The first thing to know about the Madagascar hissing cockroach, a black-and-brown invertebrate about as long as your forefinger, is that it lives up to its name. When it feels threatened, it squeaks out a hiss by quickly passing air through holes in its back. The result is something resembling the rattle of a snake's tail. Weird but cool.
The second thing to know about the Madagascar hissing cockroach is that scientists have used it to create insect cyborgs that could one day be used to monitor the environment or help with urban search and rescue missions after a natural disaster. Also weird. Also cool.
In a new study, published Monday in the journal npj Flexible Electronics, an international team of researchers revealed it has engineered a system to remotely control the legs of cockroaches from afar.
The system, which is basically a cockroach backpack wired into the creature's nervous system, has a power output about 50 times higher than previous devices and is built with an ultrathin and flexible solar cell that doesn't hinder the roach's movement. Pressing a button sends a shock to the backpack that tricks the roach into moving a certain direction.
If you're freaked out, let me explain.
Rise of the robo-roach
Cockroach cyborgs are not a new idea. Back in 2012, researchers at North Carolina State University were experimenting with, showing the critters could be remotely controlled to walk along a track.
The way scientists do this is by attaching the backpack and connecting wires to a cockroach's "cerci," two appendages at the end of the abdomen that are basically sensory nerves. One on the left, one on the right. Previous studies have shown electrical impulses to either side can stimulate the roach into moving in that direction, giving researchers some control over locomotion.
But to send and receive signals, you need to power the backpack. You might be able to use a battery but, eventually, a battery will run out of power and the cyborg cockroach will be free to disappear into the leaf litter.
The team at Riken crafted the system to be solar-powered and rechargeable. They attached a battery and stimulation module to the cockroach's thorax (the upper segment of its body). That was the first step. The second step was to make sure the solar cell module would adhere to the cockroach's abdomen, the segmented lower section of its body.
While humans have worked out optimal ways to wear a backpack, it's not quite the same for insects. The segmented nature of a cockroach's abdomen, for instance, provides it with the ability to contort itself or flip itself over should it get into a hairy situation. If you slap a sticky backpack or charging cell on it, you limit its movement and take away its ability to maneuver.
To overcome this, the Riken team tested a number of thin electronic films, subjecting their roaches to a bunch of experiments and watching how the roaches moved depending on the thickness of the film. This helped them decide on a module about 17 times thinner than a human hair. It adhered to the abdomen without greatly limiting the degree of freedom the roaches had and also stuck around for about a month, greatly outlasting previous systems.
Then, the fun part (I assume): Remote control of the insects.
In a series of experiments, the team demonstrated how the system could steer the roach right, as desired, via a wireless system. You can see that above.
And, for now, that's as far as they've got.
"The current system only has a wireless locomotion control system, so it's not enough to prepare an application such as urban rescue," said Kenjiro Fukuda, an expert in flexible electronics at Japan's Riken. "By integrating other required devices such as sensors and cameras, we can use our cyborg insects for such purposes."
Fukuda notes cameras would likely require a lot more power, but there are sensors that use little power that could be integrated into the system today. If cameras were able to be used, they would likely be very low resolution.
Notably, because of the design of the ultrathin solar cell, Fukuda notes it could be applied to other insects -- potentially even creating a flying army of robot insects controlled by human hands. Beetles and cicadas are potential candidates.
Insect robots are having a bit of a moment. In July, researchers at Rice University unveiled their spider "necrobots" -- insect-machine hybrids they used to create the world's creepiest claw machine.
But those spiders were dead. The roaches aren't.
I must admit that when I saw the images of the roboroaches crawling in a certain direction, I felt a weird pang of... guilt. Or something like it, perhaps. I wondered if there was any sort of understanding by the creepy crawlers that their legs are being steered against their own will and whether this process was painful. Fortunately, "according to research related to insects, cockroaches do not experience pain," said Fukuda. Phew.
However, there has been some research in recent years looking at how insects might experience emotive states and discussion about the ethical implications of such research. A recent piece in Undark magazine wrestled with the question of insect pain, too, noting there's still a lack of understanding about insect consciousness.