John Faith brings our attention to an item at PhysicsWeb on how to overcome friction in nanosized mechanical devices:
Friction is a big problem in nanosized devices because they have huge surface-to-volume ratios, which means that their surfaces quickly wear out and seize up. Traditional lubricants are useless in such machines because they become thick and sticky when confined in such tiny enclosed spaces. Scientists therefore need to learn how to conquer friction if nano- and microscale devices are ever to become a commercial reality.
See also the summary:
Two independent groups of researchers have taken important steps in overcoming friction in nanosized mechanical devices. A team from the University of Basel in Switzerland has shown that friction between the tip of an atomic-force microscope and a salt crystal can be cut 100-fold by applying a small vibrating force normal to the interface. Meanwhile, another group from the Lawrence Berkeley National Laboratory in California has found a way to control friction in a similar set-up using electric fields.
I’m no expert, but it’s my impression that this problem of nanomachines that “wear out and seize up” may apply less in the case of atomically-precise parts which are designed to mesh and work together. From the book Nanosystems:
Design and analysis have shown, however, that dry bearings with atomically precise surfaces need not suffer these problems. As shown in Chapters 6, 7, and 10, dynamic friction can be low, and both static friction and wear can be made negligible.