Effective impedance electrode (20), (21) are connected to an electrical activity sensor using the voltage (22) of its sensing contact, electric current (23) and active coupler (24). In operation, the anatomical area (13) of patient is connected in response to voltage and current sensing contact (22) and contact (23), the sensor current of electrical activity sensor (21) control directed flow establishes patient of equal value in voltage sensing contact (22) and sensor voltage in active electrode coupler (24) between electrical activity sensor (21) and anatomic region (13), and/or voltage and current sensing contact (22) and contactor (22) 0 of the contact impedance between patient are greater than active electrode impedance in active coupler (22) 1.
