  The nature of dark matter is still an open problem. The simplest assumption
is that gravity is the only force coupled certainly to dark matter and thus the
micro black holes could be a viable candidate. We investigated the possibility
of direct detection of micro black holes with masses around and upward the
Planck scale (10$^{-5}$ g), ensuring classical gravitational treatment of these
objects in the next generation of huge LAr detectors. We show that the signals
(ionization and scintillation) produced in LAr enable the discrimination
between micro black holes or other particles. It is expected that the
trajectories of these micro black holes will appear as crossing the whole
active medium, in any direction, producing uniform ionization and scintillation
on all the path.
