Creepy experiment uses implanted electrodes to make beetles run faster

Annalee Newitz

Just in case you were craving an army of beetle minions to do your bidding, a group of engineers in Singapore has invented a new kind of "biobot." Fitted out with a microcontroller and electrodes implanted in the muscles of its legs, it's a cyborg beetle that can be made to run faster or slower at the whim of its human master.

Similar kinds of biobots have been built before—the last few years have seen the invention of everything from ratbots to mind-controlled cockroaches—but this is the first variable-speed model. That's because the engineers are directly controlling the insect's leg muscles rather than driving it by manipulating signals in its brain or antennae.

The engineers, who report on their creation in Journal of the Royal Society Interface, admit that there are a few drawbacks to making robots out of living animals. "There are demerits and disadvantages in insect platform due to living organism including limited lifespan, relatively narrow operation temperature range," they write. That said, the team is convinced the good outweighs the bad.

Just from a purely technical perspective, it's much easier to design a biobot that uses an insect body rather than trying to reverse engineer insect motion and write an algorithm that replicates it in a robot. It's more energy-efficient (requiring just a few milliwatts of energy, compared to a few hundred milliwatts required by robots of similar size), and it doesn't require custom sensors. Plus, say the engineers, studying the way its musculature responds to electrical stimulation can teach us about anatomy in general and generate helpful data for other organisms.

They write:

Unlike man-made legged robots for which lots of tiny parts, sensors and actuators are manufactured, assembled and integrated, the insect–computer hybrid robots directly use living insects as nature’s ready-made robot platforms. The only necessary ‘assembly’ or ‘operation’ to create an insect–computer hybrid robot is to mount a miniature radio device and implant thin wire electrodes into appropriate neuromuscular sites of the insect for electrical stimulation to induce desired motor actions and behaviours.

Unlike other engineers experimenting with insect or rodent platforms for biobots, this group decided to improve upon what nature offered them. A great deal of the experiment, in fact, is devoted to optimizing the way beetles walk and run. After implanting male beetles' front two legs with electrodes and attaching them to microcontrollers, the researchers would compare the insects' typical strides with "optimal" ones, forcing the insects to speed up and slow down in response to commands. The engineers gave the insects quick, two-legged gaits they dubbed "gallop" and "tripod." Needless to say, these gaits are ones the beetles would never use under their own volition.

"Walking control with such user-adjustable modes and parameters would improve the agility of the insect–computer hybrid robot towards practical applications," the engineers conclude. Such applications might include anything from highly targeted surveillance to emergency response, where the biobots are sent through the cracks in a collapsed building to find survivors.

The researchers say their next project will be to control all six of the beetle's legs in order to optimize their speed and gait even more. What's intriguing about the researchers' work is that they aren't just steering a lifeform around, but they're actually changing the way its body functions. These biobots have technology that is fully integrated into their muscles; their movements are entirely controlled by machine, though their brains are not. They are the closest thing we have to living marionettes.

Journal of the Royal Society Interface, 2016. DOI: 10.1098/rsif.2016.0060