Conductivity detection system based on twoelectrode system
                                                                       QI Shengbo, HUANG Lin, YIN Baoan
                                                  (College of Engineering, Ocean University of China, Qingdao 266100, China)

Abstract: Aiming at the wide range signal acquisition and error compensation accuracy in the process of conductivity detection, the AC excitation source, high-precision signal sampling, automatic range switching, software calibration and temperature compensation of the conductivity detection system were researched. The detection circuit of the twoelectrode system was designed based on the principle study of the twoelectrode system. The relationship between the output and input of the conductivity was established by using the precision resistance box, and the temperature compensation model was tested by using the conductivity standard liquid, as well as the conductivity detection system was realized based on the STM32 microcontroller. The experimental results show that the conductivity can be detected in real time, and multiple functions are provided such as automatic range switching, data processing, software calibration, temperature compensation, etc. The relative error of the detection system is less than 0.5%.

Key words: conductivity; two-electrode system; bipolar square wave; software calibration; temperature compensation