Sensor specifications

Sensor type: Two electrodes sensor Electrode material: Platinum Conductivity cell constant: 1 ± 0.2 cm-1

The conductivity sensor is a two-pole cell whose resistance varies in function of the conductivity of the liquid it is immersed in. That conductivity will be proportional to the conductance of the sensor (the inverse of its resistance), multiplied by the constant cell, in the case of the Libelium sensor around 1cm-1, leading to a value in Siemens per centimeter (S/cm). For an accurate measurement, please take a look at section “Calibration Procedure” in the Smart Water Technical Guide, where the calibration procedure is detailed. To power the conductivity sensor an alternating current circuit has been installed in order to avoid the polarization of the platinum electrodes. This current’s frequency can be set at four different values (100Hz, 1kHz, 10kHz and 100kHz) to adapt the measurement to the optimal operation point, which will be a function of the conductivity of the liquid and the characteristics of the sensor. For the sensor integrated in the Smart Water board, it is recommended to use a 100Hz frequency of conductivities lower than 50μS/cm, 1kHz between 50μS/cm and 5mS/cm, 10kHz between 5mS/cm and 500mS/cm and 100kHz for conductivities higher than 500mS/cm.