Cyborg grasshoppers have been
engineered to sniff out explosives
You can find the original article here.
On the hunt for explosives
Baranidharan Raman/Washington University in St. Louis Move
over, sniffer dogs: now there are explosive-sensing grasshoppers.
Barani Raman and his colleagues at Washington University in Missouri
have tapped into the olfactory senses of the American grasshopper,
Schistocerca americana, to create biological bomb sniffers.
In insects, olfactory receptor neurons
in their antennae detect chemical odours in the air. In turn, these
neurons send electrical signals to a part of the insect brain known as
the antennal lobe. Each grasshopper antenna has approximately 50,000 of
these neurons.
To test bomb-sniffing ability, the team puffed
vapours of different explosive materials onto grasshopper antennae,
including vapours of trinitrotoluene (TNT) and its precursor
2,4-dinitrotoluene (DNT). As controls, they used non-explosives such as
hot air and benzaldehyde, the primary component in the oil of bitter
almonds.
By implanting electrodes into the antennal lobes of
grasshoppers, the researchers found that different groups of neurons
were activated upon exposure to the explosives. They analysed the
electrical signals and were able to tell the explosive vapours apart
from non-explosives, as well as from each other.
The team fitted
grasshoppers with tiny, lightweight sensor backpacks that were able to
record and wirelessly transmit the electrical activity of their
antennal lobes almost instantaneously to a computer.
The
grasshoppers continued to successfully detect explosives up to seven
hours after the researchers implanted the electrodes, before they
became fatigued and ultimately died.
The process immobilised the
grasshoppers, so the researchers put them on a wheeled,
remote-controlled platform to test their ability to sense explosives at
different locations. The grasshoppers were able to detect where the
highest concentration of explosives was when the team moved the
platform to different locations.
The team also tested the effect
of combining sensory information from multiple grasshoppers, given that
in the real world chemicals might be dispersed by environmental
factors, including wind.
Taking neural activity from seven
grasshoppers yielded an average accuracy of detection of 80 per cent,
compared with 60 per cent for a single grasshopper.
The project
was funded by the US Office of Naval Research and the researchers
believe the grasshoppers could be used for homeland security purposes.
A
limitation of the study was that it didn’t test the grasshoppers’
explosives-detecting ability when multiple odours were present at the
same time.
