Researchers are making robot beetles that ‘run’ on methanol

Researchers at the University of Southern California have created RoBeetle, a tiny 88-milligram robotic insect that contains no electronics but autonomously takes millimeter steps using methanol.

RoBeetle’s body is a reservoir for the methanol. Over its back is a wire that expands with heat and shrinks when cooled. This actuator is made of nickel-titanium alloy and has a platinum coating. The platinum facilitates a reaction of methanol with oxygen in the air, releasing heat. As a result, the temperature of the wire rises from 50 to 100 degrees in a few seconds, describes IEEE Spectrum.

This causes the wire to expand. Subsequently, the pressure on a leaf spring that is connected to the wire temporarily disappears. This sets the beetle’s front legs in motion, causing it to move about a millimeter forward. The ingenious thing about the mechanism is that it also cuts off the supply to the methanol, causing the nickel-titanium wire to shrink and increase the pressure on the leaf spring.

When the wire has crimped, the supply to the methanol is open again, restarting the process. This cycle forms the basis of the movement and the RoBeetle can achieve a speed of 0.76mm / s. It would take about 155 minutes for a full tank of methanol to be used up. The advantage of the robot beetle, according to the makers, is that it does not need a heavy battery for its movement. The disadvantage is that it can only move forward and cannot steer.