Remotely controllable “cyborg” cockroaches with self-charging batteries

⇧ [VIDÉO] You might also like this partner content (after ad)

A team of scientists has succeeded in linking electronic components to the nervous system of Madagascar cockroaches, so as to take control of their movements. This remote guidance is done by stimulating the cerci of the insects (appendages located at the end of their abdomen). This technology could one day be used for urban search and rescue missions, environmental monitoring or inspection of dangerous areas.

This is not the first time that a team has developed such robotic insects. Nevertheless, the devices proposed until now had functionalities and a field of action limited by the energy available. Indeed, remote control involves the use of batteries, which are necessarily of limited volume and weight in view of the size of the insects. One strategy is to return the cyborg insect to a recharge area before its battery runs out, but this approach remains impractical (especially in an emergency context).

An alternative is to add an energy harvesting device directly to the insect, in the form of an enzyme biofuel cell. But the highest output power obtained by this means is 333 μW (microwatts). However, controlling wireless locomotion (like other advanced functions) requires several milliwatts. A Japanese team from RIKEN therefore came up with the idea of ​​using a solar cell — which can generate 10 mW/cm2, even more in sunny conditions. The ultra-thin organic solar module they designed achieved an output power of 17.2 mW.

A device that adapts perfectly to the morphology of the insect

The researchers therefore created remote-controlled cyborg cockroaches, equipped with a wireless control module powered by a rechargeable battery attached to a solar cell. The insects used, Madagascar cockroaches (Gromphadorhina portentosa), can measure up to 6 or 7 centimeters long; the team therefore had to develop a tiny portable device, containing all the necessary components, which would remain securely attached to the insect’s back without impeding its natural movements.

To do this, they used a cockroach model 3D printed with an elastic polymer. Their final product resembles a small backpack, which conforms perfectly to the curved surface of the insect and can remain stable on the thorax for more than a month; it features the wireless control module and the lithium-polymer battery. The ultra-thin (4 µm thick) organic solar cell was mounted on the back of the abdomen; its weight per effective area is about 5 g/m2.

a) Photograph of a cyborg cockroach (scale bar, 10 mm). b) Diagram of the remote control device. c) Diagram of the mounting of rigid components on the thorax using a 3D printed backpack. © Y. Kakei et al.

The flexible materials and ultra-thin electronics used do not impede the movements of the cockroaches at all. To make sure, the scientists looked closely at the natural movements of these insects: it turns out that their abdomens change shape and parts of the exoskeleton overlap during movement. To account for this, they interleaved adhesive and non-adhesive sections on the films of the solar cells — so as to make them both fixed and flexible.

Schematic cross-sectional illustration of abdominal segments with thin films attached using an adhesive-nonadhesive interlacing structure. This allows outward bending of the thin films during deformation of the abdomen. © Y. Kakei et al.

They tested thicker or evenly attached films beforehand, but the cockroaches took twice as long to travel the same distance and had trouble righting themselves when on their backs. ” A combination of ultra-thin film electronics and an adhesive-non-adhesive interlacing structure on the insect’s abdomen has shown a success rate of over 80% in self-righting attempts “, report the researchers in npj flexible electronics.

The addition of sensors and cameras already planned

Thus equipped, the cyborg insects were tested: the battery was charged with simulated sunlight for 30 minutes, and the cockroaches were made to turn left and right using a wireless remote control. Electrical impulses applied to the insect’s cerci — two appendages located at the end of its abdomen, which are sensory nerves — prompt the cockroach to move in one direction or the other.

The device turned out to be fully functional. ” Body-mounted ultra-thin organic solar cell module achieves 17.2mW of power, which is more than 50 times the power output of current living insect energy harvesting devices said Kenjiro Fukuda, who led the team.

The measured power consumption of the wireless locomotion control system was 73.3 mW. The battery (40mAh) lasted about two hours after being fully charged. ” In the current system, most of the power consumption was used in wireless communications. By adjusting the communication intervals, the battery can last longer », underline the researchers in their article.

More upgrades are planned before this army of cyborg cockroaches is ever sent on a mission. Indeed, the current system only has a wireless locomotion control system, which is not sufficient to prepare an application such as urban rescue. ” By integrating other necessary devices, such as sensors and cameras, we can use our cyborg insects for such purposes. Fukuda told CNET. However, these components will require a higher energy input.

Fukuda also pointed out in a statement that the deformed abdomen is not unique to cockroaches, so the strategy may be adapted in the future to other insects like beetles, or possibly even flying insects. like cicadas.

Source: Y. Kakei et al., npj flexible electronics

Leave a Comment