Earth’s magnetic field for navigation and locomotion, a novel magnetic soft robotic turtle with programmable magnetization has been developed and investigated to achieve biomimetic locomotion patterns such as straight-line swimming and turning swimming. The soft robotic turtle (12.50 mm in length and 0.24 g in weight) is integrated with an Ecoflex-based torso and four magnetically programmed acrylic elastomer VHB-based limbs containing samarium-iron–nitrogen particles, and was able to carry a load more than twice its own weight. Similar to the limb locomotion characteristics of sea turtles, the magnetic torque causes the four limbs to mimic sinusoidal bending deformation under the influence of an external magnetic field, so that the turtle swims continuously forward. Significantly, when the bending deformation magnitudes of its left and right limbs differ, the soft robotic turtle switches from straight-line to turning swimming at 6.334 rad/s. Furthermore, the tracking swimming activities of the soft robotic turtle along specific planned paths, such as square-shaped, S-shaped, and double U-shaped maze, is anticipated to be utilized for special detection and targeted drug delivery, among other applications owing to its superior remote directional control ability.