  One core challenge of nanoelectromechanical systems (NEMS) is their efficient
actuation. A promising concept superseding resonant driving is
self-oscillation. Here we demonstrate voltage-sustained self-oscillation of a
nanomechanical charge shuttle. Stable transport at 4.2 K is observed for
billions of shuttling cycles, giving rise to ohmic current-voltage curves with
a sharp dissipation threshold. With only a few nanowatts of input energy the
presented scheme is suitable for operation in the millikelvin regime where
Coulomb blockade-controlled single electron shuttling is anticipated.
