for National Geographic News
At the Bristol Robotics Laboratory in England, researchers are designing their newest bug-eating robotEcobot III.
The device is the latest in a series of small robots to emerge from the lab that are powered by a diet of insects and other biomass.
"We all talk about robots being able to do stuff on their own, being intelligent and autonomous," said lab director Chris Melhuish.
"But the truth of the fact is that without energy, they can't do anything at all."
Most robots today draw that energy from electrical cords, solar panels, or batteries. But in the future some robots will need to operate beyond the reach of power grids, sunlight, or helping human hands.
Melhuish and his colleagues think such release-and-forget robots can satisfy their energy needs the same way wild animals doby foraging for food.
"Animals are the proof that this is possible," he said.
Over the last decade, Melhuish's team has produced a string of bots powered by sugar, rotten apples, or dead flies.
The biomass is converted into electricity through a series of stomachlike microbial fuel cells, or MFCs.
Living batteries, MFCs generate power from colonies of bacteria that release electrons as the microorganisms digest plant and animal matter. (Electricity is simply a flow of electrons.)
The lab's first device, named Slugbot, was an artificial predator that hunted for common garden slugs.
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