Cteno‐Bot: An Untethered Metachronally Swimming Robot With Magnetoactive Propulsors

We present an untethered, neutrally buoyant, metachronal swimmer inspired by ctenophores (comb jellies). Meridional rows of individual propulsors, made from magnetoactive elastomers, are actuated from within a rigid body using a spiral magnetic drive shaft. Two helical rows of magnets are rotated underneath the propulsor rows, producing sequential beating patterns (metachronal coordination). Using motion tracking, we explore the relationships between swimming performance and metachronal wave direction. Antiplectic coordination generally improves swimming speed compared to symplectic or synchronous beating. We also find that for this geometric arrangement of magnetically actuated propulsors, increasing the number of propulsors does not increase power requirements. Thus, there is a positive and monotonic relationship between propulsor number and swimming efficiency. While appendage‐level kinematics can still be tuned to enhance swimming performance, our robotic swimmer offers solutions to several engineering challenges. We have demonstrated that a simple actuation mechanism can coordinate hundreds of propulsors beating at a prescribed frequency and phase lag. Furthermore, the propulsors are attached to the robot with a modular sleeve and not directly linked to an actuator, easily maintaining a watertight condition. Future iterations can further investigate the physical/fluid dynamical mechanisms underpinning metachronal swimming while improving the design of bioinspired, meso‐scale, aquatic robots.