What do a worm, a jellyfish and a battery have in common? The answer is in a laboratory at Cornell University, where the modular robots they don't just imitate nature: they surpass it. Here, Energy is not stored in heavy accumulators, but literally flows through the artificial veins of the robots, combining power and movement in a single intelligent fluid. An evolutionary leap that overturns every rule: While traditionally batteries and motors are separate components, these systems merge them into a single dynamic entity, as light as a living organism. And the result? A robotic worm that contracts like a muscle and a jellyfish that dances underwater for 90 minutes without stopping.
The battery that breathes like an organism
“We are the first to use hydraulic fluid as a battery. We reduce weight because energy is needed for both movement and power”
explains Rob Shepherd, professor of aerospace engineering at Cornell, who he illustrated the project. The heart of technology is a redox flow battery (RFB) that mimics biological processes: Two reservoirs of electrolytes (chemically charged liquids) react across a membrane, generating electricity as they mix. But instead of simply producing energy, this fluid is pumped to create hydraulic pressure, activating artificial tendons. A double role which eliminates the need for separate engines, reducing weight and complexity.
For the robotic jellyfish, the system works like a rhythmically “beating” heart: When fluid pushes a tendon, the bell-shaped structure flexes, pushing water. When it relaxes, the robot sinks, ready for a new pulse. 1,5 hours of battery life (a record for soft robots of these dimensions) demonstrate the efficiency of the design.
Modular Robots: The Worm That Conquers the Land
While the robot jellyfish dominates the aquatic environment, the robotic worm faces a more complex challenge: moving on land. It succeeds thanks to modular segments independent: each of these contains a mini-fluid reservoir and a “tendon” actuator. The coordinated expansion and contraction of the modules creates an undulating motion similar to that of earthworms.
The transition from water to land required a radical redesign. Shepherd clarifies: “Underwater, buoyancy supports the body. On land, you need a structure that resists gravity.”. The solution? Rigid but lightweight segments, connected by flexible joints which mimic the hydroskeleton of invertebrates. Each module is autonomous, but communicates with the others via pressure sensors, allowing adaptive movements on uneven terrain.
Artificial Blood and the Future of Robotics
The Cornell team is no stranger to these experiments with modular robots. In 2019 had developed a robotic lionfish, with a “synthetic blood” circulatory system (a concept now evolved into the fluid battery). The difference? Here the fluid is not only a vehicle of energy, but a primary source.
The implications are vast: underwater robots for the environmental monitoring with autonomies of weeks, space probes that exploit local fluids (such as liquid methane on Titan), or lightweight, silent medical exoskeletons. “The modular approach allows the technology to be scaled”, he adds Shepherd. “We can add or remove segments like cells in an organism, depending on the mission.”
Beyond Hydraulics: Another Biomimicry Lesson from Modular Robots
These robots are not just an engineering exercise, but a reflection on life itself. The choice to imitate jellyfish and worms is not accidental: they are simple organisms with efficient movements, ideal models for testing fundamental principles.
“Earth’s evolution began with simple organisms supported by the ground. Our robotic worm follows the same path.”
Observe Shepherd, emphasizing the parallel with the evolutionary transition from fish to amphibians. The lesson? Simplicity precedes complexity, both in biology and robotics. And with “smart” fluids doing the work of metal and silicon, the future of robots could be more liquid (and more alive) than we dare imagine.