High-Sensitivity SPR Fiber-Optic Biosensor With Nano-Grating Structure for Pathogenic Bacteria Detection in Drinking Water

Drinking water that contains microbiological contamination can lead to the spread of dangerous waterborne diseases, posing a significant risk to human health. It is important to detect and identify microbial pathogens (such as bacteria, fungi, viruses, and parasites) in water accurately to prevent these negative situations. In this work, we have proposed an optical-fiber (OF) surface plasmon resonance (SPR)-based sensor for the detection of pathogenic bacteria that are Bacillus anthracis, Vibrio cholera, Enterococcus faecalis, and Escherichia coli in the drinking water. The finite element method (FEM) is implemented to determine the wavelength sensitivity (WS). The sensor shows excellent performance and can identify the samples externally. The sensor has gold (Au) and gallium nitride (GaN) as the plasmonic sensing layer in nano-grating structures over the surface of the multimode fiber (MMF). It can detect all four bacteria from the drinking water with the highest sensitivity achieved is 21276.6 nm/RIU for E. coli. The performance parameters: detection accuracy (DA), signal-to-noise ratio (SNR), resolution (R), detection limit (DL), quality factor (QF), and figure of merit (FOM), are also evaluated. The results produced by the sensor are superior in comparison to the previously reported biosensors.