Scientists have made amazing progress lately in turning insects into cyborgs. Almost every week, there's another news story about cyborg insect first responders, or cockroach fuel cells. Soon enough, when someone plants an eavesdropping device in your house, it'll literally be a "bug."
Why do insects make such great candidates to become cyborgs? And what are we learning from cyborg insects that could help design better aircraft, or unlock the secrets of the human brain? We talked to the experts, and found out. Here's our complete guide to cyborg insects.
So why do insects make such great candidates to become cyborgs in the first place? For one thing, they can move with a system of locomotion that's as sophisticated as that of most mammals. "The parallels in the control systems between arthropods and mammals is striking," says biologist Roy Ritzmann at Case Western University. Also, insects have open circulatory systems, and they recover quickly after surgery. But most of all, their locomotive and navigational abilities make them excellent cyborgs — and great templates for us to learn more about locomotion and flight in general.
People have the idea that insects are simple creatures, but Ritzmann says that's just not true. "It's not that insects are simple automatons that we can learn first and then apply to bigger animals." If anything, insects are just as complex and versatile as larger creatures.
So here are five things that we're learning from creating cyborg insects could transform the world we live in:
Before you install machinery on an insect, you'll need a power source for the technology. Why not use the same energy that powers the insect's metabolism? In order for any organism to walk, wriggle, or repair its own cells, it has to transform the food it ingests into molecular energy. And when enzymes in roaches' bodies break down sugar, the final step of the process produces a handy byproduct: electrons.
Researchers at Case Western Reserve University inserted a wire into a cockroach to conduct these electrons and harvest the electricity. Although the cockroaches only produced a tiny current — one ten millionth of the current needed to power a 100-watt lightbulb — it could be gathered to power tiny electronic devices. Further work on storing the energy that cockroaches generate is ongoing, and if successful, could turn insects into live fuel cells.
Large insects like cockroaches are particularly well suited to electrode implantation. As Ritzmann, who contributed to the work, explains to us:
They've got an open circulatory system-the blood is not in high-pressure arteries. If you were to open up the brain of a mouse and try to implant electrodes, you'd have to maintain it on a respirator to maintain circulation to the brain. With a cockroach, if you open up the head capsule and keep it moist, then you can implant these things. Cockroaches will absorb a lot of damage to their nervous systems into their bodies and be able to function well.
In fact, roaches can function so well with their implanted hardware that they typically run away after they wake up from surgery. One spirited bug raced for freedom, jumped up, and broke $300 worth of equipment. Clearly, a living, moving battery isn't any good if it keeps running away. The next step to building a mechanical Frankenbug is to exert control over its motion-particularly if it can fly.
To control cyborg insects, you need to be able to steer their flight — which turns out to have all sorts of applications for aerodynamics in general. For example, it's easier to create a model for a beetle's wings if you can first watch the beetle flapping to a set beat. At Drexel University, Minjun Kim studies fluid mechanics, including how fluid air flows around the wings of a flying insect. In collaboration with Konkuk University in South Korea, he earned an NSF grant to look at the Japanese rhinoceros beetle, or Allomyrina dichotoma.
The grant abstract stated that Kim would conduct
an integrated investigation of the mechanics and control of beetle flight, using Allomyrina dichotoma as a model organism. The objective of the proposed research project is to understand the fundamental scientific principles that elucidate the wing folding/unfolding mechanism and govern the wing-wing interaction between the [forewing] and hind wing of a beetle during free-hovering flight, as well as to demonstrate the enabling technologies necessary to incorporate wing folding/unfolding mechanisms into flapping wing micro aerial vehicles.
To examine these wings and create accurate models, Kim and his collaborators used electrodes to control the beetle. "We have successfully implanted electrodes on the beetle," Kim explains. "Two electrodes were implanted on the left and right optic bulb, one on the central nervous system, and one on the pronotum, the backside of the insect."
By sending an electronic pulse into the beetle's body, Kim could stimulate it to flap its wings at a set frequency. A signal to the probes on the left or right optic nerves forced the beetle to skew left or right. In this video, the beetle flies to the left under the electrodes' influence:
Controlling the flight of this particular beetle also has non-cyborg applications. "They have extraordinary flight capability, such as vertical takeoff and landing," Kim says. If Kim and other researchers can quantify the mechanisms that help the Japanese rhinoceros beetle fly so well, then the Defense Advanced Research projects Agency (DARPA) and the Air Force might be able to reproduce its vertical takeoff and landing in aerial vehicles.
And in addition to reproducing the beetle flight, controlling it could turn the bugs into remote-control spies. Is it realistic to imagine a beetle carrying a tiny camera? Kim thinks so. "Depending on the size of the insect, they could have the load capability. A camera can be embedded as part of the head or body. You can do military surveillance based on wireless communication — that is the project that DARPA is working on these days."
But beetles aren't the only insects to fall under electrical control. A team of scientists from MIT, University of Arizona, and University of Washington successfully implanted a flexible neural probe, or FNP, onto the ventral nerve cord of a Manduca sexta, a tobacco hawkmoth. The probe was bi-directional, which meant that it could both send stimuli to and receive signals from the moth's central nervous system. A wireless signal forced the moth to skew left or right during free flight, while the receiving function let the probe transmit information about the moth's nervous system activity.
The researchers believe that neural probes could have wider applications. In their paper's abstract, they write, "These FNPs present a potent new platform for manipulating and measuring the neural circuitry of insects, and for other nerves in humans and other animals with similar dimensions as the ventral nerve cord of the moth."
"A lot of people have been implanting probes near the muscles controlling the abdomen," Ritzmann says. "If you could tap into the areas of the brain where the animal is making the command determining where it's going to go, you could do this a lot more subtly." Of course, this type of mind control would first require knowledge of how the brain sends these commands.
But one researcher is already exerting a different type of mind control over insects, and learning more about their brains in the process. At the University of Oxford, neuroscientist Gero Miesenbock uses genetic engineering, chemicals, and lasers to modify fruit flies' brains and behavior. After isolating the parts of a fly's brain responsible for certain behaviors, such as jumping, flying, or broadcasting a mating call, Miesenbock engineered flies in which these brain cells would be sensitive to light. Shining a laser at the flies from a distance was enough to stimulate these behaviors. Miesenbock even managed to make female flies enact a male behavior: vibrating one wing to "sing" a mating call.
And Miesenbock's mind control goes deeper than influencing behavior. He has also implanted memories into fruit fly brains. And in the process, he discovered the brain circuit responsible for the flies' memory formation. In order to make fruit flies avoid a certain odor, you could give them a shock every time they were exposed to that scent. The conditioning works because the insects form memories in which the smell is associated with pain. But Miesenbock bypassed this conditioning — instead implanting memories directly into fruit flies' brains.
Miesenbock injected the fly brains with nerve-signaling chemicals, which were programmed to target specific neurons. To prevent the chemicals from activating those neurons too soon, they were contained in a light-sensitive molecular trap. When the scientists exposed the flies to the odor, they shone a laser at the fruit flies, triggering the trap to open and the neurons to activate. If the targeted neurons were those responsible for memory, then they would trick the insects into associating the scent with a shock, despite the fact that there was no pain stimulus. Through educated trial-and-error, Miesenbock's team managed to identify the 12-neuron circuit that creates fly memories, and to implant the false memory of pain.
Better Robots, Stronger Brains
Cyborg insects could have a million uses — but they could also help us design better robots. And they could lead to advances in understanding our own brains.
Search-and-rescue robots find victims in conditions too tough to reach or unsafe for human rescuers, but they also get stuck and cannot extricate themselves. Cockroaches, on the other hand, easily navigate difficult terrain. Future robot designers could learn to borrow that ability.
"We've been spending the last 20 years or so looking at cockroaches trying to get around barriers and recording what's going on," says Ritzmann. "All of our work is geared towards trying to figure out how the nervous system solves these problems." Finding out how a cockroach's nervous system directs its motion tells researchers where to implant electrodes that would control the insect's movement. But it could also lead to smarter robots. "We work with engineers," Ritzmann explains, "who design robotic systems and controllers based on what we find." Robots could traverse a disaster site a lot more effectively if they're programmed to think and move like cockroaches.
And all that work studying insect brains may contain some insight into our own minds. Neural implants, like those that make a beetle flap its wings or a moth turn left on command, could also help the neuroscientists who study human brain diseases. "Many biomedical people study Alzheimer's," says Kim. "The idea is to implant a small semiconductor chip, then introduce a small electrical stimulation on part of the brain."
A 2011 study showed that electrical stimulation reduces the brain shrinkage that occurs in Alzheimer's patients, and improves their symptoms. Better neural implants, Kim claims, could help with this type of treatment. "Based on insect cybernetics, we can further develop this kind of stimulation, and give a high impact on Alzheimer research."
What about Miesenbock's work with fruit flies? While his research improves our understanding of how their brains work, could it also help us understand, and even control, more complex organisms? Not necessarily. After all, fruit fly brains contain far fewer neurons than do human ones. And insect cyborgs don't have to be stepping stones on the way to human ones — they're an end in themselves.