A sensor system includes a multi-frequency sensor assembly including a single sensor body housing with a sensing region circuit and a sensor reader disposed in the sensor body. The sensor body is configured to be in operational contact with a fluid. The sensing region circuit is configured to generate different electric fields having different frequencies in the fluid. The sensor reader includes one or more processors configured to examine one or more impedance responses of the sensing region circuit at different frequencies and to determine one or more properties of the fluid based on the one or more impedance responses that are examined.