Investigation of the stability of thermistor based sensors for high-precision marine temperature measurement

The oceans cover approximately 71 % of the Earth's surface and serve as the largest heat reservoir globally, playing a crucial role in climate regulation. Ocean temperature, as a key hydrological parameter, influences other hydrological measurements and has profound implications for the climate system. Therefore, long-term precise monitoring of seawater temperature is essential. This study proposes a multi-dimensional stability assessment strategy and conducts stability tests on NTC thermistors widely used in marine temperature measurements. The 20 samples tested were sourced from four different manufacturers. The experimental results show that approximately 140 h of annealing treatment significantly reduced the sensor drift rate, allowing the sensors to reach a stable state more quickly. In 240 thermal shock tests, the drift of glass-encapsulated sensors was below 1 mK, while the drift of epoxy-resin-encapsulated sensors remained below 10 mK. In constant temperature environments, sensor drift exhibited a segmented linear pattern, with a faster initial rate that then stabilized. Although calibration methods affected measurement accuracy, they had no significant impact on drift characteristics. Quantitative analysis based on the Arrhenius model indicated that temperature accelerates sensor aging within the range of 10 similar to 35 degrees C, while the influence is minimal below 10 degrees C, with an activation energy of 0.06 eV, only 1/5 of that in the mid-to-high temperature range. This study establishes a systematic experimental framework, providing theoretical support for the selection, pre-treatment, long-term stability assessment, and optimization of high-precision temperature sensors, and offers reliable data assurance for long-term observations in marine and climate research.