Nanoelectromechanical systems
Nanoelectromechanical systems will be very tiny machines, with dimensions thousands of times thinner than the human hair, that could be used as motors or sensors. The technology is very new and still in the laboratory stage, but may replace microelectromechanical systems.
Compared to human scale, things work very differently at nano dimensions. For example, attractive forces between materials of the same type may push together moving parts and block a motor.