Reproducibility investigation of sensors for analysis of aqueous solutions

The online invesigation of properties of aqueous solutions like water quality or detergent concentration during the washing process requires long-term stability of the sensor and reproducibility of the measurement results. Impedance spectroscopy is a suitable but sensitive measuring principle for fluid analysis. Particularly in the low frequency range, which provides important information on the diffusion properties and the behavior of the ion solution, large variations occur in the measured values. The aims of this work are to determine the frequency range in which the error of the measurement results is not tolerable for the application and to identify the reasons for the errors. These findings are necessary for a meaningful mathematical model of the sensor signal.