TINY robot insects have long been touted as the next big thing in search and rescue. They can rummage through the rubble of a collapsed building, ferret out survivors and relay information about them back using clever electronics. But building a functional mechanical insect capable of the natural range of movement has proved tricky. So Alper Bozkurt and Tahmid Latif of North Carolina University wondered if actual bugs might be cajoled into performing man's bidding in such inhospitable circumstances.
The idea of training insects to do useful work is not wholly new. In 2009 a Pentagon-sponsored project demonstrated a “Cyborg beetle” whose flight was controlled by jolting it with mild electrical charges. Dr Bozkurt himself has experimented with moths, but nudging a gliding insect with biomechanical impulses proved tricky. So he turned to the Madagascar Hissing cockroach.
Cockroaches can withstand drastic climatic change (which is why they have been thriving for 250m years) and can get by on little or no food for months. Although wingless, the Madagascar Hissing variety are excellent climbers, both on rough surfaces like logs and smoother ones like glass. All this makes them ideal candidates for rummaging through asbestos-rich detritus, say. They weigh around 20g and are capable of carrying another 5 grams of payload, enough for a miniature camera, a microphone, a gas sensor or other handy gubbins, in addition to the all-important steering pack.
This works by harnessing its natural tendency to flee on sensing danger, by fiddling with two of cockroaches' vital sensory organs: the antennae, which detect obstacles in its path, and the cerci, a pair of tiny hairlike appendages located on its underbelly which perceive air movements, often associated with threats. An off-the-shelf printed circuit board (PCB), containing a microcontroller, a wireless receiver and a transmitter, is mounted on the insect’s back. The microcontroller is wired to tiny stainless-steel electrodes surgically implanted inside the antennae and near the region surrounding the cerci.
