Ultra-Low Friction, Without Lubricants

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, enrico.gnecco@unibas.ch) 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 website.)