Scientists build world’s tiniest engine
Scientists build world’s tiniest engine
Clive Cookson, Science Editor May 2, 2016 8:08 pm
Scientists have developed a microscopic engine, the
smallest in the world, that they say is the first one capable of driving
nanobots, including medical robots that could travel through the body.
The prototype device, known as an actuating
nano-transducer or Ant, combines microscopic gold balls with a special polymer
gel. It generates a propulsive force on a microscopic scale that is a hundred
times greater per unit weight than any known motor or muscle.
“People have been talking about making nanobots for many
years but they do not exist yet,” said Professor Jeremy Baumberg, leader of the
project at Cambridge university. “Why not? Because so far there has been no way
of making them move through liquids — which is like swimming through treacle on
the nanoscale because the molecular forces are so strong.”
He says Ant engines, described for the first time in
Proceedings of the National Academy of Sciences, would provide sufficient
power. “Like real ants they provide large forces for their weight,” he said.
“The challenge we now face is how to control the force for nano-machinery
applications.”
The Ant is powered by physical rather than chemical
reactions. It contains gold nanoparticles, each about 0.06 microns, or a
thousandth of the width of a human hair, in diameter in water with a gel-like
polymer called pNIPAM.
When the temperature is above the critical temperature of
32C, the gold particles are bound tightly together with the polymer through
intermolecular attraction. When it falls below 32C, the polymer suddenly
absorbs water and expands — and the gold particles are pushed rapidly apart
like a spring.
“It’s like an explosion,” said Tao Ding, another member
of the team. “We have hundreds of gold balls flying apart in a millionth of a
second when water molecules inflate the polymers around them.”
The reaction is completely and rapidly reversible,
experiments show. When the temperature rises again, the Ant stores a large
amount of elastic energy in a fraction of a second as the polymer coating
expels water from the gel and contracts around the gold particles. “The whole
process is like a nano-spring,” said Prof Baumberg.
The prototype Ant uses laser light to control the
system’s temperature but other mechanisms could be used instead. The transition
point could also be adjusted, for example to set the energy release point close
to 37C — the human body’s normal temperature.
The Ant might drive a nanobot through a series of piston
strokes, rather like a car engine but on a scale many billions of times
smaller.
“The concept can underpin a plethora of future designs,”
Prof Baumberg said. The team is working with Cambridge Enterprise, the
university’s commercialisation arm, to develop practical applications for the
technology.
Copyright The Financial Times Limited 2016.
Comments
Post a Comment