Yang and others., Science Robotics 2020
By Charlotte Hartley
Robots tend to be powered by batteries and plug sockets. But the RoBeetle is a little different. This insect-sized microtot (defined as less than 1 gram in weight) runs on methanol, a type of alcohol commonly found in solvents and antifreeze.
Liquid fuels such as methanol hold more energy per unit volume than batteries, especially on a small scale. This means that methanol-powered microbots do not require an additional external power source, such as wire or electromagnetic fields. They could therefore theoretically run with more autonomy than their electrically powered counterparts, while maintaining their minuscule size.
In a new study, researchers designed small artificial muscles that can contract and relax – just like the real thing. The system uses nickel-titanium alloy wires coated in a platinum powder, which accelerates the combustion of methanol vapor. This produces heat, which shortens wire in the robot’s legs and, after cooling, lengthens it again, driving the movement of the RoBeetle.
The RoBeetle weighs only 88 milligrams and can carry objects up to 2.6 times its own weight, the team reported today in Science Robotics. It can carry an extra 95 milligrams of fuel, which allows the robot to stream for a maximum of 2 hours. It is also capable of climbing heights and can navigate surfaces with all sorts of different textures, including glass, a foam slab and a concrete pavement.
Scientists must now figure out how to refuel the robot to keep it continuous over extended periods of time. If they can program the RoBeetle to communicate with its human operator, then methanol-powered microbots could one day act as artificial pollinators to help as complex surgeons.
