A measurement device for measuring disruptions in a controlled magnetic field comprising: at least one electrode consisting of a sole conductive element surrounded by the controlled magnetic field generated by the device; a controlled magnetic field sensor connected in a closed loop circuit to the at least one electrode , the sensor comprising: an oscillator comprising an active element, the oscillator being coupled to the at least one electrode , a digital module ; and a processor connected to the digital module ; wherein the oscillator is connected to a transformer (L1, L2) whose secondary winding (L1) is connected to the at least one electrode and whose primary winding (L2) is connected to the active element of the oscillator ; and the oscillator further comprises a polarisation network (R BIAS , V BIAS ) configured to polarise, at least, one input transistor (M IN ) of the active element of the oscillator ; wherein, furthermore, the signal generated by the active element of the oscillator generates a controlled magnetic field in the at least one electrode and this same signal is fed to the input (M IN ) of the active element of the oscillator through a feedback network (R F , C F ); and wherein the same signal that is applied to the input (M IN ) of the active element of the oscillator is processed digitally, in the digital module , such as to be acquired by the processor . at least one electrode consisting of a sole conductive element surrounded by the controlled magnetic field generated by the device; a controlled magnetic field sensor connected in a closed loop circuit to the at least one electrode , the sensor comprising: an oscillator comprising an active element, the oscillator being coupled to the at least one electrode , a digital module ; and a processor connected to the digital module ; wherein the oscillator is connected to a transformer (L1, L2) whose secondary winding (L1) is connected to the at least one electrode and whose primary winding (L2) is connected to the active element of the oscillator ; and the oscillator further comprises a polarisation network (R BIAS , V BIAS ) configured to polarise, at least, one input transistor (M IN ) of the active element of the oscillator ; an oscillator comprising an active element, the oscillator being coupled to the at least one electrode , a digital module ; and a processor connected to the digital module ; wherein the oscillator is connected to a transformer (L1, L2) whose secondary winding (L1) is connected to the at least one electrode and whose primary winding (L2) is connected to the active element of the oscillator ; and the oscillator further comprises a polarisation network (R BIAS , V BIAS ) configured to polarise, at least, one input transistor (M IN ) of the active element of the oscillator ; wherein, furthermore, the signal generated by the active element of the oscillator generates a controlled magnetic field in the at least one electrode and this same signal is fed to the input (M IN ) of the active element of the oscillator through a feedback network (R F , C F ); and wherein the same signal that is applied to the input (M IN ) of the active element of the oscillator is processed digitally, in the digital module , such as to be acquired by the processor . <EOS>