Australasian Science: Australia's authority on science since 1938

Robo-Roach Rescue

By Magdeline Lum

A microelectronic controller could soon make cockroaches useful in dangerous search-and-rescue and reconnaissance missions.

Cyborg insects have long been suggested as the next big thing in search-and-rescue as miniaturised electronics are not just becoming economically viable but also more powerful.

The scenario of attaching electronics to insects sent in through the cracks of collapsed rubble to relay information back to would-be rescuers is within reach, but one major barrier to this scenario is building a mechanical insect with the range of natural movement and capability. Instead, Dr Alper Bozkurt and PhD student Tahmid Latif of North Carolina State University used the Madagascar hissing cockroach to see whether insects could be used to perform tasks.

Training insects to do useful work is not a new idea. Wasps, bees and moths have been studied in the past decade to see whether they could be trained to detect minute amounts of chemicals in order to search out explosives and toxic chemicals.

Cockroaches have survived for 250 million years, withstanding drastic climate changes in that time. They have the ability to survive with little or no food for months. This ability to survive makes cockroaches suitable as possible reconnaissance agents in areas considered too dangerous for humans to enter.

Madagascar hissing cockroaches are wingless but they are excellent climbers on rough and smooth surfaces – ideal characteristics for rummaging through debris.

The cockroaches in the study weighed about 20 grams and were able to carry 5 grams, enough for a miniature camera, microphone, gas sensor or other equipment, as well as steering pack.

The steering pack exploits the natural tendency of the cockroach to flee when sensing danger. The antennae of a cockroach detect obstacles in its path, while a pair of hairlike appendages on its underbelly called cerci interprets air movements associated with threats. Cockroaches scurry away when they are detected.

Stainless steel electrodes were surgically implanted inside the antennae and also near the area surrounding the cerci. These electrodes were wired up to a microcontroller mounted on the cockroaches using magnets glued onto their backs along with an off-the-shelf printed circuit board and a wireless transmitter and receiver.

Electrical pulses wirelessly transmitted to the cerci spurred the cockroach forward. Pulses that were sent to the antennae create the illusion of an obstacle, causing the cockroach to turn. Bozkurt and Latif also made sure to prevent neural damage by using the microcontroller to monitor the interface between the current-carrying electrode and tissue. The lithium–polymer battery used to power the steering pack weighed 0.7 grams.

The degree to which the cockroaches changed direction depended on the electrical charge. The greater the electrical charge, the sharper the change in direction. The research duo were able to steer their biobots along a curved line drawn on the floor of their laboratory, although only 10% of the cockroaches were able to complete the journey in two directions.

The researchers observed that even though the Madagascar hissing cockroach is capable of carrying more than 5 grams, the weight of the payload used resulted in the low success of return journeys. They are working on miniaturising the backpack further to gain better control and to improve upon the distance that a cockroach can be manoeuvred.