This Robot Hears Using a Locust’s Severed Ear

The purpose of a microphone is to convert sound into an electrical signal, which can then be amplified, recorded, or analyzed by a computer. A typical microphone is made up of a diaphragm, a magnet, and a coil. When soundwaves moving through the air hit the diaphragm, they cause small vibrations. The vibrating diaphragm moves the magnet slightly, which induces a tiny current in the coil. That current is an electrical signal that matches the original soundwave. Biological ears work in a similar way, but are much more sensitive and efficient. A team of researchers from Tel Aviv University wanted to take advantage of that and built this robot that hears through a locust’s severed ear to accomplish the feat.

That sounds a bit macabre, but locusts are pests. If it makes you feel better, we can just assume this locust died from natural causes before its ear was harvested. Even though the locust itself died, the team had to keep its ear alive in order for it to remain functional. That was their first challenge, which they overcame by building a special apparatus to feed the ear’s tissue with oxygen and nutrients. That was enough to keep it alive for the rest of the process. While the locust’s ear is very sensitive, it also produces an electrical signal that is extremely faint. To make the signal useful, they attached tiny wires to the ear to pick up that electrical signal and amplify it enough to be analyzed by a computer.

At this point, the researchers had what was essentially a sensitive biological microphone. The electrical signal coming from the ear looks a lot like what you’d see coming from a standard microphone, though it is not as granular — likely as a result of the amplification process. While you wouldn’t want to use the locust ear to record your next pop album, it is capable of differentiating between silence and a loud clap. A computer analyzes the electrical signal and looks for the peaks that correspond to claps, then uses those to control a connected robot. If the researchers clap once, the robot moves forward. If they clap twice, the robot moves backward. At this time, there is very little practical reason to go through the trouble of amputating locust ears for use in robots. But this research is important for learning about how to interface biological organs and electronic equipment, as well as how our own sensors can be improved with lessons from nature.