Scientists develop rechargeable cyborg cockroaches

The RIKEN Cluster for Pioneering Research (CPR) researchers have equipped the robotic insects with a tiny wireless control module that is powered by a rechargeable battery attached to a solar cell, allowing the cockroaches to roam freely for long periods of time.

Wireless control of the leg segments has been one of the key challenges scientists have faced when developing cyborg insects. Moreover, in order for the devices to be used for monitoring purposes, it was fundamental that their batteries were long-lasting, to ensure that the cockroaches would be under control at all times. 

The scientists at RIKEN overcame this challenge by fitting their cyborg insect with an ultrathin 0.004mm-thick organic solar cell module, which was mounted on the dorsal side of the insect's abdomen.

“The body-mounted ultrathin organic solar cell module achieves a power output of 17.2mW, which is more than 50 times larger than the power output of current state-of-the-art energy harvesting devices on living insects,” said lead-scientist Kenjiro Fukuda. 

Cockroaches have a limited surface area. Therefore, to successfully integrate these devices into their abdomens, the research team developed a special backpack, ultrathin organic solar cell modules, and an adhesion system that keeps the machinery attached for long periods of time while also allowing natural movements. 

As part of the research process, Fukuda's team experimented with 6cm-long Madagascar cockroaches.

After examining natural cockroach movements, the researchers realised that the abdomen changes shape and portions of the exoskeleton overlap. To accommodate this, they developed an ultrathin and fully-flexible solar cell and interleaved adhesive and non-adhesive sections onto the films, which allowed them to bend but also stay attached. 

They attached the wireless leg-control module and lithium polymer battery to the top of the insect on the thorax using a specially designed backpack, which was modelled after the body of a model cockroach. The backpack was 3D-printed with an elastic polymer and conformed perfectly to the curved surface of the cockroach, allowing the rigid electronic device to be stably mounted on the thorax for more than a month

Once these components were integrated into the cockroaches, along with wires that stimulate the leg segments, the new cyborgs were tested. The battery was charged with pseudo-sunlight for 30 minutes, and animals were made to turn left and right using the wireless remote control.

“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,” Fukuda said. “Moreover, 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.”

The team's findings were reported in the journal npj Flexible Electronics, where the team behind the study expressed the hope that their experiments will help make the use of cyborg insects a practical reality.