Design and Batch Microfabrication of a High Precision Conductivity and Temperature Sensor for Marine Measurement

Abstract

Precise meshing and three-dimensional monitoring of the marine environment are very important for marine resources exploration, fishery development, and military activities. Therefore, a high-precision, low power consumption, low-cost and multiparameter integrated miniaturized sensor has been in a large-scale demand. Besides, conductivity and temperature are the basic dynamic parameters of the ocean. This paper presents a high-precision conductivity and temperature (CT) integrated sensor based on the microelectro-mechanical system (MEMS) batch microfabrication technology, which has small size, low cost, high uniformity, and efficiency in meshing and three-dimensional marine measurements. In this study, the miniaturized CT sensor shows excellent linearity of conductivity (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ≥0.99999) and temperature (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ≥0.999) measurements. The temperature sensitivity of the CT sensor is 0.0619 °C/Q, and the cell constant of the CT sensor is 2.559 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . The temperature test also shows the high repeatability with the variance coefficient of 0.6%. Furthermore, it shows an excellent consistency for batch. The coefficient of variance of cell constants is ±0.019 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and the 95% confidence intervals for the conductivity is demonstrated to be ±0.0048 mS/cm. The variance coefficient of the temperature sensor is only 1.8%. The results indicate that the batch microfabricated sensors are suitable for a large-scale deployment in the Marine Internet of Things.