A device (DEV) is disclosed for vibration controlled transient elastography, in particular to quantify liver fibrosis, comprising: an ultrasound probe (1) for elastography comprising a probe casing, at least one ultrasound transducer (US) having a symmetry axis (A), a vibrator (VIB), and a force sensor (FS), wherein the vibrator is arranged to induce a movement of the probe casing along the symmetry axis of the ultrasound transducer, the ultrasound transducer being bound to the probe casing with no motion of the ultrasound transducer relative to the probe casing, and wherein the device comprises a signal generator (9) configured to issue a contact ready signal when the force applied by the probe on the to-be-measured viscoelastic medium is greater than a minimum contact force threshold. The signal generator may further be configured to issue a measurement ready signal when the force is greater than a minimum measurement force threshold.
