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No batteries? No problem. These scavenger robots ‘eat’ metal to harvest energy

Energy Harvesting | Y-Prize Competition 2019-2020

Robots have made some pretty major advances in the past few years. However, one thing standing in the way of a science-fiction world in which robots crowd the environment like one of those future war scenes from the Terminator movies is how exactly such robots should be powered. Batteries, which store energy internally, are all well and good but have the issue of being heavy and offering a limited supply. That’s a major hurdle for present robots in real-world environments.

Researchers from the University of Pennsylvania’s School of Engineering and Applied Science may have come up with an answer though: Robots that could recharge by chowing down (in varying degrees) scrap metal as they move about. While that carries the faint whiff of robot cannibalism, it could, as strange as it might sound, result in robots that function more like biological beings.

“The most important thing in this work is that we demonstrate that there are many advantages for electronics and robotics to power themselves by extracting energy from materials in their environment,” James Pikul, assistant professor in the Department of Mechanical Engineering and Applied Mechanics, told Digital Trends. “This approach is similar to the way we humans get energy. We have to eat fuel, breathe oxygen, and drink water. Our device enables the same capability for robots, except they ‘eat’ metal as a fuel, breathe oxygen, and drink water.”

Metal consuming robot
Min Wang

Right now, the team’s prototype doesn’t resemble the form it could eventually take. It is currently a small hydrogel dragged behind a miniature motorized vehicle. With the hydrogel acting as an electrolyte, any metal surface that it comes into contact with acts as the anode of a battery. This lets electrons flow to the cathode and power the connected device. Different metals give the “metal-air scavenger” different energy densities, depending on their individual potential for oxidation. The vehicle also has a small reservoir that provides water to the hydrogel to stop it drying out.

“The ultimate goal is to make robots that can operate for considerably longer periods of time,” Pikul said. “There are some really impressive robots that people are making, especially at the centimeter scale, that have the potential to improve search and rescue, medical treatments, and industrial maintenance. But with today’s lithium-ion batteries they only last for five minutes. At the rate of current lithium-ion battery progress, it will be 16 years before they operate for 15 minutes.”

This approach would mean a robot could recharge by consuming part of a metal surface any time they were close to one (a small robot would need only the top 100 micrometers of a metal object to do so; a larger robot presumably a fair bit more.)

Hey, it certainly sounds a lot less terrifying than that proposal from a few years ago for robots that recharge by munching organic matter!

A paper describing the work was recently published in the journal ACS Energy Letters.

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Luke Dormehl
I'm a UK-based tech writer covering Cool Tech at Digital Trends. I've also written for Fast Company, Wired, the Guardian…
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