An Integrated Biological Analysis and Flow Rate Sensing for the Real-Time Detection of Carcinogen in Water Based on Co²⁺-Doped Optical Fibers

The multi-parameter measurement has significant meaning for biosensor to enhance their practical sensing performance. For the biological detection, simultaneous measurement of biological molecule and flow rate could improve the accuracy and sensitivity of sensors significantly. In this paper, an integrated biological analysis and flow rate sensing based on Co²⁺ doped tilted fiber Bragg gratings has been proposed and experimentally demonstrated for real-time the detection of the Benzo[a]pyrene molecules. A tilted fiber Bragg grating with a tilted angle of 8° was inscribed into a Co²⁺ doped fiber. The flow rate and Benzo[a]pyrene molecules can be measured simultaneously by interrogating the resonance wavelength of core mode and wavelength interval between the core mode and cladding mode according to the heat exchange and evanescent field of the cladding mode, respectively. Experimental results show that the real-time measurement sensitivities of 12 pm/pM and -0.13 nm/( $\mu \text{L}$ /s) for the Benzo[a]pyrene detection and flow rate were achieved, respectively. Thus the technique appears to have potential applications in chemistry, medicine, and biology.