Research on concentration measurement method of glucose and sodium chloride solutions based on interdigital impedance sensor

Abstract Due to the different electrical properties of glucose and sodium chloride solutions, their concentration measurements often require different sensors. To simultaneously meet the needs of measuring the concentrations of these two types of solutions with different electrical properties, an interdigital capacitive coupling impedance sensor based on the principle of capacitive coupling is proposed. First, the structural design and parameters of the interdigital capacitive coupling impedance sensor are introduced, and an equivalent circuit model of the sensor is established. Through circuit analysis and mathematical derivation, the working principle of the capacitive coupling impedance sensor is revealed. Based on this, an experimental research plan is designed, and the operating frequency of the sensor is determined through impedance spectroscopy analysis. Calibration experiments are then conducted for glucose and sodium chloride solutions, and a measurement model based on impedance parameters is established. Experimental verification shows the feasibility of this measurement method, with the concentration accuracy of both solutions within 10%. To further improve measurement accuracy, a data fusion method is used to determine the optimal parameter model for different solution concentrations, improving the accuracy to within 7% and 4%, respectively. This research preliminarily verifies the feasibility of integrated measurement using interdigital capacitive coupling impedance sensors, providing a new method for measuring the concentrations of solutions with different electrical properties.