Access disconnection systems using conductive contacts

An extracorporeal blood machine includes a blood circuit; an access device enabling the blood circuit to be connected to a patient; first and second coupling devices for connecting to first and second tubes of the circuit; first and second electrodes held by the first and second coupling devices to contact blood flowing through the blood circuit, the electrodes enabling an electrical signal to be injected into the circuit; first and second contact members contacting the first and second electrodes, wherein at least one of the coupling devices includes a stem portion enabling at least one of the first and second contact members to contact at least one of the first and second electrodes, respectively, on an outer portion of the at least one electrode without disturbing blood flowing through the coupling device; and electronics coupled operably to the first and second contact members for applying the electrical signal.