A method for making remote-controlled cyborg cockroaches has been developed by an international team led by scientists from the RIKEN Cluster for Pioneering Research (CPR). The system includes a small wireless control module powered by a rechargeable battery connected to a solar cell. Despite mechanical tools, insects can move freely thanks to flexible materials and ultra-thin electronics. These developments, published in the academic journal npj Flexible Electronics on September 5, will contribute to the spread of artificial insects.
To help survey danger zones or monitor the environment, scientists are trying to create cyborg bugs, which are part bugs and mostly machines. The ability to remotely control cyborg beetles for a long time is essential for their use to be viable.
This requires controlling the leg sections with a wireless, rechargeable battery. No one wants a team of robot cockroaches running around all of a sudden, so keeping the battery fully charged is crucial. Although docking stations can be built to recharge the battery, the need to return and recharge can hinder tasks that need to be completed on schedule. To ensure that the battery is always charged, the ideal solution is to use a built-in solar cell.
Still easier said than done. To successfully integrate these devices into a cockroach with limited surface area, the research team had to develop a custom backpack, ultra-thin organic solar cell modules, and an adhesion system that keeps the machines attached for long periods of time while still allowing natural movements.
Under the direction of Kenjiro Fukuda of RIKEN CPR, the team conducted research using a 6 cm long Madagascar cockroach. They used a custom-built backpack based on the body of a cockroach model to attach the wireless leg control module and lithium polymer battery to the top of the insect's ribcage. The rigid electronic equipment was able to be securely attached to the rib cage for more than a month, thanks to the elastic polymer backpack that was 3D-printed and perfectly shaped to the curved surface of the cockroach.
An organic solar cell module with a thickness of 0.004 mm was mounted on the dorsal side of his abdomen. Fukuda claims the power output of the 17,2mW body-mounted ultra-thin organic solar cell module is 50 times greater than the power output of the most advanced energy harvesters currently used on live insects.
Freedom of movement was made possible by the ultra-thin and flexible organic solar cell, as well as how it was attached to the insect. When the researchers closely examined the movements of cockroaches in their natural habitat, they discovered that their bellies changed shape and parts of the exoskeleton overlapped. To accommodate this, they sprinkled adhesive and non-adhesive areas on the films and allowed the films to stretch while maintaining their bond. When thicker solar cell films were tested, or when the films were properly adhered, it took the cockroaches twice as long to run the same distance. They also had trouble getting up after falling.
The new cockroach cyborgs were evaluated after these parts were introduced into the beetles, along with cables that stimulated the leg segments. After charging the battery for 30 minutes using simulated sunlight, the animals were encouraged to turn left and right using the wireless remote control.
According to Fukuda, a hybrid electronic system with rigid and flexible elements in the thorax and ultra-soft devices in the abdomen appears to be a viable design for cyborg cockroaches. “Considering the deformation of the chest and abdomen during the basic movement,” he adds. Also, since deformation of the abdomen occurs in other insects such as beetles, or in future flying insects such as cicadas, our approach can be applied to them.