This book presents the design and experimental validation of a novel liquid level sensor developed during the PhD work of the author. The sensor has a MIMO (multiple input multiple output) structure that combines multiple electric measurements inside the liquid to obtain several parameters of interest simultaneously, such as the level and the conductivity of the liquid. The sensor uses inverse problem methods that can be easily implemented in current microcontrollers to adjust electric models, developed for several vessel geometries of practical interest, to the measured data. As the algorithms implemented also adjust gain and offset errors automatically, the sensor does not require prior calibration, which makes it robust to temperature changes and instrumentation drifts for a given tank geometry. The novel level sensing system presented would be especially suited for level measurement in industrial applications in which expensive field calibration procedures could be avoided, and also for interface level sensing between insulating media and water, or between liquid conductive layers in environmental monitoring applications.