Fiber Optic based Localized SPR for Nutrients Detection in Modern Agricultural Applications

Detection of nutrients in the hydroponics system, particularly nitrogen, phosphorus, and potassium (NPK) are critical to ensure the good production of crops. Currently, nutrients are analyzed using spectroscopy and electrochemical techniques, which are tedious and sophisticated. This study was conducted to develop a localized surface plasmon resonance (LSPR) fiber optic sensor technique to measure how much content of these nutrients should be added in the soil to increase crop fertility. The main objectives of this study are to study the LSPR fiber sensor technology on NPK in hydroponic systems, to create a fiber optic sensor technique for measuring NPK in hydroponic systems, and finally to characterize the performance of fiber optic sensors for measuring NPK in hydroponic systems. The utilization of the sensing materials, chitosan in this work is to improve the sensitivity feature of the sensor. Chitosan is coated on the surface of the tapered optical fiber prior to the LSPR NPK detection. The results of the absorption spectra will be visible at the end of the experiment where the obtained data are analyzed using SpectraSuite software. The results show that a good linearity was obtained when used AgNP/chitosan as the sensing material with the sensitivity of 0.041 nm ppm-1 in comparison to that of AgNP with the sensitivity of 0.039 nm ppm-1. A better limit of detection (LOD) and limit of quantification (LOQ) was also observed for AgNP/chitosan which are 35.61 ppm and 107.91 ppm, respectively. Meanwhile, AgNP exhibits LOD and LOQ of 106.16 ppm and 494.43 ppm, respectively. It is expected that this work will be a good contributor to the United Nations Sustainable Development Goals (UN SDG), No. 2: Zero Hunger.