Robotic platforms inspired or enabled by aquatic organisms have the potential to augment conventional technologies for ocean exploration, enabling a more thorough understanding of the impacts of climate change. We present a biohybrid robotic jellyfish that leverages direct stimulation of live Aurelia aurita jellyfish muscle tissue via implanted microelectronics. We conduct swimming experiments using a 3D-printed passive mechanical attachment to streamline the jellyfish shape and enhance payload capacity. A six-meter-tall, 13,600-liter saltwater facility was constructed to enable testing of the vertical swimming capabilities of the biohybrid robotic jellyfish. We found that the combination of external swimming control and the addition of the mechanical forebody resulted in an increase in swimming speeds to 4.5 times natural jellyfish locomotion while carrying a payload volume of up to 105% of the jellyfish body volume. In order to measure the energy consumption of free-swimming jellyfish in this facility, we developed a physiological method based on laser-scanned, 3D morphological reconstructions of the animal. Computer vision-based feedback control was used to enable continuous swimming against a flow current for 50 hours without encountering the vertical limits of the tank. Changes in animal volume, measured with reconstructions, were converted to energy consumption using the body chemical composition. Free-swimming, electrically stimulated animals were found to consume 2.5 times more energy than similarly stimulated animals in a constrained environment. Simplified drag models could not fully account for the increased energy consumption. Swimmer biomechanics and energetics cannot be fully understood independently of the surrounding flow field. We experimentally investigated the increased energy consumption using three-dimensional, full velocity field Particle Image Velocimetry to simultaneously study wake energy, momentum, and animal biomechanics. We found electrical stimulation increased posterior wake energy loss by a factor of 2.9 compared to unstimulated jellyfish, primarily due to heightened pulse rates. Stimulation was also found to modify swimming biomechanics by reducing total bell margin movement and relaxation duration. Together, these results demonstrate that biohybrid robotic jellyfish can achieve substantial performance enhancements while revealing the hydrodynamic and energetic tradeoffs associated with electrically controlled swimming. This platform offers a scalable and efficient tool for ocean exploration and provides new insight into the fluid dynamics and energetics of jellyfish locomotion.
Simon R. Anuszczyk (Mon,) studied this question.