Evaluation of Differential Capacitance Technique in LC Resonant-Based Capacitance Sensor for Moisture Content Detection in Paddy Seeds

Controlling the moisture content in paddy seeds during the drying process is crucial to ensure the quality of the seeds. Although the capacitance technique can provide a straightforward moisture content detection based on the change in the seeds' dielectric properties, capacitance drift in the sensing circuit due to the temperature can affect the detection accuracy. In this work, we investigate the capacitance drift of a custom-made LC resonant-based capacitance sensor caused by the temperature from 30 to 70 °C. The capacitance of the sensor's electrodes is simulated using a finite element method, and the sensor is implemented in a printed circuit board. A differential capacitance technique is proposed to mitigate the temperature drift in the capacitance sensor where the capacitance drift is reduced by four times to 4.9 fF/°C. The differential capacitance technique showed a promising approach to enable a simple temperature compensation technique in a paddy seeds' moisture content detection system using the LC resonant-based capacitance sensor.