RIKEN team develops cyborg cockroach

The system, developed by a team at the RIKEN Cluster for Pioneering Research, involves a tiny wireless control module powered by a rechargeable battery attached to a solar cell. According to researchers, ultrathin electronics and flexible materials allow the insects to move freely, aiming to make the use of cyborg insects — part insects, part machine — a practical reality.

The RIKEN team said researchers have been trying to design cyborg insects to help inspect hazardous areas or monitor the environment, but for their use to be practical, handlers must be able to control them remotely for long periods of time. This requires wireless control of their leg segments, powered by a rechargeable battery.

Keeping the battery adequately charged is fundamental, the team said, and whilst it’s possible to build docking stations for recharging the battery, the need to return and recharge could disrupt time-sensitive missions.

Researchers believed the best solution was to include an on-board solar cell that can continuously ensure the battery stays charged. To successfully integrate these devices into a cockroach that has limited surface area required the team to develop 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.

Led by Kenjiro Fukuda, RIKEN CPR, the team experimented with Madagascar cockroaches which are approximately 6cm long. They attached the wireless leg-control module and lithium polymer battery to the top of the insect on the thorax using the specially designed backpack, modelled after the body of a model cockroach.

The researchers said the backpack was 3D printed with an elastic polymer and conformed perfectly to the cockroach’s curved surface, allowing the rigid electronic device to be stably mounted on the thorax for more than a month. The ultrathin 0.004mm thick organic solar cell module was mounted on the dorsal side of the 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 Fukada.

After examining natural cockroach movements, the team realised that the abdomen changes shape and portions of the exoskeleton overlap. To accommodate this, they interleaved adhesive and non-adhesive sections onto the films, which allowed them to bend but also stay attached. When thicker solar cell films were tested, or when the films were uniformly attached, the cockroaches took twice as long to run the same distance, and had difficulty righting themselves when on their backs.

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,” said Fukada.

“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.”

Their research is published in Flexible Electronics.