Selective detection of cadmium ions using plasmonic optical fiber gratings functionalized with bacteria

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Abstract
Environmental monitoring and potable water control are key applications where optical fiber sensing solutions can outperform other technologies. In this work, we report a highly sensitive plasmonic fiber-optic probe that has been developed to determine the concentration of cadmium ions (Cd2+) in solution. This original sensor was fabricated by immobilizing the Acinetobacter sp. around gold-coated tilted fiber Bragg gratings (TFBGs). To this aim, the immobilization conditions of bacteria on the gold-coated optical fiber surface were first experimentally determined. Then, the coated sensors were tested in vitro. The relative intensity of the sensor response experienced a change of 1.1 dB for a Cd2+ concentration increase from 0.1 to 1000 ppb. According to our test procedure, we estimate the experimental limit of detection to be close to 1 ppb. Cadmium ions strongly bind to the sensing surface, so the sensor exhibits a much higher sensitivity to Cd2+ than to other heavy metal ions such as Pb2+, Zn2+ and CrO42− found in contaminated water, which ensures a good selectivity.
Funding Information
  • Fonds De La Recherche Scientifique - FNRS (O001518F)
  • Youth Science Fund Project (61722505)
  • China Scholarship Council (201706060216, 201806780010)
  • Natural Science Foundation of Guangdong Province ((2018B030311006)
  • National Natural Science Foundation of China (61975068)

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