Taking inspiration from the natural transition of life from water to land, the Organic Robotics Lab and the Archer Group at Cornell Engineering have made an exciting advancement in modular robotics. Their latest creations—robots modeled after worms and jellyfish—embrace a groundbreaking concept known as “embodied energy,” where the energy source is integrated into the robot’s structure. This innovative approach minimizes weight and cost, mirroring the evolutionary shift from aquatic to terrestrial life.

The technology builds upon a 2019 prototype inspired by the lionfish, which utilized a hydraulic fluid system—referred to as “robot blood”—to power devices by circulating energy. This system has been enhanced over time to increase battery capacity and power density, enabling the robots to function in more complex environments. Professor Rob Shepherd explains that the jellyfish robot’s improved capacity allows it to operate longer than its aquatic predecessors, while the worm robot, their first terrestrial model, offers greater freedom of movement without the need for a rigid structure.

The core technology behind these bio-inspired robots is the redox flow battery (RFB), a system in which electrolytic fluids facilitate energy release through redox reactions. Serving as the “beating heart” of the robots, this battery system powers them efficiently and sustainably. The jellyfish robot, in particular, takes advantage of an RFB enhanced by a tendon mechanism. This design allows the robot to alter its shape—ascending when the bell expands and descending as it relaxes—mimicking the jellyfish’s natural propulsion.

Professor Rob Shepherd praises the advances in battery technology driven by Lynden Archer’s team. Their jellyfish robot is equipped with dual redox batteries that use zinc iodide and zinc bromide, with the key addition of graphene. This material prevents dendrite buildup, allowing for smoother and more reliable charging cycles. Furthermore, the addition of bromine in the zinc bromide battery enhances ion transport, which boosts the robot’s power density and operational agility. These improvements have enabled the jellyfish robot to remain active for up to 90 minutes, significantly increasing its speed and efficiency.

The worm robot’s modular design consists of interconnected pods, each containing a motor and tendon actuator. This configuration allows it to alter its shape dynamically, offering a wide range of movements. Lead author Chong-Chan Kim employed a novel dry-adhesion method during the manufacturing process, bonding Nafion separators directly to the robot’s frame. This innovation effectively separates anolytes and catholytes within the robot, optimizing energy distribution and electron flow.

Professor Shepherd also highlights the dual function of the hydraulic fluid in the worm robot, which acts both as a battery and a force provider. This dual-purpose design not only reduces the robot’s weight but also improves its energy efficiency, allowing it to travel longer distances. The worm robot can navigate diverse terrains—from inching across flat surfaces to climbing vertical pipes using a two-anchor crawling method similar to that of a caterpillar. Though not particularly fast—covering 344 feet (105 meters) in 35 hours—the worm robot is quicker than other hydraulically powered counterparts and could be instrumental in exploration tasks, such as pipeline maintenance and repairs.

Both the jellyfish and worm robots represent major steps forward in the development of efficient, energy-dense robots that can perform complex tasks in a variety of environments. Looking ahead, Professor Shepherd envisions integrating high-capacity lithium-polymer batteries into embodied-energy robots with skeletal structures. This evolution of the technology would enhance the robots’ versatility and expand their potential applications in the future.

With these advancements, Cornell Engineering’s work marks a significant leap toward creating more adaptable and sustainable robotics, bringing us closer to robots that can perform a wide range of real-world tasks with energy efficiency at the forefront.

By Impact Lab