About 3500 years ago, man
invented the wheel to make life easier. Then, thanks to Leonardo Da Vinci's,
the wheel was made smaller to obtain ball bearings. Today we are trying to get
even smaller: scientists are thinking about nano-bearings. In the future we'll
have many nano-machines capable of carrying out the most diverse tasks, for
example transporting medicines inside the human body. In order to save energy,
many of these vehicles will have to able to move efficiently, using as little
energy as possible, and nano-sized ball bearings may help achieve this goal.
Nanomechanical devices will need
tiny devices to reduce friction and make movement possible. Fullerene or buckyballs
(C60 molecule) seemed to be an excellent candidate for nano-bearings.
Scientists thought they could use C60, a hollow carbon nano-sphere as a nano-bearing.
Preliminary studies suggested that C60 molecules suddenly become free to rotate
at a particular temperature, which hopefully has a role in friction. However,
experimental results yielded conflicting results and yet to be verified in
which temperature the friction becomes less.
Simulation has been carried out using
tiny tip of an electron microscope bearing a C60 flake, which was dragged over
a surface also made of C60. It has been found that when the flake was
attached in such a way that it couldn't rotate and the friction did not
decrease, even if the temperature is raised. It's as if the bearings making up
the flake interlocked with the substrate, with no nano-bearing effect. However,
when the flake was free to rotate there was a dramatic drop in friction and the
flake could slide over the surface far more smoothly.
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