Real Time Sensing of Soil Potassium Levels Using Zinc Oxide-Multiwall Carbon Nanotube-Based Sensors
Akshaya Kumar A., S. K. Naveen Kumar, Terrance Frederick Fernandez
Abstract
There is a significant interest in the detection and monitoring of nutrient levels in agriculture farms. In this article, we report the fabrication of Zinc oxide (ZnO) modified multi-walled Carbon nanotube (F-MWCNT) sensor specifically developed for soil nutrient sensing. A thin layer of Valinomycin membrane was grown on the top of the F-MWCNT/ZnO nanocomposite active layer. The resulting composite structure Al/F-MWCNT/ZnO/Valinomycin was found to have a proportional impedance change with soil Potassium (K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> ) levels. The performance of the sensor was investigated in the 15 kHz range. The impedance magnitude was found to linearly decrease from 2.5±0.23 to 0.63±0.12 MQ range for K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> concentrations from 5 to 25 mM displaying a sensitivity of ~3 MQ/mM with a correlation coefficient (R2) of 0.95744.