Triple Probe Heat Pulse (TPHP) Soil Moisture Content and Temperature Monitoring Digital System Using Nanomaterials based Sensor Elements for Precision Agriculture

Abstract

I discuss the TPHP soil moisture content and temperature measuring digital system using Indium doped Tin Oxide nanopowder (ITO) electric heater and Nickel manganite (NiMn2O4) nanoceramic powder thermistor as a temperature sensor fabrication, characterization, calibration, and testing. The NiMn2O4 nanoceramic powder is synthesized using the wet chemical method and the ITO nanopowder-based heater is fabricated by a simple fill and press method. The heater, temperature sensor, Atmega328 microcontroller with its software, stainless steel cylindrical tubes, and 3D-printed package are used to fabricate the device. The distance between the heater and the temperature sensor is set to 0.006 m and heat pulse duration is set to 240 s. The heater consumes 3.587W electric power. The temperature sensor can measure the soil temperature up to 50°C. The system is capable of measuring volumetric soil moisture content from 3% to 37% efficiently with a strong correlation coefficient of 0.997 with respect to the standard. The test result shows that there is less than a 2.8% error which is the smallest among the category and the sensitivity of the sensor at volumetric soil moisture content ( θ v ) = 0.28 m 3 m − 3 becomes 3.14 ∘ C per m 3 m − 3 . The developed system is simple to fabricate and operate highly precise, low cost, low power and light in weight.