  Single-file diffusion is a ubiquitous physical process exploited by living
and synthetic systems to exchange molecules with their environment. It is
paramount quantifying the escape time needed for single files of particles to
exit from constraining synthetic channels and biological pores. This quantity
depends on complex cooperative effects, whose predominance can only be
established through a strict comparison between theory and experiments. By
using colloidal particles, optical manipulation, microfluidics, digital
microscopy and theoretical analysis we uncover the self-similar character of
the escape process and provide closed-formula evaluations of the escape time.
We find that the escape time scales inversely with the diffusion coefficient of
the last particle to leave the channel. Importantly, we find that at the
investigated {\bf microscale}, bias forces as tiny as $10^{-15}\;{\rm N}$
determine the magnitude of the escape time by drastically reducing
interparticle collisions. Our findings provide crucial guidelines to optimize
the design of micro- and nano-devices for a variety of applications including
drug delivery, particle filtering and transport in geometrical constrictions.
