Manta ray soft robot uses magnetic fields to swim autonomously

Researchers at the National University of Singapore have developed a manta ray-inspired soft robot that uses magnetic fields not only to propel itself but also to enhance the performance of its flexible batteries, enabling autonomous and untethered operation. Traditional flexible batteries often stiffen soft robots or degrade quickly under strain, limiting their autonomy. The team addressed this by encapsulating zinc-manganese dioxide (Zn-MnO₂) batteries in soft silicone and stacking them vertically within the robot’s body, maximizing space and maintaining flexibility. Magnetic fields generated by the robot’s actuators stabilize the battery chemistry, reduce dendrite growth (which can cause short circuits), and maintain energy output after repeated bending, nearly doubling battery life compared to unenhanced samples. The magnetic field improves battery function through two mechanisms: the Lorentz force redirects zinc ion movement to promote uniform deposition and suppress dendrite formation, while alignment of electron spins within the manganese oxide lattice strengthens atomic bonds, preventing crystal degradation. The robot’s fins flap in response to external magnetic