Fringing Field Capacitive Sensor: A Study of Different Configurations for Soil Moisture Measurement

Soil moisture plays an important role in the healthy growth of plants and crops. With the advancement of technology, different sensors are being developed for monitoring soil moisture levels. In this research work, interdigitated (IDT) fringing field capacitive sensor of five different configurations viz. 1-1-1, 1-5-1, and square (type A, B, C) were designed and fabricated using printed circuit board (PCB) technology. The designed sensors were evaluated on two different types of soil. A simple capacitance to voltage (C-V) converter circuit using a 555 timer was used and the voltage to soil moisture calibration was done using the standard gravimetric method.