Detection of Escherichia coli K12 in Water Using Slot Waveguide in Cascaded Ring Resonator

Abstract

Escherichia coli (E. coli) bacteria can cause serious fatal health problems in human, thus early and quick pathogen detection of these bacteria is a crucial issue in hospitals, food industry, and pharmaceutical companies. Detection of E. coli K12 in drinking water source can be considered of water pollution with sewage that is vitally important in public health service. In this work, a plasmonic slot waveguide from Si3N4-SiO2 is designed and applied in an asymmetric double stage ring resonator (DSRR) for the label free detection of E. coli K12 in drinking water. The performance of DSRR sensor is studied for different concentrations of Nacl and sucrose solutions and a contaminated water sample with E.coli K12 using variational finite-difference time domain (var-FDTD) method. The sensitivity of the DSRR sensor for detection of E. coli K12 in the visible wavelengths is measured to be 461–480 nm/RIU, which leads to the minimum limit of detection (LOD) of 3.33× 10−5. In comparison with the conventional devices and methods for detection of E. coli bacterium, our proposed sensor benefits of microscale size, high resolution sensing, and short time of detection.