A Self-Powered and Autonomous Fringing Field Capacitive Sensor Integrated into a Micro Sprinkler Spinner to Measure...

Area of Science:

• Electrical Engineering
• Environmental Science
• Agricultural Technology

Background:

• Accurate soil water content monitoring is crucial for efficient irrigation and crop management.
• Existing sensors often require external power sources, limiting their autonomy and deployment flexibility.
• Developing self-powered, autonomous sensors can revolutionize precision agriculture.

Purpose of the Study:

• To design and fabricate a self-powered, autonomous fringing field capacitive sensor for measuring soil water content.
• To integrate the sensor into a complete irrigation control system powered by energy harvesting.
• To evaluate the sensor's performance, power consumption, and autonomous operation duration.

Main Methods:

• Fabrication of a capacitive sensor using a printed circuit board and porous ceramic.
• Development of a signal conditioning circuit with a triangle wave generator, amplifier, rectifier, and microcontroller.
• Integration with an energy harvesting module (microgenerator on a sprinkler spinner) and a supercapacitor for power storage.
• Testing sensor sensitivity, repeatability, and system's autonomous operational capability.

Main Results:

• The sensor demonstrated a capacitance increase of 5% for a volumetric water content change from 3% to 36%.
• Achieved a sensitivity of 15.5 pF per unity change with a root mean square error of 0.13% for repeatability.
• The system exhibited very low average current consumption (<1.5 μA), enabling energy harvesting.
• The autonomous system operated for approximately 23 days on a single supercapacitor charge.

Conclusions:

• The developed self-powered capacitive sensor is suitable for autonomous soil water content monitoring.
• The integrated energy harvesting system provides a viable solution for long-term, low-power agricultural monitoring.
• This technology holds significant potential for enhancing irrigation efficiency and water resource management in precision agriculture.