"Lots of experimental robots involve a little bit of cheating. Rather than containing all the necessary electronics and energy sources, they have tethers and wires that provide power and control without weighing the robot down or taking up too much internal space. This is especially true for soft-bodied robots, which typically pump air or fluids to drive their motion. Having to incorporate a power source, pumps, and a reservoir of gas or liquid would significantly increase the weight and complexity of the robot.
A team from Cornell University has now demonstrated a clever twist that cuts down on the weight and density of all of this by figuring out how to get one of the materials to perform two functions. Like other soft robot designs, it pumps a fluid to cause its structure to expand and contract, powering movements. But in this case, the fluid is also the key component of a flow battery that powers the pumps. This allows them to put all the critical components on board their creation."
https://arstechnica.com/science/2019/06/researchers-make-a-robotic-fish-with-a-battery-for-blood/
A team from Cornell University has now demonstrated a clever twist that cuts down on the weight and density of all of this by figuring out how to get one of the materials to perform two functions. Like other soft robot designs, it pumps a fluid to cause its structure to expand and contract, powering movements. But in this case, the fluid is also the key component of a flow battery that powers the pumps. This allows them to put all the critical components on board their creation."
https://arstechnica.com/science/2019/06/researchers-make-a-robotic-fish-with-a-battery-for-blood/