Researchers in Canada have created a solar-powered
micro-machine that is no bigger than the period at the end of this sentence.
The tiny machine can carry out basic sensing tasks and can indirectly control
the movement of a swarm of bacteria in the same Petri dish.
On such a small device there is little room for
batteries, sensors or transmitters. So the solar cell on top delivers power, sending
an electric current to both a sensor and a communication circuit. The
communication component sends tiny electromagnetic pulses that are detected by
an external computer.
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The sensor meanwhile detects surrounding pH
levels–the higher the pH concentration, the faster the electromagnetic pulses emitted
by the micro-machine. The external computer uses these signals to direct a
swarm of about 3,000 magnetically-sensitive bacteria, which push the
micro-machine around as it pulses. The bacteria push the micro-machine closer to
the higher pH concentrations and change its direction if it pulses too slowly. This
is more practical than trying to attach the bacteria onto the micro-machines,
says Martel, since the bacteria only have a lifespan of a few hours. “It’s
like having a propulsion engine on demand,” he says.
Martel suggests that micro-machines could one
day be used for medical purposes although there’s still a long way to go.
The video below shows 3,000 bacteria maneuvering
a V-shaped robot around via computer control.
