Researchers have controlled the movements of free-flying
insects from afar, as if they were tiny remote-controlled
aircraft.
By connecting electrodes and radio antennas to the nervous
systems of beetles, the researchers were able to make them take
off, dive and turn on command. The cyborg insects were created at
the University of California, Berkeley, by engineers led by
Hirotaka Sato and Michel Maharbiz as part of a programme funded by
the Pentagon's Defence Advanced Research Projects Agency
(DARPA).
The project's goal is to create fully remote-controlled
insectsMovie Camera able to perform tasks such as looking for
survivors after a disaster, or acting as the ultimate spy.
Green beetles
The Berkeley team implanted electrodes into the brain and
muscles of two species: green June beetles called Cotinus texana
from the southern US, and the much larger African species
Mecynorrhina torquata. Both responded to stimulation in much the
same way, but the weight of the electronics and their battery meant
that only Mecynorrhina – which can grow to the size of a human palm
– was strong enough to fly freely under radio control.
A particular series of electrical pulses to the brain causes the
beetle to take off. No further stimulation is needed to maintain
the flight. Though the average length of flights during trials was
just 45 seconds, one lasted for more than 30 minutes. A single
pulse causes a beetle to land again.
The insects' flight can also be directed. Pulses sent to the
brain trigger a descent, on average by 60 centimetres. The beetles
can be steered by stimulating the wing muscle on the opposite side
from the direction they are required to turn, though this works
only three-quarters of the time. After each manoeuvre, the beetles
quickly right themselves and continue flying parallel to the
ground.
Brain insights
Tyson Hedrick, a biomechanist at the University of North
Carolina, Chapel Hill, who was not involved in the research, says
he is surprised at the level of control achieved, because the
controlling impulses were delivered to comparatively large regions
of the insect brain.
Precisely stimulating individual neurons or circuits may harness
the beetles more precisely, he told New Scientist, but don't expect
aerial acrobatics. "It's not entirely clear how much control a
beetle has over its own flight," Hedrick says. "If you've ever seen
a beetle flying in the wild, they're not the most graceful
insects."
The research may be more successful in revealing just how the
brain, nerves and muscles of insects coordinate flight and other
behaviours than at bringing six-legged cyborg spies into service,
Hedrick adds. "It may end up helping biologists more than it will
help DARPA."
Brain-recording backpacks
It's a view echoed by Reid Harrison, an electrical engineer at
the University of Utah, Salt Lake City, who has designed
brain-recording backpacks for insects. "I'm sceptical about their
ability to do surveillance for the following reason: no one has
solved the power issue."
Batteries, solar cells and piezoelectrics that harvest energy
from movement cannot provide enough power to run electrodes and
radio transmitters for very long, Harrison says. "Maybe we'll have
some advances in those technologies in the near future, but based
on what you can get off the shelf now it's not even close."
Journal reference:
Frontiers in Integrative Neuroscience, DOI:
10.3389/neuro.07.024.2009