Design and Fabrication of Seven Electrode Deep-Sea Conductivity Sensor with Thick Platinum Film

Seawater salinity is an indispensable key factor in the analysis of ocean current, heat transport and global water cycle dynamics. An efficient, practical and core technology for indirect salinity estimation is the monitoring of conductivity in the dynamic oceanic environment. This manuscript introduces a tubular seven-electrode conductivity sensor using a robust thick-film platinum construction, specifically tailored for the precise measurement of seawater salinity properties. The principle of the seven-electrode conductivity probe will be studied, with emphasis on the structure, material selection and preparation technology of the conductivity cells. The sensor adopts a thick-film platinum electrode that is sintered at a high temperature, which effectively improves the stability of the sensor. It was observed by scanning electron microscope that the surface of the electrode is porous, which effectively increases the specific surface area and improves the sensitivity. The static testing shows that the conductivity sensor has an accuracy of 0.0029 mS/cm and a stability of 0.003 mS/cm in the measuring range of 0∼70 mS/cm. The results show that the sensor meets the requirements of the Class I CTD specifications for conductivity sensors. The sensor can be used in a deep sea environment of 12,000 metres. Accurate monitoring of the change pattern of conductivity in different depth profiles in the ocean has important scientific research and application value.