Soil Moisture Sensors
Yasaman Sadri, Delaram Keshmiri, Sami Abdelghani
Mentor: Fadi Kurdahi
This project focuses on the design and development of a Soil Moisture Sensor using the resistive and
capacitive methods, which can be used as the main component in a smart irrigation system. A semi-cylindrical
shape was used for the design of the capacitor plates in order to maximize the accuracy of the device while
keeping the size reasonably small. The new shape was helpful to maximize the contact with the soil, resulting
in more linearity in the results. The material used in for the plates of the capacitor was aluminum; the thin
aluminum plates were mounted on a PVC pipe. An Arduino UNO and Arduino Pro-Mini was used in this
project serving as a microcontroller to generate the signal and also sending control messages to the
components in the circuit. The ultimate goal of the project was to deliver Soil Moisture Sensor, which can be
used in a smart irrigation system reducing the water consumption level considerably. It was determined that
the capacitive sensor works properly at high frequencies (2–3 MHz range) due to the small capacitance value
of the sensor (pF range). In order to compare the results with another product obtained by other methods, a
resistive soil moisture sensor was designed and developed. The resistive sensor was used to form a complete
system with the ability of displaying results on a portable device, serving as the front end sensor to measure
the soil moisture level.