Lossy Mode Resonance based Optical Fiber Sensor using Polyvinylpyrrolidone/Chitosan composite for identification of Cadmium ions in water

Abstract

Cadmium (C$\mathrm{d}^{2+}$) is one of the toxic non-essential heavy metal ions that dissolve into the soil via water and bioaccumulate in organisms and ecosystems. Consumption of C$\mathrm{d}^{2+}$ contaminated water for an extended period leads to kidney disease, lung, prostate, and breast cancer. World Health organization (WHO) reports that the permissible level of cadmium is 0.005 mg/L in water. Monitoring the C$\mathrm{d}^{2+}$ ion in water is essential for preserving the environment and preventing any harmful effects it could have on human health. Therefore, we have developed the Lossy Mode Resonance (LMR) based fiber optic sensor to detect C$\mathrm{d}^{2+}$ ions. The sensor probe comprises two layers of tin oxide (SnO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) as the LMR supportive material and polyvinylpyrrolidone (pvp)/Chitosan composite as the reactive layer. The sensor probe is tested with C$\mathrm{d}^{2+}$ ions concentration varies from 50 ppb to 1000 ppb in water. Sensor probe showed three LMR peaks (LMRI, LMR2, and LMR3) in normal water, and all three peaks showed a shift towards the blue region based on C$\mathrm{d}^{2+}$ ion concentration. The sensor responses of the probe in terms of wavelength shift are 2.5%(LMRI), 1.8%(LMR2), and 1.7%(LMR3). The sensitivity of the sensor probe towards C$\mathrm{d}^{2+}$ is 0. 009nm/ppb.