  A minimal observable length is a common feature of theories that aim to merge
quantum physics and gravity. Quantum mechanically, this concept is associated
to a nonzero minimal uncertainty in position measurements, which is encoded in
deformed commutation relations. In spite of increasing theoretical interest,
the subject suffers from the complete lack of dedicated experiments and bounds
to the deformation parameters are roughly extrapolated from indirect
measurements. As recently proposed, low-energy mechanical oscillators could
allow to reveal the effect of a modified commutator. Here we analyze the free
evolution of high quality factor micro- and nano-oscillators, spanning a wide
range of masses around the Planck mass $m_{\mathrm{P}}$ (${\approx
22\,\mu\mathrm{g}}$), and compare it with a model of deformed dynamics.
Previous limits to the parameters quantifying the commutator deformation are
substantially lowered.
