Ultra-low friction, without lubricants, has been observed in an experiment
at the University of Basel in Switzerland, with interesting implications
for possible nanotech applications.
The dragging of a force microscope tip across the surface atoms of
a sample (size regime of one-billionth meter) is not unlike the motion
of underground tectonic blocks (size scale of tens of thousands of meters):
in both cases the sideways motion of one object past another gets stuck
for a while until sufficient lateral force builds up when motion is
resumed, sometimes with a jerk and a dissipation of energy.
This "stick-slip" syndrome---the main scenario for friction at the
atomic level---can be smoothed somewhat by lubricants, but the new experiment
at Basel shows that if the load (the object on top) is made light enough
it can slide along a surface without any friction (and with no lubricants
present), at least not at a sensitivity level of 10-11 newtons.
According to Enrico Gnecco (41-61-267-3725, email@example.com)
the gliding of a force microscope tip across a sample was observed to
undergo a transition from stick-slip to continuous sliding, and that
this be very useful in the realm of nanoelectromechanical (NEM) devices,
where nano-sleds and nano-containers might be moved around with negligible
dissipation. (Socoliuc et al., Physical
Review Letters, upcoming article; also see lab