A team of researchers from the University of Southern California have created a miniscule autonomous robotic beetle, RoBeetle, that can travel for more than two hours without a battery. The 88-milligram, insect-inspired robot runs on liquid methanol, which powers its artificial muscles, and it can carry payloads 2.6 times its own body weight.
As you may know, batteries have low energy density, meaning in order to store lots of energy, they need to be pretty big. That’s a problem for microrobots, and it’s one reason that tiny bots, like Harvard’s penny-sized HAMR-JR, are often tethered to power sources. The fact that RoBeetle doesn’t need a battery means it can be ultra-tiny and crawl around untethered.
The system’s “catalytic artificial micro-muscle” is made with a nickel-titanium (NiTi) shape-memory alloy (SMA), a wire that shrinks and expands with temperature changes. That wire is coated with platinum, and when the platinum interacts with RoBeetle’s methanol fuel, a combustion reaction generates heat. The temperature changes cause a tiny vent to slide back and forth, regulating the fuel flow and causing RoBeetle to propel forward.
The researchers say RoBeetle could allow microbots to go where humans cannot. But as IEEE Spectrum points out, there are still a few challenges to overcome. RoBeetle can only move forward, and once it starts walking, it will keep walking until it runs out of fuel. Still, while other bio-inspired, untethered robots are powered by chemical fuel (Octobot), solar panels (RoboBee) or batteries, RoBeetle is a novel approach.
The researchers published their work in Science Robots this week.