(CN) — To send remote-controlled cyborg cockroaches into hazardous areas, they'll need better backpacks.
First, the international research team led by Kenjiro Fukuda needed a creature big enough to carry such an item. Enter the Madagascar hissing cockroach.
“First, they are one of the biggest roaches in the world,” Fukuda, of Japan’s RIKEN Cluster for Pioneering Research (CPR), said in an email. “The body length reached 5-7 cm (about 2-3 inches). The size is very important to generate larger power using solar cells because area determines the power output. Second, they have a long lifespan up to five years and are relatively resistant to the environment. Third, they do not fly, which makes it easy to control their motion using stimulation wires.”
In their study published Monday in npj Flexible Electronics, the researchers say they designed the backpack with a tiny wireless control module containing a rechargeable battery attached to a solar cell, ultrathin electronics and flexible materials.
According to the study, the handlers need to remotely control the cockroaches for long periods of time, which means keeping the backpack’s battery adequately charged. Otherwise, the team of cyborg cockroaches could run amok — and sending them to a docking station to recharge batteries could disrupt time-sensitive missions. At last, the researchers said the best solution included an on-board solar cell that ensures that the battery stays continuously charged.
Movement posed another problem, since everything from the control modules to the solar cell would need to fit on a surface of about 2 inches.
After realizing the cockroach’s abdomen changes shape and portions of the exoskeleton overlap, the researchers said they 3D-printed the backpack with an elastic polymer. Formed perfectly to the cockroach’s curved surface, the backpack bent and stayed attached because of the interleaving adhesive and nonadhesive sections of film.
“The adhesive can be naturally removed from the part that overlaps with other segments when deformed, and the film exhibits a hollow structure that selectively adheres only to the part that does not overlap,” Fukuda said in the email.
The researchers eventually found a way to integrate all these components. After charging the battery for 30 minutes with pseudo-sunlight, the researchers used the wireless remote control to make the cockroaches turn left and right.
Fukuda felt positive about the results. “Considering the deformation of the thorax and abdomen during basic locomotion, a hybrid electronic system of rigid and flexible elements in the thorax and ultrasoft devices in the abdomen appears to be an effective design for cyborg cockroaches," he wrote.
Still, challenges persist.
When the researchers tested thicker solar films or uniformly attached the films, the cockroaches took twice as long to run the same distance. Also, it was difficult for them to right themselves when on their backs.
For now, Fukuda says the next step is to advance the current system.
“The current system only has a wireless locomotion control system, so it’s not enough to aim [the cockroaches] to inspect hazardous areas or monitor the environment,” Fukuda wrote. “By integrating other required devices such as sensors and cameras, we can use our cyborg insects for such purposes.”
Also, he believes they can expand the backpack to other species.
"Since abdominal deformation is not unique to cockroaches, our strategy can be adapted to other insects like beetles, or perhaps even flying insects like cicadas in the future," he said.
Read the Top 8
Sign up for the Top 8, a roundup of the day's top stories delivered directly to your inbox Monday through Friday.