The CADIP sensor is going to complete potential measurements of harbor structures cathodically protected with protecting current density measurements. The sensor is based on the measurement of potential gradients generated by the current which is channeled by an isolating tube. The laboratory tests and numerical models of which results are presented enabled the sensor principle to be more deeply understood. They demonstrated that it is interesting to select the tube section as a function of the measured current density level and thus to select the amplification factor while cathodic potential perturbation are limited. These results demonstrated the necessity to control the sensor/structure interface quality to be able to well delimit the measurement area and to prevent underestimated current value. These results enabled the industrial development work of the sensor to be oriented on sensor calibration and on sensor/structure interface quality control.