A head assembly having a sensor element on the head assembly. Embodiments
of the sensor element are configured to detect non-contact induced
head-media interface instability, "onset of contact" or low level
interference. The non-contact head-media instability or interference is
detected based upon sensor feedback relating to excitation of the air
bearing resonance modes of the slider body. In embodiments of the present
invention, the sensor head assembly includes a microactuator which is
energizable to microactuate the head or transducer elements on the head
assembly.