Energy Embeded Soft Robot with Advanced Flow Battery

The multifunctionality of energy components in biology allows for both versatility and compactness. For instance, fat in many animals serves as energy storage, insulation, and a structural element. Similarly, multifunctional energy storage can extend the operating time of robots. In this work, we present a liquid energy source that can create a controllable stiff "hydroskeleton" structure for robots. This hydroskeleton can be paired with tendon actuation to achieve fast and efficient motion. We characterize this stiffening method for a generalizable structure and demonstrate its application in a soft robot inspired by marine creatures. We utilize a flow battery in this setup, where the battery electrolyte serves as the fluid in the hydroskeleton, optimizing materials and methods for integrating a flow battery into a soft robot to enhance its lifespan and performance. The power system and actuation work symbiotically: the flow battery powers the motors, which circulate the electrolyte within the robot, providing controllable stiffness to aid in swimming. At the same time, the electrolytic hydraulic fluid increases energy density and reduces system resistance. We demonstrate that flow battery soft robots are particularly competitive in swimming applications and explore further possibilities for multifunctional fluid energy storage in soft robots.