Apparatuses, devices, systems and methods for detecting access disconnection are provided. In one embodiment, a medical fluid system includes (i) a medical fluid machine and (ii) a device operable with the medical fluid machine, the device configured to provide electrical contact with a medical fluid, the device including (a) a tube used during dialysis therapy through which the medical fluid can flow, and (b) a conductive element configured to self-sealingly pierce the tube, the conductive element having a first portion exposed to the medical fluid and a second portion external to the tube.