The synthetic circulatory system pumps an energy-dense hydraulic liquid that stores energy, transmits force, and actuates the fins of the robotic fish. (Image credit: Cornell University)


Scientists from Cornell University and the University of Pennsylvania have created a synthetic circulatory system of sorts that pumps “blood” capable storing energy, transmitting force, and actuate the fins of a robotic lionfish. Most untethered robots use actuators, gears, batteries, and other single-purpose elements to provide power. Those systems are all segmented components linked together to deliver both power and actuation, while the Scientists synthetic circulatory system is an integrated design inspired by nature.


In a recently released paper titled “Electrolytic vascular systems for energy-dense robots,” the scientists describe how their systems work using a robotic lionfish that provides its own power and propulsion. The blood, or in this case an electrolyte solution, that’s pumped around the system acts as both hydraulic fluid and an energy storage medium.


The robotic lionfish was designed using a silicone outer skin, along with a series of flexible electrodes and an ion separator membrane housed inside allow the fish to bend and flex its body and fins. Actuating those fins are done using interconnected zinc-iodide flow cell batteries to power internal pumps that push the electrolytic solution into an appendage, thus flexing segmented fins.



The initial robotic lionfish prototype provided enough power to swim in an upstream current for more than 36-hours, and its synthetic circulatory system achieved an energy density of about half of a Tesla Model S Lithium-ion battery. The scientists feel their unique system could be used in soft, autonomous aquatic robots that could swim earth’s oceans on various scientific missions, for environmental tasks such as coral reef sampling, or even used to explore different planets that have liquid oceans of their own.      


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