The present disclosure relates to a sensor and a measuring system and a sensor network that incorporate one or more such sensors. An example sensor could be configured to measure a conductivity of a liquid. The sensor includes a first electrode and a second electrode, each electrode having a surface area, wherein the surface area of the electrodes determines a cell constant of the sensor (Kcell), and wherein at least one of the electrodes is provided with a switching means arranged so that the surface area of the respective electrode can be changed, thereby varying the cell constant (Kcell) of the sensor.